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Sample records for tio2 photocatalysts synthesis

  1. Facile synthesis of porous TiO2 photocatalysts using waste sludge as the template

    NASA Astrophysics Data System (ADS)

    Wang, Xiaopeng; Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Yuan, Haiping

    2015-12-01

    A resource utilization method of waste sludge is present by the synthesis of waste sludge templated TiO2 photocatalysts. The organic materials in waste sludge are used as the pore-forming agents, and the transition metals included in the remaining waste sludge through calcination (WSC) can serve as the dopants for the WSC-TiO2 (WSCT) photocatalyst. The visible and UV-visible light driven photocatalytic activities of WSCT are much better compared to those of pure TiO2 and WSC, and it is originated from the higher light absorption property and the efficient electron-hole pair separation provided by waste sludge.

  2. Water-phase strategy for synthesis of TiO2-graphene composites with tunable structure for high performance photocatalysts

    NASA Astrophysics Data System (ADS)

    Hu, Changyuan; Chen, Fei; Lu, Tiewen; Lian, Chengjiang; Zheng, Shizheng; Hu, Quanhong; Duo, Shuwang; Zhang, Rongbin

    2014-10-01

    The controllable synthesis of strongly coupled TiO2/graphene composites has been a long-standing challenge for developing advanced photocatalysts. Here, we report a facile water-phase protocol for synthesis of TiO2-graphene composites using GO aqueous suspension and TiO2 aqueous nanosols as precursors. By controlling the ratio of GO to TiO2, both high-/low-dense TiO2 nanoparticles across graphene and graphene-TiO2-graphene sandwich structured composites are successfully achieved through electrostatic attraction between negatively charged GO nanosheets and positively charged TiO2nanosols. The TiO2-graphene composites show an enhanced photocatalytic activity for the degradation of methylene blue (MB) under UV light. Interestingly, the sandwich structured TiO2-graphene composite exhibits the best photocatalytic activity and the highest photocurrent density, which is 12.2 and 35.46 times as that of pure TiO2, respectively. The outstanding photocatalytic activity of sandwich structured composite is likely due to the following two reasons, two-channel electron conduction path between TiO2 and graphene, as well as the better adsorption capability of MB molecule.

  3. Synthesis and characterization of N-doped TiO2 photocatalysts with tunable response to solar radiation

    NASA Astrophysics Data System (ADS)

    Petala, Athanasia; Tsikritzis, Dimitris; Kollia, Mary; Ladas, Spyridon; Kennou, Stella; Kondarides, Dimitris I.

    2014-06-01

    Modification of the electronic structure of wide band gap semiconductors by anion doping is an effective strategy for the development of photocatalytic materials operating under solar light irradiation. In the present work, nitrogen-doped TiO2 photocatalysts of variable dopant content were synthesized by annealing a sol-gel derived TiO2 powder under flowing ammonia at temperatures in the range of 450-800 °C, and their physicochemical and optical properties were compared to those of undoped TiO2 samples calcined in air. Results show that materials synthesized at T = 450-600 °C contain relatively small amounts of dopant atoms and their colour varies from pale yellow to dark green due to the creation of localized states above the valence band of TiO2 and the formation of oxygen vacancies. Treatment with NH3 at T > 600 °C results in phase transformation of anatase to rutile, in a significant decrease of the specific surface area and in formation of TiN at the surface of the TiO2 particles. The resulting dark grey (T = 700 °C) and black (T = 800 °C) materials display strong absorption in both the visible and NIR regions, originating from partial reduction of TiO2 and formation of Ti3+ defect states. The present synthesis method enables tailoring of the electronic structure of the semiconductor and could be used for the development of solar light-responsive photocatalysts for photo(electro)chemical applications.

  4. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    NASA Astrophysics Data System (ADS)

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-01

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03537f

  5. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-01

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products. PMID:26400095

  6. Synthesis of N-doped TiO2 Using Guanidine Nitrate: An Excellent Visible Light Photocatalyst

    EPA Science Inventory

    An excellent visible light active nitrogen-rich TiO2 photocatalyst have been synthesized by using guanidine nitrate as the doping material. The catalytic efficiency of the catalyst has been demonstrated by the decomposition of the dye, methyl orange (MO), and the pollutant, 2,4 d...

  7. Synthesis of C–N–Y tri-doped TiO2 photo-catalyst for MO degradation and characterization

    NASA Astrophysics Data System (ADS)

    Hoseinian-Maleki, F.; Nemati, A.; Joya, Yasir F.

    2015-10-01

    In this research C–N–Y tri-doped TiO2 nanopowders were synthesized by the sol–gel method. The C–N–Y TiO2 photo-catalyst was prepared using hexamine and yttrium nitrate Hexahydrate as the dopant precursors. Methyl-orange (MO) was used to study the photocatalytic performance of the doped TiO2 under UV irradiation. The synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, Transmission electron microscopy, Photoluminescence and Field emission scanning electron microscopy. The tri-doped sample with 8% N, 0.4% Y and 1.5% C exhibited enhanced photocatalytic efficiencies. After 100 min of irradiation with UV light, 87% of MO was decomposed by C–N–Y tri-doped TiO2 sample. It is suggested that the co-activity of C and N could make the intra-gap localized states above the valence band of TiO2, and carbon in TiO2 structure causes carbonate species to appear. These carbonate species acted as photosensitizer on the TiO2 surface to promote photo-catalytic activity of the as synthesized sample.

  8. Synthesis of N-doped nano TiO2 using guanidine nitrate: an excellent visible light photocatalyst.

    PubMed

    Baruwati, Babita; Varma, Rajender S

    2011-03-01

    An excellent visible light active nitrogen-rich TiO2 nanocatalyst has been synthesized by using guanidine nitrate as the nitrogen source. The catalytic efficiency of the catalyst has been demonstrated by the decomposition of the dye, methyl orange (MO), and the pollutant, 2,4 dichlorophenol (DCP), under common household lightbulbs as well as sunlight. The reactions proceed faster on exposure to solar light (less than 1 h for MO and 4 h for DCP) compared with the commercial light bulbs (3 h for MO and 6 h for DCP). The catalyst could be used up to five times without loss of activity and regenerated for further use just by washing and drying at 200 degrees C. PMID:21449345

  9. SURFACTANT TEMPLATED SOL-GEL SYNTHESIS OF MESOPOROUS TIO2 PHOTOCATALYSTS AND THEIR APPLICATION IN THE DESTRUCTION OF CYANOBACTERIAL TOXINS

    EPA Science Inventory

    In the symposium, we will present the synthesis and properties of the mesoporous TIO2 films and membranes and fundamental and systematic study on the decomposition pathway of such biological toxins.

  10. Photocatalytic oxidation of diethyl sulfide vapor over TiO2-based composite photocatalysts.

    PubMed

    Selishchev, Dmitry; Kozlov, Denis

    2014-01-01

    Composite TiO2/activated carbon (TiO2/AC) and TiO2/SiO2 photocatalysts with TiO2 contents in the 10 to 80 wt. % range were synthesized by the TiOSO4 thermal hydrolysis method and characterized by AES, BET, X-ray diffraction and FT-IR ATR methods. All TiO2 samples were in the anatase form, with a primary crystallite size of about 11 nm. The photocatalytic activities of the TiO2/AC and TiO2/SiO2 samples were tested in the gas-phase photocatalytic oxidation (PCO) reaction of diethyl sulfide (DES) vapor in a static reactor by the FT-IR in situ method. Acetaldehyde, formic acid, ethylene and SO2 were registered as the intermediate products which finally were completely oxidized to the final oxidation products - H2O, CO2, CO and SO42- ions. The influence of the support on the kinetics of DES PCO and on the TiO2/AC and TiO2/SiO2 samples' stability during three long-term DES PCO cycles was investigated. The highest PCO rate was observed for TiO2/SiO2 photocatalysts. To evaluate the activity of photocatalysts the turnover frequency values (TOF) were calculated for three photocatalysts (TiO2, TiO2/AC and TiO2/SiO2) for the same amount of mineralized DES. It was demonstrated that the TOF value for composite TiO2/SiO2 photocatalysts was 3.5 times higher than for pure TiO2. PMID:25532841

  11. TiO2 single crystal with four-truncated-bipyramid morphology as an efficient photocatalyst for hydrogen production.

    PubMed

    Zhang, Kai; Liu, Qian; Wang, Hui; Zhang, Rubo; Wu, Chunhui; Gong, Jian Ru

    2013-07-22

    Diverse titanium dioxide (TiO2 ) nanostructures have attracted much attention recently due to their potential application in photocatalytic and photovoltaic fields. Here, the synthesis of a TiO2 single crystal with a novel four-truncated-bipyramid morphology is reported for the first time, produced by a simple hydrothermal method. Both peroxo titanic acid precursor and hydrofluoric acid capping agent are essential for the formation of this unique morphology. Moreover, the as-prepared TiO2 photocatalyst exhibits excellent hydrogen production activity from an ethanol-water solution, which is attributed to exposure of both high-energy {001} oxidative and low-energy {101} reductive facets in an optimal ratio. The current findings will contribute greatly to development of more novel photocatalysts with controllable microscopic structures for hydrogen production. PMID:23780924

  12. One-dimensional mesoporous Fe2O3@TiO2 core-shell nanocomposites: Rational design, synthesis and application as high-performance photocatalyst in visible and UV light region

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Xie, Yaping; Chen, Haoxin; Guo, Jinxue; Meng, Alan; Li, Chunfang

    2014-10-01

    An ideal photocatalyst for degradation of organic pollutants should combine the features of efficient visible light response, fast electron transport, high electron-hole separation efficiency, and large specific surface area. However, these requirements usually cannot be achieved simultaneously in the present state-of-the-art research. In this work, we develop a rational synthesis strategy for the preparation of one-dimensional (1D) mesoporous Fe2O3@TiO2 core-shell composites. In this strategy, FeOOH nanorods are firstly coated by TiO2 shell, followed by a calcination process. The as-prepared composites are thoroughly investigated with X-ray powder diffraction, scanning electron microscope, energy dispersive spectroscopy, transmission electron microscope, N2 adsorption-desorption isotherms, UV-visible diffuse-reflectance spectra, and photoluminescence spectra. Endowed with the advantages of its composition and specific structural features, the presented sample possesses the combined advantages mentioned above, thus delivering evidently enhanced photocatalytic activity for the degradation of methyl orange under UV light irradiation and Rhodamine B under visible light irradiation. And the possible mechanism of the enhanced photocatalytic performance is proposed.

  13. Self-cleaning properties of cement plates loaded with N,C-modified TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Janus, Magdalena; Zatorska, Justyna; Czy?ewski, Adam; Bubacz, Kamila; Kusiak-Nejman, Ewelina; Morawski, Antoni W.

    2015-03-01

    The photocatalytic activity of cement pastes containing nitrogen and carbon co-modified TiO2 photocatalysts (TiO2-N,C) were evaluated trough the degradation of model organic water contaminate (Reactive Red 198) under UV-vis light source. It was found that cement plates containing TiO2-N,C photocatalysts exhibited higher photocatalytic efficiency than those containing unmodified TiO2.

  14. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    PubMed

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  15. Controllable Synthesis and Tunable Photocatalytic Properties of Ti3+-doped TiO2

    PubMed Central

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  16. Stable semiconductor black phosphorus (BP)@titanium dioxide (TiO2) hybrid photocatalysts

    PubMed Central

    Uk Lee, Hyun; Lee, Soon Chang; Won, Jonghan; Son, Byung-Chul; Choi, Saehae; Kim, Yooseok; Park, So Young; Kim, Hee-Sik; Lee, Young-Chul; Lee, Jouhahn

    2015-01-01

    Over the past few decades, two-dimensional (2D) and layered materials have emerged as new fields. Due to the zero-band-gap nature of graphene and the low photocatalytic performance of MoS2, more advanced semiconducting 2D materials have been prompted. As a result, semiconductor black phosphorus (BP) is a derived cutting-edge post-graphene contender for nanoelectrical application, because of its direct-band-gap nature. For the first time, we report on robust BP@TiO2 hybrid photocatalysts offering enhanced photocatalytic performance under light irradiation in environmental and biomedical fields, with negligible affected on temperature and pH conditions, as compared with MoS2@TiO2 prepared by the identical synthesis method. Remarkably, in contrast to pure few layered BP, which, due to its intrinsic sensitivity to oxygen and humidity was readily dissolved after just several uses, the BP@TiO2 hybrid photocatalysts showed a ~92% photocatalytic activity after 15 runs. Thus, metal-oxide-stabilized BP photocatalysts can be practically applied as a promising alternative to graphene and MoS2. PMID:25732720

  17. Stable semiconductor black phosphorus (BP)@titanium dioxide (TiO2) hybrid photocatalysts.

    PubMed

    Lee, Hyun Uk; Lee, Soon Chang; Won, Jonghan; Son, Byung-Chul; Choi, Saehae; Kim, Yooseok; Park, So Young; Kim, Hee-Sik; Lee, Young-Chul; Lee, Jouhahn

    2015-01-01

    Over the past few decades, two-dimensional (2D) and layered materials have emerged as new fields. Due to the zero-band-gap nature of graphene and the low photocatalytic performance of MoS2, more advanced semiconducting 2D materials have been prompted. As a result, semiconductor black phosphorus (BP) is a derived cutting-edge post-graphene contender for nanoelectrical application, because of its direct-band-gap nature. For the first time, we report on robust BP@TiO2 hybrid photocatalysts offering enhanced photocatalytic performance under light irradiation in environmental and biomedical fields, with negligible affected on temperature and pH conditions, as compared with MoS2@TiO2 prepared by the identical synthesis method. Remarkably, in contrast to pure few layered BP, which, due to its intrinsic sensitivity to oxygen and humidity was readily dissolved after just several uses, the BP@TiO2 hybrid photocatalysts showed a ~92% photocatalytic activity after 15 runs. Thus, metal-oxide-stabilized BP photocatalysts can be practically applied as a promising alternative to graphene and MoS2. PMID:25732720

  18. Solvothermal synthesis of stable nanoporous polymeric bases-crystalline TiO2 nanocomposites: visible light active and efficient photocatalysts for water treatment

    NASA Astrophysics Data System (ADS)

    Liu, Fujian; Kong, Weiping; Wang, Liang; Noshadi, Iman; Zhang, Zhonghua; Qi, Chenze

    2015-02-01

    Visible light active and stable nanoporous polymeric base-crystalline TiO2 nanocomposites were solvothermally synthesized from in situ copolymerization of divinylbenzene (DVB) with 1-vinylimidazolate (VI) or 4-vinylpyridine (Py) in the presence of tetrabutyl titanate without the use of any other additives (PDVB-VI-TiO2-x, PDVB-Py-TiO2-x, where x stands for the molar ratio of TiO2 to VI or Py), which showed excellent activity with respect to catalyzing the degradation of organic pollutants of p-nitrophenol (PNP) and rhodamine-B (RhB). TEM and SEM images show that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x have abundant nanopores, and TiO2 nanocrystals with a high degree of crystallinity were homogeneously embedded in the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x, forming a stable ‘brick-and-mortar’ nanostructure. PDVB-VI and PDVB-Py supports act as the glue linking TiO2 nanocrystals to form nanopores and constraining the agglomeration of TiO2 nanocrystals. XPS spectra show evidence of unique interactions between TiO2 and basic sites in these samples. UV diffuse reflectance shows that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x exhibit a unique response to visible light. Catalytic tests show that the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were active in catalyzing the degradation of PNP and RhB organic pollutants under visible light irradiation. The enhanced activities of the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were ascribed to synergistic effects between abundant nanopores and the unique optical adsorption of visible light in the samples.

  19. Hydrogenated TiO2 nanobelts as highly efficient photocatalytic organic dye degradation and hydrogen evolution photocatalyst.

    PubMed

    Tian, Jian; Leng, Yanhua; Cui, Hongzhi; Liu, Hong

    2015-12-15

    TiO2 nanobelts have gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Here we report the facile synthesis of hydrogenated TiO2 (H-TiO2) nanobelts, which exhibit excellent UV and visible photocatalytic decomposing of methyl orange (MO) and water splitting for hydrogen production. The improved photocatalytic property can be attributed to the Ti(3+) ions and oxygen vacancies in TiO2 nanobelts created by hydrogenation. Ti(3+) ions and oxygen vacancies can enhance visible light absorption, promote charge carrier trapping, and hinder the photogenerated electron-hole recombination. This work offers a simple strategy for the fabrication of a wide solar spectrum of active photocatalysts, which possesses significant potential for more efficient photodegradation, photocatalytic water splitting, and enhanced solar cells using sunlight as light source. PMID:26118828

  20. Synthesis and characterization of Fe3O4/TiO2 magnetic and photocatalyst bifunctional core-shell with superparamagnetic performance

    NASA Astrophysics Data System (ADS)

    Behrad, F.; Helmi Rashid Farimani, M.; Shahtahmasebi, N.; Rezaee Roknabadi, M.; Karimipour, M.

    2015-07-01

    In this research a simple method has been presented to coat magnetic nanoparticles with TiO2. Firstly, Fe3O4 nanoparticles have been prepared using a co-precipitation method. Thereafter, in order to achieve particles with better dispersibility, the surface of Fe3O4 nanoparticles has been modified with the help of trisodium citrate as stabilizer. Afterward, Fe3O4 / TiO2 core-shell nanocomposites were synthesized by the Stöber method. The prepared samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray spectroscopy (EDS) analysis and vibrating sample magnetometer (VSM). XRD results show the formation of two compounds of crystalline magnetite and brookite-type TiO2 . TEM images confirmed the formation of their core-shell structure. The surface modification of magnetite nanoparticles using trisodium citrate was confirmed by FTIR analysis. Magnetic studies also indicated that prepared core-shells exhibit superparamagnetic behavior at room temperature. Combining this property with the photocatalytic ability of TiO2 could result in a synthesized nanocomposite with different medical and environmental applications.

  1. Photooxidative desulfurization for diesel using Fe / N - TiO2 photocatalyst

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Saqib; Kait, Chong Fai; Mutalib, Mohd Ibrahim Abdul

    2014-10-01

    A series of N - TiO2 with different mol% N was synthesized via sol-gel method and characterized using thermal gravimetric analyzer and raman spectroscopy. 0.2 wt% Fe was incorporated onto the calcined (200°C) N - TiO2 followed by calcination at 200°C, 250°C and 300°C. Photooxidative desulfurization was conducted in the presence of 0.2wt% Fe / N - TiO2 with different mol% N with and without oxidant (H2O2). Oxidative desulfurization was only achieved when H2O2 was used while without H2O2 no major effect on the sulfur removal. 0.2Fe -30N - H2O2 photocatalysts showed best performance at all calcination temperatures as compared to other mol% N - H2O2 photocatalysts. 16.45% sulfur removal was achieved using photocatalysts calcined at 300 °C.

  2. Layered silicate as an excellent partner of a TiO2 photocatalyst for efficient and selective green fine-chemical synthesis.

    PubMed

    Ide, Yusuke; Torii, Masato; Sano, Tsuneji

    2013-08-14

    When the partial oxidation of benzene to phenol, which is one of the most important reactions in chemical industry, was conducted using TiO2 in the presence of a phenol-philic adsorbent derived from a layered silicate, phenol was recovered in unprecedentedly high yield and purity. This resulted from the fact that the adsorbent captured the generated phenol promptly, selectively, and effectively to prevent the overoxidation, after which the captured phenol could be easily eluted. PMID:23902420

  3. Parameters affecting the photocatalytic degradation of dyes using TiO2-based photocatalysts: a review.

    PubMed

    Akpan, U G; Hameed, B H

    2009-10-30

    This paper presents the review of the effects of operating parameters on the photocatalytic degradation of textile dyes using TiO2-based photocatalysts. It further examines various methods used in the preparations of the considered photocatalysts. The findings revealed that various parameters, such as the initial pH of the solution to be degraded, oxidizing agents, temperature at which the catalysts must be calcined, dopant(s) content and catalyst loading exert their individual influence on the photocatalytic degradation of any dye in wastewaters. It was also found out that sol-gel method is widely used in the production of TiO2-based photocatalysts because of the advantage derived from its ability to synthesize nanosized crystallized powder of the photocatalysts of high purity at relatively low temperature. PMID:19505759

  4. Improvement of Ultrasonic Disinfection Power Using TiO2 Photocatalyst

    NASA Astrophysics Data System (ADS)

    Dadjour, Mahmoud Farshbaf; Ogino, Chiaki; Matsumura, Susumu; Nakamura, Shinichi; Shimizu, Nobuaki

    2005-03-01

    The disinfection power of an ultrasonic system was enhanced using TiO2-photocatalyst in the irradiating solutions. Cultures of Legionella were used in the irradiation system with and without TiO2. A significant decrease in the concentration of viable cells was observed during irradiation in the presence of TiO2. The rate of cell killing was higher in the presence of TiO2 than it was with Al2O3, and was proportional to the amount of TiO2 used in the irradiating samples. There was no significant effect of cell concentration on the rate of cell killing in the range of 103 to 107 CFU/ml. Addition of OH radical scavengers such as glutathione, ascorbic acid and histidine to the irradiating solutions reduced the rate of disinfection, thus indicating the primary role of OH radicals in this process.

  5. Thickness dependent activity of nanostructured TiO 2/?-Fe 2O 3 photocatalyst thin films

    NASA Astrophysics Data System (ADS)

    Akhavan, O.

    2010-12-01

    The effect of thickness of TiO 2 coating on synergistic photocatalytic activity of TiO 2 (anatase)/?-Fe 2O 3/glass thin films as photocatalysts for degradation of Escherichia coli bacteria in a low-concentration H 2O 2 solution and under visible light irradiation was investigated. Nanograined ?-Fe 2O 3 films with optical band-gap of 2.06 eV were fabricated by post-annealing of thermal evaporated iron oxide thin films at 400 °C in air. Increase in thickness of the Fe 2O 3 thin film (here, up to 200 nm) resulted in a slight reduction of the optical band-gap energy and an increase in the photoinactivation of the bacteria. Sol-gel TiO 2 coatings were deposited on the ?-Fe 2O 3 (200 nm)/glass films, and then, they were annealed at 400 °C in air for crystallization of the TiO 2 and formation of TiO 2/Fe 2O 3 heterojunction. For the TiO 2 coatings with thicknesses ?50 nm, the antibacterial activity of the TiO 2/?-Fe 2O 3 (200 nm) was found to be better than the activity of the bare ?-Fe 2O 3 film. The optimum thickness of the TiO 2 coating was found to be 10 nm, resulting in about 70 and 250% improvement in visible light photo-induced antibacterial activity of the TiO 2/?-Fe 2O 3 thin film as compared to the corresponding activity of the bare ?-Fe 2O 3 and TiO 2 thin films, respectively. The improvement in the photoinactivation of bacteria on surface of TiO 2/?-Fe 2O 3 was assigned to formation of Ti-O-Fe bond at the interface.

  6. Nanostructured TiO2 photocatalysts for the determination of organic pollutants.

    PubMed

    Qiu, Jingxia; Zhang, Shanqing; Zhao, Huijun

    2012-04-15

    Owing to the inherent advantages of nanostructured TiO(2) photocatalysts, including high photocatalytic activity, strong oxidation power, low cost, environmental benignity and excellent stability, TiO(2) photocatalyts have recently attracted extensive attention from scientific researchers, technology developers and investors for use in sensing applications. The TiO(2) sensors can be used for lab-based analyses, on-line and on-site determination of organic pollutants in wastewater. This work reviews the application of TiO(2) nanomaterials in photocatalytic and photoelectrocatalytic monitoring of aggregative organic parameters such as total organic carbon (TOC) and chemical oxygen demand (COD), as well as individual organic compounds in aqueous solution. PMID:22133353

  7. TiO2 impregnated graphene nanostructures: An effectual photocatalysts for water remediation application

    NASA Astrophysics Data System (ADS)

    Rakkesh, R. Ajay; Durgalakshmi, D.; Balakumar, S.

    2015-06-01

    In this work, we describe the fabrication of nanohybrid TiO2 impregnated Graphene nanostructures by modified Hummer's method. The chemically impregnated TiO2-Graphene hybrid nanostructures drastically enhanced their photodegradation activity of methylene blue (MB) dye in an aqueous medium compare to pure TiO2 nanoparticles. The enhancement in the photocatalytic activity was ascribed by a heterojunction between TiO2-Graphene interfaces. It remarkably decreased the recombination rate and likewise increased the number of holes participating in the photodegradation process, confirmed by XPS analysis. This study can provide a new insight for constructing the hybrid photocatalysts, which can be used in environmental pollution and water treatment applications.

  8. Study on nanomagnets supported TiO2 photocatalysts prepared by a sol-gel process in reverse microemulsion combining with solvent-thermal technique.

    PubMed

    Li, Hansheng; Zhang, Yaping; Wang, Shiying; Wu, Qin; Liu, Changhao

    2009-09-30

    A sol-gel process in reverse microemulsion combined with solvent-thermal technique was developed for synthesizing a series of nanomagnets supported TiO(2) (TiO(2)/NMs) photocatalysts in this study. The structure of TiO(2)/NMs photocatalysts was characterized by Fourier transform infrared (FTIR), TG-DSC, X-ray diffraction (XRD), Raman spectrometry, TEM, BET, and VSM. The influence of CoFe(2)O(4) dosage on the photocatalytic activity and magnetism of TiO(2)/NMs photocatalysts was investigated. The results showed that nanosized anatase TiO(2) were uniformly coated on spinel CoFe(2)O(4) in the prepared TiO(2)/NMs photocatalysts. They possessed typical ferromagnetic hysteresis and performed better photocatalytic activity in degradation of methylene blue than TiO(2) prepared by the same method. The existence of CoFe(2)O(4) nanomagnets played an important role on the crystalline grain size of TiO(2) and the specific surface area of the prepared TiO(2)/NMs photocatalysts, thus had an important influence on its photocatalytic performance and magnetism. The photocatalytic performance of TiO(2)/NMs photocatalysts is related to their specific surface area, crystalline grain sizes of TiO(2) and particle size, as well as the doping effect of Fe(3+). The highest photocatalytic activity in degradation of methylene blue for TiO(2)/NMs photocatalysts at the CoFe(2)O(4) content of 20wt.% was achieved, with k(p) 28.32% higher than that of pure TiO(2) photocatalyst. Moreover, the experiments on recycled use of TiO(2)/NMs photocatalyst demonstrated a good repeatability of the photocatalytic activity. PMID:19443114

  9. Hydrogenation of Nano-Structured TiO2 Photocatalyst Through an Electrochemical Method.

    PubMed

    He, Ke Feng; Xu, En Ni; Liu, Yong; Chen, Wan Ping

    2015-01-01

    Nano-structured photocatalyst P25 was electrochemically hydrogenated through being immersed in 0.01 M NaOH solution to act as cathode to electrolyze water. With its color changed from white to bluish, its absorption in visible light range was obviously enhanced after the treatment, and its solar-driven photocatalytic activity was significantly improved for photo-degradation of methylene blue and rhodamine B. XPS spectra analyses were conducted and the photocurrent was measured, which indicate the formation of Ti3+ and oxygen vacancies, and increased separation efficiency of photoactivated electrons and holes in electrochemically hydrogenated P25. These changes are proposed responsible for the improved photocatalytic activity of P25. Electrochemical hydrogenation has been proven a facile and effective method for improving the photocatalytic activity of nano-structured TiO2 photocatalyst. PMID:26328349

  10. Preparation and Performances of RuO2/TiO2 Films Photocatalyst Supported on Float Pearls

    NASA Astrophysics Data System (ADS)

    Yao, Bing-hua; Wang, Li-ming; Wang, Cheng; Wang, Yi-xun; Zhao, Gao-yang

    2007-12-01

    RuO2/TiO2 films were deposited on float pearls (FP) by the sol-gel-dipping method. The substrates were coated with RuO2/TiO2 precursor sol, air-dried at 120°C and further heated at 500°C to obtain the coupled photocatalyst of RuO2/TiO2 films supported on FP (RuO2/TiO2/FP). The structure of coupled photocatalyst was characterized by SEM, XRD, and FT-IR technique, respectively. The results showed TiO2 has anatase structure and doped RuO2 was highly dispersed on the surface of TiO2 particles as amorphous. The average thickness of RuO2/TiO2 films (3 layers) on FP was determined to be about 1 ?m. This study was carried out under the following conditions: volume 60 mL, initial concentration of beta-cypermethrin (BEC) 45 mg/L, pH 6.5, amount of RuO2/TiO2/PF 5 g/L, air flow rate 200 mL/min, reaction time 60 min. The degradation rates of BEC are 88.1% (125 W Hg lamp), 82.8% (8 W UV lamp), and 75.1% (8 W solar lamp), respectively. The photocatalytic degradation of BEC was experimentally demonstrated to follow the Langmuir-Hinshelwood kinetic model, and the reaction rate constant (17.5 mg/(L min)) and the adsorption constant (3.486 L/g) were determined, respectively. It was also found that the RuO2/TiO2/FP photocatalyst has significantly the visible light photoactivity for degradation of BEC.

  11. Quick and Facile Preparation of Visible light-Driven TiO2 Photocatalyst with High Absorption and Photocatalytic Activity

    PubMed Central

    Yang, Yucheng; Zhang, Ting; Le, Ling; Ruan, Xuefeng; Fang, Pengfei; Pan, Chunxu; Xiong, Rui; Shi, Jing; Wei, Jianhong

    2014-01-01

    Self-doping TiO2 has recently attracted considerable attention for its high photocatalytic activity under visible-light irradiation. However, the literature reported synthetic methods until now were very time-consuming. In this study, we establish a quick and facile method for obtaining self-doping TiO2 with the use of directly treated commercial P25 at a desired temperature for only 5?min through spark plasma sintering technology. With the using of this method, the modified P25 samples exhibit significantly high photoelectric and photocatalytic performance. Furthermore, the sample prepared at 600°C exhibits the optimum catalytic activity. The photodegradation and H2 evolution rates of this samples are significantly higher than those of unmodified P25 sample under visible-light irradiation. The physical origin of the visible-light absorption for the modified P25 samples is investigated in detail according to their structural, optical, and electronic properties. This work will provide a quick and facile method for the large-scale synthesis of visible-light driven photocatalyst for practical applications. PMID:25391987

  12. Quick and facile preparation of visible light-driven TiO2 photocatalyst with high absorption and photocatalytic activity.

    PubMed

    Yang, Yucheng; Zhang, Ting; Le, Ling; Ruan, Xuefeng; Fang, Pengfei; Pan, Chunxu; Xiong, Rui; Shi, Jing; Wei, Jianhong

    2014-01-01

    Self-doping TiO2 has recently attracted considerable attention for its high photocatalytic activity under visible-light irradiation. However, the literature reported synthetic methods until now were very time-consuming. In this study, we establish a quick and facile method for obtaining self-doping TiO2 with the use of directly treated commercial P25 at a desired temperature for only 5 min through spark plasma sintering technology. With the using of this method, the modified P25 samples exhibit significantly high photoelectric and photocatalytic performance. Furthermore, the sample prepared at 600 °C exhibits the optimum catalytic activity. The photodegradation and H2 evolution rates of this samples are significantly higher than those of unmodified P25 sample under visible-light irradiation. The physical origin of the visible-light absorption for the modified P25 samples is investigated in detail according to their structural, optical, and electronic properties. This work will provide a quick and facile method for the large-scale synthesis of visible-light driven photocatalyst for practical applications. PMID:25391987

  13. Influence of Ag-Au microstructure on the photoelectrocatalytic performance of TiO2 nanotube array photocatalysts.

    PubMed

    Wang, Qingyao; Wang, Xiaotong; Zhang, Miao; Li, Guihua; Gao, Shanmin; Li, Mingyang; Zhang, Yiqing

    2016-02-01

    In this work, vertically-aligned TiO2 nanotube arrays (TiO2 NTs) were grown on Ti substrates via a facile electrochemical anodization method followed by calcinations. Then, Ag-Au alloy nanoparticles and Ag@Au core-shell nanoparticles were deposited on the obtained TiO2 NTs via UV reduction and displacement reaction, respectively. X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that Ag-Au alloy nanoparticles and Ag@Au core-shell nanoparticles grew uniformly on the walls of TiO2 NTs. Investigation results from removal of methyl orange (MO) and Cr(IV) ions indicated that the as-prepared bimetal plasmonic photocatalysts exhibited excellent photoelectrocatalytic (PEC) activities. The influences of Ag-Au alloy and core-shell microstructures on PEC properties of TiO2 NTs were investigated and the TiO2 NTs/Ag@Au photocatalyst showed more outstanding PEC removal efficiency than that of TiO2 NTs/Ag-Au due to the regular core-shell microstructure and low recombination of photogenerated electrons and holes. PMID:26555961

  14. Polyaniline nanotubes coated with TiO2&?-Fe2O3@graphene oxide as a novel and effective visible light photocatalyst for removal of rhodamine B from water

    NASA Astrophysics Data System (ADS)

    Ghavami, Monireh; Kassaee, Mohammad Zaman; Mohammadi, Reza; Koohi, Maryam; Haerizadeh, Bibi Narjes

    2014-12-01

    Synthesis of polyaniline-nanotubes (PANI-NT), in the presence of TiO2 and ?-Fe2O3 functionalized graphene oxide (GO), gives a green and magnetically recyclable photocatalyst, TiO2&?-Fe2O3@GO/PANI-NT. The later orchestrates 94% photocatalytic efficiency in removal of rhodamine B (RB) from water, under simulated solar light irradiation. This is far higher than the 36% observed in the presence of TiO2&?-Fe2O3@GO alone, where PANI-NT is excluded from the structure. Morphology, composition, and structural properties of our economically sound photocatalyst are characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, thermo-gravimetric, transmission electron microscopy, inductively coupled plasma, RAMAN and Fourier-transform infrared spectroscopy.

  15. Preparation and photocatalytic activity of B, Ce Co-doped TiO2 hollow fibers photocatalyst

    NASA Astrophysics Data System (ADS)

    Qiu, Jingping; Sun, Xiaogang; Xing, Jun; Liu, Xiaobo

    2014-07-01

    A series of B, Ce co-doped TiO2 (B, Ce-TiO2) photocatalytic materials with a hollow fiber structure were successfully prepared by template method using boric acid, ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500°C in an N2 atmosphere for 2 h. Scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption measurements, and UV-visible spectroscopy (UV-Vis) were employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photocatalytic performance of the samples was studied by photodegradation phenol in water under UV light irradiation. The results showed that the TiO2 fiber materials have hollow structures, and the fiber structure materials showed better photocatalytic properties for the degradation of phenol than pure TiO2 under UV light. In the experiment condition, the photocatalytic activity of B, Ce co-doped TiO2 fibers was optimal of all the prepared samples. In addition, the possibility of cyclic usage of B, Ce co-doped TiO2 fiber photocatalyst was also confirmed, the photocatalytic activity of TiO2 fibers remained above 90% of that of the fresh sample after being used four times. The material was easily removed by centrifugal separation from the medium. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

  16. A highly efficient TiO2@ZnO n-p-n heterojunction nanorod photocatalyst

    NASA Astrophysics Data System (ADS)

    Lin, Lin; Yang, Yingchao; Men, Long; Wang, Xin; He, Dannong; Chai, Yuchao; Zhao, Bin; Ghoshroy, Soumitra; Tang, Qunwei

    2012-12-01

    Shell@core-nanostructured TiO2@ZnO n-p-n heterojunction nanorods with diameter of 30 nm were successfully fabricated via a hydrothermal method. The photodegradation rate of the TiO2@ZnO n-p-n nanorods evaluated by photodegrading methyl orange has been demonstrated to increase three times compared to that of wurtzite hexagonal ZnO. Anatase TiO2 and Ti2O3 grow along ZnO crystal lattices, which forms p-type Zn2+ doped Ti2O3 in the interface of TiO2/ZnO and therefore numerous n-p-n heterojunctions owing to the substitution of Ti3+ by Zn2+. Under the drive of inner electric field, the photogenerated electrons are both injected to the conduction band of Zn2+ doped Ti2O3 from conduction bands of ZnO and TiO2, which efficiently enhances the separation of photogenerated electron-hole pairs and accelerates the transport of charges. The results suggest that TiO2@ZnO n-p-n heterojunction nanorods are very promising for enhancing the photocatalytic activity of photocatalysts.

  17. Preparation, characterization and visible light photocatalytic activity of silver, nitrogen co-doped TiO2 photocatalyst

    NASA Astrophysics Data System (ADS)

    Khan, Matiullah; Ramin Gul, Sahar; Li, Jing; Cao, Wenbin; Mamalis, Athanasios G.

    2015-06-01

    TiO2 photocatalyst codoped with Silver (Ag) and Nitrogen (N) with different Ag doping concentrations is successfully synthesized by hydrothermal method. The as-synthesized samples are characterized through x-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-vis. absorption spectra and x-ray photoelectron spectroscopy (XPS). The photocatalytic response is evaluated by the photodegradation of methylene blue under visible light irradiations. All synthesized samples are composed of pure anatase phase with good crystallinity. The absorption edge of codoped TiO2 is shifted towards visible light region. X-ray photoelectron spectroscopy confirmed the existence of silver and nitrogen in the codoped samples. All the codoped samples demonstrated improved photocatalytic activity compared to pure TiO2. Among the different codoped samples, the one with silver doping concentration of 4 at. % exhibited the highest photoactivity.

  18. Self-Cleaning Effect of Solid Immersion Lens Using Photocatalyst TiO2 Film for Near-Field Recording

    NASA Astrophysics Data System (ADS)

    Hong, Hyun-Guk; Kim, Young-Joo

    2008-07-01

    A novel approach using the self-cleaning effect of photocatalyst TiO2 film was proposed and studied experimentally to solve the critical contamination issues in solid immersion lens (SIL) based near-field recording (NFR). To evaluate the feasibility of the self-cleaning approach, the surface of a hemispherical (half-ball) SIL and a glass disk were coated with TiO2 film which constituted the final layer of an antireflection (AR) coating for better optical transmittance. The hydrophilic property of the TiO2-coated SIL and disk was confirmed by the contact angle measurement with deionized water after thermal treatment to form an anatase structure and by the irradiation of UV light. To determine the effectiveness of the self-cleaning effect, a removal test was conducted with different contaminants such as a fingerprint and laser toner particles. The effects of the wavelength and intensity of UV light were tested over a range of irradiation times. The air flow during the rotation of the disk was also helpful for removing the contaminants. From the experimental results, it was confirmed that the self-cleaning effect of photocatalyst TiO2 film is very effective for removing organic contaminants from the surfaces of an SIL and disk, which means that this approach can be applied to SIL-based NFR systems.

  19. Rapid destruction of the rhodamine B using TiO2 photocatalyst in the liquid phase plasma

    PubMed Central

    2013-01-01

    Background Rhodamine B (RhB) is widely used as a colorant in textiles and food stuffs, and is also a well-known water tracer fluorescent. It is harmful to human beings and animals, and causes irritation of the skin, eyes and respiratory tract. The carcinogenicity, reproductive and developmental toxicity, neurotoxicity and chronic toxicity toward humans and animals have been experimentally proven. RhB cannot be effectively removed by biological treatment due to the slow kinetics. Therefore, RhB is chosen as a model pollutant for liquid phase plasma (LPP) treatment in the present investigation. Results This paper presents experimental results for the bleaching of RhB from aqueous solutions in the presence of TiO2 photocatalyst with LPP system. Properties of generated plasma were investigated by optical emission spectroscopy methods. The results of electrical-discharge degradation of RhB showed that the decomposition rate increased with the applied voltage, pulse width, and frequency. The oxygen gas addition to reactant solution increases the degradation rate by active oxygen species. The RhB decomposition rate was shown to increase with the TiO2 particle dosage. Conclusion This work presents the conclusions on the photocatalytic oxidation of RhB, as a function of plasma conditions, oxygen gas bubbling as well as TiO2 particle dosage. We knew that using the liquid phase plasma system with TiO2 photocatalyst at high speed we could remove the organic matter in the water. PMID:24041151

  20. High-Throughput Synthesis and Screening of Titania-Based Photocatalysts.

    PubMed

    Nursam, Natalita M; Wang, Xingdong; Caruso, Rachel A

    2015-10-12

    Titanium dioxide is widely known as a prominent photocatalyst material and research in this area has increased substantially over the last decades. However, the photoactivity of TiO2 is hindered by several factors, such as a relatively high photogenerated electron-hole recombination rate and a wide bandgap of ?3.2 eV, rendering it inactive under visible light. Approaches to optimize the TiO2 photocatalyst, either by altering its morphological or chemical properties, have been conducted for many years, yet further modification of this semiconductor has the potential to yield photocatalysts with excellent properties and higher photocatalytic activity. This could be effectively explored using combinatorial synthesis coupled with high-throughput characterization approaches. Such an approach has been widely applied for the discovery of new functional materials, including photocatalysts. By using high-throughput synthesis and characterization technology, preparation and screening of materials on small sample scales can be accelerated; hence, new TiO2-based photocatalysts with enhanced photocatalytic activity can be acquired more rapidly. Additionally, the large database of materials being systematically examined will greatly build our fundamental understanding of the relation between materials structure/composition and photocatalytic activity. This review details various high-throughput syntheses and characterization techniques applied to improve the photocatalytic properties of TiO2 materials and discuss several challenges that have been raised or may be encountered in the future when using this approach. PMID:26371558

  1. Reduced graphene oxide and Ag wrapped TiO2 photocatalyst for enhanced visible light photocatalysis

    NASA Astrophysics Data System (ADS)

    Leong, Kah Hon; Sim, Lan Ching; Bahnemann, Detlef; Jang, Min; Ibrahim, Shaliza; Saravanan, Pichiah

    2015-10-01

    A well-organised reduced graphene oxide (RGO) and silver (Ag) wrapped TiO2 nano-hybrid was successfully achieved through a facile and easy route. The inherent characteristics of the synthesized RGO-Ag/TiO2 were revealed through crystalline phase, morphology, chemical composition, Raman scattering, UV-visible absorption, and photoluminescence analyses. The adopted synthesis route significantly controlled the uniform formation of silver nanoparticles and contributed for the absorption of light in the visible spectrum through localized surface plasmon resonance effects. The wrapped RGO nanosheets triggered the electron mobility and promoted visible light shift towards red spectrum. The accomplishment of synergised effect of RGO and Ag well degraded Bisphenol A under visible light irradiation with a removal efficiency of 61.9%.

  2. Investigation of TiO2 photocatalyst performance for decolorization in the presence of hydrodynamic cavitation as hybrid AOP.

    PubMed

    Bethi, Bhaskar; Sonawane, S H; Rohit, G S; Holkar, C R; Pinjari, D V; Bhanvase, B A; Pandit, A B

    2016-01-01

    In this article, an acoustic cavitation engineered novel approach for the synthesis of TiO2, cerium and Fe doped TiO2 nanophotocatalysts is reported. The prepared TiO2, cerium and Fe doped TiO2 nanophotocatalysts were characterized by XRD and TEM analysis to evaluate its structure and morphology. Photo catalytic performance of undoped TiO2 catalyst was investigated for the decolorization of crystal violet dye in aqueous solution at pH of 6.5 in the presence of hydro dynamic cavitation. Effect of catalyst doping with Fe and Ce was also studied for the decolorization of crystal violet dye. The results shows that, 0.8% of Fe-doped TiO2 exhibits maximum photocatalytic activity in the decolorization study of crystal violet dye due to the presence of Fe in the TiO2 and it may acts as a fenton reagent. Kinetic studies have also been reported for the hybrid AOP (HAOP) that followed the pseudo first-order reaction kinetics. PMID:26384894

  3. The Use of Nanoscale Visible Light-Responsive Photocatalyst TiO2-Pt for the Elimination of Soil-Borne Pathogens

    PubMed Central

    Chen, Ya-Lei; Chen, Yao-Shen; Chan, Hao; Tseng, Yao-Hsuan; Yang, Shu-Ru; Tsai, Hsin-Ying; Liu, Hong-Yi; Sun, Der-Shan; Chang, Hsin-Hou

    2012-01-01

    Exposure to the soil-borne pathogens Burkholderia pseudomallei and Burkholderia cenocepacia can lead to severe infections and even mortality. These pathogens exhibit a high resistance to antibiotic treatments. In addition, no licensed vaccine is currently available. A nanoscale platinum-containing titania photocatalyst (TiO2-Pt) has been shown to have a superior visible light-responsive photocatalytic ability to degrade chemical contaminants like nitrogen oxides. The antibacterial activity of the catalyst and its potential use in soil pathogen control were evaluated. Using the plating method, we found that TiO2-Pt exerts superior antibacterial performance against Escherichia coli compared to other commercially available and laboratory prepared ultraviolet/visible light-responsive titania photocatalysts. TiO2-Pt-mediated photocatalysis also affectively eliminates the soil-borne bacteria B. pseudomallei and B. cenocepacia. An air pouch infection mouse model further revealed that TiO2-Pt-mediated photocatalysis could reduce the pathogenicity of both strains of bacteria. Unexpectedly, water containing up to 10% w/v dissolved soil particles did not reduce the antibacterial potency of TiO2-Pt, suggesting that the TiO2-Pt photocatalyst is suitable for use in soil-contaminated environments. The TiO2-Pt photocatalyst exerted superior antibacterial activity against a broad spectrum of human pathogens, including B. pseudomallei and B. cenocepacia. Soil particles (<10% w/v) did not significantly reduce the antibacterial activity of TiO2-Pt in water. These findings suggest that the TiO2-Pt photocatalyst may have potential applications in the development of bactericides for soil-borne pathogens. PMID:22384003

  4. Density functional theory calculations of dense TiO2 polymorphs: implication for visible-light-responsive photocatalysts.

    PubMed

    Kuo, Ming-Yu; Chen, Cheng-Lung; Hua, Chih-Yu; Yang, Hsiao-Ching; Shen, Pouyan

    2005-05-12

    Structural parameters and electronic band gaps of dense TiO(2) polymorphs, i.e., alpha-PbO(2), baddeleyite, fluorite, and cotunnite types of structures, were calculated using a first-principles density functional method with local-density approximation. The ambient phases, i.e., rutile and anatase, with known theoretical and experimental data were used to ensure the validity of the calculations. The fluorite-type TiO(2) turned out to have the narrowest band gap, 1.08 or 2.18 eV after applying a very approximate band gap correction, due to highly symmetrical TiO(8) polyhedra with Ti(3d) and O(2p) orbitals in the most mixed state. Ti with eight coordinated oxygens, as feasible under high pressure or residual stress, may have potential applications as a visible-light-responsive photocatalyst. PMID:16852029

  5. TiO2/carboxylate-rich porous carbon: A highly efficient visible-light-driven photocatalyst based on the ligand-to-metal charge transfer (LMCT) process

    NASA Astrophysics Data System (ADS)

    Qu, Lingling; Huang, Dongliang; Shi, Hefei; Gu, Mengbin; Li, Jilei; Dong, Fei; Luo, Zhijun

    2015-10-01

    A novel visible-light-driven photocatalyst based on TiO2/carboxylate-rich porous carbon composite (TiO2/CRPC) was successfully synthesized by low temperature carbonization process in air. Sodium gluconate plays a crucial role in the formation of TiO2/CRPC. Different functional groups of sodium gluconate play synergetic roles in the formation of TiO2/CRPC. XRD and Raman spectra studies indicated that there are two different TiO2 crystalline phases existing in TiO2/CRPC, which are anatase and brookite, and the CRPC is amorphous. Via FT-IR and XPS spectra investigations, it was demonstrated that carboxylate group, the ligand-to-metal charge transfer (LMCT) forming functional group, was solidified into the CRPC and form the LMCT complex on TiO2 surface through the fabrication of TiO2/CRPC. Compared with the pure TiO2, TiO2/CRPC exhibit enhanced absorption in the UV and visible light region around 260-600 nm. The strong absorption in the visible light region gives TiO2/CRPC advantages over pure TiO2 for the degradation of organic pollutants. TiO2/CRPC can activate O2 in air under mild conditions and exhibit excellent visible-light-driven photocatalytic activities. However, TiO2/C composite obtained by using glucose instead of sodium gluconate exhibits poor photocatalytic activity, which demonstrated that carboxylate-TiO2 complexes are responsible for the prominent photocatalytic properties of TiO2/CRPC under visible light irradiation.

  6. Feasibility of Silver Doped TiO2/Glass Fiber Photocatalyst under Visible Irradiation as an Indoor Air Germicide

    PubMed Central

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-01-01

    This study investigated the feasibility of using Ag-TiO2 photocatalyst supported on glass fiber (Ag-TiO2/GF) prepared by a sol-gel method as an indoor air germicide. An experimental model was designed to investigate the bacterial disinfection efficiency of Staphylococcus (Staph), the most popular bacterium in hospitals in Korea, by the Ag-TiO2/GF photocatalyst. The silver content in Ag/TiO2 was altered from 1 to 10% to investigate the optimal ratio of Ag doped on TiO2/glass fiber (TiO2/GF) for photocatalytic disinfection of Staph. This study confirmed that Ag in Ag-TiO2/GF could work as an electron sink or donor to increase photocatalytic activity and promote the charge separation of electron-hole pairs generated from TiO2 after photon absorption. Ag also acts as an intermediate agent for the transfer of photo-generated electrons from the valence band of TiO2 to an acceptor (O2 gas) to promote photo-oxidation processes. The photocatalytic disinfection activity of Ag-TiO2/GF under visible light increased with the increase in silver content up to 7.5% and then slightly decreased with further increasing silver content. The highest disinfection efficiency and disinfection capacity of Staph using 7.5% Ag-TiO2/GF were 75.23% and 20 (CFU?s?1?cm?2) respectively. The medium level of humidity of 60% ± 5% showed better photocatalytic disinfection than the lower (40% ± 5%) or higher (80% ± 5%) levels. PMID:24658408

  7. Fullerene C70 decorated TiO2 nanowires for visible-light-responsive photocatalyst

    NASA Astrophysics Data System (ADS)

    Cho, Er-Chieh; Ciou, Jing-Hao; Zheng, Jia-Huei; Pan, Job; Hsiao, Yu-Sheng; Lee, Kuen-Chan; Huang, Jen-Hsien

    2015-11-01

    In this study, we have synthesized C60 and C70-modified TiO2 nanowire (NW) through interfacial chemical bonding. The results indicate that the fullerenes (C60 and C70 derivatives) can act as sinks for photogenerated electrons in TiO2, while the fullerene/TiO2 is illuminated under ultraviolet (UV) light. Therefore, in comparison to the pure TiO2 NWs, the modified TiO2 NWs display a higher photocatalytic activity under UV irradiation. Moreover, the fullerenes also can function as a sensitizer to TiO2 which expand the utilization of solar light from UV to visible light. The results reveal that the C70/TiO2 NWs show a significant photocatalytic activity for degradation of methylene blue (MB) in visible light region. To better understand the mechanism responsible for the effect of fullerenes on the photocatalytic properties of TiO2, the electron only devices and photoelectrochemical cells based on fullerenes/TiO2 are also fabricated and evaluated.

  8. Highly efficient and recyclable triple-shelled Ag@Fe3O4@SiO2@TiO2 photocatalysts for degradation of organic pollutants and reduction of hexavalent chromium ions

    NASA Astrophysics Data System (ADS)

    Su, Jianwei; Zhang, Yunxia; Xu, Sichao; Wang, Shuan; Ding, Hualin; Pan, Shusheng; Wang, Guozhong; Li, Guanghai; Zhao, Huijun

    2014-04-01

    Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues.Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues. Electronic supplementary information (ESI) available: Synthesis of TiO2 microspheres; synthesis of Fe3O4@SiO2@TiO2 nanospheres; synthesis of Ag@Fe3O4@TiO2 nanospheres; SEM images of the as-prepared products: (a) Ag@Fe3O4, (b) Ag@Fe3O4@SiO2 and (c) Ag@Fe3O4@SiO2@TiO2 (Fig. S1); TEM images of the Ag@Fe3O4@SiO2 synthesized with adding different amount of TEOS (Fig. S2); SEM, TEM and EDS spectrum of Fe3O4@SiO2@TiO2 NPs (Fig. S3); SEM and TEM images of as-prepared TiO2 microspheres (Fig. S4); nitrogen adsorption-desorption isotherm and pore size distribution plot for as-prepared Fe3O4@SiO2@TiO2 and TiO2 microspheres (Fig. S5); adsorption rate curve of MB in dark for Ag@Fe3O4@SiO2@TiO2 samples (Fig.

  9. Low temperature synthesis of polyaniline-crystalline TiO2-halloysite composite nanotubes with enhanced visible light photocatalytic activity.

    PubMed

    Li, Cuiping; Wang, Jie; Guo, Hong; Ding, Shujiang

    2015-11-15

    A series of one-dimensional polyaniline-crystalline TiO2-halloysite composite nanotubes with different mass ratio of polyaniline to TiO2 are facilely prepared by employing the low-temperature synthesis of crystalline TiO2 on halloysite nanotubes. The halloysite nanotubes can adsorb TiO2/polyaniline precursors and induce TiO2 nanocrystals/polyaniline to grow on the support in situ simultaneously. By simply adjusting the acidity of reaction system, PANI-crystalline TiO2-HA composite nanotubes composed of anatase, a mixed phase TiO2 and different PANI redox state are obtained. The XRD and UV-vis results show that the surface polyaniline sensitization has no effect on the crystalline structure of halloysite and TiO2 and the light response of TiO2 is extended to visible-light regions. Photocatalysis test results reveal the photocatalytic activity will be affected by the pH value and the volume ratio of ANI to TTIP. The highest photocatalytic activity is achieved with the composite photocatalysts prepared at pH 0.5 and 1% volume ratio of ANI and TTIP owing to the sensitizing effect of polyaniline and the charge transfer from the photoexcited PANI sensitizer to TiO2. Moreover, the PANI-TiO2-HA composite nanotubes synthesized by one-step at pH 0.5 with 1% volume ratio of ANI to TTIP exhibit higher visible light photocatalytic activity than those synthesized by the two-step. Heterogeneous PANI-TiO2-HA composite nanotubes prepared at pH 0.5 exhibit a higher degradation activity than that prepared at pH 1.5. The redoped experiment proves that the PANI redox state plays the main contribution to the enhanced visible light catalytic degradation efficiency of PANI-TiO2-HA prepared at pH 0.5. Furthermore, the heterogeneous PANI-crystalline TiO2-HA nanotubes have good photocatalytic stability and can be reused four times with only gradual loss of activity under visible light irradiation. PMID:26197106

  10. OXYGENATION OF HYDROCARBONS USING NANOSTRUCTURED TIO2 AS A PHOTOCATALYST: A GREEN ALTERNATIVE

    EPA Science Inventory

    High-value organic compounds have been synthesized successfully from linear and cyclic saturated hydrocarbons by a photocatalytic oxidation process using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxygenated in both aqueous and gaseous...

  11. Green microwave switching from oxygen rich yellow anatase to oxygen vacancy rich black anatase TiO2 solar photocatalyst using Mn(ii) as 'anatase phase purifier'.

    PubMed

    Ullattil, Sanjay Gopal; Periyat, Pradeepan

    2015-12-01

    Green and rapid microwave syntheses of 'yellow oxygen rich' (YAT-150) and 'black oxygen vacancy rich' (BAT-150) anatase TiO2 nanoparticles are reported for the first time. YAT-150 was synthesized using only titanium(iv) butoxide and water as precursors. The in situ precursor modification by Mn(ii) acetate switched anatase TiO2 from YAT-150 to BAT-150. The entry of Mn(2+) into the crystal lattice of anatase TiO2 paved the way for peak texturing in the existing peak orientations along with the origin of three new anatase TiO2 peaks in the (103), (213) and (105) directions. The as synthesized ultra-small (?5 nm) yellow and black anatase TiO2 nanoparticles were found to be two fold and four fold more photoactive than the commercially available photocatalyst Degussa-P25 under sunlight illumination. PMID:26523536

  12. Preparation and characterization of SeO2/TiO2 composite photocatalyst with excellent performance for sunset yellow azo dye degradation under natural sunlight illumination

    NASA Astrophysics Data System (ADS)

    Rajamanickam, D.; Dhatshanamurthi, P.; Shanthi, M.

    2015-03-01

    To improve the solar light induced photocatalytic application performances of TiO2, in this study, the SeO2 modified TiO2 composite photocatalysts with various ratios of SeO2 to TiO2 were prepared by sol-gel method. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM), energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area measurement methods. The photocatalytic activity of SeO2/TiO2 was investigated for the degradation of sunset yellow (SY) in aqueous solution using solar light. The SeO2/TiO2 is found to be more efficient than prepared TiO2 and TiO2-P25 at pH 7 for the mineralization of SY. The effects of operational parameters such as the amount of photocatalyst, dye concentration and initial pH on photo mineralization of SY have been analyzed. The degradation was strongly enhanced in the presence of electron acceptors such as oxone, KIO4 and KBrO3. The kinetics of SY photodegradation was found to follow the pseudo-first order rate law and could be described in terms of Langmuir-Hinshelwood model. The mineralization of SY has been confirmed by COD measurements. The catalyst is found to be reusable.

  13. TiO2 synthesis inspired by biomineralization: control of morphology, crystal phase, and light-use efficiency in a single process.

    PubMed

    Nonoyama, Takayuki; Kinoshita, Takatoshi; Higuchi, Masahiro; Nagata, Kenji; Tanaka, Masayoshi; Sato, Kimiyasu; Kato, Katsuya

    2012-05-30

    Hydroxyapatite is mineralized along the long axis of collagen fiber during osteogenesis. Mimicking such biomineralization has great potential to control inorganic structures and is fast becoming an important next-generation inorganic synthesis method. Inorganic matter synthesized by biomineralization can have beautiful and functional structures that cannot be created artificially. In this study, we applied biomineralization to the synthesis of the only photocatalyst in practical use today, titanium dioxide (TiO(2)). The photocatalytic activity of TiO(2) mainly relates to three properties: morphology, crystal phase, and light-use efficiency. To optimize TiO(2) morphology, we used a simple sequential peptide as an organic template. TiO(2) mineralized by a ?-sheet peptide nanofiber template forms fiber-like shapes that are not observed for mineralization by peptides in the shape of random coils. To optimize TiO(2) crystal phase, we mineralized TiO(2) with the template at 400 °C to transform it into the rutile phase and at 700 °C to transform it into a mixed phase of anatase and rutile. To optimize light-use efficiency, we introduced nitrogen atoms of the peptide into the TiO(2) structure as doped elemental material during sintering. Thus, this biomineralization method enables control of inorganic morphology, crystal phase, and light-use efficiency in a single process. PMID:22578231

  14. Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes.

    PubMed

    Xie, Yi; Heo, Sunghwan; Yoo, Seunghwa; Ali, Ghafar; Cho, Sungoh

    2009-01-01

    A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs) is presented. Anatase TiO2 nanoparticles (NPs) with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2. PMID:20671780

  15. Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Yoo, Seung Hwa; Ali, Ghafar; Cho, Sung Oh

    2010-03-01

    A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs) is presented. Anatase TiO2 nanoparticles (NPs) with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

  16. Constructing inverse V-type TiO2-based photocatalyst via bio-template approach to enhance the photosynthetic water oxidation

    NASA Astrophysics Data System (ADS)

    Jiang, Jinghui; Zhou, Han; Ding, Jian; Zhang, Fan; Fan, Tongxiang; Zhang, Di

    2015-08-01

    Bio-template approach was employed to construct inverse V-type TiO2-based photocatalyst with well distributed AgBr in TiO2 matrix by making dead Troides Helena wings with inverse V-type scales as the template. A cross-linked titanium precursor with homogenous hydrolytic rate, good liquidity, and low viscosity was employed to facilitate a perfect duplication of the template and the dispersion of AgBr based on appropriate pretreatment of the template by alkali and acid. The as-synthesized inverse V-type TiO2/AgBr can be turned into inverse V-type TiO2/Ag0 from AgBr photolysis during photocatalysis to achieve in situ deposition of Ag0 in TiO2 matrix, by this approach, to avoid the deformation of surface microstructure inherited from the template. The result showed that the cooperation of perfect inverse V-type structure and the well distributed TiO2/Ag0 microstructures can efficiently boost the photosynthetic water oxidation compared to non-inverse V-type TiO2/Ag0 and TiO2/Ag0 without using template. The anti-reflection function of inverse V-type structure and the plasmatic effect of Ag0 might be able to account for the enhanced photon capture and efficient photoelectric conversion.

  17. Design of H3PW12O40/TiO2 nano-photocatalyst for efficient photocatalysis under simulated sunlight irradiation

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Lu, Ying; Lu, Nan; Zhao, Yahui; Yuan, Xing; Zhang, Hao; Teng, Lianghui; Li, Fu

    2013-11-01

    H3PW12O40/TiO2 (PW12/TiO2) nano-photocatalyst was successfully synthesized through a modified sol-gel-hydrothermal method. The X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectra, UV-vis diffuse reflectance spectrum (UV-vis DRS), and N2 adsorption-desorption isotherms were characterized respectively to investigate the physical and chemical properties of prepared catalysts. Under simulated sunlight (320 nm < ? < 780 nm) irradiation, the degradation of fuchsin acid, malachite green and p-nitrophenol (PNP) were carried out to evaluate the photocatalytic activity of PW12/TiO2. The results showed that the pollutants degradation followed first-order kinetics, and the kinetic constants of photocatalytic degradation of fuchsin acid, malachite green and PNP were 2.82, 4.66, and 3.48 times as great as that using pristine TiO2, respectively. The high pollutants degradation efficiency was ascribed to the synergistic effect between H3PW12O40 and TiO2, which resulted in enhanced quantum efficiency and high light harvesting efficiency. We believe this work could provide new insights into the fabrication of photocatalyst with high photocatalytic performance and facilitate their practical application in environmental issues.

  18. Mesoporous core-shell TiO(2) walnuts for photocatalysts and photodetectors with improved performances.

    PubMed

    He, Fei; Zhang, Chao; Zhou, Di; Cheng, Ling; Li, Tao; Li, Guangxing

    2014-05-28

    Mesoporous core-shell TiO2 walnuts (CSTWs) were successfully prepared by a facile one-step hydrothermal method. This superior micro-nanostructure endowed the sample with hierarchical mesopores and a high surface area of 90.97 m(2) g(-1). Their particle size, diameter and morphology could be readily controlled by varying the growth parameters. The influence of the glucose amount, the urea amount and the calcination temperature on the formation of microspheres was investigated. The formation mechanism of the mesoporous CSTWs was studied. The photocatalytic activity of CSTWs had been carried out by degradation of gaseous benzene. The results indicated that, compared with commercial TiO2 (Degussa P25), CSTWs exhibited significant photocatalytic activity. Moreover, the mesoporous CSTWs were also configured as high-performance photodetectors. When illuminated by UV light with a wavelength of 365 nm, the current was found to be significantly enhanced, and an IUV/Idark of about 500, a good rise time and decay time were obtained. PMID:24695865

  19. On sol-gel derived Au-enriched TiO2 and TiO2-ZrO2 photocatalysts and their investigation in photocatalytic reduction of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Mat?jová, Lenka; Ko?í, Kamila; Reli, Martin; ?apek, Libor; Mat?jka, Vlastimil; Šolcová, Olga; Obalová, Lucie

    2013-11-01

    Gold-enriched TiO2 and TiO2-ZrO2 and their parent counterparts were prepared by using the sol-gel process controlled within the reverse micelles environment, followed by impregnation in AuCl3 solution. Catalysts were characterized by organic elementary analysis (OEA), inductively coupled plasma mass spectrometry (ICP MS), N2 physisorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM) combined with electron diffraction, UV-vis spectroscopy, and tested in CO2 photocatalytic reduction. The performance of photocatalysts iluminated by UV-lamp with the wavelenght maximum at 254 nm was decreasing in the order TiO2-ZrO2 > Au/TiO2-ZrO2 > TiO2 > Au/TiO2 > TiO2 Evonic P25. The photocatalytic performance decrease over Au/TiO2-ZrO2 and Au/TiO2, compared to their parent counterparts, can be explained by the presence of too large Au particles, which block the oxide surface and either reduce the light absorption capability of the catalysts, or serve as the recombination centres. Higher photocatalytic performance of the amorphous TiO2-ZrO2 than of the nanocrystalline TiO2 can be ascribed to the enlarged surface area and higher photoactivity of titania-zirconia oxide mixture under the UV lamp with the wavelenght maximum at 254 nm. With regard to crystalline materials the appropriate anatase crystallite-size plays a key role in performance of CO2 photocatalytic reduction. Moreover, correlation between the adsorption edge and the anatase crystallite-size was revealed.

  20. Green microwave switching from oxygen rich yellow anatase to oxygen vacancy rich black anatase TiO2 solar photocatalyst using Mn(ii) as `anatase phase purifier'

    NASA Astrophysics Data System (ADS)

    Ullattil, Sanjay Gopal; Periyat, Pradeepan

    2015-11-01

    Green and rapid microwave syntheses of `yellow oxygen rich' (YAT-150) and `black oxygen vacancy rich' (BAT-150) anatase TiO2 nanoparticles are reported for the first time. YAT-150 was synthesized using only titanium(iv) butoxide and water as precursors. The in situ precursor modification by Mn(ii) acetate switched anatase TiO2 from YAT-150 to BAT-150. The entry of Mn2+ into the crystal lattice of anatase TiO2 paved the way for peak texturing in the existing peak orientations along with the origin of three new anatase TiO2 peaks in the (103), (213) and (105) directions. The as synthesized ultra-small (~5 nm) yellow and black anatase TiO2 nanoparticles were found to be two fold and four fold more photoactive than the commercially available photocatalyst Degussa-P25 under sunlight illumination.Green and rapid microwave syntheses of `yellow oxygen rich' (YAT-150) and `black oxygen vacancy rich' (BAT-150) anatase TiO2 nanoparticles are reported for the first time. YAT-150 was synthesized using only titanium(iv) butoxide and water as precursors. The in situ precursor modification by Mn(ii) acetate switched anatase TiO2 from YAT-150 to BAT-150. The entry of Mn2+ into the crystal lattice of anatase TiO2 paved the way for peak texturing in the existing peak orientations along with the origin of three new anatase TiO2 peaks in the (103), (213) and (105) directions. The as synthesized ultra-small (~5 nm) yellow and black anatase TiO2 nanoparticles were found to be two fold and four fold more photoactive than the commercially available photocatalyst Degussa-P25 under sunlight illumination. Electronic supplementary information (ESI) available: Photographs of YAT-150 and BAT-150, wide range XPS and SEM images, EDX and UV-Visible absorption spectra of the degradation of methylene blue using as synthesized samples and Degussa-P25 are included. See DOI: 10.1039/c5nr05975e

  1. Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Pan, Xiaoyang; Yang, Min-Quan; Fu, Xianzhi; Zhang, Nan; Xu, Yi-Jun

    2013-04-01

    Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00476g

  2. Efficient photocatalytic degradation of organic pollutants by magnetically recoverable nitrogen-doped TiO2 nanocomposite photocatalysts under visible light irradiation.

    PubMed

    Hamzezadeh-Nakhjavani, Sahar; Tavakoli, Omid; Akhlaghi, Seyed Parham; Salehi, Zeinab; Esmailnejad-Ahranjani, Parvaneh; Arpanaei, Ayyoob

    2015-12-01

    Preparation of novel nanocomposite particles (NCPs) with high visible-light-driven photocatalytic activity and possessing recovery potential after advanced oxidation process (AOP) is much desired. In this study, pure anatase phase titania (TiO2) nanoparticles (NPs) as well as three types of NCPs including nitrogen-doped titania (TiO2-N), titania-coated magnetic silica (Fe3O4 cluster@SiO2@TiO2 (FST)), and a novel magnetically recoverable TiO2 nanocomposite photocatalyst containing nitrogen element (Fe3O4 cluster@SiO2@TiO2-N (FST-N)) were successfully synthesized via a sol-gel process. The photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) with an energy-dispersive X-ray (EDX) spectroscopy analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM). The photocatalytic activity of as-prepared samples was further investigated and compared with each other by degradation of phenol, as a model for the organic pollutants, in deionized (DI) water under visible light irradiation. The TiO2-N (55?±?1.5 %) and FST-N (46?±?1.5 %) samples exhibited efficient photocatalytic activity in terms of phenol degradation under visible light irradiation, while undoped samples were almost inactive under same operating conditions. Moreover, the effects of key operational parameters, the optimum sample calcination temperature, and reusability of FST-N NCPs were evaluated. Under optimum conditions (calcination temperature of 400 °C and near-neutral reaction medium), the obtained results revealed efficient degradation of phenol for FST-N NCPs under visible light irradiation (46?±?1.5 %), high yield magnetic separation and efficient reusability of FST-N NCPs (88.88 % of its initial value) over 10 times reuse. PMID:26206125

  3. Graphene and TiO2 co-modified flower-like Bi2O2CO3: A novel multi-heterojunction photocatalyst with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ao, Yanhui; Xu, Liya; Wang, Peifang; Wang, Chao; Hou, Jun; Qian, Jin; Li, Yi

    2015-11-01

    In this paper, graphene (GR) and titania co-modified flower-like Bi2O2CO3 multi-heterojunction composite photocatalysts were prepared by a simple and feasible two step hydrothermal process. The prepared samples were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrometry (DRS), photoluminescence (PL), N2 adsorption-desorption isotherm, and photo-induced current. The photocatalytic activity was investigated by the degradation of MO under UV light irradiation. The as prepared multi-heterojunction GR/Bi2O2CO3/TiO2 composites exhibited much higher photocatalytic activity than pure Bi2O2CO3, TiO2 and GR-Bi2O2CO3. The higher performance of GR/Bi2O2CO3/TiO2 can be ascribed to the formation of multi-heterojunctions, which promote the effective separation of photo-induced electron-hole pairs. Moreover, the higher photocatalytic activity can also be ascribed to the high surface area of GR and TiO2, which offers more active sites for the photodegradation reaction. Furthermore, the photocatalytic activity of GR/Bi2O2CO3/TiO2 remained without striking decrease after five cycles, which indicates the excellent stability of GR/Bi2O2CO3/TiO2 composites. This work would pave a way to the design of high efficient multi-heterojunction photocatalysts.

  4. N-doped TiO 2 photo-catalyst for the degradation of 1,2-dichloroethane under fluorescent light

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsing; Chiu, Tang-Chun; Hsueh, Hsin-Ta; Chu, Hsin

    2011-12-01

    The photo-catalytic degradation of 1,2-dichloroethane (1, 2-DCE) using nitrogen-doped TiO2 photo-catalysts under fluorescent light irradiation was investigated. Highly pure TiO2 and nitrogen-doped TiO2 were prepared by a sol-gel method and characterized by thermo-gravimetric/differential-thermal analysis (TG/DTA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that the photo-catalysts were mainly nano-size with an anatase-phase structure. The degradation reaction of 1,2-DCE was operated under visible-light irradiation, and the photo-catalytic oxidation was conducted in a batch photo-reactor with various nitrogen doping ratios (N/Ti = 0-25 mol%). The relative humidity (RH) was controlled at 0-20% and the oxygen concentration was controlled at 0-21%. The photo-degradation with nitrogen-doped TiO2 showed superior photo-catalytic activity compared to that for pure TiO2. TiO2 doped with 15 mol% nitrogen exhibited the best photo-catalytic efficiency under the tested conditions. The products from the 1,2-DCE photo-catalytic oxidation were CO2 and water; the by-products included dichloromethane, methyl chloride, ethyl chloride, carbon monoxide, and hydrogen chloride. The reaction pathway of 1,2-DCE indicates that oxygen molecules are the major factor that causes the degradation of 1,2-DCE in the gas phase.

  5. Ultrasonic synthesis and photocatalytic characterization of H3PW12O40/TiO2 (anatase).

    PubMed

    Lee, Jia; Dong, Xiaoli; Dong, Xuewei

    2010-04-01

    A novel H(3)PW(12)O(40)/TiO(2) (anatase) composite photocatalyst was prepared by a high-intensity ultrasonic method using a lower temperature (80 degrees C) and was characterized by XRD and FT-IR. Its photocatalytic activity, using solar light, was evaluated through the degradation of organic dye methylene blue (MB) in aqueous. When MB solution (50mg/l, 200 ml) containing H(3)PW(12)O(40)/TiO(2) (anatase) (0.4 g) was degraded by solar irradiation after 90 min, the removal of concentration and TOC of MB reached 95% and 73%, respectively. The photocatalyst activity of H(3)PW(12)O(40)/TiO(2) (anatase) was much higher than TiO(2) which was prepared in the same way. H(3)PW(12)O(40)/TiO(2) remained efficient after five repeated experiments. PMID:20171134

  6. One pot synthesis of nanosized anion doped TiO2: Effect of irradiation of sound waves on surface morphology and optical properties

    NASA Astrophysics Data System (ADS)

    Sharotri, Nidhi; Sud, Dhiraj

    2015-08-01

    Commercialization of AOP's for remediation of pollutants from environmental matrix required the process to be operated by solar light. Semiconductor TiO2 has emerged as an effective and preferred photocatalyst in the field of environmental photocatalysis due to its; (i) biological and chemical inertness (ii) resistance to chemical and photo corrosion, (iii) can absorb natural UV light due to appropriate energetic separation between its valence and conduction band. However, unfortunately the optical band gap of TiO2 (3.0-3.23 eV) with absorption cut off ˜ 380 nm, enables it to harness only a small fraction (˜ 5%) of the entire solar spectrum. One of the current areas of research is modification of TiO2 photocatalyst. In present paper one pot greener synthesis from titanium isopropoxide and hydroxylamine hydrochloride has been used as titanium and nitrogen precursor under ultrasonic waves. The as synthesized TiO2 nanomaterials were dried at 100°C and further calcinated at different temperatures. The effect of reaction parameters such as ultrasonication time on the yield, surface morphology, spectroscopic data and optical properties was also investigated. The results confirm that the anatase phase is a main phase with a crystallite size of 35-77 nm and the calculated band gap of nanomaterials varies from 2.10-3.1 eV.

  7. High pressure synthesis of amorphous TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Quanjun; Liu, Ran; Wang, Tianyi; Xu, Ke; Dong, Qing; Liu, Bo; Liu, Jing; Liu, Bingbing

    2015-09-01

    Amorphous TiO2 nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO2 nanotubes. The structural phase transitions of anatase TiO2 nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD) method. The starting anatase structure is stable up to ˜20GPa, and transforms into a high-density amorphous (HDA) form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO2 nanoparticles and nanoribbons. The relationship between the LDA form and ?-PbO2 phase was revealed by high-resolution transmission electron microscopy (HRTEM) study. In addition, the bulk modulus (B0 = 158 GPa) of the anatase TiO2 nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa). We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO2 nanotubes.

  8. TiO2 Fibers Supported ?-FeOOH Nanostructures as Efficient Visible Light Photocatalyst and Room Temperature Sensor

    PubMed Central

    Zhu, Ting; Li Ong, Wei; Zhu, Liangliang; Wei Ho, Ghim

    2015-01-01

    Hierarchical heterostructures of beta-iron oxyhydroxide (?-FeOOH) nanostructures on electrospun TiO2 nanofibers were synthesized by a facile hydrothermal method. This synthesis method proves to be versatile to tailoring of ?-FeOOH structural design that cuts across zero-dimensional particles (TF-P), one-dimensional needles (TF-N) to two-dimensional flakes (TF-F). In addition, synthesizing such oxyhyroxide nanostructures presents the advantage of exhibiting similar functional performances to its oxides counterpart however, without the need to undergo any annealing step which leads to undesirable structural collapse or sintering. The as-prepared hierarchical heterostructures possess high surface area for dye adsorptivity, efficient charge separation and visible photocatalytic activity. Also, for the first time, hydrogen gas sensing has been demonstrated on ?-FeOOH nanostructures at room temperature. The reported hierarchical heterostructures of ?-FeOOH on TiO2 nanofibers afford multiple functions of photocatalysis and sensing which are highly promising for environment monitoring and clean up applications. PMID:26030002

  9. Synthesis and characterization of sulfated TiO2 nanorods and ZrO2/TiO2 nanocomposites for the esterification of biobased organic acid.

    PubMed

    Li, Zhonglai; Wnetrzak, Renata; Kwapinski, Witold; Leahy, James J

    2012-09-26

    TiO(2) nanorods and ZrO(2)-modified TiO(2) nanocomposites have been prepared by hydrothermal synthesis and the deposition-precipitation method. Their sulfated products were tested as solid superacid catalysts for the esterification of levulinic acid which was used as a model bio-oil molecule. SEM and TEM characterization showed that TiO(2) nanorods with diameters ranging from 20 to 200 nm and with lengths of up to 5 ?m were synthesized by a hydrothermal method at 180 °C. ZrO(2) nanoparticles with the diameters ranging from 10 to 20 nm were evenly deposited on TiO(2) nanorods. IR and XPS results suggested that sulfated ZrO(2)/TiO(2) nanocomposite has higher content of sulfate groups on the surface with a S/(Zr+Ti) ratio of 13.6% than sulfated TiO(2) nanorods with a S/Ti ratio of 4.9%. The HPLC results showed that sulfated ZrO(2)/TiO(2) nanocomposite have enhanced catalytic activity for esterification reaction between levulinic acid and ethanol compared to sulfated TiO(2) nanorods. The conversion of levulinic acid to ethyl levulinate can reach to 90.4% at the reaction temperature of 105 °C after 180 min. PMID:22891691

  10. Facile Scalable Synthesis of TiO2/Carbon Nanohybrids with Ultrasmall TiO2 Nanoparticles Homogeneously Embedded in Carbon Matrix.

    PubMed

    Wang, Xiaoyan; Meng, Jian-Qiang; Wang, Meimei; Xiao, Ying; Liu, Rui; Xia, Yonggao; Yao, Yuan; Metwalli, Ezzeldin; Zhang, Qian; Qiu, Bao; Liu, Zhaoping; Pan, Jing; Sun, Ling-Dong; Yan, Chun-Hua; Müller-Buschbaum, Peter; Cheng, Ya-Jun

    2015-11-01

    A facile scalable synthesis of TiO2/C nanohybrids inspired by polymeric dental restorative materials has been developed, which creates ultrasmall TiO2 nanoparticles homogeneously embedded in the carbon matrix. The average size of the nanoparticles is tuned between about 1 and 5 nm with the carbon content systematically increased from 0% to 65%. Imaging analysis and a scattering technique have been applied to investigate the morphology of the TiO2 nanoparticles. The composition, nature of carbon matrix, crystallinity, and tap density of the TiO2/C nanohybrids have been studied. The application of the TiO2/C nanohybrids as lithium-ion battery anode is demonstrated. Unusual discharge/charge profiles have been exhibited, where characteristic discharge/charge plateaus of crystalline TiO2 are significantly diminished. The tap density, cyclic capacities, and rate performance at high current densities (10 C, 20 C) of the TiO2/C nanohybrid anodes have been effectively improved compared to the bare carbon anode and the TiO2/C nanohybrids with larger particle size. PMID:26465800

  11. Synthesis and characterization of anionic/nonionic surfactant-interceded iron-doped TiO2 to enhance sorbent/photo-catalytic properties

    NASA Astrophysics Data System (ADS)

    Sharma, Ajit; Lee, Byeong-Kyu

    2015-09-01

    We investigated the synthesis, characterization, and application of surfactant-interceded Fe nanoparticle-doped TiO2 (TiO2/Fe-S1 and TiO2/Fe-S2) that were used as adsorbents and photo-catalysts for the removal of As(V) ions from aqueous media. Two types of surfactant (anionic (sodium dodecyl sulfate), S1 and non-ionic (Triton X-100), S2) were used to obtain the separation and mono-dispersion of Fe(III) ions in the reaction solution. The nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and elemental mapping analysis before and after As(V) removal. The Langmuir capacities (qe, mg/g) of the sodium dodecyl sulfate (SDS) and Triton X-100 interceded nanocomposites (TiO2/Fe-S1 and TiO2/Fe-S2, respectively) for arsenic removal were determined to be 65.79 and 50.76 mg/g, respectively, in aqueous media with As(V) concentration ranges of 0-10 mg/L at pH 6.5.

  12. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis

    NASA Astrophysics Data System (ADS)

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A.

    2014-08-01

    In this work, Fe-doped TiO2 nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO2 nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO2 analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO2 were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO2. The resulting assemblies were tested for photodegradation under visible light using 17?-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2.

  13. TiO2 nanotubes: synthesis and applications.

    PubMed

    Roy, Poulomi; Berger, Steffen; Schmuki, Patrik

    2011-03-21

    TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field. PMID:21394857

  14. Nanostructured AgBr loaded TiO2: An efficient sunlight active photocatalyst for degradation of Reactive Red 120

    PubMed Central

    2011-01-01

    The AgBr loaded TiO2 catalyst was prepared by a feasible approach with AgBr and tetraisopropyl orthotitanate and characterized by BET surface area measurement, diffuse reflectance spectra (DRS), scanning electron microscope (SEM), energy dispersive spectra (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM) and atomic force microscope (AFM) analysis. The results of characterization reveal that AgBr loaded TiO2 has a nanostructure. Formation of the nanostructure in AgBr loaded TiO2 results in substantial shifting of the absorption edge of TiO2 to red and enhancement of visible light absorption. Electrochemical impedance spectroscopy measurements reveal that AgBr loaded TiO2 has a higher photoconductivity than prepared TiO2 due to higher separation efficiency of electron-hole pairs. Cyclic voltammetric studies reveal enhanced conductivity in AgBr loaded TiO2, which causes an increase in its photocatalytic activity. AgBr loaded TiO2 exhibited a higher photocatalytic activity than TiO2-P25 and prepared TiO2 in the photodegradation of Reactive Red 120 (RR 120). PMID:21801445

  15. Gold and gold-palladium alloy nanoparticles on heterostructured TiO2 nanobelts as plasmonic photocatalysts for benzyl alcohol oxidation

    NASA Astrophysics Data System (ADS)

    Jiang, Tongtong; Jia, Chuancheng; Zhang, Lanchun; He, Shuren; Sang, Yuanhua; Li, Haidong; Li, Yanqing; Xu, Xiaohong; Liu, Hong

    2014-11-01

    Plasmonic photocatalysts composed of Au and bimetallic Au-Pd alloy nanoparticles (NPs) on one-dimensional TiO2 nanobelts (TiO2-NBs) were used for the aerobic oxidation of benzyl alcohol under visible light irradiation. Remarkable light-promoted activity was observed for the as-synthesized M/TiO2-NB (M = Au, Au-Pd) nanostructures based on the TiO2(B)/anatase heterostructured nanobelt. The difference in band structure and the well matched interface between the TiO2(B) and anatase phases, coupled with the one-dimensional nanostructure, enable an enhanced charge transfer within the heterostructured nanobelt. This inter-phase charge transfer greatly facilitates the flow of hot electrons from the metal NPs to TiO2 and promotes benzyl alcohol oxidation. This efficient electron transfer was identified by the much higher photocurrent response measured for the Au/TiO2-NB nanostructure with the TiO2(B)/anatase heterojunction than those with either of the single phases under visible light irradiation. Alloying Au with Pd in Au-Pd/TiO2-NB results in a significant improvement in the visible light-promoted activity compared to the monometallic Au/TiO2-NB sample. It is supposed that the plasmon-mediated charge distribution within the alloy NPs is mainly responsible for the enhanced photocatalytic activity of the bimetallic nanostructures.Plasmonic photocatalysts composed of Au and bimetallic Au-Pd alloy nanoparticles (NPs) on one-dimensional TiO2 nanobelts (TiO2-NBs) were used for the aerobic oxidation of benzyl alcohol under visible light irradiation. Remarkable light-promoted activity was observed for the as-synthesized M/TiO2-NB (M = Au, Au-Pd) nanostructures based on the TiO2(B)/anatase heterostructured nanobelt. The difference in band structure and the well matched interface between the TiO2(B) and anatase phases, coupled with the one-dimensional nanostructure, enable an enhanced charge transfer within the heterostructured nanobelt. This inter-phase charge transfer greatly facilitates the flow of hot electrons from the metal NPs to TiO2 and promotes benzyl alcohol oxidation. This efficient electron transfer was identified by the much higher photocurrent response measured for the Au/TiO2-NB nanostructure with the TiO2(B)/anatase heterojunction than those with either of the single phases under visible light irradiation. Alloying Au with Pd in Au-Pd/TiO2-NB results in a significant improvement in the visible light-promoted activity compared to the monometallic Au/TiO2-NB sample. It is supposed that the plasmon-mediated charge distribution within the alloy NPs is mainly responsible for the enhanced photocatalytic activity of the bimetallic nanostructures. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05905k

  16. Highly efficient and stable Au/CeO2-TiO2 photocatalyst for nitric oxide abatement: potential application in flue gas treatment.

    PubMed

    Zhu, Wei; Xiao, Shuning; Zhang, Dieqing; Liu, Peijue; Zhou, Hongjun; Dai, Wenrui; Liu, Fanfan; Li, Hexing

    2015-10-01

    In the present work, highly efficient and stable Au/CeO2-TiO2 photocatalysts were prepared by a microwave-assisted solution approach. The Au/CeO2-TiO2 composites with optimal molar ratio of Au/Ce/Ti of 0.004:0.1:1 delivered a remarkably high and stable NO conversion rate of 85% in a continuous flow reactor system under simulated solar light irradiation, which far exceeded the rate of 48% over pure TiO2. The tiny Au nanocrystals (?1.1 nm) were well stabilized by CeO2 via strong metal-support bonding even it was subjected to calcinations at 550 °C for 6 h. These Au nanocrystals served as the very active sites for activating the molecule of nitric oxide and reducing the transmission time of the photogenerated electrons to accelerate O2 transforming to reactive oxygen species. Moreover, the Au-Ce(3+) interface formed and served as an anchoring site of O2 molecule. Then more adsorbed oxygen could react with photogenerated electrons on TiO2 surfaces to produce more superoxide radicals for NO oxidation, resulting in the improved efficiency. Meanwhile, O2 was also captured at the Au/TiO2 perimeter site and the NO molecules on TiO2 sites were initially delivered to the active perimeter site via diffusion on the TiO2 surface, where they assisted O-O bond dissociation and reacted with oxygen at these perimeter sites. Therefore, these finite Au nanocrystals can consecutively expose active sites for oxidizing NO. These synergistic effects created an efficient and stable system for breaking down NO pollutants. Furthermore, the excellent antisintering property of the catalyst will allow them for the potential application in photocatalytic treatment of high-temperature flue gas from power plant. PMID:26390086

  17. Design of composite photocatalyst of TiO2 and Y-zeolite for degradation of 2-propanol in the gas phase under UV and visible light irradiation.

    PubMed

    Kamegawa, Takashi; Ishiguro, Yasushi; Kido, Ryota; Yamashita, Hiromi

    2014-01-01

    Hydrophobic Y-zeolite (SiO2/Al2O3 = 810) and TiO2 composite photocatalysts were designed by using two different types of TiO2 precursors, i.e., titanium ammonium oxalate and ammonium hexafluorotitanate. The porous structure, surface property and state of TiO2 were investigated by various characterization techniques. By using an ammonium hexafluorotitanate as a precursor, hydrophobic modification of the Y-zeolite surface and realizing visible light sensitivity was successfully achieved at the same time after calcination at 773 K in the air. The prepared sample still maintained the porous structure of Y-zeolite and a large surface area. Highly crystalline anatase TiO2 was also formed on the Y-zeolite surface by the role of fluorine in the precursor. The usages of ammonium hexafluorotitanate were effective for the improvement of the photocatalytic performance of the composite in the degradation of 2-propanol in the gas phase under UV and visible light (? > 420 nm) irradiation. PMID:25314607

  18. SiH/TiO2 and GeH/TiO2 Heterojunctions: Promising TiO2-based Photocatalysts under Visible Light

    PubMed Central

    Niu, Mang; Cheng, Daojian; Cao, Dapeng

    2014-01-01

    We use hybrid density functional calculations to find that the monolayer silicane (SiH) and the anatase TiO2(101) composite (i.e. the SiH/TiO2 heterojunction) is a promising TiO2-based photocatalyst under visible light. The band gap of the SiH/TiO2(101) heterojunction is 2.082?eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs. Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane. Finally, the proper interface charge distribution facilitates the carrier separation in the SiH/TiO2(101) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis. PMID:24787027

  19. Preparation and characterization of Zr-N-codoped TiO2 nano-photocatalyst and its activity enhanced-mechanism.

    PubMed

    Du, Fengwei; Yu, Shuyu

    2014-09-01

    Zr-N-codoped TiO2 nano-photocatalyst was prepared through sol-gel method using ammonia water and zirconium nitrate as the source of N and Zr, respectively. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). XRD results showed that codoping with Zr and N elements could greatly inhibit the phase transformation of TiO2 from anatase to rutile. XPS analysis indicated that Zr4+ was incorporated into the lattice of TiO2 through substituting titanium atoms. Meanwhile, N was also incorporated into the lattice of TiO2 through substituting oxygen atoms and existed in the form of N-Ti-O. DRS revealed that the light absorption edge of Zr-N-TiO2 was significantly red-shifted to visible region, leading to a narrower band gap and higher visible photocatalytic activity. The enhanced visible activity was attributed to the well anatase crystallite, intense light absorbance in visible region and narrow band gap. PMID:25924356

  20. A novel route for the production of TiO2 photocatalysts with low energy gap, via Triton-X and oleic acid surfactants

    NASA Astrophysics Data System (ADS)

    Athanasiou, A.; Mitsionis, A.; Vaimakis, T.; Pomonis, P.; Petrakis, D.; Loukatzikou, L.; Todorova, N.; Trapalis, C.; Ladas, S.

    2014-11-01

    Mesoporous anatase TiO2 photocatalysts with high specific surface area between 70 and 110 m2/g were prepared via a novel sol-gel technique using surfactants oleic acid and Triton-X in the presence or absence of diethanolamine. Titania materials showed increased photocatalytic performance in UV light. The production of active species seem to be high enough to perform the degradation of methylene blue dye solution in low catalyst concentration; and a relatively high efficiency in NO oxidation in gaseous phase. All materials prepared showed high photocatalytic activity and degradation efficiency similar or higher compared to commercial Degussa P25 material.

  1. Investigation of the antibacterial effects of silver-modified TiO2 and ZnO plasmonic photocatalysts embedded in polymer thin films.

    PubMed

    Tallósy, Szabolcs Péter; Janovák, László; Ménesi, Judit; Nagy, Elisabeth; Juhász, Ádám; Balázs, László; Deme, István; Buzás, Norbert; Dékány, Imre

    2014-10-01

    Nanosilver-modified TiO2 and ZnO photocatalysts were studied against methicillin-resistant Staphylococcus aureus on the surface and against naturally occurring airborne microorganisms. The photocatalysts/polymer nanohybrid films were prepared by spray coating technique on the surface of glass plates and on the inner surface of the reactive light source. The photoreactive surfaces were activated with visible light emitting LED light at ? = 405 nm. The optical properties of the prepared photocatalyst/polymer nanohybrid films were characterized by diffuse reflectance measurements. The photocatalytic properties were verified with the degradation of ethanol by gas chromatography measurements. The destruction of the bacterial cell wall component was examined with transmission electron microscope. The antibacterial effect of the photocatalyst/polymer nanohybrid films was tested with different methods and with the associated standard ISO 27447:2009. With the photoreactive coatings, an extensive disinfectant film was developed and successfully prepared. The cell wall component of S. aureus was degraded after 1 h of illumination. The antibacterial effect of the nanohybrid films has been proven by measuring the decrease of the number of methicillin-resistant S. aureus on the surface and in the air as the function of illumination time. The photocatalyst/polymer nanohybrid films could inactivate 99.9 % of the investigated bacteria on different thin films after 2 h of illumination with visible light source. The reactive light source with the inner-coated photocatalyst could kill 96 % of naturally occurring airborne microorganisms after 48 h of visible light illumination in indoor air sample. The TEM results and the microbiological measurements were completed with toxicity tests carried out with Vibrio fischeri bioluminescence bacterium. PMID:24497305

  2. Hydrothermal synthesis spherical TiO2 and its photo-degradation property on salicylic acid

    NASA Astrophysics Data System (ADS)

    Guo, Wenlu; Liu, Xiaolin; Huo, Pengwei; Gao, Xun; Wu, Di; Lu, Ziyang; Yan, Yongsheng

    2012-07-01

    Anatase TiO2 spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO2 consisted of well-defined spheres with size of 3-5 ?m. The photocatalytic activity of spherical TiO2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO2 which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S-1 of the salicylic acid onto TiO2 (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg-1 of the salicylic acid onto TiO2 (temperature: 150, time: 48 h).

  3. Synthesis and characterization of TiO2 loaded cashew nut shell activated carbon and photocatalytic activity on BG and MB dyes under sunlight radiation

    NASA Astrophysics Data System (ADS)

    Ragupathy, S.; Raghu, K.; Prabu, P.

    2015-03-01

    Synthesis of titanium dioxide (TiO2) nanoparticles and TiO2 loaded cashew nut shell activated carbon (TiO2/CNSAC) had been undertaken using sol-gel method and their application in BG and MB dyes removal under sunlight radiation has been investigated. The synthesized photocatalysts were characterized by X-ray diffraction analysis (XRD), Fourier infra-red spectroscopy (FT-IR), UV-Vis-diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The various experimental parameters like amount of catalyst, contact time for efficient dyes degradation of BG and MB were concerned in this study. Activity measurements performed under solar irradiation has shown good results for the photodegradation of BG and MB in aqueous solution. It was concluded that the higher photocatalytic activity in TiO2/CNSAC was due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. The kinetic data were also described by the pseudo-first-order and pseudo-second-order kinetic models.

  4. Synthesis and characterization of TiO2 loaded cashew nut shell activated carbon and photocatalytic activity on BG and MB dyes under sunlight radiation.

    PubMed

    Ragupathy, S; Raghu, K; Prabu, P

    2015-03-01

    Synthesis of titanium dioxide (TiO2) nanoparticles and TiO2 loaded cashew nut shell activated carbon (TiO2/CNSAC) had been undertaken using sol-gel method and their application in BG and MB dyes removal under sunlight radiation has been investigated. The synthesized photocatalysts were characterized by X-ray diffraction analysis (XRD), Fourier infra-red spectroscopy (FT-IR), UV-Vis-diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The various experimental parameters like amount of catalyst, contact time for efficient dyes degradation of BG and MB were concerned in this study. Activity measurements performed under solar irradiation has shown good results for the photodegradation of BG and MB in aqueous solution. It was concluded that the higher photocatalytic activity in TiO2/CNSAC was due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. The kinetic data were also described by the pseudo-first-order and pseudo-second-order kinetic models. PMID:25506648

  5. A study of parameter setting and characterization of visible-light driven nitrogen-modified commercial TiO2 photocatalysts.

    PubMed

    Kuo, Yu-Lin; Su, Te-Li; Kung, Fu-Chen; Wu, Tsai-Jung

    2011-06-15

    An optimal condition applied to the Taguchi method with an L(9) orthogonal array for preparing a visible-light driven nitrogen-modified TiO(2) (N-TiO(2)) photocatalyst by a simple hydrolysis method has been examined for material characteristics and a photodecolorization test of methyl blue (MB) under various visible light source (fluorescent and blue LED lamps) irradiations. Results of the material characterization showed that the absorption of prepared N-TiO(2) powder exhibited a significant extension into visible light regimes with an optical bandgap (Eg) of around 2.96 eV, which subsequently improved the visible-light photocatalytic activity of N-TiO(2) samples. The superior photocatalytic properties, the pseudo first-order reaction rate constants (k) and photodecolorization efficiency (?%) of a N-TiO(2) photocatalyst during the photodecolorization test of methyl blue (MB) under two different visible light irradiations were very evident compared to those for pure TiO(2). For photodecolorization of practical dyeing from the waste water from the dyeing and finishing industry, a higher photodecolorization efficiency of N-TiO(2) powder toward Direct blue-86 (DB-86) (Direct Fast Turquoise Blue GL) dye was also achieved. PMID:21555185

  6. Incorporation of N-doped TiO2 nanorods in regenerated cellulose thin films fabricated from recycled newspaper as a green portable photocatalyst.

    PubMed

    Mohamed, Mohamad Azuwa; Salleh, W N W; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Jamil, Siti Munira

    2015-11-20

    In this work, an environmental friendly RC/N-TiO2 nanocomposite thin film was designed as a green portable photocatalyst by utilizing recycled newspaper as sustainable cellulose resource. Investigations on the influence of N-doped TiO2 nanorods incorporation on the structural and morphological properties of RC/N-TiO2 nanocomposite thin film are presented. The resulting nanocomposite thin film was characterized by FESEM, AFM, FTIR, UV-vis-NIR spectroscopy, and XPS analysis. The results suggested that there was a remarkable compatibility between cellulose and N-doped TiO2 nanorods anchored onto the surface of the RC/N-TiO2 nanocomposite thin film. Under UV and visible irradiation, the RC/N-TiO2 nanocomposite thin film showed remarkable photocatalytic activity for the degradation of methylene blue solution with degradation percentage of 96% and 78.8%, respectively. It is crucial to note that the resulting portable photocatalyst produced via an environmental and green technique in its fabrication process has good potential in the field of water and wastewater treatment application. PMID:26344299

  7. Rapid construction of TiO2 aggregates using microwave assisted synthesis and its application for

    E-print Network

    Cao, Guozhong

    Rapid construction of TiO2 aggregates using microwave assisted synthesis and its application, with a size of $500 nm have been synthesized by a microwave assisted method at 150 C in a short time ($10 as the solvent and titanium precursor, respectively. The rapid heating rate and superheating/"hot spots

  8. A Designed TiO2 /Carbon Nanocomposite as a High-Efficiency Lithium-Ion Battery Anode and Photocatalyst.

    PubMed

    Peng, Liang; Zhang, Huijuan; Bai, Yuanjuan; Feng, Yangyang; Wang, Yu

    2015-10-12

    Herein, a peapod-like TiO2 /carbon nanocomposite has successfully been synthesized by a rational method for the first time. The novel nanostructure exhibits a distinct feature of TiO2 nanoparticles encapsulated inside and the carbon fiber coating outside. In the synthetic process, H2 Ti3 O7 nanotubes serve as precursors and templates, and glucose molecules act as the green carbon source. With the alliciency of hydrogen bonding between H2 Ti3 O7 and glucose, a thin polymer layer is hydrothermally assembled and subsequently converted into carbon fibers through calcinations under an inert atmosphere. Meanwhile, the precursors of H2 Ti3 O7 nanotubes are transformed into the TiO2 nanoparticles encapsulated in carbon fibers. The achieved unique nanocomposites can be used as excellent anode materials in lithium-ion batteries (LIBs) and photocatalytic reagents in the degradation of rhodamine?B. Due to the synergistic effect derived from TiO2 nanoparticles and carbon fibers, the obtained peapod-like TiO2 /carbon cannot only deliver a high specific capacity of 160?mAh?g(-1) over 500?cycles in LIBs, but also perform a much faster photodegradation rate than bare TiO2 and P25. Furthermore, owing to the low cost, environmental friendliness as well as abundant source, this novel TiO2 /carbon nanocomposite will have a great potential to be extended to other application fields, such as specific catalysis, gas sensing, and photovoltaics. PMID:26310518

  9. Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

    NASA Astrophysics Data System (ADS)

    Zhang, Yanlin; Liu, Peihong; Wu, Honghai

    2015-02-01

    One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV-vis absorption spectrum. The incorporation of N and S into TiO2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO2 nanoparticles and S-doped TiO2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron-hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600 °C.

  10. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE PAGESBeta

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipitation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400 ? nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFemore » 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol. « less

  11. Controlled synthesis and facets-dependent photocatalysis of TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Roy, Nitish; Park, Yohan; Sohn, Youngku; Pradhan, Debabrata

    2015-04-01

    Titanium dioxide (TiO2) is a wide band gap semiconductor that has been extensively used in several environmental applications including degradation of organic hazardous chemicals, water splitting to generate hydrogen, dye sensitized solar cells, self cleaning agents, and pigments. Herein we demonstrate the synthesis of TiO2 nanocrystals (NCs) with the shapes of ellipsoids, rods, cuboids, and sheets with different exposed facets using a noncorrosive and nontoxic chemical (i.e. diethanolamine) as the shape controlling agent, unlike hydrofluoric acid commonly used. The TiO2 NCs of diverse shapes with different exposed facets were tested for photocatalytic hydroxyl radical (OH•) formation, which determines their photocatalytic behavior and the results were compared with the standard P-25 Degussa. The formation rate of OH• per specific surface area was found to be >6 fold higher for rod-shaped TiO2 NCs than that of commercial Degussa P25 catalyst. The highest photocatalytic activity of rod-shaped TiO2 NCs is ascribed to the unique chemical environment of {010} exposed facets which facilitates the electron/hole separation in presence of {101} facets.

  12. TiO2 as a photocatalyst for control of the aquatic invasive alga, Cladophora, under natural and artificial light

    USGS Publications Warehouse

    Peller, J.R.; Whitman, R.L.; Griffith, S.; Harris, P.; Peller, C.; Scalzitti, J.

    2007-01-01

    Cladophora, a nuisance and invasive, filamentous algae (Chlorophyta), massively accumulates along the shores of the lower Great Lakes each summer causing great economic damage and compromising recreational opportunity and perhaps public health. In vitro experiments showed that Cladophora samples were physically and biologically degraded when subjected to TiO2-mediated photocatalysis. For the most successful photocatalytic process, TiO2 was immobilized on a glass surface and used in combination with either sunlight or artificial UV light. The loss of vital algal pigments was monitored using UV-vis spectrophotometry, and cell structural changes were determined by microscopic observation. Cladophora, in the presence of TiO2-covered glass beads, experienced a loss of chloroplast pigments after 2 h of UV lamp light irradiation. In a separate experiment, sunlight exposure over 4 days (???24 h) resulted in the complete oxidative degradation of the green chloroplast pigments, verified by the UV spectra of the algal extracts. These results suggest that TiO2, mobilized on sunlit silicates may be useful in controlling growth and survival of this alga in the Great Lakes, thus mitigating many of the economic, aesthetic ecological impacts of this invasive alga. ?? 2006 Elsevier B.V. All rights reserved.

  13. Synthesis and optical properties of TiO2-based magnetic nanocomposites

    NASA Astrophysics Data System (ADS)

    Scarisoreanu, M.; Morjan, I.; Fleaca, C.-T.; Morjan, I. P.; Niculescu, A.-M.; Dutu, E.; Badoi, A.; Birjega, R.; Luculescu, C.; Vasile, E.; Danciu, V.; Filoti, G.

    2015-05-01

    Magnetic titania nanoparticles covered/embedded in SiO2 shell/matrix were simultaneously manufactured by the single-step laser pyrolysis. The present study is a continuation of our previous investigations on the TiO2/Fe and TiO2/HMDSO (hexamethyldisiloxane) derived-systems. The aim of this work is to study the synthesis by IR (Infrared) laser pyrolysis of magnetic TiO2 based nanocomposites which implies many concurrent processes induced in the gas phase by the laser radiation. The dependence between characteristic properties and the synthesis parameters was determined by many analytical and complementary methods: XRD (X-ray diffraction) structural analysis, UV-vis (ultraviolet-visible) and EDAX (energy-dispersive X-ray) spectroscopy, TEM and HRTEM (transmission electron microscopy at low and high resolution) analysis and magnetic measurements. The results of analysis indicate the presence of disordered silica, Fe, ?-Fe2O3 and mixtures of anatase and rutile phases with mean crystallite dimensions (in the 14-34 nm range) with typical character of diluted magnetic oxide systems and a lower bandgap energy (Eg = 1.85 eV) as compared with TiO2 P25 Degussa sample.

  14. Nitrogen-doping of bulk and nanotubular TiO2 photocatalysts by plasma-assisted atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Creatore, Mariadriana; Ma, Quan-Bao; El Boukili, Aishah; Gao, Lu; Verheijen, Marcel A.; Verhoeven, M. W. G. M. (Tiny); Hensen, Emiel. J. M.

    2015-03-01

    Plasma-assisted atomic layer deposition (PA-ALD) was adopted to deposit TiO2-xNx ultrathin layers on Si wafers, calcined Ti foils and nanotubular TiO2 arrays. A range of N content and chemical bond configurations were obtained by varying the background gas (O2 or N2) during the Ti precursor exposure, while the N2/H2-fed inductively coupled plasma exposure time was varied between 2 and 20 s. On calcined Ti foils, a positive effect from N doping on photocurrent density was observed when O2 was the background gas with a short plasma exposure time (5 and 10 s). This correlates with the presence of interstitial N states in the TiO2 with a binding energy of 400 eV (Ninterst) as measured by X-ray photoelectron spectroscopy. A longer plasma time or the use of N2 as background gas results in formation of N state with a binding energy of 396 eV (Nsubst) and very low photocurrents. These Nsubst are linked to the presence of Ti3+, which act as detrimental recombination center for photo-generated electron-hole pairs. On contrary, PA-ALD treated nanotubular TiO2 arrays show no variation of photocurrent density (with respect to the pristine nanotubes) upon different plasma exposure times and when the O2 recipe was adopted. This is attributed to constant N content in the PA-ALD TiO2-xNx, regardless of the adopted recipe.

  15. Formation of TiO2 nanotubes via anodization and potential applications for photocatalysts, biomedical materials, and photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Sreekantan, Srimala; Arifah Saharudin, Khairul; Wei, Lai Chin

    2011-03-01

    One-dimensional nanotube systems with high surface-to-volume ratios possess unique properties and are thus utilized in various applications. In this study, self-organized TiO2 nanotubes were prepared by anodization of a Ti foil in glycerol containing 5 wt% ammonium fluoride (NH4F) and 6 wt% ethylene glycol (EG). The surface morphology, average inner diameter, and average length of the nanotubes varied with the electrochemical anodization parameters. Nanotubes with uniform surface morphologies, an average diameter of 85 nm, and an average length of 1.1 ?m were obtained at 30 V for 1 h The as-prepared nanotubes were amorphous but they crystallized in the anatase phase after heating at about 400 °C for 2 h in an argon atmosphere. The photocatalytic activity of the TiO2 nanotubes was evaluated through the degradation of methyl orange (MO) and by investigating their bactericidal effect. Optimum photocatalysis of MO was achieved at a kinetic rate constant of 10-3 min-1. Furthermore, cell viability rapidly decreased on UV illumination and complete killing was achieved at 60 min in the presence of TiO2 nanotubes. For biomedical applications, the cellular activity on TiO2 nanotubes was determined using PA6 cells. Higher cellular activities were achieved using the anatase phase of 85-nm-diameter nanotubes than the amorphous phase. Photoelectrochemical hydrogen generation was investigated using nanotube photoanodes in 1 M potassium hydroxide (KOH) containing 1 wt% EG and xenon lamp. The maximum photocurrent density was 0.55 mA/cm2. These findings demonstrate that TiO2 nanotubes are promising for use in multifunctional applications.

  16. Facile synthesis of TiO2/trititanate heterostructure with enhanced photoelectric efficiency for an improved photocatalysis

    NASA Astrophysics Data System (ADS)

    Chen, Feitai; Li, Youji; Liu, Zhi; Fang, Pengfei

    2015-06-01

    TiO2/trititanate photocatalyst was prepared by alkaline hydrothermal treatment of TiO2, and characterized by transmission electron microscopy, X-ray diffraction, and Raman etc. The photocatalytic activities of catalysts were evaluated by the photocatalytic degradation of rhodamine B (RhB). It is found that the heterostructure can be directly formed via the conversion of surface TiO2 into trititanate. The coupled nanostructure possesses enhanced adsorption ability for RhB as compared with the raw TiO2, owing to the formation of an increased amount of hydroxyl groups on the prepared catalyst surface. Besides, the generated trititanate can successfully introduce a shallow energy level in the coupled composite, which results in the improvement of separation efficiency of photoinduced electron-hole pairs. In the degradation experiments, TiO2/trititanate exhibits much higher photocatalytic activity than the bare TiO2. These advantages of the coupled nanostructure in adsorption capacity and photoelectric efficiency may make it a wider application for the removal of organic pollutants.

  17. Synthesis of highly-ordered TiO2 nanotube arrays with tunable sizes

    NASA Astrophysics Data System (ADS)

    Wang, Xian; Zha, Chenyang; Ji, Cheng; Zhang, Xiaoyan; Shen, Liming; Wang, Yifeng; Gupta, Arunava; Yoriya, Sorachon; Bao, Ningzhong

    2014-09-01

    Vertically-oriented one-dimensional TiO2 nanotube (TNT) arrays have been fabricated by anodic oxidation using different electrolyte solvents, including ethylene glycol (EG), diethylene glycol (DEG), and dimethyl sulfoxide (DMSO), in the presence of hydrofluoric acid (HF) or ammonium fluoride (NH4F). The influence of synthetic conditions, including the nature of the electrolyte and anodization voltage, on nanotube microstructure has been systematically investigated. Highly-ordered TNTs with tube length of ˜0.5-26.7 ?m, inner diameter of ˜13-201 nm, and outer diameter of ˜28-250 nm have been obtained. The conversion of as-prepared TNT arrays from amorphous phase to crystalline structure has been achieved by a post-synthetic annealing at 500 °C for 3 h in oxygen ambient. The TNT arrays with tunable sizes and structures are attractive for use as electrode materials in fabrication of thin film solar cells and highly active photocatalysts.

  18. TiO2 nanotubes: recent advances in synthesis and gas sensing properties.

    PubMed

    Galstyan, Vardan; Comini, Elisabetta; Faglia, Guido; Sberveglieri, Giorgio

    2013-01-01

    Synthesis--particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes. PMID:24184919

  19. TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

    PubMed Central

    Galstyan, Vardan; Comini, Elisabetta; Faglia, Guido; Sberveglieri, Giorgio

    2013-01-01

    Synthesis—particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes. PMID:24184919

  20. Highly reactive {001} facets of TiO2-based composites: synthesis, formation mechanism and characterization

    NASA Astrophysics Data System (ADS)

    Ong, Wee-Jun; Tan, Lling-Lling; Chai, Siang-Piao; Yong, Siek-Ting; Mohamed, Abdul Rahman

    2014-01-01

    Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are thoroughly examined, with additional insights related to the charge transfer events for each strategy of the modified-TiO2 composites. Finally, we offer a summary and some invigorating perspectives on the major challenges and new research directions for future exploitation in this emerging frontier, which we hope will advance us to rationally harness the outstanding structural and electronic properties of {001} facets for various environmental and energy-related applications.

  1. Highly reactive {001} facets of TiO2-based composites: synthesis, formation mechanism and characterization.

    PubMed

    Ong, Wee-Jun; Tan, Lling-Lling; Chai, Siang-Piao; Yong, Siek-Ting; Mohamed, Abdul Rahman

    2014-02-21

    Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are thoroughly examined, with additional insights related to the charge transfer events for each strategy of the modified-TiO2 composites. Finally, we offer a summary and some invigorating perspectives on the major challenges and new research directions for future exploitation in this emerging frontier, which we hope will advance us to rationally harness the outstanding structural and electronic properties of {001} facets for various environmental and energy-related applications. PMID:24384624

  2. Solvothermal synthesis of carbon coated N-doped TiO2 nanostructures with enhanced visible light catalytic activity

    NASA Astrophysics Data System (ADS)

    Yan, Xue-Min; Kang, Jialing; Gao, Lin; Xiong, Lin; Mei, Ping

    2013-01-01

    Visible light-active carbon coated N-doped TiO2 nanostructures(CTS-TiO2) were prepared by a facile one-step solvothermal method with chitosan as carbon and nitrogen resource at 180 °C. The as-prepared samples were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. The CTS-TiO2 nanocomposites possess anatase phase of nanocrystalline structure with average particle size of about 5-7 nm. A wormhole mesostructure can be observed in the CTS-TiO2 nanocomposites due to the constituent agglomerated of nanoparticles. It has been evidenced that the nitrogen was doped into the anatase titania lattice and the carbon species were modified on the surface of TiO2. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methylene blue (MB) under visible light irradiation at ? ? 400 nm. The results show that CTS-TiO2 nanostructures display a higher visible light photocatalytic activity than pure TiO2, commercial P25 and C-coated TiO2 (C-TiO2) photocatalysts. The higher photocatalytic activity could be attributed to the band-gap narrowed by N-doping and the accelerated separation of the photo-generated electrons and holes by carbon modification.

  3. TiO 2/carbon nanotube hybrid nanostructures: Solvothermal synthesis and their visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Tian, Lihong; Ye, Liqun; Deng, Kejian; Zan, Ling

    2011-06-01

    MWCNT/TiO 2 hybrid nanostructures were prepared via solvothermal synthesis and sol-gel method with benzyl alcohol as a surfactant. As-prepared hybrid materials were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results showed that MWCNTs were uniformly decorated with anatase nanocrystals in solvothermal condition, but MWCNTs were embedded in a majority of TiO 2 nanoparticles by sol-gel method. When the weight ratio of MWCNTs to TiO 2 was 20%, MWCNT/TiO 2 hybrid nanostructures prepared by solvothermal synthesis exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. Post-annealing of MWCNT/TiO 2 nanostructures at 400 °C resulted in the formation of the carbonaceous Ti-C bonds on the interface between TiO 2 and MWCNTs, which enhanced the photoabsorbance of the hybrid materials in the visible light region and improved the visible-light degradation efficiency of methylene blue.

  4. Electronic basis of visible region activity in high area Sn-doped rutile TiO2 photocatalysts.

    PubMed

    Oropeza, Freddy E; Davies, Bethan; Palgrave, Robert G; Egdell, Russell G

    2011-05-01

    The influence of Sn doping on the anatase-to-rutile phase transition has been investigated in high area powders prepared by a sol-gel route involving alkoxide precursors. Sn doping facilitates conversion of anatase to rutile at lower temperatures than observed for undoped material. At the same time Sn-doping inhibits sintering as gauged by line widths in X-ray diffraction and gas-adsorption surface area measurements. These observations are linked to the finding of pronounced segregation of Sn to the surface of rutile TiO(2) observed in X-ray photoemission spectra. Sn-doped TiO(2) is found to exhibit enhanced visible region photocatalytic activity as compared with undoped material in dye degradation experiments. This is attributed to narrowing of the bulk bandgap at low doping levels coupled with the introduction of surface states associated with segregated Sn ions in the divalent state. The Sn(II) surface states lie above the top of the main valence band and can therefore act as trapping sites for holes produced under photoexcitation. PMID:21445426

  5. Facile synthesis of the Ti3+ self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis

    PubMed Central

    Qiu, Bocheng; Zhou, Yi; Ma, Yunfei; Yang, Xiaolong; Sheng, Weiqin; Xing, Mingyang; Zhang, Jinlong

    2015-01-01

    This study developed a facile approach for preparing Ti3+ self-doped TiO2-graphene photocatalyst by a one-step vacuum activation technology involved a relative lower temperature, which could be activated by the visible light owing to the synergistic effect among Ti3+ doping, some new intersurface bonds generation and graphene oxide reduction. Compared with the traditional methods, the vacuum activation involves a low temperature and low-costing, which can achieve the reduction of GO, the self doping of Ti3+ in TiO2 and the loading of TiO2 nanoparticles on GR surface at the same time. These resulting TiO2-graphene composites show the high photodegradation rate of MO, high hydrogen evolution activity and excellent IPCE in the visible light irradiation. The facile vacuum activation method can provide an effective and practical approach to improve the performance of TiO2-graphene and other metal oxides-graphene towards their practical photocatalytic applications. PMID:25716132

  6. Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: the impact of wastewater components.

    PubMed

    Wang, Dawei; Li, Yi; Li Puma, Gianluca; Wang, Chao; Wang, Peifang; Zhang, Wenlong; Wang, Qing

    2015-03-21

    The effect of the water matrix components of a secondary effluent of a urban wastewater treatment plant on the photocatalytic activity of Ag/AgCl @ chiral TiO2 nanofibers and the undergoing reaction mechanisms were investigated. These effects were evaluated through the water components-induced changes on the net rate of hydroxyl radical (?OH) generation and modeled using a relative rate technique. Dissolved organic matter DOM (k=-2.8×10(8) M(-1) s(-1)) scavenged reactive oxygen species, Cl(-) (k=-5.3×10(8) M(-1) s(-1)) accelerated the transformation from Ag to AgCl (which is not photocatalytically active under visible-light irradiation), while Ca(2+) at concentrations higher than 50 mM (k=-1.3×10(9) M(-1) s(-1)) induced aggregation of Ag/AgCl and thus all of them revealed inhibitory effects. In contrast, NO3(-) (k=6.9×10(8) M(-1) s(-1)) and CO3(2-) (k=3.7×10(8) M(-1) s(-1)) improved the photocatalytic activity of Ag/AgCl slightly by improving the rate of HO? generation. Other ubiquitous secondary effluent components including SO4(2-) (k=3.9×10(5) M(-1) s(-1)), NH3(+) (k=3.5×10(5) M(-1) s(-1)) and Na(+) (k=2.6×10(4) M(-1) s(-1)) had negligible effects. 90% of 17-?-ethynylestradiol (EE2) spiked in the secondary effluent was removed within 12 min, while the structure and size of Ag/AgCl @ chiral TiO2 nanofibers remained stable. This work may be helpful not only to uncover the photocatalytic mechanism of Ag/AgCl based photocatalyst but also to elucidate the transformation and transportation of Ag and AgCl in natural water. PMID:25524623

  7. A facile one-step solvothermal synthesis of graphene/rod-shaped TiO2 nanocomposite and its improved photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Dong, Pengyu; Wang, Yuhua; Guo, Linna; Liu, Bin; Xin, Shuangyu; Zhang, Jia; Shi, Yurong; Zeng, Wei; Yin, Shu

    2012-07-01

    Graphene sheets were obtained through solvothermal reduction of colloidal dispersion of graphene oxide in benzyl alcohol. The graphene/rod-shaped TiO2 nanocomposite was synthesized by this novel and facile solvothermal method. During the solvothermal reaction, both the reduction of graphene oxide and the growth of rod-shaped TiO2 nanocrystals as well as its deposition on graphene occur simultaneously. The photocatalytic activity of graphene/rod-shaped TiO2 and graphene/spherical TiO2 nanocomposites was compared. In the photocatalytic degradation of methyl orange (MO), the graphene/rod-shaped TiO2 nanocomposite with the optimized graphene content of 0.48 wt% shows good stability and exhibits a significant enhancement of photocatalytic activity compared to the bare commercial TiO2 (P25) and graphene/spherical TiO2 nanocomposite with the same graphene content. Photocurrent experiments were performed, which demonstrate that the photocurrent of the graphene/rod-shaped TiO2 nanocomposite electrode is about 1.2 times as high as that of the graphene/spherical TiO2 nanocomposite electrode. The photocatalytic mechanism of graphene/rod-shaped TiO2 nanocomposite was also discussed on the basis of the experimental results. This work is anticipated to open a possibility in the integration of graphene and TiO2 with various morphologies for obtaining high-performance photocatalysts in addressing environmental protection issues.Graphene sheets were obtained through solvothermal reduction of colloidal dispersion of graphene oxide in benzyl alcohol. The graphene/rod-shaped TiO2 nanocomposite was synthesized by this novel and facile solvothermal method. During the solvothermal reaction, both the reduction of graphene oxide and the growth of rod-shaped TiO2 nanocrystals as well as its deposition on graphene occur simultaneously. The photocatalytic activity of graphene/rod-shaped TiO2 and graphene/spherical TiO2 nanocomposites was compared. In the photocatalytic degradation of methyl orange (MO), the graphene/rod-shaped TiO2 nanocomposite with the optimized graphene content of 0.48 wt% shows good stability and exhibits a significant enhancement of photocatalytic activity compared to the bare commercial TiO2 (P25) and graphene/spherical TiO2 nanocomposite with the same graphene content. Photocurrent experiments were performed, which demonstrate that the photocurrent of the graphene/rod-shaped TiO2 nanocomposite electrode is about 1.2 times as high as that of the graphene/spherical TiO2 nanocomposite electrode. The photocatalytic mechanism of graphene/rod-shaped TiO2 nanocomposite was also discussed on the basis of the experimental results. This work is anticipated to open a possibility in the integration of graphene and TiO2 with various morphologies for obtaining high-performance photocatalysts in addressing environmental protection issues. Electronic supplementary information (ESI) available: The TEM images of as-prepared pure rod-shaped TiO2 nanocrystals and the other graphene/rod-shaped TiO2 nanocomposites, the MO adsorption isotherms, the XRD pattern, TEM image and UV-vis diffuse reflectance spectrum of graphene/spherical TiO2 nanocomposite with the graphene content of 0.48 wt%, photocatalytic degradation of MO solution over graphene/spherical TiO2 nanocomposites, and plots of ln(C0/C) versus irradiation time for graphene/rod-shaped TiO2 and graphene/spherical TiO2 nanocomposites. See DOI: 10.1039/c2nr31231j

  8. A novel synthesis method for TiO2 particles with magnetic Fe3O4 cores.

    PubMed

    Dong, Qi; Zhang, Keqiang; An, Yi

    2014-01-01

    TiO2@(AC/Fe3O4) (AC is activated carbon) was prepared by using AC and Fe3O4 as joint support. The morphological features, crystal structure, and magnetism of the final product were characterized. The results indicate that TiO2 particles formed on the surface of AC and Fe3O4; the sizes of TiO2 and Fe3O4 were 0.5 and 0.7 ?m respectively, and that of AC fell within a wide range. The highly crystalline cubic structures of the TiO2 particles was in accord with the standard X-ray diffractometry spectrum of magnetite and anatase. The maximum saturation magnetization of TiO2@(AC/Fe3O4) was 75 emu g(-1), which was enough to support magnetic recovery. The rate of methylene blue (MB) removal photocatalyzed by TiO2@(AC/Fe3O4) was higher by 50% than that achieved with AC/Fe3O4 photocatalysis, and similar to that achieved with TiO2@AC. The removal rate (kobs) decreased drastically from 1.77 × 10(-2) to 9.36 × 10(-3)min(-1) when the initial concentration of MB solution increased from 2.0 to 5.0 mg L(-1). The kobs value increased from 9.41 × 10(-3) to 1.34 × 10(-2)min(-1) with increasing photocatalyst dosage from 0.2 to 1.0 g, then slightly decreased to 1.33 × 10(-2)min(-1) at 2.0 g dosage. PMID:24845326

  9. TiO2/vanadate (Sr10V6O25, Ni3V2O8, Zn2V2O7) heterostructured photocatalysts with enhanced photocatalytic activity for photoreduction of CO2 into CH4.

    PubMed

    Yan, Yabin; Yu, Yanlong; Wu, Di; Yang, Yajun; Cao, Yaan

    2015-12-23

    A series of TiO2/vanadate (Sr10V6O25, Ni3V2O8, Zn2V2O7) heterostructured photocatalysts were prepared by a simple sol-gel method. The theoretical calculations imply the possible energy band match between TiO2 and vanadates. Characterized by XRD, Raman, TEM, EDX, XPS, absorption spectra, PL and time-resolved PL decay curves, it is revealed that the vanadates, which exist on the surface of TiO2, could suppress the recombination of charge carriers, prolong the life-time of photogenerated electrons and provide surface reactive hole sites, improving the photocatalytic activity for photo-reduction of CO2 into CH4. PMID:26662343

  10. Efficient phyto-synthesis and structural characterization of rutile TiO2 nanoparticles using Annona squamosa peel extract

    NASA Astrophysics Data System (ADS)

    Roopan, Selvaraj Mohana; Bharathi, A.; Prabhakarn, A.; Abdul Rahuman, A.; Velayutham, K.; Rajakumar, G.; Padmaja, R. D.; Lekshmi, Mohan; Madhumitha, G.

    2012-12-01

    In the present study, the biosynthesis of rutile TiO2 nanoparticles (TiO2 NPs) was achieved by a novel, biodegradable and convenient procedure using fruit peel Annona squamosa aqueous extract. This is the first report on the new, simple, rapid, eco-friendly and cheaper methods for the synthesis of rutile TiO2 NPs at lower temperature using agricultural waste. Rutile TiO2 NPs were characterized by UV, XRD, SEM, TEM and EDS studies. The UV-Vis spectrophotometer results were promising and showed a rapid production of TiO2 NPs with a surface plasmon resonance occurring at 284 nm. The formation of the TiO2 NPs as observed from the XRD spectrum is confirmed to be TiO2 particles in the rutile form as evidenced by the peaks at 2? = 27.42°, 36.10°, 41.30° and 54.33° when compared with the literature. The TEM images showed polydisperse nanoparticles with spherical shapes and size 23 ± 2 nm ranges.

  11. Enhanced visible-light-driven photocatalytic inactivation of Escherichia coli using g-C3N4/TiO2 hybrid photocatalyst synthesized using a hydrothermal-calcination approach.

    PubMed

    Li, Guiying; Nie, Xin; Chen, Jiangyao; Jiang, Qi; An, Taicheng; Wong, Po Keung; Zhang, Haimin; Zhao, Huijun; Yamashita, Hiromi

    2015-12-01

    Biohazards are widely present in wastewater, and contaminated water can arouse various waterborne diseases. Therefore, effectively removing biohazards from water is a worldwide need. In this study, a novel visible-light-driven (VLD) graphitic carbon nitride (g-C3N4)/TiO2 hybrid photocatalyst with high photocatalytic bacterial inactivation activity was successfully synthesized using a facile hydrothermal-calcination approach. The optimum synthesized hybrid photocatalyst is composed of micron-sized TiO2 spheres (average diameter: ca. 2 ?m) and wrapped with lamellar g-C3N4 (thickness: ca. 2 nm), with narrowing bandgap (ca. 2.48 eV), leading to a significant improvement of visible light (VL) absorption and effective separation of photo-generated electron-hole pairs. This greatly enhances VL photocatalytic inactivation activity towards bacteria in water. Using this hybrid photocatalyst, 10(7) cfu mL(-1) of Escherichia coli K-12 could be completely inactivated within 180 min under VL irradiation. SEM images indicate that bacterial cells were greatly damaged, leading to a severe leakage of intracellular components during photocatalytic inactivation processes. The study concludes that bacterial cell destruction and water disinfection can be achieved using this newly fabricated VLD hybrid photocatalyst. PMID:26084941

  12. Directed synthesis of mesoporous TiO2 microspheres: catalysts and their photocatalysis for bisphenol A degradation.

    PubMed

    Guo, Changsheng; Ge, Ming; Liu, Lu; Gao, Guandao; Feng, Yinchang; Wang, Yuqiu

    2010-01-01

    This paper describes the fabrication of two different 3D mesoporous TiO2 microspheres via one-step solvothermal process without templates using different titanium sources. The resulting materials were characterized by XRD, FESEM, TEM, and nitrogen adsorption techniques. Their photodegradation of bisphenol A [2,2-bis(4-hydroxyphenyl)propane, BPA] in aqueous suspension was investigated under UV irradiation. The experimental results revealed that the photocatalytic effect of the two 3D mesoporous TiO2 microspheres was superior to the commercial P25 TiO2, and as-prepared samples as catalysts demonstrated that the smaller pore size it is, the higher the effective degradation for BPA is. Particular attention was paid to the identification of intermediates and analysis of photocatalytic degradation mechanism of BPA by HPLC-MS and HPLC-MS-MS. Five main intermediates were formed during photocatalytic degradation, and their evolution was discussed. On the basis of the evidence of oxidative intermediate formation, a detailed degradation pathway of BPA degradation by two mesoporous TiO2 microspheres photocatalysts are proposed. PMID:19928897

  13. THERMALLY STABLE NANOCRYSTALLINE TIO2 PHOTOCATALYSTS SYNTHESIZED VIA SOL-GEL METHODS MODIFIED WITH IONIC LIQUID AND SURFACTANT MOLECULES

    EPA Science Inventory

    Recently, sol-gel methods employing ionic liquids (ILs) have shown significant implications for the synthesis of well-defined nanostructured inorganic materials. Herein, we synthesized nanocrystalline TiO2 particles via an alkoxide sol-gel method employing a water-immi...

  14. Green synthesis of highly crystalline and visible-light sensitive C-, N- and S- codoped with Ag TiO2 nanocatalyst

    EPA Science Inventory

    Titanium dioxide (TiO2) has been a focus of attention as chemically stable, relatively nontoxic, inexpensive and highly efficient photocatalyst applicable for a wide array of uses. However, main disadvantage that severely limits its wider use is the large band gap, 3.0 eV and 3.2...

  15. Microwave-assisted synthesis and photocatalytic properties of sulphur and platinum modified TiO2 nanofibers

    NASA Astrophysics Data System (ADS)

    Drunka, R.; Grabis, J.; Jankovica, Dz; Krumina, A.; Rasmane, Dz

    2015-03-01

    In the present work formation of active TiO2 nanofibers in microwave synthesis and their modification with platinum were studied. Mixture of anatase and rutile nanopowder and 10M KOH solution were used as raw materials. Microwave assisted synthesis method permitted to obtain TiO2 nanofibres with a diameter of 10nm and a specific surface area up to 40.2 m2/g. In order to modify TiO2 nanofibers with platinum it was stirred in H2PtCl6 solution and illuminated with UV irradiation or reduced with sodium boronhydride. To modify titania with sulphur and prepare co-doped nanofibers platinum doped samples were extra treated in hydrogen sulphide atmosphere. Photocatalytic activity was determined by degradation of the methylene blue (MB) solution under UV and visible light irradiation. The obtained samples showed higher photocatalytic activity with respect to pure TiO2 nanofibers. The doped TiO2 nanofibers were appropriate for degradation of harmful organic compounds.

  16. Nanomaterial synthesis and characterization for toxicological studies: TiO2 case study

    USGS Publications Warehouse

    Valsami-Jones, E.; Berhanu, D.; Dybowska, A.; Misra, S.; Boccaccini, A.R.; Tetley, T.D.; Luoma, S.N.; Plant, J.A.

    2008-01-01

    In recent years it has become apparent that the novel properties of nanomaterials may predispose them to a hitherto unknown potential for toxicity. A number of recent toxicological studies of nanomaterials exist, but these appear to be fragmented and often contradictory. Such discrepancies may be, at least in part, due to poor description of the nanomaterial or incomplete characterization, including failure to recognise impurities, surface modifications or other important physicochemical aspects of the nanomaterial. Here we make a case for the importance of good quality, well-characterized nanomaterials for future toxicological studies, combined with reliable synthesis protocols, and we present our efforts to generate such materials. The model system for which we present results is TiO2 nanoparticles, currently used in a variety of commercial products. ?? 2008 The Mineralogical Society.

  17. Application of microwave superheating for the synthesis of TiO2 rods.

    PubMed

    Pol, Vilas G; Langzam, Yaakov; Zaban, Arie

    2007-10-23

    A simple microwave irradiation method for the large-scale synthesis of submicrometer-sized TiO2 rods at normal atmospheric pressure and the boiling temperature of the solvent is demonstrated. It is emphasized that only 1-3 min of microwave irradiation is adequate to react tetra-isopropyl orthotitanate with ethylene glycol to produce rods of titanium glycolate [TG] with diameters of approximately 0.4 microm and lengths up to 5 microm. The as-formed TG rods, followed by calcination under air for 2 h, fabricated anatase (500 degrees C) and rutile (900 degrees C) titania without changing their rod-shaped morphology. The crystallinity, structure, morphology, and thermal analysis are carried out by several techniques. A mechanism based on microwave superheating phenomena is presented with the support of previous reports and several control experiments. PMID:17892315

  18. Nanocomposite of a chromium Prussian blue with TiO2. Redox reactions and the synthesis of Prussian blue

    E-print Network

    Girolami, Gregory S.

    Nanocomposite of a chromium Prussian blue with TiO2. Redox reactions and the synthesis of Prussian similar to those of the ``all-chromium'' Prussian blue CrII [CrIII (CN)6]0.67 Æ 6H2O. All data, including to generate the crystalline all-chromium PB species. The electrochemical potentials suggest that the [Cr

  19. Facile synthesis of TiO2/microcrystalline cellulose nanocomposites: photocatalytically active material under visible light irradiation

    EPA Science Inventory

    Doped TiO2 nanocomposites were prepared in situ by a facile and simple synthesis utilizing benign and renewable precursors such as microcrystalline cellulose (MC) and TiCl4 through hydrolysis in alkaline medium without the addition of organic solvents. The as-prepared nanocompos...

  20. Synthesis of TiO2-poly(3-hexylthiophene) hybrid particles through surface-initiated Kumada catalyst-transfer polycondensation.

    PubMed

    Boon, Florian; Moerman, David; Laurencin, Danielle; Richeter, Sébastien; Guari, Yannick; Mehdi, Ahmad; Dubois, Philippe; Lazzaroni, Roberto; Clément, Sébastien

    2014-09-30

    TiO2/conjugated polymers are promising materials in solar energy conversion where efficient photoinduced charge transfers are required. Here, a "grafting-from" approach for the synthesis of TiO2 nanoparticles supported with conjugated polymer brushes is presented. Poly(3-hexylthiophene) (P3HT), a benchmark material for organic electronics, was selectively grown from TiO2 nanoparticles by surface-initiated Kumada catalyst-transfer polycondensation. The grafting of the polymer onto the surface of the TiO2 nanoparticles by this method was demonstrated by (1)H and (13)C solid-state NMR, X-ray photoelectron spectrometry, thermogravimetric analysis, transmission electron microscopy, and UV-visible spectroscopy. Sedimentation tests in tetrahydrofuran revealed improved dispersion stability for the TiO2@P3HT hybrid material. Films were produced by solvent casting, and the quality of the dispersion of the modified TiO2 nanoparticles was evaluated by atomic force microscopy. The dispersion of the P3HT-coated TiO2 NPs in the P3HT matrix was found to be homogeneous, and the fibrillar structure of the P3HT matrix was maintained which is favorable for charge transport. Fluorescence quenching measurements on these hybrid materials in CHCl3 indicated improved photoinduced electron-transfer efficiency. All in all, better physicochemical properties for P3HT/TiO2 hybrid material were reached via the surface-initiated "grafted-from" approach compared to the "grafting-onto" approach. PMID:25188446

  1. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    PubMed Central

    Banerjee, Arghya Narayan

    2011-01-01

    Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and organic synthesis. PMID:24198485

  2. Photochemical synthesis, characterization and enhanced visible light induced photocatalysis of Ag modified TiO2 nanocatalyst.

    PubMed

    Ko, Seonghyuk

    2014-09-01

    Nanocomposite of titania (TiO2) and silver (Ag) has been synthesized by a photochemical deposition method. We investigated the simultaneous enhancement of visible light sensitivity and photocatalytic activities of as-prepared Ag-TiO2 nanocomposite photocatalyst. The resulting Ag-TiO2 nanomaterials were characterized by various analytical techniques including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). Photocatalytic activity was evaluated by decomposition of methylene blue (MB) dye solution under simulated visible light irradiation. Ag nanoparticles were well dispersed on the surface of TiO2 and composite nanoparticles were effectively enhanced in visible light-induced photocatalytic activity compared to that of Ag free TiO2. It was found that the enhanced activity is result from simultaneous effects of nano-Ag deposits by increasing the absorption capacity in visible region and by acting as electron trappers to promote charge separation of photoinduced electrons (e-) and holes (h+). The effect of the amount of Ag nanoparticles on its photoactivity under simulated visible light was also investigated. PMID:25924350

  3. Photovoltaic performance of dye-sensitized solar cells using TiO2 nanotubes aggregates produced by hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Chen, Qiufan; Sun, Xiaonan; Liu, Anping; Zhang, Qifeng; Cao, Guozhong; Zhou, Xiaoyuan

    2015-09-01

    This paper reports the synthesis, detailed structural characterization of aggregated TiO2 nanotubes and the application of such aggregated TiO2 nanotubes as photoelectrodes in solar cells (dye sensitized DSCs). A maximum overall conversion efficiency of 7.9% has been achieved, which use conventional dyes without any additional chemical treatments under circumstances of an open-circuit voltage of 710 mV, a short-circuit current density of 16.8mA/cm2, and a fill factor of 66%. This impressive performance is believed to attribute to the micron-sized aggregate structure which may be favorable for light harvesting, the desired high specific surface area and pure anatase phase for dye absorption. This significant improvement in the conversion efficiency indicates that DSCs based on aggregated TiO2 nanotubes are a promising alternative to semiconductor-based solar cells.

  4. Fabrication, characterization and application of a reusable immobilized TiO2-PANI photocatalyst plate for the removal of reactive red 4 dye

    NASA Astrophysics Data System (ADS)

    Razak, S.; Nawi, M. A.; Haitham, K.

    2014-11-01

    A method for immobilizing TiO2-PANI composite using ENR and PVC as adhesives was successfully developed. The immobilized system known as TiO2/PANI/ENR/PVC plate was characterized by FTIR, Raman, diffuse reflectance UV-vis, photo luminescence spectroscopy and HRTEM. The optimum weight ratio for the TiO2:PANI composite was 1:0.0035. The band gap energy of the optimum immobilized composite TiO2/PANI/ENR/PVC (1:0035) was 2.86 eV where polyaniline (PANI) formed a core-shell coating of about 0.9 nm with a strong TiO2-PANI interaction. Photo-etching of the immobilized TiO2/PANI/ENR/PVC (1:0.0035) composite for 7 h increased its surface area and improved its photocatalytic activity. TiO2/PANI/ENR/PVC (1:0.0035)-7 h was visible light sensitive where 85% of 30 mg L-1 reactive red 4 (RR4) dye was decolorized after 60 min of irradiation. The immobilized TiO2/PANI/ENR/PVC (1:0.0035)-7 h was reusable and its photocatalytic activity was sustainable with an average pseudo first order rate constant value of 0.103 ± 0.002 min-1. Adding PANI to the immobilized P25 TiO2 has enhanced its photocatalytic activity throughout the entire ten recycled applications due to the increased BET surface area and lower ecb and h+ recombination.

  5. Microemulsion-mediated hydrothermal synthesis of photocatalytic TiO2 powders.

    PubMed

    Lu, Chung-Hsin; Wu, Wei-Hong; Kale, Rohidas B

    2008-06-15

    A reverse microemulsion-mediated hydrothermal route has been employed to synthesize photocatalytic titanium dioxide (TiO2) powders. Nano-crystalline monophasic anatase TiO2 powders were successfully prepared when the microemulsion-derived precursors were hydrothermally treated. The advantage of using this microemulsion mediated hydrothermal route is the significant reduction in reaction time and temperatures as compared with the conventional hydrothermal process. The oil/water emulsion ratio significantly affected the particle sizes of the obtained TiO2 powders. The specific surface area of TiO2 powders was increased with the oil/water ratio, thereby leading to enhanced photocatalytic activity of TiO2 powders. As the hydrothermal temperature was elevated, the morphology of the TiO2 particles changed from a rod-like shape into a polyhedral shape. The variation in microstructures decreased the specific surface area of the TiO2 powders and lowered the photocatalytic activity. PMID:18077085

  6. Enhanced catalytic activity of the surface modified TiO2-MWCNT nanocomposites under visible light.

    PubMed

    Boži?, Mojca; Vivod, Vera; Vogrin?i?, Robert; Ban, Irena; Jakša, Gregor; Hribernik, Silvo; Fakin, Darinka; Kokol, Vanja

    2016-03-01

    Fusing multiwall carbon nanotubes (MWCNTs) with TiO2 at the nano-scale level promotes the separation of those electron-hole charges generated upon UV and daylight irradiation. In this study, we investigated facile sonochemical synthesis, combined with the calcination process for the preparations of TiO2-MWCNT composites with different mole ratios of titanium and carbon. In order to produce stable nano dispersions we exploited an innovative biotechnology-based approach for the covalent functionalizations of TiO2-MWCNTs with in-situ synthesized soluble phenoxazine dye molecules. The none and functionalized TiO2-MWCNTs composites were analyzed by a range of analytical techniques including XRD, Raman, XPS, SEM and UV-vis diffuse reflectance spectroscopy (DRS), and dynamic light scattering (DLS). The photocatalytic activity was evaluated toward the liquid-phase degradation of MB in aqueous solution under both UV and visible light irradiation. TiO2-MWCNTs with optimized mole ratio exhibit much higher photocatalytic activity and stability than bare TiO2. The as-prepared TiO2-MWCNTs photocatalyst possessed good adsorptivity of dyes, extended light absorption range and efficient charge separation properties simultaneously. The results indicated that the soluble phenoxazine dyes and amino-benzenesulfonic acid monomers were covalently grafted on to the surfaces of TiO2-MCNTs, which promoted good aquatic dispersibility and extended light absorption, resulting in increased photocatalytic efficiency. PMID:26669495

  7. Visible Light-Driven Photocatalytic Activity of Oleic Acid-Coated TiO2 Nanoparticles Synthesized from Absolute Ethanol Solution.

    PubMed

    Li, Huihui; Liu, Bin; Yin, Shu; Sato, Tsugio; Wang, Yuhua

    2015-12-01

    The one-step synthesis of oleic acid-coated TiO2 nanoparticles with visible light-driven photocatalytic activity was reported by this manuscript, using oleic acid-ethanol as crucial starting materials. The photocatalytic degradation of nitrogen monoxide (deNOx) in the gas phase was investigated in a continuous reactor using a series of TiO2 semiconductors, prepared from oleic acid- or acetic acid-ethanol solution. The surface modification on TiO2 by organic fatty acid, oleic acid, could reinvest TiO2 photocatalyst with the excellent visible light response. The deNOx ability is almost as high as 30 % destruction in the visible light region (??>?510 nm) which is similar to the nitrogen-doped TiO2. Meanwhile, acetic acid, a monobasic acid, has a weaker ability on visible light modification of TiO2. PMID:26494237

  8. Visible Light-Driven Photocatalytic Activity of Oleic Acid-Coated TiO2 Nanoparticles Synthesized from Absolute Ethanol Solution

    NASA Astrophysics Data System (ADS)

    Li, Huihui; Liu, Bin; Yin, Shu; Sato, Tsugio; Wang, Yuhua

    2015-10-01

    The one-step synthesis of oleic acid-coated TiO2 nanoparticles with visible light-driven photocatalytic activity was reported by this manuscript, using oleic acid-ethanol as crucial starting materials. The photocatalytic degradation of nitrogen monoxide (deNOx) in the gas phase was investigated in a continuous reactor using a series of TiO2 semiconductors, prepared from oleic acid- or acetic acid-ethanol solution. The surface modification on TiO2 by organic fatty acid, oleic acid, could reinvest TiO2 photocatalyst with the excellent visible light response. The deNOx ability is almost as high as 30 % destruction in the visible light region ( ? > 510 nm) which is similar to the nitrogen-doped TiO2. Meanwhile, acetic acid, a monobasic acid, has a weaker ability on visible light modification of TiO2.

  9. Synthesis of TiO 2(B) using glycolato titanium complex and post-synthetic hydrothermal crystal growth of TiO 2(B)

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Tomita, K.; Fujita, K.; Kobayashi, M.; Petrykin, V.; Kakihana, M.

    2009-01-01

    Titanium dioxide (TiO 2)(B), one of metastable polymorphs of TiO 2 was prepared by hydrothermal reaction of glycolato peroxotitanium complex ([Ti 4(C 2H 2O 3) 4(C 2H 3O 3) 2(O 2) 2] 6-) in the presence of H 2SO 4 as an additive. Characterization by X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM) revealed that the obtained powders were single-phase TiO 2(B) with rod-like shape. Particle size and aspect ratio of TiO 2(B) can be controlled by post-synthetic hydrothermal crystal growth (PHCG) of the as-prepared powder sample.

  10. Enhanced photocatalytic performance of Hemin (chloro(protoporhyinato)iron(III)) anchored TiO2 photocatalyst for methyl orange degradation: A surface modification method

    NASA Astrophysics Data System (ADS)

    Devi, L. Gomathi; ArunaKumari, M. L.

    2013-07-01

    TiO2 was prepared by sol-gel method through the hydrolysis of TiCl4 and its surface derivatization was carried out with molecular catalyst like Hemin (chloro(protoporhyinato)iron(III)). Catalyst was characterized by various analytical techniques like UV-vis spectroscopy, FT-IR, FE-SEM and XRD. The anchoring of Hemin on titania surface is confirmed by FT-IR spectra through the linkage of Odbnd Csbnd Osbnd Ti bond and also by TGA-DSC and elemental analysis. The photocatalytic activity of the surface modified catalyst is tested for the degradation of methyl orange (MO) as a model compound under UV light. The Hemin impregnated TiO2 (H-TiO2) in presence of H2O2 shows an excellent photocatalytic activity compared to pristine TiO2, Hemin, H2O2, TiO2/H2O2, and Hemin/H2O2 systems. The enhancement in the photocatalytic activity is attributed to the presence of iron (III) porphyrin ring on the TiO2 surface, which reduces the electron-hole recombination rate and also by acting as a mediator for continuous production of enriched concentration of hydroxyl radicals along with various other reactive free radicals.

  11. Photo and Chemical Reduction of Copper onto Anatase-Type TiO2 Nanoparticles with Enhanced Surface Hydroxyl Groups as Efficient Visible Light Photocatalysts.

    PubMed

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Mohammadi Ziarani, Ghodsi

    2015-01-01

    In this study, the photocatalytic efficiency of anatase-type TiO2 nanoparticles synthesized using the sol-gel low-temperature method, were enhanced by a combined process of copper reduction and surface hydroxyl groups enhancement. UV-light-assisted photo and NaBH4 -assisted chemical reduction methods were used for deposition of copper onto TiO2. The surface hydroxyl groups of TiO2 were enhanced with the assistance of NaOH modification. The prepared catalysts were immobilized on glass plates and used as the fixed-bed systems for the removal of phenazopyridine as a model drug contaminant under visible light irradiation. NaOH-modified Cu/TiO2 nanoparticles demonstrated higher photocatalytic efficiency than that of pure TiO2 due to the extending of the charge carriers lifetime and enhancement of the adsorption capacity of TiO2 toward phenazopyridine. The relationship of structure and performance of prepared nanoparticles has been established by using various techniques, such as XRD, XPS, TEM, EDX, XRF, TGA, DRS and PL. The effects of preparation variables, including copper content, reducing agents rate (NaBH4 concentration and UV light intensity) and NaOH concentration were investigated on the photocatalytic efficiency of NaOH-modified Cu/TiO2 nanoparticles. PMID:25809844

  12. Controlled synthesis of highly dispersed TiO2 nanoparticles using SBA-15 as hard template.

    PubMed

    Zhao, Li; Yu, Jiaguo

    2006-12-01

    Highly dispersed TiO2 nanoparticles were successfully synthesized by a wet impregnation method using SBA-15 as hard template for confining the growth of TiO2 nanocrystals, and then calcined at 550 degrees C in muffle furnace for 2 h. The as-synthesized samples were characterized with Fourier transform infrared spectra (FTIR), Raman spectroscopy, diffuse reflectance UV-visible spectroscopy (UV-vis), powder X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), nitrogen adsorption, transmission electron microscopy (TEM) and photoluminescence spectra (PL). It was found that SBA-15 contained abundant silanol groups after removal of triblock copolymers by ethanol extraction and could easily adsorb a great number of titanium alkoxide via chemisorption. After subsequent hydrolysis of the anchored Ti complexes and calcination of the amorphous TiO2, anatase TiO2 nanocrystals with spherical shape and uniform particle diameter of about 6 nm were formed. A blue shift was observed in UV-vis absorption spectra due to the quantum size effect of TiO2 nanoparticles. Moreover, the as-prepared TiO2 nanoparticles showed a high PL intensity due to an increase in the recombination rate of photogenerated electrons and holes under UV light irradiation. PMID:16989852

  13. Facile synthesis of porous TiO2 nanospheres and their photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Huang, Jiarui; Ren, Haibo; Liu, Xiaosi; Li, Xuexue; Shim, Jae-Jin

    2015-05-01

    Uniform and monodisperse porous TiO2 nanospheres were synthesized by a hydrothermal method. Techniques of X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption, UV-vis absorption spectroscopy, and transmission electron microscopy were used to characterize the structure and morphology of the products. The BET surface area of the porous TiO2 nanospheres was calculated to be 26.1 cm2 g-1. In addition, the obtained porous TiO2 nanospheres were used as catalyst to photodegrade methylene blue, Rhodamine B, methyl orange, p-nitrophenol, and eosin B. Compared to commercial TiO2 powder, the as-prepared porous TiO2 nanospheres exhibited higher catalytic activities due to their large surface areas and porous nanostructures. The photocatalytic reaction rate constant of the porous TiO2 nanospheres in photocatalytic decomposition of methylene blue and Rhodamine B under simulated solar light were calculated as 0.0545 min-1 and 0.0579 min-1, respectively. Moreover, the catalyst was demonstrated to have good stability and reusability.

  14. Facile Synthesis of Robust Free-Standing TiO2 Nanotubular Membranes for Biofiltration Applications

    PubMed Central

    Schweicher, Julien; Desai, Tejal A.

    2014-01-01

    Robust monodisperse nanoporous membranes have a wide range of biotechnological applications, but are often difficult or costly to fabricate. Here, a simple technique is reported to produce free-standing TiO2 nanotubular membranes with through-hole morphology. It consists in a 3-step anodization procedure carried out at room temperature on a Ti foil. The first anodization (1 h at 80 V) is used to pattern the surface of the metallic foil. Then, the second anodization (24 h at 80 V) produces the array of TiO2 nanotubes that will constitute the final membrane. A higher voltage anodization (3-5 minutes at 180 V) is finally applied to detach the TiO2 nanotubular layer from the underlying Ti foil. In order to completely remove the barrier layer that obstructs some pores of the membrane, the latter is etched 2 minutes in a buffered oxide etch solution. The overall process produces 60 ?m-thick TiO2 nanotubular membranes with tube openings of 110 nm on one side and 73 nm on the other side. The through-hole morphology of these membranes has been verified by performing diffusion experiments with glucose, insulin and immunoglobulin G where in differences in diffusion rate are observed based on molecular weight. Such biocompatible TiO2 nanotubular membranes, with controlled pore size and morphology, have broad biotechnological and biomedical applications. PMID:24634542

  15. Solid-state NMR and EPR analysis of carbon-doped titanium dioxide photocatalysts (TiO(2-)(x)C(x)).

    PubMed

    Reyes-Garcia, Enrique A; Sun, Yanping; Reyes-Gil, Karla R; Raftery, Daniel

    2009-04-01

    Carbon-doped TiO(2) have received attention recently because of their potential for environmental photocatalysis and solar hydrogen conversion applications. Three different carbon-doped TiO(2) nanoparticle materials were synthesized via sol-gel and hydrothermal procedures, and analyzed by (13)C solid-state nuclear magnetic resonance (SSNMR) and other methods to characterize the environment of the doping species. UV/vis spectra and powder X-ray diffraction (XRD) patterns showed that the synthesized materials absorbed visible light and their crystal structures corresponded to anatase. (13)C SSNMR analyses of TiO(2-)(x)C(x) displayed signals corresponding to carbonate-type or sp(2)-type carbon species. Variable contact CP-MAS and dipolar dephasing analyses gave evidence for the presence and proximity of H atoms near these carbonate species. Electron paramagnetic resonance (EPR) spectroscopy showed that the thermally oxidized TiO(2-)(x)C(x) displayed a complex mixture of point defects, electron and hole trapping centers, all attributable to the incorporation of carbon, while the XPS data ruled out the presence of carbide species. PMID:19307109

  16. Synthesis of Pt-Loaded Self-Interspersed Anatase TiO2 with a Large Fraction of (001) Facets for Efficient Photocatalytic Nitrobenzene Degradation.

    PubMed

    Wang, Wei-Kang; Chen, Jie-Jie; Li, Wen-Wei; Pei, Dan-Ni; Zhang, Xing; Yu, Han-Qing

    2015-09-16

    TiO2 is capable of directly utilizing solar energy for sustainable energy harvest and water purification. Facet-dependent performance of TiO2 has attracted enormous interests due to its tunable photocatalytic activity toward photoredox transformations, but information about the noble-metal-loaded TiO2 for its facet-dependent photocatalytic performance, especially in pollutant degradation systems, is limited. In this work, inspired by our previous theoretical calculations about the roles of the crystal surface in Pt-loaded TiO2 in its enhanced photocatalytic capacity, TiO2 nanocrystals with interspersed polyhedron nanostructures and coexposed (001) and (101) surfaces as a support of Pt nanoparticles are prepared in a simple and relatively green route. Also, their performance for photocatalytic degradation of nitrobenzene (NB), a model organic pollutant, is explored. The experimental results demonstrate that the NB photodegradation and photoconversion efficiencies are significantly enhanced by uniformly loading Pt nanoparticles on the crystal surfaces, but the Pt nanoparticles deposited on only the (101) surface have no contribution to the improved NB photodegradation. Furthermore, the liquid chromatography mass spectrometry results also show that NB photodegradation tends to proceed on the (001) surface of Pt/TiO2 for the generation of nitrophenol intermediates through the photooxidation pathway. This work provides a new route to design and construct advanced photocatalysts toward pollutant photoredox conversions and deepens our fundamental understanding about crystal surface engineering. PMID:26308282

  17. Synthesis of uniform TiO2 nanoparticles with egg albumen proteins as novel biotemplate.

    PubMed

    Yan, Jingjing; Wu, Guangjun; Li, Landong; Yu, Aimin; Sun, Xiaohong; Guan, Naijia

    2010-09-01

    A novel bio-templated route was reported for the fabrication of uniform and well dispersed TiO, nanoparticles using denatured egg albumen (EA) proteins network as template. Anatase TiO2 nanoparticles of ca. 9 nm with narrow size distribution were obtained under employed reaction conditions, as proved by the XRD and TEM results. The as-prepared TiO2 nanoparticles were further characterized by means of XPS, FTIR, TG-DTA and UV-Vis. Based on the characterization results, a possible process of heat-induced denatured protein network as template matrix to fabricate TiO2 nanoparticles was carefully proposed. The method with egg albumen as bio-template provides us a cheap, green and repeatable route for the fabrication of nanoparticles under mild conditions. PMID:21133103

  18. Synthesis, characterization and photocatalytic behavior of Ag doped TiO2 thin film

    NASA Astrophysics Data System (ADS)

    Bensouici, F.; Souier, T.; Dakhel, A. A.; Iratni, A.; Tala-Ighil, R.; Bououdina, M.

    2015-09-01

    In this study, structure, microstructure, optical properties and photocatalytic degradation of Rhodamine B (RhB) have been investigated in an aqueous heterogeneous media containing pure and Ag doped TiO2 nanostructures thin films which were prepared by a simple sol-gel route. Thermal analysis demonstrated that Ag content decreased the temperature of anatase-to-rutile phase transformation. X-ray diffraction analysis confirmed that the prepared nanostructures crystallize within anatase-type structure and that the dopant Ag ions were not fully incorporated within TiO2 host lattice, meanwhile both the refractive index and optical band gap were affected by Ag concentration. The photodegradation of Rhodamine B under UV-C radiation by using pure and Ag-doped TiO2 nanostructures showed that Ag played an important role in a significant improvement of the photodegradation efficiency and that the optimum content of Ag ions was found to be 0.5% molar ratio.

  19. Microwave-Assisted Synthesis of Carbon-Based (N, Fe)-Codoped TiO2 for the Photocatalytic Degradation of Formaldehyde

    NASA Astrophysics Data System (ADS)

    Tian, Fei; Wu, Zhansheng; Tong, Yanbin; Wu, Zhilin; Cravotto, Giancarlo

    2015-09-01

    A microwave-assisted sol-gel method was used to synthesize (N, Fe)-codoped activated carbon (AC)/TiO2 photocatalyst for enhanced optical absorption in the visible light region. The prepared samples were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, ultraviolet-visible light spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The results showed no significant difference in the surface area of AC/TiO2 (approximately 500 m2/g) after doping. TiO2 was uniformly distributed on the surface of AC, which exhibited coexisting anatase and rutile structures with a mean crystallite diameter of approximately 20 nm. N and Fe monodoping on AC/TiO2 reduced the energy band gap of TiO2 to 2.81 and 2.79 eV, respectively, which mainly attributed to the impurity energy formed in the energy gap of TiO2. In (N, Fe)-codoped AC/TiO2, N and Fe are incorporated into the TiO2 framework and narrow the band gap of TiO2 to 2.58 eV, thereby causing a large redshift. Codoping of N and Fe enhanced the production of hydroxyl radicals (?OH) and improved the photocatalytic activity of the resultant AC/TiO2 compared with those of undoped and N- or Fe-monodoped AC/TiO2. N-Fe-AC/TiO2 degraded 93 % of the formaldehyde under Xe-lamp irradiation. Moreover, the photocatalyst was easily recyclable. In summary, a novel and efficient method to mineralize low concentrations of HCHO in wastewater was discovered.

  20. Microwave-Assisted Synthesis of Carbon-Based (N, Fe)-Codoped TiO2 for the Photocatalytic Degradation of Formaldehyde.

    PubMed

    Tian, Fei; Wu, Zhansheng; Tong, Yanbin; Wu, Zhilin; Cravotto, Giancarlo

    2015-12-01

    A microwave-assisted sol-gel method was used to synthesize (N, Fe)-codoped activated carbon (AC)/TiO2 photocatalyst for enhanced optical absorption in the visible light region. The prepared samples were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, ultraviolet-visible light spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The results showed no significant difference in the surface area of AC/TiO2 (approximately 500 m(2)/g) after doping. TiO2 was uniformly distributed on the surface of AC, which exhibited coexisting anatase and rutile structures with a mean crystallite diameter of approximately 20 nm. N and Fe monodoping on AC/TiO2 reduced the energy band gap of TiO2 to 2.81 and 2.79 eV, respectively, which mainly attributed to the impurity energy formed in the energy gap of TiO2. In (N, Fe)-codoped AC/TiO2, N and Fe are incorporated into the TiO2 framework and narrow the band gap of TiO2 to 2.58 eV, thereby causing a large redshift. Codoping of N and Fe enhanced the production of hydroxyl radicals (?OH) and improved the photocatalytic activity of the resultant AC/TiO2 compared with those of undoped and N- or Fe-monodoped AC/TiO2. N-Fe-AC/TiO2 degraded 93 % of the formaldehyde under Xe-lamp irradiation. Moreover, the photocatalyst was easily recyclable. In summary, a novel and efficient method to mineralize low concentrations of HCHO in wastewater was discovered. PMID:26377213

  1. Synthesis and characterization of a POM-based nanocomposite as a novel magnetic photocatalyst

    NASA Astrophysics Data System (ADS)

    Shi, Yan-Li; Qiu, Wei; Zheng, Ying

    2006-11-01

    A novel magnetic photocatalyst, prepared by grafting polyoxometalates (POM) anions PW12O403- onto Fe3O4 nanoparticles via a layer of Ag, was synthesized and characterized. The coated Ag layer was used as an intermediate bond for anchoring POM anions onto the magnetite cores. Resulting materials have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption desorption isotherm, magnetization, and inductively coupled plasma (ICP). The activity of the photocatalyst was tested by the photocatalytic degradation of Rhodamine B. It was found that, compared to pure POM, the decolorization fraction of Rhodamine B in 2 h operation was 2.8 3.4 times higher by using the POM-based nanocomposite. ICP analysis of the concentration of Fe, W and P in treated water showed that photodissolution was minimal. In addition, as the synthesized composite possesses a magnetite core, it is possible to retrieve the photocatalyst by exerting an external magnetic field, which is easier than the recovery of conventional TiO2 fine particles and homogeneous POM photocatalysts. The exhibited photocatalytic activity and magnetization of the novel photocatalyst provide a promising solution for the degradation of water contaminants and photocatalyst recovery.

  2. Glycothermal Synthesis and Photocatalytic Properties of Highly Crystallized Anatase TiO2 Nanoparticles.

    PubMed

    Kil, Hyun-Sig; Jung, Yong-Jin; Moon, Jung-In; Song, Jeong-Hwan; Lim, Dae-Young; Cho, Seung-Beom

    2015-08-01

    Highly crystallized anatase TiO2 nanoparticles were synthesized at a temperature as low as 120 °C through a glycothermal reaction using amorphous titanium hydrous gel as precursor and 1,4-butanediol and water as solvent. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data support that the glycothermal processing method provides a simple low-temperature route for producing highly crystallized anatase TiO2 nanoparticles without pH adjustment. It is demonstrated that the shape and dispersability of TiO2 nanoparticles can be controlled by the reaction conditions, such as the reaction temperature and variation of the volume ratio of 1,4- butanediol/water (B/W). It was observed that TiO2 samples glycothermally prepared at 220 °C and the B/W ratio of 8/0 showed excellent photocatalytic behavior. The high activity is attributed to the high crystallinity and bipyramidal shape of the particles, which have fewer defects and more active {101} surfaces. PMID:26369224

  3. Synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles and nanowires.

    PubMed

    Xie, Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh

    2010-01-01

    We present the synthesis and visible-light-induced catalytic activity of Ag(2)S-coupled TiO(2) nanoparticles (NPs) and TiO(2) nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag(2)S NPs and TiO(2) NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag(2)S NPs on TiO(2) NWs was created. Due to the coupling with such a low bandgap material as Ag(2)S, the TiO(2) nanocomposites could have a visible-light absorption capability much higher than that of pure TiO(2). As a result, the synthesized Ag(2)S/TiO(2) nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO(2) (Degussa P25, Germany) under visible light. PMID:19946150

  4. Synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles and nanowires

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh

    2010-01-01

    We present the synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles (NPs) and TiO2 nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag2S NPs and TiO2 NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag2S NPs on TiO2 NWs was created. Due to the coupling with such a low bandgap material as Ag2S, the TiO2 nanocomposites could have a visible-light absorption capability much higher than that of pure TiO2. As a result, the synthesized Ag2S/TiO2 nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO2 (Degussa P25, Germany) under visible light.

  5. Non-solvolytic synthesis of aqueous soluble TiO2 nanoparticles and real-time dynamic measurements of the nanoparticle formation

    PubMed Central

    2012-01-01

    Highly aqueously dispersible (soluble) TiO2 nanoparticles are usually synthesized by a solution-based sol–gel (solvolysis/condensation) process, and no direct precipitation of titania has been reported. This paper proposes a new approach to synthesize stable TiO2 nanoparticles by a non-solvolytic method - direct liquid phase precipitation at room temperature. Ligand-capped TiO2 nanoparticles are more readily solubilized compared to uncapped TiO2 nanoparticles, and these capped materials show distinct optical absorbance/emission behaviors. The influence of ligands, way of reactant feeding, and post-treatment on the shape, size, crystalline structure, and surface chemistry of the TiO2 nanoparticles has been thoroughly investigated by the combined use of X-ray diffraction, transmission electron microscopy, UV-visible (UV–vis) spectroscopy, and photoluminescence (PL). It is found that all above variables have significant effects on the size, shape, and dispersivity of the final TiO2 nanoparticles. For the first time, real-time UV–vis spectroscopy and PL are used to dynamically detect the formation and growth of TiO2 nanoparticles in solution. These real-time measurements show that the precipitation process begins to nucleate after an initial inhibition period of about 1?h, thereafter a particle growth occurs and reaches the maximum point after 2?h. The synthesis reaction is essentially completed after 4?h. PMID:22676412

  6. The Comparative Photodegradation Activities of Pentachlorophenol (PCP) and Polychlorinated Biphenyls (PCBs) Using UV Alone and TiO2-Derived Photocatalysts in Methanol Soil Washing Solution

    PubMed Central

    Zhou, Zeyu; Zhang, Yaxin; Wang, Hongtao; Chen, Tan; Lu, Wenjing

    2014-01-01

    Photochemical treatment is increasingly being applied to remedy environmental problems. TiO2-derived catalysts are efficiently and widely used in photodegradation applications. The efficiency of various photochemical treatments, namely, the use of UV irradiation without catalyst or with TiO2/graphene-TiO2 photodegradation methods was determined by comparing the photodegadation of two main types of hydrophobic chlorinated aromatic pollutants, namely, pentachlorophenol (PCP) and polychlorinated biphenyls (PCBs). Results show that photodegradation in methanol solution under pure UV irradiation was more efficient than that with either one of the catalysts tested, contrary to previous results in which photodegradation rates were enhanced using TiO2-derived catalysts. The effects of various factors, such as UV light illumination, addition of methanol to the solution, catalyst dosage, and the pH of the reaction mixture, were examined. The degradation pathway was deduced. The photochemical treatment in methanol soil washing solution did not benefit from the use of the catalysts tested. Pure UV irradiation was sufficient for the dechlorination and degradation of the PCP and PCBs. PMID:25254664

  7. A systematic study on visible-light N-doped TiO2 photocatalyst obtained from ethylenediamine by sol-gel method

    NASA Astrophysics Data System (ADS)

    Li, Hui; Hao, Yubao; Lu, Haiqiang; Liang, Liping; Wang, Yuanyang; Qiu, Jianhao; Shi, Xianchao; Wang, Ying; Yao, Jianfeng

    2015-07-01

    N-doped titania is prepared using ethylenediamine as the nitrogen source by a sol-gel method. The preparation conditions, such as the volume ratio of ethylenediamine to sol, and the heat temperature on the nitrogen doping are systematically examined. UV results indicate the N-doped TiO2 catalysts have enhanced absorption in the visible light region, and exhibit high activities on the visible light photocatalytic reactions to the hydrogen production and methyl orange degradation. X-ray diffraction (XRD) and FT-IR results reveal that N species have been incorporated into the TiO2 lattice at a high N-doping level. N-doped titania prepared with an ethylenediamine to sol volume ratio of 1:1 and sintering temperature of 500 °C performed the highest hydrogen production rate (2.98 mmol g-1 h-1) and best methyl orange degradation performance. A conceivable structure change of N-doped TiO2 sintered at different temperature was proposed.

  8. Low-Temperature Synthesis of a TiO2/Si Heterojunction.

    PubMed

    Sahasrabudhe, Girija; Rupich, Sara M; Jhaveri, Janam; Berg, Alexander H; Nagamatsu, Ken A; Man, Gabriel; Chabal, Yves J; Kahn, Antoine; Wagner, Sigurd; Sturm, James C; Schwartz, Jeffrey

    2015-12-01

    The classical SiO2/Si interface, which is the basis of integrated circuit technology, is prepared by thermal oxidation followed by high temperature (>800 °C) annealing. Here we show that an interface synthesized between titanium dioxide (TiO2) and hydrogen-terminated silicon (H:Si) is a highly efficient solar cell heterojunction that can be prepared under typical laboratory conditions from a simple organometallic precursor. A thin film of TiO2 is grown on the surface of H:Si through a sequence of vapor deposition of titanium tetra(tert-butoxide) (1) and heating to 100 °C. The TiO2 film serves as a hole-blocking layer in a TiO2/Si heterojunction solar cell. Further heating to 250 °C and then treating with a dilute solution of 1 yields a hole surface recombination velocity of 16 cm/s, which is comparable to the best values reported for the classical SiO2/Si interface. The outstanding performance of this heterojunction is attributed to Si-O-Ti bonding at the TiO2/Si interface, which was probed by angle-resolved X-ray photoelectron spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) showed that Si-H bonds remain even after annealing at 250 °C. The ease and scalability of the synthetic route employed and the quality of the interface it provides suggest that this surface chemistry has the potential to enable fundamentally new, efficient silicon solar cell devices. PMID:26579554

  9. Synthesis of iron-doped TiO2 for degradation of reactive Orange16

    PubMed Central

    2014-01-01

    In this study the optimum conditions for preparing the iron-doped TiO2 nanoparticles were investigated. Samples were synthesized by sol–gel impregnation method. Three effective parameters were optimized using Taguchi method, consisted of: (i) atomic ratios of Fe to Ti; (ii) sintering temperature; (iii) sintering time. The characterization of samples was determined using X-ray diffraction, BET- specific surface area, UV- Vis reflectance spectra (DRS) and scanning electron microscope (SEM). The XRD patterns of the samples indicated the existence of anatase crystal phase in structure. UV- Vis reflectance spectra showed an enhancement in light absorbance in the visible region (wavelength?>?400 nm) for iron-doped samples. The photocatalytic activity of samples was investigated by the degradation of RO 16 (RO 16) dye under UV irradiation. The results illustrated that the photocatalytic activity of iron-doped TiO2 was more than pure TiO2, because of the smaller crystal size, grater BET surface area and higher light absorption ability. PMID:24405975

  10. Synthesis and photocatalytic performances of the TiO2 pillared montmorillonite.

    PubMed

    Chen, Daimei; Zhu, Qian; Zhou, Fengsan; Deng, Xutao; Li, Fatang

    2012-10-15

    TiO(2) pillared clay materials were prepared by montmorillonite (Mt) and acidic solutions of hydrolyzed Ti alkoxides in the presence of high-molecular-weight polyoxypropylene (POP)-backboned di-quaternary salts (POP). The as-prepared materials were characterized by means of XRD, FTIR, TG-DTA, XRF, specific surface area and porosity determinations, TEM and SEM, respectively. The experiments showed that the resulting material was a porous delaminated structure containing pillared fragments and nano-scaled TiO(2) particles well dispersed among each other. Introducing polymer surfactant POP as an expanding agent of Mt cannot only promote the formation of the delaminated structure, but significantly improve the porosity and surface area of the composites. The resulting TiO(2) pillared Mt exhibited a good thermal stability as indicated by its surface area after calcination at 800 °C. No phase transformation from anatase to rutile was observed even under calcination at 900 °C. The grain size of anatase in as-prepared sample decreased with the increase of the POP concentration, but increased with the increment of calcination temperature. The photocatalytic performances of these new porous materials were evaluated by using methylene blue degradation. The composite solid exhibited superior photocatalyic property and the maximum removal efficiency was up to 98% within 90 min. PMID:22884731

  11. Synthesis and characterization of carbon modified TiO2 nanotube and photocatalytic activity on methylene blue under sunlight

    NASA Astrophysics Data System (ADS)

    Li, Yinchang; Wang, Yongqian; Kong, Junhan; Jia, Hanxiang; Wang, Zhengshu

    2015-07-01

    Carbon modified TiO2 nanotube was successfully synthesized via anodic oxidation method and its photocatalytic activity was evaluated by photodegrading methylene blue. The full width at half maximum of carbon modified TiO2 nanotube is smaller than that of pristine TiO2 nanotube, indicating the fact that carbon modifying leads to the increase of TiO2 crystallinity. TiO2 nanotube modified by carbon has a great enhancement on visible light absorption while contrasting with the pristine TiO2 nanotube. A tentative mechanism for the enhancement of sunlight absorption is proposed.

  12. AAO-assisted synthesis of highly ordered, large-scale TiO2 nanowire arrays via sputtering and atomic layer deposition.

    PubMed

    Yao, Zhao; Wang, Cong; Li, Yang; Kim, Nam-Young

    2015-01-01

    Highly ordered nanoporous anodic aluminum oxide (AAO) thin films were fabricated in oxalic acid under a constant voltage via a two-step anodization process. To investigate the high-aspect-ratio (7.5:1) filling process, both sputtering and atomic layer deposition (ALD) were used to form TiO2 nanowires. Field emission scanning electron microscopy and high-resolution transmission electron microscopy images indicated that mushroom-like TiO2 structures were sputtered onto the AAO template surface, and the ALD-coated TiO2 exhibited fine filling results and clear crystal grain boundaries. Large-scale and free-standing TiO2 nanowire arrays were liberated by selectively removing the aluminum substrate and AAO template via a wet etching process with no collapsing or agglomeration after the drying process. ALD-deposited TiO2 nanowire arrays that were 67 nm in diameter and 400 nm high were transferred from the AAO template. The ALD process enabled the rapid, simple synthesis of highly ordered TiO2 nanowire arrays with desired parameters such as diameter, density, and thickness determined using diverse AAO templates. PMID:25897309

  13. AAO-assisted synthesis of highly ordered, large-scale TiO2 nanowire arrays via sputtering and atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Yao, Zhao; Wang, Cong; Li, Yang; Kim, Nam-Young

    2015-04-01

    Highly ordered nanoporous anodic aluminum oxide (AAO) thin films were fabricated in oxalic acid under a constant voltage via a two-step anodization process. To investigate the high-aspect-ratio (7.5:1) filling process, both sputtering and atomic layer deposition (ALD) were used to form TiO2 nanowires. Field emission scanning electron microscopy and high-resolution transmission electron microscopy images indicated that mushroom-like TiO2 structures were sputtered onto the AAO template surface, and the ALD-coated TiO2 exhibited fine filling results and clear crystal grain boundaries. Large-scale and free-standing TiO2 nanowire arrays were liberated by selectively removing the aluminum substrate and AAO template via a wet etching process with no collapsing or agglomeration after the drying process. ALD-deposited TiO2 nanowire arrays that were 67 nm in diameter and 400 nm high were transferred from the AAO template. The ALD process enabled the rapid, simple synthesis of highly ordered TiO2 nanowire arrays with desired parameters such as diameter, density, and thickness determined using diverse AAO templates.

  14. Synthesis of scaly Sn3O4/TiO2 nanobelt heterostructures for enhanced UV-visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chen, Guohui; Ji, Shaozheng; Sang, Yuanhua; Chang, Sujie; Wang, Yana; Hao, Pin; Claverie, Jerome; Liu, Hong; Yu, Guangwei

    2015-02-01

    A novel scaly Sn3O4/TiO2 nanobelt heterostructured photocatalyst was fabricated via a facile hydrothermal route. The scaly Sn3O4 nanoflakes can be synthesized in situ and assembled on surface coarsened TiO2 nanobelts through a hydrothermal process. The morphology and distribution of Sn3O4 nanoflakes can be well-controlled by simply tuning the Sn/Ti molar ratio of the reactants. Compared with single phase nanostructures of Sn3O4 and TiO2, the scaly hybrid nanobelts exhibited markedly enhanced photoelectrochemical (PEC) response, which caused higher photocatalytic hydrogen evolution even without the assistance of Pt as a co-catalyst, and enhanced the degradation ability of organic pollutants under both UV and visible light irradiation. In addition to the increased exposure of active facets and broad light absorption, the outstanding performance is ascribed to the matching energy band structure between Sn3O4 and TiO2 at the two sides of the heterostructure, which efficiently reduces the recombination of photo-excited electron-hole pairs and prolongs the lifetime of charge carriers. Both photocatalytic assessment and PEC tests revealed that Sn3O4/TiO2 heterostructures with a molar ratio of Sn/Ti of 2/1 exhibited the highest photocatalytic activity. This study provides a facile and low-cost method for the large scale production of Sn3O4 based materials in various applications.A novel scaly Sn3O4/TiO2 nanobelt heterostructured photocatalyst was fabricated via a facile hydrothermal route. The scaly Sn3O4 nanoflakes can be synthesized in situ and assembled on surface coarsened TiO2 nanobelts through a hydrothermal process. The morphology and distribution of Sn3O4 nanoflakes can be well-controlled by simply tuning the Sn/Ti molar ratio of the reactants. Compared with single phase nanostructures of Sn3O4 and TiO2, the scaly hybrid nanobelts exhibited markedly enhanced photoelectrochemical (PEC) response, which caused higher photocatalytic hydrogen evolution even without the assistance of Pt as a co-catalyst, and enhanced the degradation ability of organic pollutants under both UV and visible light irradiation. In addition to the increased exposure of active facets and broad light absorption, the outstanding performance is ascribed to the matching energy band structure between Sn3O4 and TiO2 at the two sides of the heterostructure, which efficiently reduces the recombination of photo-excited electron-hole pairs and prolongs the lifetime of charge carriers. Both photocatalytic assessment and PEC tests revealed that Sn3O4/TiO2 heterostructures with a molar ratio of Sn/Ti of 2/1 exhibited the highest photocatalytic activity. This study provides a facile and low-cost method for the large scale production of Sn3O4 based materials in various applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05749j

  15. Synthesis of TiO2 Nanofluids by Wet Mechanochemical Process

    NASA Astrophysics Data System (ADS)

    Harjanto, S.; Sutanto, H.; Setiaji, R.; Yuwono, A. H.; Ferdian, D.

    2011-12-01

    Nanofluids have been developed in a search of new coolants with higher thermal conductivity compared to the conventional coolants, such as water or ethylene glycol. This research is conducted to observe the main characteristics, such as particle size, suspension stability, and thermal conductivity, of nanofluids produced from wet mechanochemical process with the addition of 0.02 vol% oleic acid. Milling process was conducted in conventional planetary ball mill for 15 hours. The results showed that nanoparticle was formed from micron size raw materials and dan dispersed simultaneously in water. Particle size distribution of particles which are less than 100 nm size were in the range of 51-100%. The ratio of thermal conductivity enhancement of the 1% vol TiO2 nanofluids compared with water without surfactant is 1.1. The ratio of thermal conductivity of TiO2 nanofluids increases in higher concentration of nanofluids. Oleic acid addition increases the particle stability of nanofluids and its ratio of thermal conductivity.

  16. Nanomechanical Properties of TiO2 Granular Houman Yaghoubi,,

    E-print Network

    Volinsky, Alex A.

    , Tehran 14588, Iran, Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran (15-19), air treatment (3, 5, 20-23), and food storage (24, 25). TiO2 is a favored photocatalyst

  17. Directed synthesis of hierarchical nanostructured TiO2 catalysts and their morphology-dependent photocatalysis for phenol degradation.

    PubMed

    Liu, Lu; Liu, Huajie; Zhao, Ya-Ping; Wang, Yuqiu; Duan, Yueqin; Gao, Guandao; Ge, Ming; Chen, Wei

    2008-04-01

    Nanostructured TiO2 with different hierarchical morphologies were synthesized via a warmly hydrothermal route. The properties of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption, UV-vis spectroscopy, etc. Two of the products, TiO2 1D nanorods (one-dimensional rutile TiO2 nanorods) and TiO2 3D0D microspheres (three-dimensional anatase TiO2 nanoparticle-assembled microspheres) exhibited superior photocatalytic effects on phenol degradation under UV illumination, compared with TiO2 3D1D microspheres (three-dimensional rutile TiO2 nanorods-assembled microspheres). Moreover, TiO2 3D0D was superior to TiO2 1D, as indicated by a 30% higher mineralization of dissolved phenol. Dihydroxybenze, 4,4'-dihydroxybiphenyl, benzoquinone, maleic anhydride, etc. were identified as the degradation intermediates. The excellent catalytic effect was attributed to the structural features of TiO2 1D nanorods and TiO2 3D0D microspheres, that is, a larger amount of surface active sites and a higher band gap energy resulted in more efficient decomposition of organic contaminants. PMID:18504963

  18. Enhanced photo-catalytic activity of Sr and Ag co-doped TiO2 nanoparticles for the degradation of Direct Green-6 and Reactive Blue-160 under UV & visible light.

    PubMed

    Naraginti, Saraschandra; Thejaswini, T V L; Prabhakaran, D; Sivakumar, A; Satyanarayana, V S V; Arun Prasad, A S

    2015-10-01

    This work is focused on sol-gel synthesis of silver and strontium co-doped TiO2 nanoparticles and their utilization as photo-catalysts in degradation of two textile dyes. Effect of pH, intensity of light, amount of photo-catalyst, concentration of dye, sensitizers, etc., were studied to optimize conditions for obtaining enhanced photo-catalytic activity of synthesized nanoparticles. XRD, BET, HR-TEM, EDAX and UV-Vis (diffused reflectance mode) techniques were used to characterize the nanoparticles. Interestingly, band gap of Sr and Ag co-doped TiO2 nanoparticles showed considerable narrowing (2.6 eV) when compared to Ag doped TiO2 (2.7 eV) and undoped TiO2 (3.17 eV) nanoparticles. Incorporation of Ag and Sr in the lattice of TiO2 could bring isolated energy levels near conduction and valence bands thus narrowing band gap. The XRD analysis shows that both Ag and Sr nanoparticles are finely dispersed on the surface of titania framework, without disturbing its crystalline structure. TEM images indicate that representative grain sizes of Ag-doped TiO2 & Sr and Ag co-doped TiO2 nanoparticles are in the range of 8-20 nm and 11-25 nm, respectively. Effective degradation of Direct Green-6 (DG-6) and Reactive Blue-160 (RB-160) under UV and visible light has been achieved using the photo-catalysts. Sr and Ag co-doped TiO2 photo-catalysts showed higher catalytic activity during degradation process in visible region when compared to Ag-doped and undoped TiO2 nanoparticles which could be attributed to the interactive effect caused by band gap narrowing and enhancement in charge separation. For confirming degradation of the dyes, total organic carbon (TOC) content was monitored periodically. PMID:25983059

  19. Size-controlled synthesis of anisotropic TiO2 single nanocrystals using microwave irradiation and their application for dye-sensitized solar cells.

    PubMed

    Manseki, Kazuhiro; Kondo, Yosuke; Ban, Takayuki; Sugiura, Takashi; Yoshida, Tsukasa

    2013-03-14

    A microwave hydrothermal reaction of colloidal titanates is presented as a cost-effective synthesis to produce TiO(2) single nanocrystals. The photoelectrode consisting of anisotropic nanorods and V-shaped twins has a significant advantage for achieving an appreciable incident photon-to-current conversion efficiency of 85.6% for the dye-sensitized solar cell. PMID:23307102

  20. Synthesis, characterization and degradation of Bisphenol A using Pr, N co-doped TiO 2 with highly visible light activity

    NASA Astrophysics Data System (ADS)

    Yang, Juan; Dai, Jun; Li, Jiantong

    2011-08-01

    Praseodymium and nitrogen co-doped titania (Pr/N-TiO 2) photocatalysts, which could degrade Bisphenol A (BPA) under visible light irradiation, were prepared by the modified sol-gel process. Tetrabutyl titanate, urea and praseodymium nitrate were used as the sources of titanium, nitrogen and praseodymium, respectively. The resulting materials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), N 2 adsorption-desorption isotherm and Fourier transform infrared spectra (FTIR). It was found that Pr doping inhibited the growth of crystalline size and the transformation from anatase to rutile. The degradation of BPA under visible light illumination was taken as probe reaction to evaluate the photo-activity of the co-doped photocatalyst. In our experiments, the optimal dopant amount of Pr was 1.2 mol% and the calcination temperature was 500 °C for the best photocatalytic activity. Pr/N-TiO 2 samples exhibited enhanced visible-light photocatalytic activity compared to N-TiO 2, undoped TiO 2 and commercial P25. The nitrogen atoms were incorporated into the crystal of titania and could narrow the band gap energy. Pr doping could slow the radiative recombination of photogenerated electrons and holes in TiO 2. The improvement of photocatalytic activity was ascribed to the synergistic effects of nitrogen and Pr co-doping.

  1. Synthesis and characterization of porous TiO2 with wormhole-like framework structure

    SciTech Connect

    Narayanaswamy, A.; McBride, J.; Swafford, L.A.; Dhar, S.; Budai, John D; Feldman, Leonard C.; Rosenthal, Sandra

    2008-01-01

    A fast and reliable synthetic route for preparing contaminant-free porous TiO2 with a wormhole-like framework and close packed macropores is demonstrated based on a sol-gel process involving acid hydrolysis of an alkoxide in the presence of a cationic surfactant. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements have been used to characterize the porous structure and the crystallinity. The XRD patterns, TEM and scanning electron microscopy (SEM) images confirm that these materials have disordered wormhole-like topology with close-packed nearly hexagonal macropores. The mesopore diameters and surface area of titanium dioxide, evaluated from the N2-sorption isotherms, indicate average pore diameters of about 7 and 6 nm and surface areas of about 100 and 335 m2/g, for as-prepared and calcined samples at 400 C.

  2. A direct synthesis of B-doped TiO2 and its photocatalytic performance on degradation of RhB

    NASA Astrophysics Data System (ADS)

    Li, Liang; Yang, Yulin; Liu, Xinrong; Fan, Ruiqing; Shi, Yan; Li, Shuo; Zhang, Lingyun; Fan, Xiao; Tang, Pengxiao; Xu, Rui; Zhang, Wenzhi; Wang, Yazhen; Ma, Liqun

    2013-01-01

    B-doped TiO2 was synthesized by a direct hydrolyzation of n-tetrabutyl titanate in a solution of boric acid, and was treated by hydro-thermal synthesis. The powder was characterized by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM), surface photoviolet spectra, UV-visible absorption spectra and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) degradation was used as a probe reaction to evaluate the photocatalytic activity of B-doped TiO2 under simulate sunlight, and excellent photocatalytic performance was achieved.

  3. Synthesis, features and solar-light-driven photocatalytic activity of TiO2 nanotube arrays loaded with SnO2.

    PubMed

    Sim, Lan Ching; Ng, Kai Wern; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-09-01

    In the present study TiO2 nanotube arrays (TNTs) were loaded with a post-transition metal oxide particles namely SnO2 via incipient wet impregnation method by varying its concentration (1.59 wt%, 2.25 wt% and 2.84 wt%). The photocatalytic activity of the prepared photocatalyst was evaluated for the degradation of methylene blue (MB) in presence of natural solar light irradiation. The morphological analyses revealed that the prepared TNTs had average inner diameter of 109 nm, wall thickness of 15 nm and tube length of 7-10 ?m, respectively, while the crystalline phase and Raman spectra confirmed the 100% anatase mineral form of TiO2. Further, the presence of SnO2 in TNTs was confirmed by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The visible light absorption properties of TNTs improved drastically with increasing SnO2 loadings. The coupling effect of SnO2 and TiO2 significantly enhanced degradation efficiency of MB. An 84% degradation of MB was achieved in 6 h of irradiation under clear sky condition. PMID:25924362

  4. Synthesis and anti-staphylococcal activity of TiO2 nanoparticles and nanowires in ex vivo porcine skin model.

    PubMed

    Nataraj, Namrata; Anjusree, G S; Madhavan, Asha Anish; Priyanka, P; Sankar, Deepthi; Nisha, N; Lakshmi, S V; Jayakumar, R; Balakrishnan, Avinash; Biswas, Raja

    2014-05-01

    Staphylococcus aureus is one of the major causes of skin and soft tissue infections. In this study we compared the antimicrobial activity of two different TiO2 nanoformulations against Staphylococcus aureus. We synthesized TiO2 nanoparticles of approximately 80 nm diameter and TiO2 nanowires of approximately 100 nm diameter. Both nanoformulations possess anti-microbial activity; were non-hemolytic and cytocompatible. However, the anti-staphylococcal activity of TiO2 nanowires was better than the nanoparticles. In broth culture, growth of S. aureus was only partially inhibited by 2% and 4 wt% TiO2 nanoparticles and completely inhibited by TiO2 nanowires till 24 h. TiO2 nanowires treated S. aureus cells exhibits diminished membrane potential than nanoparticle treated cells. The anti-microbial properties of both TiO2 nanoformulations were validated using ex vivo porcine skin model which supplements the in vitro assays. Anti-bacterial activity of the TiO2 nanowires were also validated against multi drug resistant pathogenic strains of S. aureus, showing the clinical potency of the TiO2 nanowires compared to its nanoparticles. PMID:24734539

  5. Synthesis of uniform layered protonated titanate hierarchical spheres and their transformation to anatase TiO2 for lithium-ion batteries.

    PubMed

    Wu, Hao Bin; Lou, Xiong Wen David; Hng, Huey Hoon

    2012-02-13

    Layered protonated titanates (LPTs), a class of interesting inorganic layered materials, have been widely studied because of their many unique properties and their use as precursors to many important TiO(2)-based functional materials. In this work, we have developed a facile solvothermal method to synthesize hierarchical spheres (HSs) assembled from ultrathin LPT nanosheets. These LPT hierarchical spheres possess a porous structure with a large specific surface area and high stability. Importantly, the size and morphology of the LPT hierarchical spheres are easily tunable by varying the synthesis conditions. These LPT HSs can be easily converted to anatase TiO(2) HSs without significant structural alteration. Depending on the calcination atmosphere of air or N(2), pure anatase TiO(2) HSs or carbon-supported TiO(2) HSs, respectively, can be obtained. Remarkably, both types of TiO(2) HSs manifest excellent cyclability and rate capability when evaluated as anode materials for high-power lithium-ion batteries. PMID:22246679

  6. Ultrasonic-assisted sol-gel synthesis of samarium, cerium co-doped TiO2 nanoparticles with enhanced sonocatalytic efficiency.

    PubMed

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Ziarani, Ghodsi Mohammadi

    2015-09-01

    In this work, pure TiO2 and samarium, cerium mono-doped and co-doped TiO2 catalysts were synthesized by an ultrasonic-assisted sol-gel method and their sonocatalytic efficiency studied toward removal of Methyl Orange as a model organic pollutant from the textile industry. The relationship of structure and sonocatalytic performance of catalysts was established by using various techniques, such as XRD, TEM, SEM, EDX, DRS, and PL. A comparison on the removal efficiency of sonolysis alone and sonocatalytic processes was performed. The results showed that the samarium, cerium co-doped TiO2 catalyst with narrower band gap energy and smaller particle size leads to a rapid removal of pollutant. It was believed that Sm(3+) and Ce(4+) ions can serve as superficial trapping for electrons at conduction band of TiO2 and prolonged the lifetime of electron-hole pairs. Finally, the effect of synthesis and operational variables on the sonocatalytic activity of co-doped TiO2 catalyst was studied and optimized using response surface methodology as a statistical technique. The results showed that the maximum removal efficiency (96.33%) was achieved at the optimum conditions: samarium content of 0.6 wt%, cerium content of 0.82 wt%, initial pollutant concentration of 4.31 mg L(-1), catalyst dosage of 0.84 mg L(-1), ultrasonic irradiation power of 700 W, and irradiation time of 50 min. PMID:25682738

  7. Catalytic and photocatalytic behavior of TiO2 based nanoparticles—their use in the synthesis of a novel TICT probe

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Prasad Mandal, Ranju; Dutta, Saheb; Nandi, Nilashis; De, Swati

    2015-06-01

    Biologically inspired synthesis of titanium dioxide (TiO2) nanoparticles (NPs) and Au/TiO2 nanocomposites (NCs) using L-tryptophan is reported. Highly crystalline composite NPs are obtained by this totally ‘clean’ synthesis. The TiO2 NPs and Au/TiO2 NCs cause efficient photocatalytic degradation of the well-known dye pollutant malachite green. The surface area, pore volume and probability of dye reduction by photogenerated electrons and holes are important considerations for the photodegradation efficiency. Contrary to popular belief, the Au/TiO2 NCs show decreased photocatalytic efficiency. The TiO2 NPs and Au/TiO2 NCs also function as very efficient catalysts in a novel multi component reaction (MCR). In contrast to photocatalysis, Au/TiO2 NCs shows better catalytic efficiency. A comparison is made of the difference in photocatalytic and catalytic behaviors of the NPs. This is the first report of the catalysis of an MCR by TiO2-based NPs. The product of the MCR is a novel fluorescent probe which shows evidence for the existence of a twisted intramolecular charge transfer state. Thus this work shows promise for the development of new catalysts for synthesis of novel fluorescent probes.

  8. Synthesis of Highly Photocatalytic TiO2 Microflowers Based on Solvothermal Approach Using N,N-Dimethylformamide.

    PubMed

    Bastakoti, Bishnu Prasad; Sakka, Yoshio; Wu, Kevin C W; Yamauchi, Yusuke

    2015-06-01

    Crystallized anatase TiO2 microflowers with high surface area are synthesized by a simple template-free solvothermal method using N,N-dimethylformamide (DMF). Titanium sources undergo well-organized assembly in DMF to form flower-shaped TiO2 particles. After the calcination, the anatase frameworks are highly crystallized, and the surface area is increased up to 256 m2 x g(-1). The calcined TiO2 microflowers show superior photocatalytic performance over the commercially available TiO2 product (P25) in the degradation of methylene blue. PMID:26369107

  9. TiO2-based nanotubes modified with nickel: synthesis, properties, and improved photocatalytic activity.

    PubMed

    Qamar, M; Kim, S J; Ganguli, A K

    2009-11-11

    Titanate nanotubes containing 2.5 wt% Ni were synthesized from TiO2 sol using alkali hydrothermal treatment followed by a simple ion-exchange process. The changes in phase, shape and morphology, surface area, and photocatalytic activity of these nanotubes have been explored as a function of calcination temperature. The samples were characterized using standard techniques, including x-ray diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma spectrometry, energy dispersive x-ray spectroscopy, and Brauner-Emmett-Teller surface area analysis. The study revealed that the titanate phase containing Ni ions can be converted to the anatase phase after certain heat treatments but, at the same time, the tubular morphology was partially lost. Investigation of photocatalytic properties demonstrated that the as-prepared Ni-titanate nanotubes were photocatalytically inactive, but when heated at temperatures below 500 degrees C their activity was significantly enhanced with the change in phase. The calcined nanotube samples carrying nickel ion showed better photocatalytic activity than calcined nanotube samples containing protons. The hydrogen adsorption capacity of these titanates has also been measured, and it was found that Ni-titanate nanotubes can adsorb more hydrogen than its counterpart Na-titanate. PMID:19834243

  10. Modeling Geometric Arrangements of TiO2-Based Catalyst Substrates and Isotropic Light Sources to Enhance the Efficiency of a Photocatalystic Oxidation (PCO) Reactor

    NASA Technical Reports Server (NTRS)

    Richards, Jeffrey T.; Levine, Lanfang H.; Husk, Geoffrey K.

    2011-01-01

    The closed confined environments of the ISS, as well as in future spacecraft for exploration beyond LEO, provide many challenges to crew health. One such challenge is the availability of a robust, energy efficient, and re-generable air revitalization system that controls trace volatile organic contaminants (VOCs) to levels below a specified spacecraft maximum allowable concentration (SMAC). Photocatalytic oxidation (PCO), which is capable of mineralizing VOCs at room temperature and of accommodating a high volumetric flow, is being evaluated as an alternative trace contaminant control technology. In an architecture of a combined air and water management system, placing a PCO unit before a condensing heat exchanger for humidity control will greatly reduce the organic load into the humidity condensate loop ofthe water processing assembly (WPA) thereby enhancing the life cycle economics ofthe WPA. This targeted application dictates a single pass efficiency of greater than 90% for polar VOCs. Although this target was met in laboratory bench-scaled reactors, no commercial or SBIR-developed prototype PCO units examined to date have achieved this goal. Furthermore, the formation of partial oxidation products (e.g., acetaldehyde) was not eliminated. It is known that single pass efficiency and partial oxidation are strongly dependent upon the contact time and catalyst illumination, hence the requirement for an efficient reactor design. The objective of this study is to maximize the apparent contact time and illuminated catalyst surface area at a given reactor volume and volumetric flow. In this study, a Ti02-based photocatalyst is assumed to be immobilized on porous substrate panels and illumination derived from linear isotropic light sources. Mathematical modeling using computational fluid dynamics (CFD) analyses were performed to investigate the effect of: 1) the geometry and configuration of catalyst-coated substrate panels, 2) porosity of the supporting substrate, and 3) varying the light source and spacing on contact time and illuminated catalyst area.

  11. Tuning the surface structure of nitrogen-doped TiO2 nanofibres--an effective method to enhance photocatalytic activities of visible-light-driven green synthesis and degradation.

    PubMed

    Zheng, Zhanfeng; Zhao, Jian; Yuan, Yong; Liu, Hongwei; Yang, Dongjiang; Sarina, Sarina; Zhang, Hongjie; Waclawika, Eric R; Zhu, Huaiyong

    2013-04-26

    Nitrogen-doped TiO2 nanofibres of anatase and TiO2(B) phases were synthesised by a reaction between titanate nanofibres of a layered structure and gaseous NH3 at 400-700 °C, following a different mechanism than that for the direct nitrogen doping from TiO2. The surface of the N-doped TiO2 nanofibres can be tuned by facial calcination in air to remove the surface-bonded N species, whereas the core remains N doped. N-Doped TiO2 nanofibres, only after calcination in air, became effective photocatalysts for the decomposition of sulforhodamine B under visible-light irradiation. The surface-oxidised surface layer was proven to be very effective for organic molecule adsorption, and the activation of oxygen molecules, whereas the remaining N-doped interior of the fibres strongly absorbed visible light, resulting in the generation of electrons and holes. The N-doped nanofibres were also used as supports of gold nanoparticle (Au NP) photocatalysts for visible-light-driven hydroamination of phenylacetylene with aniline. Phenylacetylene was activated on the N-doped surface of the nanofibres and aniline on the Au NPs. The Au NPs adsorbed on N-doped TiO2(B) nanofibres exhibited much better conversion (80 % of phenylacetylene) than when adsorbed on undoped fibres (46 %) at 40 °C and 95 % of the product is the desired imine. The surface N species can prevent the adsorption of O2 that is unfavourable for the hydroamination reaction, and thus, improve the photocatalytic activity. Removal of the surface N species resulted in a sharp decrease of the photocatalytic activity. These photocatalysts are feasible for practical applications, because they can be easily dispersed into solution and separated from a liquid by filtration, sedimentation or centrifugation due to their fibril morphology. PMID:23463719

  12. Synthesis, characterization and application of TiO2 nanopowders as special paper coating pigment

    NASA Astrophysics Data System (ADS)

    El-Sherbiny, Samya; Morsy, Fatma; Samir, Marwa; Fouad, Osama A.

    2014-03-01

    TiO2 nanopigments in two pure crystallographic forms (anatase and rutile) have been synthesized successfully by two methods; hydrothermal and hydrolysis. The produced pigments from the two methods were investigated physicochemically by several analyses tools. Then they were applied in paper coating mixtures and their influence on coated paper properties was systematically investigated. XRD and FTIR investigations showed that the prepared pigments using hydrothermal method at 100 and 120 °C were a mixture of anatase and brookite and pure anatase, respectively, whereas hydrolysis method produced pure rutile phase pigment. TEM investigation showed that the crystallite size of anatase, mixture of anatase and brookite and rutile samples are 6.2, 11.7, and 9.2 nm, respectively. BET studies proved that anatase pigment has 140.74 m2/g, 0.237 cc/g and 18.33 Å, whereas rutile has 60.621 m2/g, 0.122 cc/g and 14.669 Å, surface area, pore volume and pore diameter, respectively. UV-Vis absorption and PL emission characteristics of the prepared pigments showed that the energy gaps for anatase, mixture of anatase and brookite and rutile are 3.36, 3.30 and 3.37 eV, respectively. The addition of the prepared nanopigments in conjugation with clay in coating mixture increased both brightness and opacity of the coated papers. The greatest effect was obtained upon using rutile nanopigment. Also there was a significant decrease in coated paper roughness while the air permeance started to decrease then increased at 50 % addition levels. In all coated paper, rutile pigment showed the highest enhancement effect on coated paper properties.

  13. Facile synthesis of hierarchical porous TiO(2) ceramics with enhanced photocatalytic performance for micropolluted pesticide degradation.

    PubMed

    Xing, Zipeng; Zhou, Wei; Du, Fan; Zhang, Linlin; Li, Zhenzi; Zhang, Hang; Li, Wei

    2014-10-01

    In this research, hierarchical porous TiO2 ceramics were successfully synthesized through a camphene-based freeze-drying route. The well-dispersed TiO2 slurries were first frozen and dried at room temperature, followed by high-temperature sintering. The ceramics were analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Results indicated that the obtained TiO2 ceramics could inhibit undesirable anatase-to-rutile phase transformation and grain growth even at temperatures as high as 800 °C. In this experiment, optimal compressive strength and porosity of the TiO2 ceramics were produced with the initial TiO2 slurry content of ?15 wt %. The resultant TiO2 ceramics performed excellently in the photodegradation of atrazine and thiobencarb, and the total organic carbon removal efficiency was up to 95.7% and 96.7%, respectively. More importantly, the TiO2 ceramics were easily recyclable. No obvious changes of the photocatalytic performance were observed after six cycles. Furthermore, the ceramics also effectively degraded other pesticides such as dimethoate, lindane, dipterex, malathion, and bentazone. These hierarchical porous TiO2 ceramics have potential applications in environmental cleanup. PMID:25198508

  14. Controlled hydrolysis synthesis and luminescence properties of uniform TiO2 spheres with different titanium alkoxides.

    PubMed

    Zhang, Cuimiao; Huo, Shuying; Shen, Shigang; Jia, Guang; Sun, Jing

    2013-06-01

    A series of uniform and well-dispersed TiO2 spheres have been successfully synthesized through a controlled hydrolysis route by using different titanium alkoxides as reactants. The types of titanium alkoxides and stirring time have an effect on the uniformity and dispersion of the TiO2 spherical particles. The addition of a small amount of salt also plays a crucial role for the formation of the monodisperse TiO2 spheres. Under ultraviolet excitation, the as-obtained Eu(3+)-doped TiO2 spheres exhibit red emission corresponding to the electric-dipole allowed 5D0-7F2 transition of Eu3+ ions, which is induced by the lack of inversion symmetry at the Eu3+ ions site. The Eu(3+)-doped TiO2 phosphors might find potential applications in the fields such as optical displays, photoelectric devices, and light-emitting diodes (LEDs). PMID:23862520

  15. Fe2 O3 -TiO2 nanocomposites for enhanced charge separation and photocatalytic activity.

    PubMed

    Moniz, Savio J A; Shevlin, Stephen A; An, Xiaoqiang; Guo, Zheng-Xiao; Tang, Junwang

    2014-11-17

    Photocatalysis provides a cost effective method for both renewable energy synthesis and environmental purification. Photocatalytic activity is dominated by the material design strategy and synthesis methods. Here, for the first time, we report very mild and effective photo-deposition procedures for the synthesis of novel Fe2 O3 -TiO2 nanocomposites. Their photocatalytic activities have been found to be dramatically enhanced for both contaminant decomposition and photoelectrochemical water splitting. When used to decompose a model contaminant herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), monitored by both UV/Vis and total organic carbon (TOC) analysis, 10% Fe-TiO2 -H2 O displayed a remarkable enhancement of more than 200?% in the kinetics of complete mineralisation in comparison to the commercial material P25 TiO2 photocatalyst. Furthermore, the photocurrent is nearly double that of P25. The mechanism for this improvement in activity was determined using density functional theory (DFT) and photoluminescence. These approaches ultimately reveal that the photoelectron transfer is from TiO2 to Fe2 O3 . This favours O2 reduction which is the rate-determining step in photocatalytic environmental purification. This in situ charge separation also allows for facile migration of holes from the valence band of TiO2 to the surface for the expected oxidation reactions, leading to higher photocurrent and better photocatalytic activity. PMID:25280047

  16. Synthesis and Characterization of TiO2 Nanotubes Sensitized with CdS Quantum Dots Using a One-Step Method

    NASA Astrophysics Data System (ADS)

    Song, Jiahui; Zhang, Xinguo; Zhou, Chunyan; Lan, Yuwei; Pang, Qi; Zhou, Liya

    2015-01-01

    A novel one-step synthesis process was used to assemble CdS quantum dots (QDs) into TiO2 nanotube arrays (TNTAs). The sensitization time of the TiO2 nanotubes can be adjusted by controlling the CdS QD synthesis time. The absorption band of sensitized TNTAs red-shifted and broadened to the visible spectrum. The photoelectric conversion efficiency increased to 0.83%, the open-circuit voltage to 776 mV, and the short-circuit current density ( J SC) to 2.30 mA cm-2 with increased sensitization time. The conversion efficiency with this new sensitization method was five times that of nonsensitized TNTAs, providing novel ideas for study of TNTA solar cells.

  17. Preillumination of TiO2 and Ta2O5 photoactive thin films as a tool to tailor the synthesis of composite materials.

    PubMed

    Sánchez-Valencia, Juan R; Borrás, Ana; Barranco, Angel; Rico, Victor J; Espinós, Juan P; González-Elipe, Agustín R

    2008-09-01

    Illumination of TiO 2 thin films with UV light is known to induce the transformation of the surface of this material from partially hydrophobic into fully hydrophilic. The present work shows that this transformation is accompanied by other effects that may be used to control the synthesis of composite materials. For this purpose, TiO 2 and Ta 2O 5 transparent thin films with a columnar structure and open pores were prepared by electron evaporation at glancing angles. Transparent TiO 2 thin films with micropores (i.e., pores smaller than 2 nm) prepared by plasma enhanced chemical vapor deposition (PECVD) were also used. All these films became hydrophilic upon UV illumination. Rhodamine 6G and Rhodamine 800 dyes were irreversibly adsorbed within the columns of the TiO 2 and Ta 2O 5 thin films by immersion into a water solution of these molecules. Isolated and aggregated molecules of these two dyes were detected by visible absorption spectroscopy. The infiltration adsorption efficiency was directly correlated with the acidity of the medium, increasing at basic pHs as expected from simple considerations based on the concepts of the point of zero charge (PZC) in colloidal oxides. The infiltration experiments were repeated with columnar TiO 2 and Ta 2O 5 thin films that were subjected to preillumination with UV light. It was found that this treatment produced a modification in the type (isolated or aggregated) and amount of dye molecules incorporated into the pores. Moreover, the selective adsorption of a given dye in preilluminated areas of the films permitted the lithographic coloring of the films. Preillumination also controls the UV induced deposition of silver on the surface of the microporous TiO 2 thin films. It was found that the size distribution of the formed silver nanoparticles was dependent on the preillumination treatment and that a well-resolved surface plasmon resonance at around 500 nm was only monitored in the preilluminated films. A model is proposed to account for the effects induced by UV preillumination on the TiO 2 and Ta 2O 5 oxide surfaces. The possibilities of this type of light treatment for the tailored synthesis of nanocomposite thin films (i.e., dye-oxide, metal nanoparticles-oxide) are highlighted. PMID:18642860

  18. Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation.

    PubMed

    Banerjee, Biplab; Amoli, Vipin; Maurya, Abhayankar; Sinha, Anil Kumar; Bhaumik, Asim

    2015-06-21

    We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h(-1) g(-1) has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature. PMID:26008203

  19. Influence of calcination parameters on the synthesis of N-doped TiO2 by the polymeric precursors method

    NASA Astrophysics Data System (ADS)

    Dawson, Margaret; Soares, Gabriela Byzynski; Ribeiro, Caue

    2014-07-01

    In this paper, the influence of calcination parameters on the synthesis of N:TiO2 catalysts obtained through the polymeric precursors method was evaluated. The powders were prepared by annealing Ti4+ precursor resins at different temperature-time conditions in air, resulting in powders with different degrees of crystallinity for N doping, which was done by adding urea to the as-prepared powders and calcining in N2 atmosphere. The N doping process resulted in band gap narrowing of TiO2 and, varying annealing temperature and time, can be an alternative method for preferential formation of substitutional N or interstitial N. It was found that the percentage of interstitial N increased with an increase in annealing temperature, resulting in the complete absence of substitutional N at 400 °C. The photocatalytic performance of the powders was evaluated using Rhodamine-B and Atrazine solutions under ultraviolet and visible irradiations. The coefficients revealed that interstitial N had a positive correlation to both ultraviolet and visible photoactivity. In contrast, substitutional N showed a negative correlation. Further, the ratio of substitutional N to interstitial N indicated a strong negative correlation to ultraviolet light photoactivity and no correlation to visible light photoactivity. However, substitutional N should be controlled for better photocatalytic properties.

  20. Sonochemical synthesis and photocatalytic activity of meso- and macro-porous TiO(2) for oxidation of toluene.

    PubMed

    Liu, Yang; Li, Yan; Wang, Yuntao; Xie, Lei; Zheng, Jie; Li, Xingguo

    2008-01-15

    Meso-and macro-porous TiO(2) were synthesized by ultrasonic induced solvothermal method. Octadecylamine as a soft template was used to direct the formation of porous structure. The as-prepared porous TiO(2) was characterized by low angle and wide angle X-ray diffraction, N(2) adsorption-desorption isotherms and BET surface area. The energy influence of ultrasound and heat and concentration of nitric acid for post extraction on formation of porous structure were investigated. The photocatalytic activities of TiO(2) were investigated by degrading toluene gas under UV light. The results revealed that proper energy facilitates the formation of porous structure and too low concentration of nitric acid cannot extract template from pores. The photocatalytic activities of TiO(2) with porous structure are higher than those of nonporous ones. PMID:17560714

  1. Synthesis of monodisperse colloidal TiO2 microspheres and performance of their dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhu, Zhenfeng; Zhu, Chunkui; Liu, Hui; Wu, Yingfeng; Chen, Guanhong; Lv, Ting

    2014-07-01

    Monodisperse colloidal TiO2 microspheres with different size have been synthesized via controlled hydrolysis of tetrabutyltitanate (TBOT) in ethanol with addition of a salt solution. The photoelectric conversion performances of dye-sensitized solar cells (DSSCs) based on TiO2 microspheres were investigated. The results revealed that these TiO2 microspheres, which were well dispersed and uniform, and their size became gradually smaller with the increasing KCl concentration. The DSSC based on smaller TiO2 microspheres exhibited an enhanced photocurrent and conversion efficiency, which was attributed to its better absorption properties of dye molecules and superior conductivity. After the further optimization, the total conversion efficiency of DSSC with electrode 2 was 5.72%.

  2. Synthesis and photocatalytic activity of N-doped TiO2 produced in a solid phase reaction

    NASA Astrophysics Data System (ADS)

    Xin, Gang; Pan, Hongfei; Chen, Dan; Zhang, Zhihua; Wen, Bin

    2013-02-01

    N-doped TiO2 was synthesized by calcining a mixture of titanic acid and graphitic carbon nitride (g-C3N4) at temperatures above 500 °C. The final samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and UV-vis diffuse reflectance spectra. The photocatalytic activity of N-doped TiO2 was studied by assessing the degradation of methylene blue in an aqueous solution, under visible light and UV light irradiation. It was found that the N-doped TiO2 displayed higher photocatalytic activity than pure TiO2, under both visible and UV light.

  3. In situ synthesis of TiO2(B) nanotube/nanoparticle composite anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Sun, Qian; Ng, Alan M. C.; Djuriši?, Aleksandra B.; Xie, Maohai; Liao, Changzhong; Shih, Kaimin; Vranješ, Mila; Nedeljkovi?, Jovan M.; Deng, Zhaofeng

    2015-10-01

    Titania nanotubes were prepared by a simple hydrothermal route. Their electrochemical performance has been examined in detail and compared to TiO2(B) nanoparticles, TiO2 anatase and P25 titania nanoparticles. The cycling and rate performance of TiO2 nanotubes is superior to both types of nanoparticles, and it can be further improved by an in situ titanium precursor treatment, which results in the formation of TiO2 nanoparticles on/between the nanotubes. The obtained specific capacity after 200 cycles at 0.2 A g-1 charge/discharge rate remained above 130 mAh g-1. The enhanced lithium storage properties of these samples can be attributed to their unique morphology and crystal structure.

  4. In situ synthesis of TiO2(B) nanotube/nanoparticle composite anode materials for lithium ion batteries.

    PubMed

    Liu, Xiang; Sun, Qian; Ng, Alan M C; Djuriši?, Aleksandra B; Xie, Maohai; Liao, Changzhong; Shih, Kaimin; Vranješ, Mila; Nedeljkovi?, Jovan M; Deng, Zhaofeng

    2015-10-23

    Titania nanotubes were prepared by a simple hydrothermal route. Their electrochemical performance has been examined in detail and compared to TiO2(B) nanoparticles, TiO2 anatase and P25 titania nanoparticles. The cycling and rate performance of TiO2 nanotubes is superior to both types of nanoparticles, and it can be further improved by an in situ titanium precursor treatment, which results in the formation of TiO2 nanoparticles on/between the nanotubes. The obtained specific capacity after 200 cycles at 0.2 A g(-1) charge/discharge rate remained above 130 mAh g(-1). The enhanced lithium storage properties of these samples can be attributed to their unique morphology and crystal structure. PMID:26421360

  5. Atomic Layer Deposition of Pd Nanoparticles on TiO2 Nanotubes for Ethanol Electrooxidation: Synthesis and Electrochemical Properties.

    PubMed

    Assaud, Loïc; Brazeau, Nicolas; Barr, Maïssa K S; Hanbücken, Margrit; Ntais, Spyridon; Baranova, Elena A; Santinacci, Lionel

    2015-11-11

    Palladium nanoparticles are grown on TiO2 nanotubes by atomic layer deposition (ALD), and the resulting three-dimensional nanostructured catalysts are studied for ethanol electrooxidation in alkaline media. The morphology, the crystal structure, and the chemical composition of the Pd particles are fully characterized using scanning and transmission electron microscopies, X-ray diffraction, and X-ray photoelectron spectroscopy. The characterization revealed that the deposition proceeds onto the entire surface of the TiO2 nanotubes leading to the formation of well-defined and highly dispersed Pd nanoparticles. The electrooxidation of ethanol on Pd clusters deposited on TiO2 nanotubes shows not only a direct correlation between the catalytic activity and the particle size but also a steep increase of the response due to the enhancement of the metal-support interaction when the crystal structure of the TiO2 nanotubes is modified by annealing at 450 °C in air. PMID:26477631

  6. Effect of synthesis temperature on the morphology, structure and photocatalytic activity of TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Nayak, J.; Mohapatra, A. K.; Kim, Heeje

    2015-06-01

    Nanocrystals of TiO2 were synthesized by a single-step chemical reaction between oleic acid and titanium (IV) iso-propoxide. The morphology and structure of the crystals were studied by X-ray diffraction and transmission electron microscopy. The vibrational properties of the nanocrystals were studied by Raman spectroscopy. The ultraviolet photocatalytic activity of the TiO2 nanocrystals was investigated by studying the photodegradation of aqueous solution of protocatecheuic acid (3,4-dihydroxy benzoic acid).

  7. TiO2 Nanoparticles Are Phototoxic to Marine Phytoplankton

    PubMed Central

    Miller, Robert J.; Bennett, Samuel; Keller, Arturo A.; Pease, Scott; Lenihan, Hunter S.

    2012-01-01

    Nanoparticulate titanium dioxide (TiO2) is highly photoactive, and its function as a photocatalyst drives much of the application demand for TiO2. Because TiO2 generates reactive oxygen species (ROS) when exposed to ultraviolet radiation (UVR), nanoparticulate TiO2 has been used in antibacterial coatings and wastewater disinfection, and has been investigated as an anti-cancer agent. Oxidative stress mediated by photoactive TiO2 is the likely mechanism of its toxicity, and experiments demonstrating cytotoxicity of TiO2 have used exposure to strong artificial sources of ultraviolet radiation (UVR). In vivo tests of TiO2 toxicity with aquatic organisms have typically shown low toxicity, and results across studies have been variable. No work has demonstrated that photoactivity causes environmental toxicity of TiO2 under natural levels of UVR. Here we show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO2 nanoparticles to marine phytoplankton, the most important primary producers on Earth. No effect of TiO2 on phytoplankton was found in treatments where UV light was blocked. Under low intensity UVR, ROS in seawater increased with increasing nano-TiO2 concentration. These increases may lead to increased overall oxidative stress in seawater contaminated by TiO2, and cause decreased resiliency of marine ecosystems. Phototoxicity must be considered when evaluating environmental impacts of nanomaterials, many of which are photoactive. PMID:22276179

  8. Confined-space synthesis of single crystal TiO2 nanowires in atmospheric vessel at low temperature: a generalized approach

    PubMed Central

    Wang, Xiaoyue; Wang, Hai; Zhou, Yu; Liu, Yong; Li, Baojun; Zhou, Xiang; Shen, Hui

    2015-01-01

    Extensive efforts have been devoted to develop innovative synthesis strategies for nanomaterials in order to exploit the true potential of nanotechnology. However, most approaches require high temperature or high pressure to favor crystallization. Here we highlight an unconventional approach for the confined-space synthesis of the single crystal TiO2 nanowires in the atmospheric vessel at low temperature by cleverly manipulating the unique physical properties of straight-chain saturated fatty acids. Our method also applys to icosane due to its straight-chain saturated hydrocarbon structure and similar physical properties to the saturated fatty acids. Interestingly, we also found that the unsaturated fatty acids can facilitate the crystal growth, but their bent chains lead to the formation of TiO2 particle aggregates. In addition, we demonstrate the growth of TiO2 nanowires on arbitrary substrates, which are of great importance for their wider applications. We thus anticipate our presented method to be a possible starting point for non-classical crystallization strategies and be easily adapted for the fabrication of all other inorganic materials. PMID:25634804

  9. Photocatalytic degradation of monoethanolamine in wastewater using nanosized TiO2 loaded on clinoptilolite.

    PubMed

    Khodadoust, Saeid; Sheini, Azarmidokht; Armand, Nezam

    2012-06-15

    The use of titanium dioxide (TiO(2)) as photocatalyst to degrade the organic compounds is an effective method of oxidation process and has been widely studied in environmental engineering. In this investigation photocatalytic degradation of monoethanolamine (MEA) using TiO(2) (in form of anatase) loaded on surface of clinoptilolite (CP) (TiO(2)-CP) in wastewater was studied. The surface interaction between TiO(2) and CP was investigated by means of transmission electron microscope (TEM), atom force microscope (AFM), IR and X-ray diffraction (XRD). Then the effects of some parameters such as pH, amount of photocatalyst, and initial concentration of MEA on degradation percentage of MEA were examined. The obtained results show that the TiO(2)-CP is an active photocatalyst as compared with TiO(2) nanopowders. All these results indicated that this proposed method can be useful for the development of wastewater treatment applications. PMID:22446755

  10. Synergistic Decolouration of Azo Dye by Pulsed Streamer Discharge Immobilized TiO2 Photocatalysis

    NASA Astrophysics Data System (ADS)

    Li, Jie; Wang, Huijuan; Li, Guofeng; Wu, Yan; Quan, Xie; Liu, Zhigang

    2007-08-01

    Photocatalyst was prepared by immobilizing TiO2 on glass beads using the traditional sol-gel method. Ultraviolet light (UV) produced by pulsed streamer discharge was then used to induce photocatalytic activity of TiO2 photocatalyst. Decolouration efficiency of the representative azo dye (acid orange 7, AO7) was investigated using the synergistic system of pulsed streamer discharge plasma and TiO2 photocatalysis. The obtained results showed that the decolouration rate of AO7 could be increased by 16.7% under the condition of adding supported TiO2 in the pulsed streamer discharge system, compared to that in the sole pulsed streamer discharge plasma system, due to the synergistic effect of pulsed streamer discharge and TiO2 photocatalysis induced by pulsed streamer discharge. The synergistic system of pulsed streamer discharge and TiO2 photocatalyst was found to have more reactive radicals for degradation of organic compounds in water.

  11. Thermal conduction effects impacting morphology during synthesis of columnar nanostructured TiO2 thin films

    SciTech Connect

    An, Woo-Jin; Jiang, David D.; Matthews, James R.; Borrelli, Nicholas F.; Biswas, Pratim

    2011-01-01

    The aerosol chemical vapor deposition (ACVD) process allows for the synthesis of nanostructured films with well tuned morphologies that can be controlled based on the desired functionality and application. A robust understanding of the process parameters that result in desired features of the film is elucidated. One dimensional TiO? nanostructured columns that have superior properties for solar energy harvesting and conversion applications were deposited on tin doped indium oxide (ITO) substrates. The sintering of the deposited particles was a key factor in the growth of the 1D structure with desired crystal planes. By ensuring that the sintering rate is faster than the arrival rate of deposited particles; a 1D columnar structure could be obtained. The sintering rate was controlled by the temperature and depositing particle size. As the columns grew in length, the increased thermal conduction resistance resulted in a drop in temperature and subsequently a slowing of the sintering process in upper regions of the film. This led to growth of branched structures rather than continued growth in a preferred direction. The growth of the branched structure could be overcome by enhancing the sintering rate by increasing the substrate temperature or reducing the depositing particle size (by lowering the feed rate of the precursor). The phenomenon was also confirmed by using different deposition substrates, such as FTO and glass. Dye sensitized solar cell performance efficiencies with different column lengths of 2 and 7 µm were determined to be 1.8 and 2.7% respectively.

  12. A study on the band gap and the doping level of V-doped TiO2 with respect to the visible-light photocatalytic activity.

    PubMed

    Choi, Ah Young; Han, Chul-Hee

    2014-10-01

    The visible-light response is a necessary but not a sufficient condition for semiconductor photocatalyst to function as a visible-light active photocatalyst. To shed more light on the issue of visible-light response of semiconductor photocatalysts, the band-gaps and the doping levels of multivalency vanadium-doped TiO2 were investigated from sonochemically prepared samples. Sonochemical doping, which relies on acoustic cavitation phenomena, is a one step process excluding chemical synthesis, and three types of vanadium doped TiO2 nanopowder were prepared using such vanadium oxides as V2O3, V2O4, and V2O5. The band-gaps of as-prepared samples were obtained from the diffuse reflectance measurement, and the doping levels of vanadium in these samples were measured using electron probe micro analyzer. In addition, X-ray photoelectron spectrometer was introduced to complement electron probe micro analyzer. Furthermore, quantum-chemical calculations on simple cluster models for TiO2 and V-doped TiO2 were performed, and the resulting computational results in conjunction with experimental findings provided valuable information on oxygen vacancy and doping mechanism. PMID:25942925

  13. Low-Temperature Synthesis of Anatase TiO2 Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

    PubMed Central

    Li, Ye; Qin, Zhenping; Guo, Hongxia; Yang, Hanxiao; Zhang, Guojun; Ji, Shulan; Zeng, Tingying

    2014-01-01

    In this work, the positively or negatively charged anatase TiO2 nanoparticles were synthesized via a low temperature precipitation-peptization process (LTPPP) in the presence of poly(ethyleneimine) (PEI) and poly(sodium4- styrenesulfonate) (PSS). X-ray diffraction (XRD) pattern and high-resolution transmission electron microscope (HRTEM) confirmed the anatase crystalline phase. The charges of the prepared TiO2, PEI-TiO2 and PSS-TiO2 nanoparticles were investigated by zeta potentials. The results showed that the zeta potentials of PEI-TiO2 nanoparticles can be tuned from +39.47 mV to +95.46 mV, and that of PSS-TiO2 nanoparticles can be adjusted from ?56.63 mV to ?119.32 mV. In comparison with TiO2, PSS-TiO2 exhibited dramatic adsorption and degradation of dye molecules, while the PEI modified TiO2 nanoparticles showed lower photocatalytic activity. The photocatalytic performances of these charged nanoparticles were elucidated by the results of UV-vis diffuse reflectance spectra (DRS) and the photoluminescence (PL) spectra, which indicated that the PSS-TiO2 nanoparticles showed a lower recombination rate of electron-hole pairs than TiO2 and PEI-TiO2. PMID:25506839

  14. The Synthesis and Photocatalytic Properties of TiO2 Nanotube Array by Starch-Modified Anodic Oxidation.

    PubMed

    Zhang, Fengjun; Liu, Zijian; Lu, Wei; Lyu, Cong; Lyu, Chuan; Wang, Xiansheng

    2015-11-01

    In this study, the characterization and photocatalytic activity of TiO2 nanotube arrays prepared by anodization process with starch addition were investigated in detail. The results suggested that the optimum mass fraction of starch added in anodization process was 0.1%, with which TiO2 nanotube arrays owning good tubular structure were synthesized. The tube length and average inner diameter of nanotubes were approximately 4 ?m and 30 nm, respectively. Through the characterization of TiO2 nanotube arrays by energy dispersive spectrometer, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier Transform Infrared (FTIR) spectroscopy, it was found that the as-prepared nanotubes possessed well uniformed and higher photodegradation responsive than the pure TiO2 . Moreover, it was expected that the as-prepared nanotubes exhibited good photocatalytic activity for the degradation of RhB under UV-light irradiation, which could be ascribed to their good morphology, enhanced UV-light absorption property and electron transmission ability during the photocatalytic reaction. In addition, the nanotubes were not significantly regenerated during the cycling runs experiment. Overall, this study could provide a principle method to synthesize TiO2 nanotube arrays with enhanced photocatalytic activity by anodization process with starch addition for environmental purification. PMID:26010757

  15. Synthesis and photolysis of NaYF4@SiO2@TiO2 core-shell nanocomposites

    NASA Astrophysics Data System (ADS)

    Shi, Guoyou; Mao, Yifu; Ren, Guozhong; Gong, Lunjun; Zhi, Zhugong

    2014-12-01

    Monodisperse ?-NaYF4 nanocrystals were synthesized with oleic acid as capping ligands by solvothermal method, and then, SiO2 and TiO2 were coated successively. Intense ultraviolet light is emitted from NaYF4:Yb/Tm under the 980 nm laser and the intensity of ultraviolet light reduce dramatically after these nanocrystals were coated with SiO2 and TiO2 shells, which means NaYF4@SiO2@TiO2 core-shell nanocomposites can be used to realize the infared photocatalysis. Photocatalytic activity of these nanocomposites is demonstrated using methyl orange (MO) as a chemical probe under the 980 nm laser excitation.

  16. Modified microwave method for the synthesis of visible light-responsive TiO2/MWCNTs nanocatalysts.

    PubMed

    Alosfur, Firas K Mohamad; Jumali, Mohammad Hafizuddin Haji; Radiman, Shahidan; Ridha, Noor J; Yarmo, Mohd Ambar; Umar, Akrajas Ali

    2013-01-01

    Recently, TiO2/multi-walled carbon nanotube (MWCNT) hybrid nanocatalysts have been a subject of high interest due to their excellent structures, large surface areas and peculiar optical properties, which enhance their photocatalytic performance. In this work, a modified microwave technique was used to rapidly synthesise a TiO2/MWCNT nanocatalyst with a large surface area. X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller measurements were used to characterise the structure, morphology and the surface area of the sample. The photocatalytic activity of the hybrid nanocatalysts was evaluated through a comparison of the degradation of methylene blue dye under irradiation with ultraviolet and visible light. The results showed that the TiO2/MWCNT hybrid nanocatalysts degraded 34.9% of the methylene blue (MB) under irradiation with ultraviolet light, whereas 96.3% of the MB was degraded under irradiation with visible light. PMID:23919496

  17. Palladium nanoparticles anchored to anatase TiO2 for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

    PubMed Central

    Leong, Kah Hon; Chu, Hong Ye; Ibrahim, Shaliza

    2015-01-01

    Summary Freely assembled palladium nanoparticles (Pd NPs) on titania (TiO2) nano photocatalysts were successfully synthesized through a photodeposition method using natural sunlight. This synthesized heterogeneous photocatalyst (Pd/TiO2) was characterized through field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), BET surface area, UV–vis diffuse reflectance spectra (UV-DRS), Raman and photoluminescence (PL) analyses. The simple and smart synthesis anchored well the deposition with controlled Pd NPs size ranging between 17 and 29 nm onto the surface of TiO2. Thus, it gives the characteristic for Pd NPs to absorb light in the visible region obtained through localized surface plasmon resonance (LSPRs). Apparently, the photocatalytic activity of the prepared photocatalysts was evaluated by degrading the endocrine disrupting compound (EDC) amoxicillin (AMX) excited under an artificial visible light source. In the preliminary run, almost complete degradation (97.5%) was achieved in 5 h with 0.5 wt % Pd loading and the degradation followed pseudo-first-order kinetics. The reusability trend proved the photostability of the prepared photocatalysts. Hence, the study provides a new insight about the modification of TiO2 with noble metals in order to enhance the absorption in the visible-light region for superior photocatalytic performance. PMID:25821683

  18. Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation

    NASA Astrophysics Data System (ADS)

    Banerjee, Biplab; Amoli, Vipin; Maurya, Abhayankar; Sinha, Anil Kumar; Bhaumik, Asim

    2015-06-01

    We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h-1 g-1 has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature.We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h-1 g-1 has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02097b

  19. Instability of Hydrogenated TiO2.

    PubMed

    Nandasiri, Manjula I; Shutthanandan, Vaithiyalingam; Manandhar, Sandeep; Schwarz, Ashleigh M; Oxenford, Lucas; Kennedy, John V; Thevuthasan, Suntharampillai; Henderson, Michael A

    2015-11-19

    Hydrogenated TiO2 (H-TiO2) is touted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using nuclear reaction analysis (NRA), Rutherford backscattering spectrometry, ultraviolet photoelectron spectroscopy, and X-ray photoelectron spectroscopy. Protons (40 keV) implanted at a ?2 atom % level within a ?120 nm wide profile of rutile TiO2(110) were situated ?300 nm below the surface. NRA revealed that this H-profile broadened toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (?800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile at low temperatures, as well as its interfacial activity toward reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. PMID:26545303

  20. Instability of Hydrogenated TiO2

    SciTech Connect

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  1. Synthesis of highly active thin film based on TiO2 nanomaterial for self-cleaning application

    NASA Astrophysics Data System (ADS)

    Saif, M.; El-Molla, S. A.; Aboul-Fotouh, S. M. K.; Hafez, H.; Ibrahim, M. M.; Abdel-Mottaleb, M. S. A.; Ismail, L. F. M.

    2013-08-01

    Highly active self-cleaning surfaces were prepared from hydrothermally treated TiO2 nanomaterials for different times (0, 12, 24 and 36 h) under acidic condition. TiO2 thin films were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). TiO2 thin film (hydrothermal 24 h) exhibited hybrid morphology from accumulated plates, clusters, rods and spheres. The photo self-cleaning activity in term of quantitative determination of the active oxidative species (rad OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results show that, the highly active thin film is the hydrothermally treated for 24 h at 200 °C. The structural, morphology and photoactivity properties of nano-TiO2 thin films make it promising surfaces for self-cleaning application. Mineralization of commercial textile dye (Remazol Red RB-133, RR) from highly active TiO2 thin film surface was applied. Moreover, the durability of this nano-TiO2 thin film (hydrothermal 24 h) was studied.

  2. Synthesis of Ag ion-implanted TiO2 thin films for antibacterial application and photocatalytic performance.

    PubMed

    Hou, Xinggang; Ma, Huiyan; Liu, Feng; Deng, Jianhua; Ai, Yukai; Zhao, Xinlei; Mao, Dong; Li, Dejun; Liao, Bin

    2015-12-15

    TiO2 thin films were deposited by spin coating method. Silver ions were implanted into the films using a Metal Vapor Vacuum Arc implanter. The antibacterial ability of implanted films was tested using Escherichia coli removal under fluorescent irradiation and in the dark. The concentration of E. coli was evaluated by plating technique. The photocatalytic efficiency of the implanted films was studied by degradation of methyl orange under fluorescent illumination. The surface free energy of the implanted TiO2 films was calculated by contact angle testing. Vitamin C was used as radical scavengers to explore the antibacterial mechanism of the films. The results supported the model that both generation of reactive oxygen species and release of silver ions played critical roles in the toxic effect of implanted films against E. coli. XPS experimental results demonstrated that a portion of the Ag(Ag(3+)) ions were doped into the crystalline lattice of TiO2. As demonstrated by density functional theory calculations, the impurity energy level of subtitutional Ag was responsible for enhanced absorption of visible light. Ag ion-implanted TiO2 films with excellent antibacterial efficiency against bacteria and decomposed ability against organic pollutants could be potent bactericidal surface in moist environment. PMID:26093355

  3. Synthesis of hybrid cellulose nanocomposite bonded with dopamine SiO2/TiO2 and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Ramesh, Sivalingam; Kim, Gwang-Hoon; Kim, Jaehwan; Kim, Joo-Hyung

    2015-04-01

    Organic-inorganic hybrid material based cellulose was synthesized by the sol-gel approach. The explosion of activity in this area in the past decade has made tremendous progress in industry or academic both fundamental understanding of sol-gel process and applications of new functionalized hybrid materials. In this present research work, we focused on cellulose-dopamine functionalized SiO2/TiO2 hybrid nanocomposite by sol-gel process. The cellulose-dopamine hybrid nanocomposite was synthesized via ?-aminopropyltriethoxysilane (?-APTES) coupling agent by in-situ sol-gel process. The chemical structure of cellulose-amine functionalized dopamine bonding to cellulose structure with covalent cross linking hybrids was confirmed by FTIR spectral analysis. The morphological analysis of cellulose-dopamine nanoSiO2/TiO2 hybrid nanocomposite materials was characterized by XRD, SEM and TEM. From this different analysis results indicate that the optical transparency, thermal stability, control morphology of cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite. Furthermore cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite was tested against pathogenic bacteria for antimicrobial activity.

  4. Synthesis and visible light photoactivity of anatase Ag, and garlic loaded TiO2 nanocrystalline catalyst

    EPA Science Inventory

    An excellent visible light activated Ag and S doped TiO2 nanocatalyst was prepared by using AgNO3 and garlic (Allium sativum) as Ag+ and sulfur sources, respectively. The catalyst resisted the change from anatase to rutile phase even at calcination at 700 oC. The photocatalytic e...

  5. Electrical Properties of Nb-, Ga-, and Y-Substituted Nanocrystalline Anatase TiO2 Prepared by Hydrothermal Synthesis

    E-print Network

    Poeppelmeier, Kenneth R.

    to improve the charge collection and power conversion efficiencies in dye- sensitized and Pb as a transparent conducting oxide and as a core component in optoelectronic devices such as dye-sensitized solarS-heterojunction solar cells3,5 and eliminates the need for TiCl4-based post treatments.6,7 The role of the TiO2

  6. Synthesis and characterization of undoped and cobalt-doped TiO2 nanoparticles via sol-gel technique

    NASA Astrophysics Data System (ADS)

    Mugundan, S.; Rajamannan, B.; Viruthagiri, G.; Shanmugam, N.; Gobi, R.; Praveen, P.

    2015-04-01

    TiO2 nanoparticles doped with different concentrations of cobalt (4, 8, 12 and 16 %) were synthesized by sol-gel method at room temperature with appropriate reactants. In general, TiO2 can exist in anatase, rutile, and brookite phases. In this present study, we used titanium tetra iso propoxide and 2-propanol as a common starting materials and the obtained products were calcined at 500 °C and 800 °C to get anatase and rutile phases, respectively. The crystalline sizes of the doped and undoped TiO2 nanoparticles were observed with X-ray diffraction (XRD) analysis. The functional groups of the samples were identified by Fourier transform infrared spectroscopy (FTIR). From UV-VIS diffuse reflectance spectra (DRS), the band gap energy and excitation wavelength of doped and undoped TiO2 nanoparticles were identified. The defect oriented emissions were seen from photoluminescence (PL) study. The spherical uniform size distribution of particles and elements present in the samples was determined using two different techniques viz., scanning electron microscopy (SEM) with energy-dispersive spectrometer (EDX) and transmission electron microscope (TEM) with selected area electron diffraction (SAED) pattern. The second harmonic generation (SHG) efficiency was also found and the obtained result was compared with potassium di hydrogen phosphate (KDP).

  7. Controllable synthesis and luminescence properties of TiO2:Eu3+ nanorods, nanoparticles and submicrospheres by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Qi, Xiaofei; Song, Yanhua; Sheng, Ye; Zhang, Hongguang; Zhao, Huan; Shi, Zhan; Zou, Haifeng

    2014-12-01

    Eu3+-doped TiO2 nanocrystals with three kinds of morphologies (nanorods, nanoparticles, and submicrospheres) have been successfully fabricated in cetyltrimethylammonium bromide (CTAB)/water/cyclohexane/n-pentanol reverse micelle by hydrothermal method for the first time and their photoluminescence (PL) properties have also been studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), FT-IR, and PL spectra were used to characterize the samples. The acidic and alkaline conditions of the microemulsion play an important role in determining the geometric morphologies of the final products. TiO2:Eu3+ with three different morphologies all exist only in anatase phase and show high luminescence intensity without further calcinations, which show its advantages of energy saving. The shape of emission spectra was independent of the morphologies of the products but the luminescence intensity of the TiO2:Eu3+ materials is strongly dependent on their morphology. The results show that TiO2:Eu3+ nanorods possess the strongest luminescence intensity among the three nanostructured samples.

  8. Photocatalytic degradation of methyl orange over nitrogen-fluorine codoped TiO2 nanobelts prepared by solvothermal synthesis.

    PubMed

    He, Zuoli; Que, Wenxiu; Chen, Jing; Yin, Xingtian; He, Yucheng; Ren, Jiangbo

    2012-12-01

    Anatase type nitrogen-fluorine (N-F) codoped TiO(2) nanobelts were prepared by a solvothermal method in which amorphous titania microspheres were used as the precursors. The as-prepared TiO(2) nanobelts are composed of thin narrow nanobelts and it is noted that there are large amount of wormhole-like mesopores on these narrow nanobelts. Photocatalytic activity of the N-F codoped TiO(2) nanobelts was measured by the reaction of photocatalytic degradation of methyl orange. Results indicate that the photocatalytic activity of the N-F codoped TiO(2) nanobelts is higher than that of P25, which is mainly ascribed to wormhole-like mesopores like prison, larger surface area, and enhanced absorption of light due to N-F codoping. Interestingly, it is also found that the photocatalytic activity can be further enhanced when tested in a new testing method because more photons can be captured by the nanobelts to stimulate the formation of the hole-electron pair. PMID:23148575

  9. Synthesis of molecular imprinted polymer modified TiO 2 nanotube array electrode and their photoelectrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Lu, Na; Chen, Shuo; Wang, Hongtao; Quan, Xie; Zhao, Huimin

    2008-10-01

    A tetracycline hydrochloride (TC) molecularly imprinted polymer (MIP) modified TiO 2 nanotube array electrode was prepared via surface molecular imprinting. Its surface was structured with surface voids and the nanotubes were open at top end with an average diameter of approximately 50 nm. The MIP-modified TiO 2 nanotube array with anatase phase was identified by XRD and a distinguishable red shift in the absorption spectrum was observed. The MIP-modified electrode also exhibited a high adsorption capacity for TC due to its high surface area providing imprinted sites. Photocurrent was generated on the MIP-modified photoanode using the simulated solar spectrum and increased with the increase of positive bias potential. Under simulated solar light irradiation, the MIP-modified TiO 2 nanotube array electrode exhibited enhanced photoelectrocatalytic (PEC) activity with the apparent first-order rate constant being 1.2-fold of that with TiO 2 nanotube array electrode. The effect of the thickness of the MIP layer on the PEC activity was also evaluated.

  10. Facile Aluminum Reduction Synthesis of Blue TiO2 with Oxygen Deficiency for Lithium-Ion Batteries.

    PubMed

    Zheng, Jing; Ji, Guangbin; Zhang, Peng; Cao, Xingzhong; Wang, Baoyi; Yu, Linhui; Xu, Zhichuan

    2015-12-01

    An ultrafacile aluminum reduction method is reported herein for the preparation of blue TiO2 nanoparticles (donated as Al-TiO2 , anatase phase) with abundant oxygen deficiency for lithium-ion batteries. Under aluminum reduction, the morphology of the TiO2 nanosheets changes from well-defined rectangular into uniform round or oval nanoparticles and the particle size also decreases from 60 to 31?nm, which can aggressively accelerate the lithium-ion diffusion. Electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) results reveal that plentiful oxygen deficiencies relative to the Ti(3+) species were generated in blue Al-TiO2 ; this effectively enhances the electron conductivity of the TiO2 . X-ray photoelectron spectrometry (XPS) analysis indicates that a small peak is observed for the Al?O bond, which probably plays a very important role in the stabilization of the oxygen deficiencies/Ti(3+) species. As a result, the blue Al-TiO2 possesses significantly higher capacity, better rate performance, and a longer cycle life than the white pure TiO2 . Such improvements can be attributed to the decreased particle size, as well as the existence of the oxygen deficiencies/Ti(3+) species. PMID:26511473

  11. Synthesis and characterization of a mixed phase of anatase TiO2 and TiO2(B) by low pressure chemical vapour deposition (LPCVD) for high photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chimupala, Y.; Hyett, G.; Simpson, R.; Brydson, R.

    2014-06-01

    This project is concerned with enhancing photocatalytic activity by preparing a mixed phase of nano-sized TiO2. TiO2 thin films were synthesized by using Low Pressure Chemical Vapour Deposition (LPCVD). Titanium isopropoxide and N2 gas were used as the precursor and carrier gas respectively. The effects of reaction temperature, carrier gas flow rate and deposited area were studied. TiO2 thin films with nano-sized TiO2 particles were obtained under suitable conditions and SEM, TEM, powder XRD and Raman spectroscopy were employed to characterize the phase and physical appearance of synthesized materials. Preliminary results show that a dual phase (TiO2(B) and anatase) thin film nanopowder was successfully prepared by LPCVD with needle- and polygonal plate-shape crystallites respectively. This thin film deposit produced a preferred orientation of TiO2(B) needles in the [001] direction of average crystallite size 50-80 nm in length and 5-10 nm in width, whilst the crystallite size of anatase polygonal-plates was around 200 nm. The optimal LPCVD condition for preparing this mixed phase of TiO2 was 600°C with a 1 mL/s N2 flow rate.

  12. Nanostructured nitrogen and carbon codoped TiO2 thin films: Synthesis, structural characterization and optoelectronic properties

    NASA Astrophysics Data System (ADS)

    Ruzybayev, Inci

    TiO2 is widely used in applications like photocatalysis, sensors, solar cells, and memory devices because it is inexpensive, abundant, nontoxic and stable in aqueous solution. Another exciting application where TiO 2 has the potential to be a very useful catalyst is the clean hydrogen generation using solar radiation. Energy consumption is increasing every year and, as a result, renewable and sustainable alternative energy sources are becoming increasingly important. Therefore, clean hydrogen generation research is becoming more and more important. This study aims at the preparation and characterization of nitrogen and carbon (N-C) codoped TiO2 photoanode material that could potentially be used in photoelectrochemical cells for hydrogen generation. The solar spectrum peaks around 500 nm (2.48 eV) which is in the visible part of the spectrum. The photoanode material to be used for solar hydrogen generation should absorb visible light photons to yield high efficiency. The challenge with TiO2 is that the wide band gap (3.00--3.20 eV) absorbs only ultra-violet (UV) photons and only a small percentage of the solar spectrum is in the UV range. There are various ways to overcome the challenge of sensitizing the material to visible light absorption and this study focuses on one of the most promising ways: band modification of TiO2 by N-C codoping. The role of pure oxygen pressure on pulsed laser deposited N-C codoped TiO2 films were investigated. At low pressures rutile phase of TiO2 was dominant and a microstructure with densely packed grains was obtained. However, at high pressures anatase phase became dominant and columnar structure was favored. Therefore, the anatase-rutile phase ratio as well as the microstructure of the films can be controlled by adjusting oxygen pressure and introducing N and C into the TiO2 matrix. Optimized oxygen pressure and higher doping concentrations yielded films with more effective absorption in the visible region. The preparation and characterization of pulsed laser deposited N-C codoped TiO2 thin films were investigated for dopant incorporation using N2 and CH4 gases. Polycrystalline anatase structured films were obtained. A 2 theta shift of the anatase (101) X-ray diffraction main peak towards lower values indicated carbon incorporation into the lattice. N incorporation was confirmed with observed Ti-N bonds using X-ray photoelectron spectroscopy. Optical data showed significant reduction, approximately 1.00 eV, of the band gap. The reduction of the band gap allowed the photons in the visible part of the solar spectrum to be absorbed. Through a collaborative work with scientists at Brookhaven National Laboratory and Yonsei University, precise modeling of the electronic structure of N-C codoped TiO2 films were carried out to reveal the underlying physics of band gap reduction. Experimental results were compared with first-principle density functional theory calculations. Hard X-ray photoelectron spectroscopy showed that O, N and C 2p states overlapped effectively and shifts in the valence band maximum towards the Fermi level were observed. Optical band gap results showed that N-C codoping is an effective route for band gap reduction in TiO2. Comparison of the measured valence band structure with theoretical photoemission density of states further revealed C substitution on the Ti site and N substitution on the O site. Finally, films grown using radio frequency (rf) magnetron sputtering were compared with the pulsed laser deposited films. Sputtered N-C codoped TiO2 films showed phase transformation from anatase to rutile at constant argon pressure with increasing doping concentration. Moreover, with slow-rate N-C codoping of TiO2, a texturing effect was observed in X-ray diffraction scans such that anatase (004) Bragg reflection plane became more favored over anatase (101). Optical band gap was reduced but the reduction was not as significant as in the films prepared with the pulsed laser deposition method. Electrochemical methods were applied in the photoelectrochemical cell and the sample prep

  13. Photoelectrochemical synthesis, optical properties and plasmon-induced charge separation behaviour of gold nanodumbbells on TiO2

    NASA Astrophysics Data System (ADS)

    Katagi, Yu; KazumaPresent Address: Riken, Hirosawa, Wako, Saitama 351-0198, Japan., Emiko; Tatsuma, Tetsu

    2014-11-01

    Chemically synthesized, commercially available Au nanorods were adsorbed on a TiO2 thin film, and photoelectrochemically transformed to Au nanodumbbells by photoelectrochemical deposition of Au at both ends of the NRs under UV irradiation. The nanodumbbells show about fourfold greater light absorption than the nanorods based on localized surface plasmon resonance (LSPR) in the visible to near infrared region. The absorption intensities and wavelengths of the Au nanodumbbells depend on the size of their spheroidal caps, which can be controlled by UV exposure time. The nanodumbbells can be applied to LSPR sensors, as their absorption peak redshifts with increasing local refractive index near the metal surface. The Au nanodumbbells on TiO2 are also suitable for photofunctional materials and devices based on plasmon-induced charge separation (PICS) at the Au-TiO2 interface, because of their higher photoabsorption intensity, better wavelength tunability and greater PICS efficiency than nanorods.

  14. Large-Scale Synthesis of Transition-Metal-Doped TiO2 Nanowires with Controllable Overpotential

    SciTech Connect

    Liu, Bin; Chen, HaoMing; Liu, Chong; Andrews, Sean; Han, Chris; Yang, Peidong

    2013-03-13

    Practical implementation of one-dimensional semiconductors into devices capable of exploiting their novel properties is often hindered by low product yields, poor material quality, high production cost, or overall lack of synthetic control. Here, we show that a molten-salt flux scheme can be used to synthesize large quantities of high-quality, single-crystalline TiO2 nanowires with controllable dimensions. Furthermore, in situ dopant incorporation of various transition metals allows for the tuning of optical, electrical, and catalytic properties. With this combination of control, robustness, and scalability, the molten-salt flux scheme can provide high-quality TiO2 nanowires to satisfy a broad range of application needs from photovoltaics to photocatalysis.

  15. Synthesis of TiO2 nanotube array thin films and determination of the optical constants using transmittance data

    NASA Astrophysics Data System (ADS)

    Ahmadi, K.; Abdolahzadeh Ziabari, Ali; Mirabbaszadeh, K.; Ahmadi, S.

    2015-01-01

    TiO2 nanotube arrays were grown on glass substrate by ZnO nanorod sol-gel template process. XRD analysis and FESEM microscopy were employed to characterize the structural and morphological properties of the prepared nanotube. EDX and UV-Vis spectroscopy were used to assess the chemical composition and study the optical properties of the film. An optical model has been performed to simulate the optical constants and thicknesses of the films from transmittance data using the Levenberg-Marquardt algorithm via Drude model. The simulated transmittance is in good agreement with the measured spectrum in the whole measurement wavelength range. The refractive index and extinction coefficient, thickness and dielectric function of TiO2 nanotube films were calculated by Drude model. Also, the related absorption coefficient, optical bandgap and porosity were determined.

  16. A simple, template-free route for the synthesis of bicrystalline mesoporous TiO2 materials.

    PubMed

    Su, Zhili; Yang, Chun

    2009-11-01

    A simple, low-temperature and green template-free synthetic route has been used to prepare mesoporous TiO2 with anatase and brookite bicrystalline framework. This route combines a quick hydrolysis at ambient temperature and sequent hydrothermal treatment at 80-180 egrees C without further calcination. The resultant materials were characterized by XRD, TEM and nitrogen adsorption. It was found that the wormhole-like mesostructure and the bicrystalline framework could be formed in the hydrothermal treatment, and high surface areas of 160-250 m2 x g(-1) could be obtained due to the avoidance of calcination at high temperature. The effect of hydrothermal temperature on mesoporosity and crystallinity was also investigated and discussed. The as-prepared TiO2 samples exhibited higher photocatalytic activities than pure anatase TiO2 and corresponding calcined samples in the degradation of methyl orange, which can be attributed to the combined effect of composite crystalline phase and high surface area. PMID:19908583

  17. One-pot synthesis of Cd1- x In x Te semiconductor as a sensitizer on TiO2 mesoporous for potential solar cell devices

    NASA Astrophysics Data System (ADS)

    Singsa-ngah, Mutika; Tubtimtae, Auttasit

    2015-08-01

    We demonstrated the synthesis of a new ternary semiconductor nanoparticle Cd1- x In x Te, as a sensitizer for solar cell devices via a one-pot mixed precursor solution. The Cd1- x In x Te nanoparticles (NPs) were prepared using the chemical bath deposition process and coated onto a TiO2 photoelectrode. A tetragonal structure of Cd1- x In x Te NPs was constituted on the TiO2 photoelectrode with a diameter range ˜25-30 nm, and the atomic percentages of the chemical elements showed that the structure could be Cd0.1In0.9Te incorporated with the CdIn2Te4 structure. When the dipping cycle increased, the energy gaps became narrower from 1.2 to 0.6 eV due to the increasing amount and the larger size of nanoparticles. The photovoltaic properties of various cycles were investigated, and the best power conversion efficiency ( ?) of 0.49 % under full 1 sun illumination (100 mW/cm2, AM 1.5G) was obtained for the seven-cycle-Cd1- x In x Te NPs with a current density ( J sc) of 2.64 mA/cm2, an open-circuit voltage ( V oc) of 638 mV, and a fill factor ( FF) of 0.29. The efficiency of this material can be further improved for higher potential solar cell devices.

  18. Synthesis, characterization and binding interactions of amino acids coupled perylene diimides with colloidal doped and undoped TiO2

    NASA Astrophysics Data System (ADS)

    Kavery, E.; Nagarajan, N.; Paramaguru, G.; Renganathan, R.

    2015-07-01

    Two sensitizers based on amino acids coupled with perylene moiety having absorption in the visible region have been designed and their interaction with doped and undoped TiO2 for the application of dye sensitized solar cells (DSSCs) has been studied. The synthesized compounds PDI-PA and PDI-AA were characterized using 1H and 13C NMR, Mass and FT-IR spectroscopic techniques. The optical properties and lifetime measurements of the sensitizers were analyzed using various solvents with different polarity. The solvatochromism effect was studied using Lippert-Mataga plot. The electrochemical studies of both dyes were investigated in DMF with various scan rate ranging from 200 to 1000 mV s-1. Colloidal doped and undoped TiO2 was prepared and characterized by using absorption measurements. Binding ability of the sensitizers with the nanoparticles was studied through absorption, fluorescence quenching, cyclic voltammetry and FT-IR measurements. Results obtained from all the above analysis suggest the mode of quenching may be static. The binding constant values were calculated using Kamat-Fox equation indicates the binding behavior of the sensitizers with the nanoparticles. The fluorescence quenching was mainly attributed to electron transfer from the excited state of PDI's to the conduction band of colloidal semiconductors. The electron transfer mechanism was explained based on the Rehm-Weller equation as well as the energy level diagram.

  19. Electric-field-assisted swirl-flame synthesis of high-porosity nanostructured titania (TiO2) films

    NASA Astrophysics Data System (ADS)

    Kulkarni, Aditi

    Nanostructured mesoporous metal-oxide films can be used in various applications, including dye-sensitized solar cells based on titania. Optimization of the properties of these films is crucial in improving their efficiency. Nanostructured TiO2 films with high uniformity and porosity are grown in a stagnation swirl flame setup under an applied electric field. The effects of external electric-field magnitude and polarity are studied for different substrate temperatures and precursor loading concentrations. The results show considerable differences in film characteristics, for differing electric fields, with more columnar structures and higher porosities under low voltages up to +/-400 V. The films have higher packing density at higher voltages of +/-800 V. At low substrate temperatures, the morphology and structure are more prominent owing to less on-substrate sintering of the nanoparticles. At low voltages, oppositely-charged particles will be attracted to the substrate increasing the electrophoretic velocity but decreasing the in-flame agglomeration; while at high voltages, the particles will be repelled and stay in the flame longer, thus increasing the in-flame agglomeration. A simple model is proposed which predicts the trend for deposition of particles and formation of nanostructured TiO2 films of a given morphology by balancing the effects of thermophoresis, electrophoresis, and Brownian motion of the particles. The model's trend for packing density agrees with the experiments.

  20. Polyol thermolysis synthesis of TiO2 nanoparticles and its paste formulation to fabricate photoanode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Pratheep, P.; Vijayakumar, E.; Subramania, A.

    2015-05-01

    Titanium dioxide (TiO2) nanoparticles (NPs) were prepared by a simple polyol thermolysis process using various mole ratios of titanium tetrachloride (TiCl4) and polyvinylpyrrolidone (PVP). The prepared TiO2 NPs were characterized by TG/DTA, XRD, SEM, and BET analysis. The TiO2 NPs obtained using 0.1 M of TiCl4 and 0.02 M of PVP have high surface area with lesser particles size than the same obtained using 0.1 M of TiCl4 with other mole ratios of PVP. The high surface area TiO2 NPs were used to formulate TiO2 paste. The impact of ethyl cellulose, terpineol, and dibutyl phthalate in the formulation of TiO2 paste was optimized with respect to standard TiO2 paste ( Dyesol Ltd.) on the adsorption of dye was studied by UV-Vis spectroscopy. The photovoltaic performance of DSSCs fabricated using the formulated TiO2 paste has achieved 97.83 % of power conversion efficiency (PCE) (? = 4.5 %) with respect to the standard TiO2 paste ( Dyesol Ltd.) and its PCE were found to be 4.6 % (?). This PCE value was nearly closer to that of the same DSSC fabricated using the standard TiO2 paste ( Dyesol Ltd.) and higher than the P25 TiO2 ( Degussa) paste and its achieved PCE were found to be 86.04 %.

  1. 130-fold enhancement of TiO2 photocatalytic activities by ball milling

    NASA Astrophysics Data System (ADS)

    Saitow, Ken-ichi; Wakamiya, Tomoji

    2013-07-01

    Submicrometer TiO2 particles were prepared by changing the mechanochemical parameters in planetary ball milling. The TiO2 particles before and after milling were characterized by five experimental methods. The photocatalytic activities of the TiO2 particles were evaluated by the photoreduction of an aqueous solution of methylene blue. The activity of milled TiO2 was 136 times that of TiO2 (anatase) before milling and 62 times that of commercial available TiO2 photocatalyst (P25). In addition to the reduction in particle size and increase in specific surface area due to milling, the disorder TiO2, involving amorphous and srilankite phases, significantly increased the catalytic performance.

  2. Facile Synthesis of Defective TiO2?x Nanocrystals with High Surface Area and Tailoring Bandgap for Visible-light Photocatalysis

    NASA Astrophysics Data System (ADS)

    Wajid Shah, Muhammad; Zhu, Yunqing; Fan, Xiaoyun; Zhao, Jie; Li, Yingxuan; Asim, Sumreen; Wang, Chuanyi

    2015-10-01

    A facile hydrothermal approach has been developed to prepare defective TiO2?x nanocrystals using Ti(III)-salt as a precursor and L-ascorbic acid as reductant and structure direction agent. The prepared TiO2?x nanocrystals are composed of a highly crystallized TiO2 core and a disordered TiO2?x outer layer, possessing high surface area, controlled oxygen vacancy concentration and tunable bandgap via simply adjusting the amount of added L-ascorbic acid. The defective TiO2?x shows high photocatalytic efficiency in methylene blue and phenol degradation as well as in hydrogen evolution under visible light, underlining the significance of the present strategy for structural and bandgap manipulation in TiO2-based photocatalysis.

  3. Facile Synthesis of Defective TiO2?x Nanocrystals with High Surface Area and Tailoring Bandgap for Visible-light Photocatalysis

    PubMed Central

    Wajid Shah, Muhammad; Zhu, Yunqing; Fan, Xiaoyun; Zhao, Jie; Li, Yingxuan; Asim, Sumreen; Wang, Chuanyi

    2015-01-01

    A facile hydrothermal approach has been developed to prepare defective TiO2?x nanocrystals using Ti(III)-salt as a precursor and L-ascorbic acid as reductant and structure direction agent. The prepared TiO2?x nanocrystals are composed of a highly crystallized TiO2 core and a disordered TiO2?x outer layer, possessing high surface area, controlled oxygen vacancy concentration and tunable bandgap via simply adjusting the amount of added L-ascorbic acid. The defective TiO2?x shows high photocatalytic efficiency in methylene blue and phenol degradation as well as in hydrogen evolution under visible light, underlining the significance of the present strategy for structural and bandgap manipulation in TiO2-based photocatalysis. PMID:26515503

  4. Facile Synthesis of Defective TiO2-x Nanocrystals with High Surface Area and Tailoring Bandgap for Visible-light Photocatalysis.

    PubMed

    Wajid Shah, Muhammad; Zhu, Yunqing; Fan, Xiaoyun; Zhao, Jie; Li, Yingxuan; Asim, Sumreen; Wang, Chuanyi

    2015-01-01

    A facile hydrothermal approach has been developed to prepare defective TiO2-x nanocrystals using Ti(III)-salt as a precursor and L-ascorbic acid as reductant and structure direction agent. The prepared TiO2-x nanocrystals are composed of a highly crystallized TiO2 core and a disordered TiO2-x outer layer, possessing high surface area, controlled oxygen vacancy concentration and tunable bandgap via simply adjusting the amount of added L-ascorbic acid. The defective TiO2-x shows high photocatalytic efficiency in methylene blue and phenol degradation as well as in hydrogen evolution under visible light, underlining the significance of the present strategy for structural and bandgap manipulation in TiO2-based photocatalysis. PMID:26515503

  5. Ultrathin TiO2 layer coated-CdS spheres core-shell nanocomposite with enhanced visible-light photoactivity.

    PubMed

    Chen, Zhang; Xu, Yi-Jun

    2013-12-26

    Development of various strategies for controllable fabrication of core-shell nanocomposites (CSNs) with highly active photocatalytic performance has been attracting ever-increasing research attention. In particular, control of the ultrathin layer TiO2 shell in constructing CSNs in an aqueous phase is a significant but technologically challenging issue. Here, this paper demonstrates the interface assembly synthesis of CdS nanospheres@TiO2 core-shell photocatalyst via the electrostatic interaction of negatively charged water-stable titania precursor with positively charged CdS nanospheres (CdS NSPs), followed by the formation of the ultrathin-layer TiO2 shell through a facile refluxing process in aqueous phase. The as-formed CdS NSPs@TiO2 core-shell nanohybrid exhibits a high visible-light-driven photoactivity for selective transformation and reduction of heavy metal ions. The ultrathin TiO2 layer coated on CdS NSPs results in excellent light transmission property, enhanced adsorption capacity, and improved transfer of charge carriers and lifespan of photoinduced electron-hole pairs, which would prominently contribute to the significant photoactivity enhancement. It is anticipated that this facile aqueous-phase synthesis strategy could be extended to design a variety of more efficient CSN photocatalysts with controllable morphology toward target applications in diverse photoredox processes. PMID:24245797

  6. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors.

    PubMed

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-01-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail. PMID:24369051

  7. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    PubMed Central

    2013-01-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail. PMID:24369051

  8. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  9. Synthesis of TiO2 nano-powders prepared from purified sulphate leach liquor of red mud.

    PubMed

    Tsakiridis, P E; Oustadakis, P; Katsiapi, A; Perraki, M; Agatzini-Leonardou, S

    2011-10-30

    The research work presented in this paper is focused on the development of a purification process of red mud sulphate leach liquor for the recovery of titanium oxide (TiO(2)) nano-powders in the form of anatase. Initially, titanium was extracted over iron and aluminium from the leach liquor by solvent extraction using Cyanex 272 in toluene, at pH: 0.3 and T: 25°C, with 40% extractant concentration. Stripping of the loaded, with titanium, organic phase was carried out by diluted HCl (3 mol/L) at ambient temperature. Finally, the recovery of titanium nano-powder, in the form of anatase, was performed by chemical precipitation at pH: 6 and T: 95°C, using 10 wt% MgO pulp as neutralizing agent. The produced precipitates were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric/differential thermal analysis (TGA/DTA). Their morphological characteristics and microstructure were studied by scanning electron microscopy (SEM). High grade titanium white precipitate, in the form of anatase, was obtained. Iron concentration in the precipitate did not exceed 0.3%, whereas no aluminium was detected. PMID:21868153

  10. Synthesis and characterization of Pt-MoO x -TiO2 electrodes for direct ethanol fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Xiu-Yu; Zhang, Jing-Chang; Cao, Xu-Dong; Jiang, Yuan-Sheng; Zhu, Hong

    2011-10-01

    To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells, carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method. The physicochemical characterizations of the catalysts were carried out by using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy of adsorbed probe ammonia molecules. The electrocatalytic properties of the catalysts for methanol oxidation were investigated by the cyclic voltammetry technique. The results show that Pt-Mo/CNTs@TiO2 electrode exhibits the highest performance in all the electrodes. It is explained that, the structure, the oxidation states, and the acid-base properties of the catalysts are influenced due to the strong interaction between Ti and Mo species by adding TiO2 and MoO x to the Pt-based catalysts.

  11. Photodegradation of nalidixic acid assisted by TiO(2) nanorods/Ag nanoparticles based catalyst.

    PubMed

    Petronella, F; Diomede, S; Fanizza, E; Mascolo, G; Sibillano, T; Agostiano, A; Curri, M L; Comparelli, R

    2013-05-01

    Two different nanosized TiO2-based catalysts supported onto glass with tailored photocatalytic properties upon irradiation by UV light were successfully employed for the degradation of nalidixid acid, a widely diffused antibacterial agent of environmental relevance known to be non-biodegradable. Anatase rod-like TiO2 nanocrystals (TiO2NRs) and a semiconductor oxide-noble metal nanocomposite TiO2 NRs/Ag nanoparticles (NPs), synthesized by colloidal chemistry routes, were cast onto glass slide and employed as photocatalysts. A commercially available catalyst (TiO2 P25), also immobilized onto a glass slide, was used as a reference material. It was found that both TiO2 NRs/Ag NPs composite and TiO2 NRs demonstrated a photocatalytic efficiency significantly higher than the reference TiO2 P25. Specifically, TiO2 NRs/Ag NPs showed a photoactivity in nalidixic acid degradation 14 times higher than TiO2 P25 and 4 times higher than bare TiO2 NRs in the first 60min of reaction. Several by-products were identified by HPLC-MS along the nalidixic acid degradation, thus getting useful insight on the degradation pathway. All the identified by-products resulted completely removed after 6h of reaction. PMID:23466278

  12. Electrochemical characterization of TiO2/WOx nanotubes for photocatalytic application

    PubMed Central

    2014-01-01

    TiO2/WOx nanotubes have unique photo-energy retention properties that have gathered scientific interest. Herein, we report the synthesis, morphological characterization, and the electrochemical characterization of TiO2/WOx nanotubes compared with pure TiO2 nanotubes, prepared by anodization technique. Significant structural differences were not observed in TiO2/WOx nanotubes as observed by using scanning electron microscopy and transmission electron microscopy. The charge transfer resistance of TiO2/WOx before and after photo irradiation determined by using electrochemical impedance spectroscopy proves the inherent energy retention property which was not observed in pure TiO2 nanotubes. PMID:25346647

  13. Low-temperature synthesis of high-ordered anatase TiO2 nanotube array films coated with exposed {001} nanofacets.

    PubMed

    Ding, Jie; Huang, Zhennan; Zhu, Jihao; Kou, Shengzhong; Zhang, Xiaobin; Yang, Hangsheng

    2015-01-01

    High-ordered anatase TiO2 nanotube array films coated with exposed high-reactive {001} nanofacets were fabricated by a modified hydrothermal method using amorphous anodic TiO2 nanotube arrays (ATONAs) as starting materials. It was found that the reaction between gas phase HF and solid ATONAs played a key role in the transformation process from amorphous to anatase TiO2, and the TiO2 tubular structure kept unchanged during the surface modification with an exposed {001} facets up to 76.5%, which could be attributed to the low reaction temperature of 130?°C. Our study provided a novel route for the facile preparation of {001} facets exposed anatase TiO2. PMID:26634815

  14. Low-temperature synthesis of high-ordered anatase TiO2 nanotube array films coated with exposed {001} nanofacets

    PubMed Central

    Ding, Jie; Huang, Zhennan; Zhu, Jihao; Kou, Shengzhong; Zhang, Xiaobin; Yang, Hangsheng

    2015-01-01

    High-ordered anatase TiO2 nanotube array films coated with exposed high-reactive {001} nanofacets were fabricated by a modified hydrothermal method using amorphous anodic TiO2 nanotube arrays (ATONAs) as starting materials. It was found that the reaction between gas phase HF and solid ATONAs played a key role in the transformation process from amorphous to anatase TiO2, and the TiO2 tubular structure kept unchanged during the surface modification with an exposed {001} facets up to 76.5%, which could be attributed to the low reaction temperature of 130?°C. Our study provided a novel route for the facile preparation of {001} facets exposed anatase TiO2. PMID:26634815

  15. Photocatalytic synthesis of anilides from nitrobenzenes under visible light irradiation: 2 in 1 reaction.

    PubMed

    Zand, Zahra; Kazemi, Foad; Partovi, Adel

    2015-11-01

    An efficient method has been developed for the synthesis of a series of anilides via a two in one reaction of nitrobenzenes with anhydride in the presence of TiO2 as a nanocatalyst and photocatalyst under sunlight or blue LED irradiation. In this method simultaneously, nitrobenzenes convert to the corresponding anilines via photocatalytic reduction on the TiO2 surface, and a condensation of aniline with the anhydride performed on the Lewis acid site of the TiO2 surface. Interestingly amidation step leads to the promotion of better reaction and good selectivity in reduction of nitrocompounds. This method is simple, rapid, high yield, and green. PMID:25744492

  16. A method for large-scale synthesis of Al-doped TiO2 nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

    NASA Astrophysics Data System (ADS)

    Kodama, Naoto; Tanaka, Yasunori; Kita, K.; Uesugi, Y.; Ishijima, T.; Watanabe, S.; Nakamura, K.

    2014-05-01

    A unique method of large-scale synthesis of Al-doped TiO2 nanopowder was developed, using 20 kW Ar-O2 pulse-modulated induction thermal plasmas (PMITP) with time-controlled feedstock feeding (TCFF). This PMITP-TCFF method is characterized by intermittent feedstock powder feeding synchronized with modulation of the power of the PMITP. The method enables heavy-load feeding of raw material powder to the thermal plasmas for complete evaporation. The nanopowder synthesized was analysed using different methods including field emission scanning electron microscopy, x-ray diffraction (XRD) spectroscopy, bright-field transmission electron microscopy (TEM), TEM/energy dispersive x-ray (EDX) mapping, x-ray photoelectron spectroscopy, and spectrophotometry. The results showed that Al-doped TiO2 nanopowder can be synthesized with mean diameters of 50-60 nm. The Al doping in TiO2 was confirmed from the constituent structure in the XRD spectra, the uniform presence of Al in the nanopowder in the TEM/EDX mapping, the chemical shift in the x-ray photoelectron spectra, and the absorption edge shift in the optical properties. The rate of production of the Al-doped TiO2 nanopowder was estimated as 400 g h-1.

  17. Acid-assisted hydrothermal synthesis of nanocrystalline TiO2 from titanate nanotubes: influence of acids on the photodegradation of gaseous toluene.

    PubMed

    Chen, Kunyang; Zhu, Lizhong; Yang, Kun

    2015-01-01

    In order to efficiently remove volatile organic compounds (VOCs) from indoor air, one-dimensional titanate nanotubes (TiNTs) were hydrothermally treated to prepare TiO2 nanocrystals with different crystalline phases, shapes and sizes. The influences of various acids such as CH3COOH, HNO3, HCl, HF and H2SO4 used in the treatment were separately compared to optimize the performance of the TiO2 nanocrystals. Compared with the strong and corrosive inorganic acids, CH3COOH was not only safer and more environmentally friendly, but also more efficient in promoting the photocatalytic activity of the obtained TiO2. It was observed that the anatase TiO2 synthesized in 15 mol/L CH3COOH solution exhibited the highest photodegradation rate of gaseous toluene (94%), exceeding that of P25 (44%) by a factor of more than two. The improved photocatalytic activity was attributed to the small crystallite size and surface modification by CH3COOH. The influence of relative humidity (20%-80%) on the performance of TiO2 nanocrystals was also studied. The anatase TiO2 synthesized in 15 mol/L CH3COOH solution was more tolerant to moisture than the other TiO2 nanocrystals and P25. PMID:25597682

  18. Facile synthesis of anatase TiO(2) quantum-dot/graphene-nanosheet composites with enhanced electrochemical performance for lithium-ion batteries.

    PubMed

    Mo, Runwei; Lei, Zhengyu; Sun, Kening; Rooney, David

    2014-04-01

    A facile method to synthesize well-dispersed TiO2 quantum dots on graphene nanosheets (TiO2 -QDs/GNs) in a water-in-oil (W/O) emulsion system is reported. The TiO2 /graphene composites display high performance as an anode material for lithium-ion batteries (LIBs), such as having high reversible lithium storage capacity, high Coulombic efficiency, excellent cycling stability, and high rate capability. The excellent electrochemical performance and special structure of the composites thus offer a way to prepare novel graphene-based electrode materials for high-energy-density and high-power LIBs. PMID:24347361

  19. TiO2@C Core-Shell Nanoparticles Formed by Polymeric Nano-Encapsulation

    NASA Astrophysics Data System (ADS)

    Vasei, Mitra; Das, Paramita; Cherfouh, Hayet; Marsan, Benoit; Claverie, Jerome

    2014-07-01

    TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e. the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN) around each TiO2 nanoparticles. Upon pyrolisis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent.

  20. TiO2@C core-shell nanoparticles formed by polymeric nano-encapsulation

    PubMed Central

    Vasei, Mitra; Das, Paramita; Cherfouth, Hayet; Marsan, Benoît; Claverie, Jerome P.

    2014-01-01

    TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e., the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN) around each TiO2 nanoparticles. Upon pyrolysis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent. PMID:25072054

  1. UV-vis light activated Ag decorated monodisperse TiO2 for treatment of pharmaceuticals in water

    EPA Science Inventory

    Recently, many researchers have made a lot of effort to utilize the visible light portion of the solar spectrum to activate TiO2 photocatalyst for environmental applications, such as water, air, and soil remediation. The deposition of noble metals on photocatalysts is of great in...

  2. Rapid flame synthesis of internal Mo6+ doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters for lithium ion storage

    NASA Astrophysics Data System (ADS)

    Li, Yunfeng; Hu, Yanjie; Shen, Jianhua; Jiang, Haibo; Min, Guoquan; Qiu, Shengjie; Song, Zhitang; Sun, Zhuo; Li, Chunzhong

    2015-11-01

    The rational design of nanoheterostructured materials has attracted much attention because of its importance for developing highly efficient LIBs. Herein, we have demonstrated that internal Mo6+ doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters have been realized by a facile and rapid flame spray pyrolysis route for electrochemical energy storage. In such intriguing nanostructures, internal Mo6+ doping can improve the conductivity of electrode materials and facilitate rapid Li+ intercalation and ion transport and the heteroassembly of highly dispersed ultrafine MoO3 clusters with excellent electrochemical activity endows the TiO2 with extra Li+ ion storage ability as well as incorporates Mo6+. Thus, the as-prepared nanohybrid electrodes exhibit a high specific capacity and superior rate capability due to the maximum synergetic effect of TiO2, Mo6+ and ultrafine MoO3 clusters. Moreover, the aerosol flame process with a unique temperature gradient opens a new strategy to design novel hybrid materials by the simultaneous doping and heteroassembly engineering for next-generation LIBs.The rational design of nanoheterostructured materials has attracted much attention because of its importance for developing highly efficient LIBs. Herein, we have demonstrated that internal Mo6+ doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters have been realized by a facile and rapid flame spray pyrolysis route for electrochemical energy storage. In such intriguing nanostructures, internal Mo6+ doping can improve the conductivity of electrode materials and facilitate rapid Li+ intercalation and ion transport and the heteroassembly of highly dispersed ultrafine MoO3 clusters with excellent electrochemical activity endows the TiO2 with extra Li+ ion storage ability as well as incorporates Mo6+. Thus, the as-prepared nanohybrid electrodes exhibit a high specific capacity and superior rate capability due to the maximum synergetic effect of TiO2, Mo6+ and ultrafine MoO3 clusters. Moreover, the aerosol flame process with a unique temperature gradient opens a new strategy to design novel hybrid materials by the simultaneous doping and heteroassembly engineering for next-generation LIBs. Electronic supplementary information (ESI) available: SEM, TEM images, XRD patterns, EDX and the discharge-charge capacity of Mo6+-TiO2/MoO3 NHs, TiO2, and Mo6+-TiO2/MoO3 NHs after sulfuration, and nitrogen adsorption/desorption isotherms of Mo6+-TiO2/MoO3 NHs. See DOI: 10.1039/c5nr05586e

  3. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    PubMed Central

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-01-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1??mol g?1·h?1 and ~99.5% degradation Rhodamine B (RhB) in 60?min, suggesting their promising application in efficient photocatalysts. PMID:26470013

  4. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    NASA Astrophysics Data System (ADS)

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-10-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1??mol g-1·h-1 and ~99.5% degradation Rhodamine B (RhB) in 60?min, suggesting their promising application in efficient photocatalysts.

  5. Visible-Light-Driven Oxidation of Primary C-H Bonds over CdS with Dual Co-catalysts Graphene and TiO2

    NASA Astrophysics Data System (ADS)

    Yang, Min-Quan; Zhang, Yanhui; Zhang, Nan; Tang, Zi-Rong; Xu, Yi-Jun

    2013-11-01

    Selective activation of primary C-H bonds for fine chemicals synthesis is of crucial importance for the sustainable exploitation of available feedstocks. Here, we report a viable strategy to synthesize ternary GR-CdS-TiO2 composites with an intimate spatial integration and sheet-like structure, which is afforded by assembling two co-catalysts, graphene and TiO2, into the semiconductor CdS matrix with specific morphology as a visible light harvester. The GR-CdS-TiO2 composites are able to serve as a highly selective visible-light-driven photocatalyst for oxidation of saturated primary C-H bonds using benign oxygen as oxidant under ambient conditions. This work demonstrates a wide, promising scope of adopting co-catalyst strategy to design more efficient semiconductor-based photocatalyst toward selective activation of C-H bonds using solar light and molecular oxygen.

  6. Visible-Light-Driven Oxidation of Primary C–H Bonds over CdS with Dual Co-catalysts Graphene and TiO2

    PubMed Central

    Yang, Min-Quan; Zhang, Yanhui; Zhang, Nan; Tang, Zi-Rong; Xu, Yi-Jun

    2013-01-01

    Selective activation of primary C–H bonds for fine chemicals synthesis is of crucial importance for the sustainable exploitation of available feedstocks. Here, we report a viable strategy to synthesize ternary GR-CdS-TiO2 composites with an intimate spatial integration and sheet-like structure, which is afforded by assembling two co-catalysts, graphene and TiO2, into the semiconductor CdS matrix with specific morphology as a visible light harvester. The GR-CdS-TiO2 composites are able to serve as a highly selective visible-light-driven photocatalyst for oxidation of saturated primary C–H bonds using benign oxygen as oxidant under ambient conditions. This work demonstrates a wide, promising scope of adopting co-catalyst strategy to design more efficient semiconductor-based photocatalyst toward selective activation of C–H bonds using solar light and molecular oxygen. PMID:24264835

  7. In situ synthesis of TiO2/SnO(x)-Au ternary heterostructures effectively promoting visible-light photocatalysis.

    PubMed

    Dong, Zhao; Wu, Minghua; Wu, Jiaying; Ma, Yuanyuan; Ma, Zhenzhen

    2015-07-14

    TiO2/SnOx-Au ternary heterostructures were successfully fabricated via a simple in situ reduction of AuCl4(-) on TiO2 surfaces pre-modified with Sn(2+). The samples were characterized by XRD, TEM, XPS, N2 physical absorption and UV-vis diffuse reflectance spectra. Photocatalytic activity toward degradation of methylene blue (MB) aqueous solution under visible light irradiation was investigated. The results suggested that the highly dispersive and ultrafine Au nanoparticles (NPs) covered with SnOx were deposited onto the surface of TiO2. The heterostructures significantly enhanced the photocatalytic activity compared with the traditional TiO2/Au sample prepared by the impregnation method and also enhanced the activity more than the binary TiO2/SnOx sample. Moreover, the size of the Au NPs could be well controlled by simply tuning the dosage of HAuCl4, and the optimized catalytic activity of the ternary heterostructures was obtained when the dosage of Au was 1% and the Au particle size was ?2.65 nm. The enhancement of photocatalytic performance could be attributed to the surface plasmon resonance effect of the Au NPs and the electron-sink function of the SnOx, which improve the optical absorption properties as well as photoinduced charge carrier separation, synergistically facilitating the photocatalysis. PMID:26061220

  8. Synthesis and characterization of photochromic Ag-embedded TiO2 nanocomposite thin films by non-reactive RF-magnetron sputter deposition

    NASA Astrophysics Data System (ADS)

    Zuo, J.; Keil, P.; Grundmeier, G.

    2012-07-01

    Ag-embedded TiO2 nanocomposite thin film with reversible photochromic properties were prepared by layer-by-layer non-reactive RF-magnetron sputtering. Films were produced in Ar/O2 and pure Ar atmospheres. In the oxidizing regime, a diffusion of Ag from the film volume to the outer film surface was observed. Therefore, pure Ar plasma was applied in the deposition of TiO2. The electronic and optical properties of the TiO2 film were almost not affected by the presence of oxygen. Transmission electron microscopy (TEM) and reflection mode X-ray absorption spectroscopy (XAS) were performed to study the morphology, crystal structure and chemical state of the embedded Ag nanoparticles before and after the annealing step. Annealing of the film led to the crystallization of the TiO2 matrix. Moreover, the Ag nanoparticles in the film underwent Ostwald ripening leading to particle agglomerate. No oxidation of the embedded Ag during the sputter deposition and subsequent annealing process was found as confirmed by XAS measurements. The non-reactive RF-magnetron method is believed to avoid the energetic oxygen ions attack to Ag during the deposition of Ag-embedded TiO2 nanocomposite and thus the films are expected to have better optical properties and long-term stability.

  9. Room temperature synthesis of nanocrystalline anatase sols and preparation of uniform nanostructured TiO2 thin films: optical and structural properties

    NASA Astrophysics Data System (ADS)

    Hosseingholi, M.; Pazouki, M.; Hosseinnia, A.; Aboutalebi, S. H.

    2011-02-01

    Transparent TiO2 thin films were deposited on soda-lime glass substrates via the sol-gel method using a nanocrystalline TiO2 sol solution prepared at room temperature employing the dip-coating method. The effects of pH on crystallinity, particle size and stability of the synthesized TiO2 sols were investigated, systematically. TiO2 thin films were thickened by means of a sequential dip-coating process. The TiO2 films were transparent and exhibited proper adherence. The effects of thickness and annealing temperature on the structural and optical properties of the thin films were evaluated. The prepared powder was crystalline without any thermal treatment. The crystallite size of the particles (anatase) was in the range 4.2-12.1 nm depending on the initial pH value. Although only the anatase phase was observed at room temperature and 400 °C, a further increase in annealing temperature up to 700 °C resulted in the formation of the rutile phase. Even at high annealing temperatures, fairly smooth and homogeneous surfaces with no cracks and pores were observed. It was demonstrated that the films were transparent in the visible region with characteristic absorption in the UV region. Band gap of the as-deposited film was estimated to be 3.34 eV and was found to decrease with increasing annealing temperature.

  10. Large scale synthesis of FeS coated Fe nanoparticles as reusable magnetic photocatalysts

    NASA Astrophysics Data System (ADS)

    Feng, He; Si, Ping-Zhan; Xiao, Xiao-Fei; Jin, Chen-Hao; Yu, Sen-Jiang; Li, Zheng-Fa; Ge, Hong-Liang

    2013-09-01

    The FeS coated Fe nanoparticles were prepared by using high temperature reactions between the commercial Fe nanoparticles and the S powders in a sealed quartz tube. The simple method developed in this work is effective for large scale synthesis of FeS/Fe nanoparticles with tunable shell/core structures, which can be obtained by controlling the atomic ratio of Fe to S. The structural, magnetic and photocatalytic properties of the nanoparticles were investigated systematically. The good photocatalytic performance originating from the FeS shell in degradation of methylene blue under visible light and the high saturation magnetization originating from the ferromagnetic Fe core make the FeS/Fe nanoparticles a good photocatalyst that can be collected and recycled easily with a magnet. An exchange bias up to 11 mT induced in Fe by FeS was observed in the Fe/FeS nanoparticles with ferro/antiferromagnetic interfaces. The enhanced coercivity up to 32 mT was ascribed to the size effect of Fe core.

  11. Synthesis of magnetic mesoporous titania colloidal crystals through evaporation induced self-assembly in emulsion as effective and recyclable photocatalysts.

    PubMed

    Chen, Jeffrey E; Lian, Hong-Yuan; Dutta, Saikat; Alshehri, Saad M; Yamauchi, Yusuke; Nguyen, Mai Thanh; Yonezawa, Tetsu; Wu, Kevin C-W

    2015-10-14

    This study illustrates the directed self-assembly of mesoporous TiO2 with magnetic properties due to its colloidal crystal structure with Fe3O4. The Fe3O4 nanoparticles were synthesized using co-precipitation techniques to a size of 28.2 nm and a magnetic saturation of 66.9 emu g(-1). Meanwhile, mesoporous titania nanoparticles (MTNs) with a particle diameter of 373 nm, a specific surface area of 236.3 m(2) g(-1), and a pore size of 2.8 nm were prepared by controlling the rate of hydrolysis. Magnetic colloidal crystals (a diameter of 10.2 ?m) were formed by the aggregation of Fe3O4 and MTNs caused by the interface phenomena during solvent evaporation in emulsion. Even the anatase octahedrite produced from the colloidal crystal after a hydrothermal reaction retained a magnetic saturation of 2.8 emu g(-1). This study also investigates the photodegradation activity of our synthesized material as a photocatalyst, while utilizing its capability for magnetic separation to prove its usefulness in catalyst recycling. PMID:26428279

  12. Designing Photocatalysts for Hydrogen Evolution: Are Complex Preparation Strategies Necessary to Produce Active Catalysts?

    PubMed

    Grewe, Tobias; Tüysüz, Harun

    2015-09-21

    A facile synthetic route for the preparation of highly active photocatalysts was developed. The protocol involves the preparation of a photocatalyst through the direct injection of metal alkoxide precursors into solutions in a photoreactor. As a proof of concept, a tantalum oxide based photocatalyst was chosen as a model system. Tantalum ethoxide [Ta(OEt)5 ] was injected rapidly into a photoreactor filled with a water/methanol mixture, and a TaOx (OH)y composite formed and was able to produce hydrogen under light illumination. Compared to commercial and mesostructured Ta2 O5 and NaTaO3 materials, TaOx (OH)y produced by direct injection shows superior hydrogen production activity. Notably, the samples prepared by direct injection are amorphous; however, their photocatalytic performance is much higher than those of their crystalline equivalents. If Ta(OEt)5 was dispersed in methanol before injection, an amorphous framework with higher surface area and larger pore volume was formed, and the hydrogen production rate increased further. The addition of a sodium precursor during the injection further boosted the photocatalytic activity. Furthermore, this concept has also been applied to a titanium-based photocatalyst, and a much better hydrogen production rate has been obtained in comparison with that of commercial TiO2 (P25-Degussa); therefore, the direct-injection synthesis is a flexible method that opens the door to the facile preparation of highly active nanostructured photocatalysts for hydrogen production. PMID:26261010

  13. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ?O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. PMID:25497036

  14. Visible Light-activated TiO2 photocatalytic Films; Synthesis, Characterization and Environmental Application for the Destruction of Microcystin-LR

    EPA Science Inventory

    Titanium dioxide (TiO2) photocatalysis has become one of the most effective advanced oxidation technologies (AOTs) for the treatment of persistent organic contaminants. To generate hydroxyl radicals, a non-selective, reactive oxidizing species and responsible for the oxidation of...

  15. Laser synthesis of hierarchically organized nanostructured TiO2 films on microfibrous carbon paper substrate: Characterization and electrocatalyst supporting properties

    NASA Astrophysics Data System (ADS)

    Wang, Youling; Tabet-Aoul, Amel; Mohamedi, Mohamed

    2015-12-01

    Titanium dioxide is cheap, non-toxic, exhibits a high mechanical resistance, very stable in acidic and oxidative environments is being studied as alternative to carbon as catalyst support in low-temperature fuel cells. Herein, via pulsed laser deposition, various morphologies of TiO2 thin films are synthesized at room temperature onto conductive microfibrous carbon paper substrate, which is the type of substrate, employed in energy storage and conversion devices. TiO2 films deposited under vacuum and in the presence of mild pressure of oxygen are very smooth and dense. Instead, TiO2 films deposited in the presence of helium atmosphere are of porous structures and vertically aligned. An increase in the helium pressure leads to the formation of forest-like vertically aligned nanostructures. Micro-Raman spectroscopy reveals that the films are amorphous and of rutile phase. X-ray photoelectron spectroscopy shows that Ti is in fully oxidized state of Ti4+. The electrocatalytic supporting properties to Pt are investigated in H2SO4 and O2-saturated H2SO4 solution. It is found that regardless of the film morphology, all the synthesized TiO2 films dramatically increase the electroactive surface area of Pt and enhance its electroactivity towards oxygen reduction reaction as compared with bare Pt electrode.

  16. Synthesis and photocatalytic activity of TiO2 nanowires in the degradation of p-aminobenzoic acid: A comparative study with a commercial catalyst.

    PubMed

    Soto-Vázquez, Loraine; Cotto, María; Ducongé, José; Morant, Carmen; Márquez, Francisco

    2016-02-01

    The photocatalytic degradation of p-aminobenzoic acid was studied using TiO2 nanowires as the catalyst synthesized through a hydrothermal procedure. The as-synthesized TiO2 nanowires were fully characterized by SEM, TEM, XRD and Raman with a very high surface area of 512 m(2) g(-1). The photocatalytic degradation of p-aminobenzoic acid was carried out under 180 min of constant radiation and the results were compared with P25 as commercial catalyst. Optimal experimental conditions were determined for TiO2 nanowires with a catalyst dosage of 1.0 g L(-1) under acidic conditions with a 20 ?M p-aminobenzoic acid solution obtaining 95% of degradation. Under similar experimental conditions comparative studies were performed obtaining 98% of degradation when P25 is employed. In both systems, a pseudo first order reaction was found to provide the best correlations, with constant rates of 2.0 × 10(-2) min(-1) and 2.4 × 10(-2) min(-1) for TiO2 nanowires and P25, respectively. PMID:26610195

  17. Synthesis of three-dimensional agaric-like biomorphic TiO2 by a facile method with Coscinodiscus sp. frustule

    NASA Astrophysics Data System (ADS)

    Zhang, Qianqian; Chen, Ran; Li, Ling

    2012-12-01

    The paper aims to expand the application of natural marine algae. Marine diatoms, which have intricate frustule structures, can serve as bio-template for preparing three-dimensional materials. A simple and effective approach to synthesize the corrugated agaric-like biomorphic TiO2 templated with frustule of Coscinodiscus sp. is reported. In the sol-gel preparation process, the titania-coating on the frustule is prepared through the deposition and condensation with the aid of acetylacetone (acac) as a controlling agent to make the precursor Ti(BuO)4 hydrolyze slowly. The as-prepared titania-coated frustule and biomorphic TiO2 is characterized by scanning electron microscopy (SEM) attached with energy dispersive X-ray spectrometer (EMAX) and X-ray diffraction (XRD). The microstructure of the corresponding titania nanoparticles appears to be sphere with the diameters distributed around 10-20 nm. The templating process is repeated for three cycles. Subsequently, the three-dimensional freestanding corrugated agaric-like biomorphic TiO2 structure is obtained by a selective removal in the NaOH solution. As far as we known, the 3D freestanding corrugated agaric-like biomorphic TiO2 with greatly increased surface area is obtained for the first time.

  18. Facile synthesis of hierarchical Ag3PO4/TiO2 nanofiber heterostructures with highly enhanced visible light photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Xie, Jinlei; Yang, Yefeng; He, Haiping; Cheng, Ding; Mao, Minmin; Jiang, Qinxu; Song, Lixin; Xiong, Jie

    2015-11-01

    Heterostructured semiconductor nanostructures have provoked great interest in the areas of energy, environment and catalysis. Herein, we report a novel hierarchical Ag3PO4/TiO2 heterostructure consisting of nearly spherical Ag3PO4 particles firmly coupled on the surface of TiO2 nanofibers (NFs). The construction of Ag3PO4/TiO2 heterostructure with tailored morphologies, compositions and optical properties was simply achieved via a facile and green synthetic strategy involving the electrospinning and solution-based processes. Owing to the synergetic effects of the components, the resulting hybrid heterostructures exhibited much improved visible light photocatalytic performance, which could degrade the RhB dye completely in 7.5 min. In addition, the coupling of Ag3PO4 particles with UV-light-sensitive TiO2 NFs enabled full utilization of solar energy and less consumption of noble metals, significantly appealing for their practical use in new energy sources and environmental issues. The developed synthetic strategy was considered to be applicable for the rational design and construction of other heterostructured catalysts.

  19. Microwave assisted hydrothermal synthesis of Ag/AgCl/WO{sub 3} photocatalyst and its photocatalytic activity under simulated solar light

    SciTech Connect

    Adhikari, Rajesh; Gyawali, Gobinda; Sekino, Tohru; Wohn Lee, Soo

    2013-01-15

    Simulated solar light responsive Ag/AgCl/WO{sub 3} composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV-Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO{sub 3} nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst. Highlights: Black-Right-Pointing-Pointer Successful synthesis of Ag/AgCl/WO{sub 3} nanocomposite. Black-Right-Pointing-Pointer Photocatalytic experiment was performed under simulated solar light. Black-Right-Pointing-Pointer Nanocomposite photocatalyst was very active as compared to WO{sub 3} commercial powder. Black-Right-Pointing-Pointer SPR effect due to Ag nanoparticles enhanced the photocatalytic activity.

  20. Biochemical effects of six TiO2 and four CeO2 nanomaterials in HepG2 cells

    EPA Science Inventory

    Biochemical effects of six TiO2 and four CeO2 nanomaterials in HepG2 cellsBecause of their growing number of uses, nanoparticles composed of CeO2 (cosmetics, polishing materials and automotive fuel additives) and TiO2 (pigments, sunscreens and photocatalysts) are of particular to...

  1. Synthesis of Ag-doped TiO2 nanoparticles by combining laser decomposition of titanium isopropoxide and ablation of Ag for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Al-Kamal, Ahmed Kamal

    Nanostructured powders of TiO2 and Ag-doped TiO2 are synthesized by a novel pulsed-laser process that combines laser ablation of a silver (Ag) disc with laser decomposition of a titanium tetra-isopropoxide (TTIP) solution. Nanoparticles are formed by rapid condensation of vaporized species in the plasma plume generated by the high power laser, resulting in the formation of rapidly quenched Ag-doped TiO2 nanoparticles that have far-from-equilibrium or metastable structures. The uniqueness of the new ablation process is that it is a one-step process, in contrast to the two-step process developed by previous researchers in the field. Moreover, its ability to synthesize an extended-solid solution phase of Ag in TiO 2 may also be unique. The present work implies that other oxide phases, such as Al2O3, MgO and MgAl2O4, can be doped with normally insoluble metals, such as Pt and Ir, thus opening new opportunities for catalytic applications. Again, there is the prospect of being able to synthesize nanopowders of diamond, c-BN, and mixtures thereof, which are of interest for applications in machine tools, rock-drill bits, and lightweight armor. A wet-chemistry method is also investigated, which has much in common with that adopted by previous workers in the field. However, photo-voltaic properties do not measure up to expectations based on published data. A possible explanation is that the selected Ag concentrations are too high, so that recombination of holes and electrons occurs via a quantum-tunneling mechanism reduces photo-activity. Future work, therefore, will investigate lower concentrations of Ag dopant in TiO2, while also examining the effects of metastable states, including extended solid solution, amorphous, and semi-crystalline structures.

  2. Improved photocatalytic activity of gold decorated differently doped TiO2 nanoparticles: A comparative study.

    PubMed

    Pal, Nabin Kumar; Kryschi, Carola

    2016-02-01

    In this paper, undoped and several differently doped (with Fe(3+), N(-), and ?-Al2O3) TiO2-nanoparticle-based photocatalysts and those covered with ultrasmall gold nanoparticles (AuNPs) were engineered. Their photocatalytic performance was studied by utilizing them for the liquid-phase decomposition of the model dye methylene blue (MB) under visible-light irradiation. The structural, morphological, physico-chemical, and optical properties of the photocatalysts were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, diffuse-reflectance UV-Vis absorption spectroscopy, Raman spectroscopy and transmission electron microscopy. Photodegradation kinetics of MB was followed by measuring the absorbance of MB at 664 nm at different irradiation times, whereas the mineralization of MB was examined by determining the total organic carbon (TOC) content. The photocatalytic activity of TiO2 nanoparticles was shown to be significantly increased by introducing dopants into the crystal lattice and depositing AuNPs on the surface. Among those, ?-Al2O3 doped TiO2 nanoparticles covered with deposited AuNPs show the best photocatalytic performance. Altogether, the here engineered photocatalysts as consisting of doped TiO2 nanoparticles decorated with AuNPs establish novel three-component nanocomposite systems, where synergetic interactions between surface AuNPs, dopants and TiO2 were shown to significantly enhance the photocatalytic activity. PMID:26519796

  3. Photocatalytic Destruction of an Organic Dye Using TiO2 and Solar Energy.

    ERIC Educational Resources Information Center

    Giglio, Kimberly D.; And Others

    1995-01-01

    Describes a general chemistry experiment that is carried out in sunlight to illustrate the ability of TiO2 to act as a photocatalyst by mineralizing an organic dye into carbon dioxide. Details about the construction of the reactor system used to perform this experiment are included. (DDR)

  4. Electrochemical and photocatalytic properties of TiO2/WO3 photoelectrodes

    NASA Astrophysics Data System (ADS)

    Oliveira, Haroldo G.; Silva, Erika D.; Longo, Claudia

    2010-08-01

    Porous films of TiO2 and TiO2/WO3 were deposited onto transparent electrodes from aqueous suspensions with polyethylene glycol, TiO2 particles and different amounts of tungistic acid. After annealing, crystalline samples were obtained. The band gap energy, approximately 3.1 eV for TiO2, decreased from 2.9 to 2.7 eV for varying W/Ti molar ratios from 3 to 12 %. The electrochemical properties were investigated in Na2SO4 aqueous solution; for the TiO2 electrode, the open circuit potential changed from 0.18 V in the dark to -0.25 V under irradiation from a solar simulator. For hybrid TiO2/WO3 electrodes, the VOC values were almost independent of the WO3 content and corresponded to 0.3 V in the dark and -0.1 V under irradiation; however, photocurrent and interfacial capacitance increased with a higher WO3 concentration. The electrodes were then used as photocatalysts for 17-?-etinylestradiol removal from water, and the mixed TiO2/WO3 exhibited better performance for photocatalytic oxidation of estradiol than TiO2. Adding WO3 enhances the visible light harvesting and minimizes the charge recombination resulting in higher efficiency for solar energy conversion.

  5. TiO2 Photocatalytic Degradation of Phenylarsonic Acid

    PubMed Central

    Zheng, Shan; Cai, Yong; O’Shea, Kevin E.

    2010-01-01

    Phenyl substituted arsenic compounds are widely used as feed additives in the poultry industry and have become a serious environmental concern. We have demonstrated that phenylarsonic acid (PA) is readily degraded by TiO2 photocatalysis. Application of the Langmuir–Hinshelwood kinetic model for the initial stages of the TiO2 photocatalysis of PA yields an apparent rate constant (kr) of 2.8 µmol/L·min and the pseudo-equilibrium constant (K) for PA is 34 L/mmol. The pH of the solution influences the adsorption and photocatalytic degradation of PA due to the surface charge of TiO2 photocatalyst and speciation of PA. Phenol, catechol and hydroquinone are observed as the predominant products during the degradation. The roles of reactive oxygen species, •OH, 1O2, O2?• and hVB+ were probed by adding appropriate scavengers to the reaction medium and the results suggest that •OH plays a major role in the degradation of PA. By-products studies indicate the surface of the catalyst plays a key role in the formation of the primary products and the subsequent oxidation pathways leading to the mineralization to inorganic arsenic. TiO2 photocatalysis results in the rapid destruction of PA and may be attractive for the remediation of a variety of organoarsenic compounds. PMID:20473340

  6. Effective nitrogen doping into TiO2 (N-TiO2) for visible light response photocatalysis.

    PubMed

    Yoshida, Tomoko; Niimi, Satoshi; Yamamoto, Muneaki; Nomoto, Toyokazu; Yagi, Shinya

    2015-06-01

    The thickness-controlled TiO2 thin films are fabricated by the pulsed laser deposition (PLD) method. These samples function as photocatalysts under UV light irradiation and the reaction rate depends on the TiO2 thickness, i.e., with an increase of thickness, it increases to the maximum, followed by decreasing to be constant. Such variation of the reaction rate is fundamentally explained by the competitive production and annihilation processes of photogenerated electrons and holes in TiO2 films, and the optimum TiO2 thickness is estimated to be ca. 10nm. We also tried to dope nitrogen into the effective depth region (ca. 10nm) of TiO2 by an ion implantation technique. The nitrogen doped TiO2 enhanced photocatalytic activity under visible-light irradiation. XANES and XPS analyses indicated two types of chemical state of nitrogen, one photo-catalytically active N substituting the O sites and the other inactive NOx (1?x?2) species. In the valence band XPS spectrum of the high active sample, the additional electronic states were observed just above the valence band edge of a TiO2. The electronic state would be originated from the substituting nitrogen and be responsible for the band gap narrowing, i.e., visible light response of TiO2 photocatalysts. PMID:25670537

  7. Nonaqueous TiO2 nanoparticle synthesis: a versatile basis for the fabrication of self-supporting, transparent, and UV-absorbing composite films.

    PubMed

    Koziej, Dorota; Fischer, Fabian; Kränzlin, Niklaus; Caseri, Walter R; Niederberger, Markus

    2009-05-01

    A successful strategy to obtain self-supporting (100 microm), UV-absorbing, and, in the visible region, highly transparent TiO2-poly(methyl methacrylate) (PMMA) films was developed. The 15 nm large anatase TiO2 nanocrystals were prepared in a nonaqueous sol-gel approach involving the mixing of Ti(O(i)Pr)4 and benzyl alcohol. The surfaces of the resulting particles were modified with minute amounts of organic ligands in order to make the particles easily dispersible in nonpolar media like xylene and dichloromethane and compatible with PMMA, a polymer of high optical transparency and considerable technical importance. The empirical optimization process of composite fabrication was supplemented by fundamental studies of the crystallization and growth mechanism of anatase particles in a nonaqueous medium. After the preparation of corresponding nanocomposites, the materials were investigated with respect to their UV absorption capability, optical transparency in the visible-wavelength region, and photodegradation. PMID:20355897

  8. Laser deposition of TiO2 for urethral catheter

    NASA Astrophysics Data System (ADS)

    Jelínek, Miroslav; Remsa, Jan; Zezulová, Markéta

    2010-10-01

    Catheters and medicals tubes are widely used to introduce pharmaceuticals and nutrients into arteries and veins, and to drain fluids or urine from urethra or the digestive organs. It is well known that illuminated TiO2 photocatalysts can decompose most noxious or toxic organic compounds. We studied the properties of titanium dioxide layers created by pulsed laser deposition from pure titanium and titanium dioxide targets with the goal to develop urethral catheter using TiO2 coated plastic tube. To reach crystalline structure at low substrate temperatures the radio-frequency discharge between the target and the substrate was implemented. The crystalline structure of layers was determined by X-ray diffraction and Fourier Transform Infrared Spectroscopy. Morphology was studied by atomic force microscopy (AFM). Using RF discharge, mixture of anatase and rutile was found at substrate temperature of 90°C (which was reached only by RF discharge).

  9. Purification of water by bipolar pulsed discharge plasma combined with TiO2 catalysis

    NASA Astrophysics Data System (ADS)

    Zhang, Yongrui; Zhang, Ruobing; Ma, Wenchang; Zhang, Xian; Wang, Liming; Guan, Zhicheng

    2013-03-01

    In the process of water treatment by bipolar pulsed discharge plasma, there are not only the chemical effects such as the cold plasma, but also the physical effects such as the optical radiation. The energy of the optical radiation can be used by photocatalyst. Therefore, the effect of the photocatalyst to the degradation of the organic pollutant was investigated using a packed bed reactor by bipolar pulsed discharge in the air-liquid-solid mixture. The nanoparticle TiO2 photocatalyst was obtained using the sol-gel method and the typical dye solution Indigo Carmine was chosen as the degradation target to test the catalytic effect of the nanoparticle TiO2 photocatalyst. Experiment results proved that the degradation efficiency of the Indigo Carmine solution was increased by a certain extent with the TiO2 photocatalyst. It was totally decolorized within 3 minutes by bipolar pulsed discharge in the condition that the peak voltage was 30 kV and the air flow was 1.0 m3 h-1.

  10. The interactions between TiO2 and graphene with surface inhomogeneity determined using density functional theory.

    PubMed

    Bukowski, Brandon; Deskins, N Aaron

    2015-11-28

    TiO2/graphene composites have shown promise as photocatalysts, leading to improved electronic properties. We have modeled using density functional theory TiO2/graphene interfaces formed between graphene with various defects/functional groups (C vacancy, epoxide, and hydroxyl) and TiO2 clusters of various sizes. We considered clusters from 3 to 45 atoms, the latter a nanoparticle of ?1 nm in size. Our results show that binding to pristine graphene is dominated by van der Waals forces, and that C vacancies or epoxide groups lead to much stronger binding between the graphene and TiO2. Such sites may serve to anchor TiO2 to graphene. Graphene surfaces with hydroxyls however lead to OH transfer to TiO2 and weak interactions between the graphene and the hydroxylated TiO2 cluster. Charge transfer may occur between TiO2 and graphene in various directions (graphene to TiO2 or TiO2 to graphene), depending on the state of the graphene surface, based on overlap of the density of states. Our work indicates that graphene surface defects or functional groups may have a significant effect on the stability, structure, and photoactivity of these materials. PMID:26477857

  11. Rapid flame synthesis of internal Mo(6+) doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters for lithium ion storage.

    PubMed

    Li, Yunfeng; Hu, Yanjie; Shen, Jianhua; Jiang, Haibo; Min, Guoquan; Qiu, Shengjie; Song, Zhitang; Sun, Zhuo; Li, Chunzhong

    2015-11-28

    The rational design of nanoheterostructured materials has attracted much attention because of its importance for developing highly efficient LIBs. Herein, we have demonstrated that internal Mo(6+) doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters have been realized by a facile and rapid flame spray pyrolysis route for electrochemical energy storage. In such intriguing nanostructures, internal Mo(6+) doping can improve the conductivity of electrode materials and facilitate rapid Li(+) intercalation and ion transport and the heteroassembly of highly dispersed ultrafine MoO3 clusters with excellent electrochemical activity endows the TiO2 with extra Li(+) ion storage ability as well as incorporates Mo(6+). Thus, the as-prepared nanohybrid electrodes exhibit a high specific capacity and superior rate capability due to the maximum synergetic effect of TiO2, Mo(6+) and ultrafine MoO3 clusters. Moreover, the aerosol flame process with a unique temperature gradient opens a new strategy to design novel hybrid materials by the simultaneous doping and heteroassembly engineering for next-generation LIBs. PMID:26490363

  12. Synthesis, characterization and photocatalytic activity of noble metal-modified TiO2 nanosheets with exposed {0 0 1} facets

    NASA Astrophysics Data System (ADS)

    Diak, Magdalena; Grabowska, Ewelina; Zaleska, Adriana

    2015-08-01

    Pt, Pd, Ag and Au nanoparticles were photodeposited on the {0 0 1} crystal facets of the TiO2 anatase nanosheets. Morphological and surface characterization of the samples as well as photocatalytic activity were studied. The influence of metal precursor concentration used during photodeposition (0.05-0.5%) on size of formed metal nanoparticles together with UV and vis-mediated activity of Pt, Pd, Ag or Au-TiO2 was investigated. Generally, samples obtained by photodeposition of noble metal nanoparticles using their 0.2% precursor solutions revealed highest activity in phenol degradation reaction under visible light (? > 420 nm). The photoactivity of the as-prepared samples with respect to the modified metal species was ordered Ag?Pd > Au > Pt. TEM analysis showed that photodeposited metal nanoparticles appeared only on {0 0 1} facets of TiO2. The average degradation rate of phenol in the presence of Pd and Ag-TiO2 was 0.5 ?mol dm-3 min-1 after 60 min of irradiation under visible light, and was five times higher than that of pure TiO2 nanosheets.

  13. A maskless synthesis of TiO2-nanofiber-based hierarchical structures for solid-state dye-sensitized solar cells with improved performance

    PubMed Central

    2014-01-01

    TiO2 hierarchical nanostructures with secondary growth have been successfully synthesized on electrospun nanofibers via surfactant-free hydrothermal route. The effect of hydrothermal reaction time on the secondary nanostructures has been studied. The synthesized nanostructures comprise electrospun nanofibers which are polycrystalline with anatase phase and have single crystalline, rutile TiO2 nanorod-like structures growing on them. These secondary nanostructures have a preferential growth direction [110]. UV–vis spectroscopy measurements point to better dye loading capability and incident photon to current conversion efficiency spectra show enhanced light harvesting of the synthesized hierarchical structures. Concomitantly, the dye molecules act as spacers between the conduction band electrons of TiO2 and holes in the hole transporting medium, i.e., spiro-OMeTAD and thus enhance open circuit voltage. The charge transport and recombination effects are characterized by electrochemical impedance spectroscopy measurements. As a result of improved light harvesting, dye loading, and reduced recombination losses, the hierarchical nanofibers yield 2.14% electrochemical conversion efficiency which is 50% higher than the efficiency obtained by plain nanofibers. PMID:24410851

  14. Visible light photocatalytic degradation of 4-chlorophenol using vanadium and nitrogen co-doped TiO2

    NASA Astrophysics Data System (ADS)

    Jaiswal, R.; Patel, N.; Kothari, D. C.; Miotello, A.

    2013-02-01

    Vanadium and Nitrogen were codoped in TiO2 photocatalyst by Sol-gel method to utilize visible light more efficiently for photocatalytic reactions. A noticeable shift of absorption edge to visible light region was obtained for the singly-doped namely V-TiO2, N-TiO2 and codoped V-N-TiO2 samples in comparison with undoped TiO2, with smallest band gap obtained with codoped-TiO2. The photocatalytic activities for all TiO2 photocatalysts were tested by 4-chlorophenol (organic pollutant) degradation under visible light irradiation. It was found that codoped TiO2 exhibits the best photocatalytic activity, which could be attributed to the synergistic effect produced by V and N dopants.

  15. Photocatalytic Activity of Immobilized Geometries of TiO2

    NASA Astrophysics Data System (ADS)

    Koohestani, Hassan; Sadrnezhaad, Sayed Khatiboleslam

    2015-07-01

    Photocatalysts that are used for waste water treatment are often suspended in the waste water during processing and then must be removed from the water after treatment. To reduce the post-degradation expenses and time, separation is facilitated by an immobilization process. The effect of immobilized TiO2 geometries on the photocatalytic behavior of the photocatalyst is investigated in this work. Powder, fiber, film, and network-shaped TiO2 nanocatalysts were produced by using different templates. The cellulose fiber and ceramic templates were used as substrates for fiber and film/network geometry production. The products were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurement. The photocatalytic performance was determined by methyl orange degradation and cyanide photo-oxidation under ultraviolet irradiation. From the SEM images, the size range of the TiO2 particles in the film and in the network geometries were 20-60 nm. The nanoparticles had covered the surface of the substrate, uniformly. Removal of the cellulose substrate by heat treatment yielded hollow TiO2 fibers with diameters of 0.5-1 µm and lengths of 30 µm. The efficiencies of both photocatalytic reactions were obtained in the following order: powder > network > film > fiber geometry. The rate constant of the dye degradation reaction using powder catalyst was 0.0118 min-1. For network catalyst, it was 0.0083 min-1. Corresponding results for cyanide disinfection were 0.0055 and 0.0046 min-1. Although powder samples had higher rate constants, network geometry was preferred due to its higher immobility.

  16. Photocatalytic Property of TiO2-Vermiculite Composite Nanofibers via Electrospinning.

    PubMed

    Tang, Chao; Hu, Meiling; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Liu, Wenjuan; Wang, Meng; Huang, Zhaohui

    2015-12-01

    Titanium dioxide (TiO2) is one of the most common photocatalysts. In this study, TiO2-vermiculite composite nanofibers with a mesh structure and a diameter of approximately 300 nm were prepared via sol-gel approach combined with electrospinning technique. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, etc. The photocatalytic property was also evaluated. The TiO2-vermiculite composite nanofibers annealed at 550 °C for 3 h exhibited the best absorption and photo-degradation ability for the treatment of methylene blue. The results implied that the combination of mineral vermiculite powders with TiO2 enhanced the absorption-degradation performance of the as-prepared photocatalytic materials, consequently promoting the materials' ability to degrade methylene blue. PMID:26130024

  17. Mesoporous Foam TiO2 Nanomaterials for Effective Hydrogen Production.

    PubMed

    Krishnappa, Manjunath; Souza, Virgínia S; Ganganagappa, Nagaraju; Scholten, Jackson D; Teixeira, Sérgio R; Dupont, Jairton; Thippeswamy, Ramakrishnappa

    2015-12-01

    Hydrolysis of TiCl4 in a diether-functionalized imidazolium ionic liquid (IL), namely 1-methyl-3-[2-(2-methoxy(ethoxy)ethyl]imidazolium methane sulfonate (M(MEE)I?CH3 SO3 ), results in a heterostructured organic/inorganic and sponge-like porous TiO2 material. The thermal treatment (300?°C) followed by calcination (500?°C) affords highly porous TiO2 . The characterization of the obtained samples (with and without IL, before and after calcination) by XRD, SEM, and TEM reveals TiO2 anatase crystalline phases and irregular-shaped particles with different porous structures. These hierarchical-structured mesoporous TiO2 nanomaterials were employed as efficient photocatalysts in the water-splitting process, yielding up to 1304??mol?g(-1) on hydrogen production. PMID:26492871

  18. Photocatalytic Property of TiO2-Vermiculite Composite Nanofibers via Electrospinning

    NASA Astrophysics Data System (ADS)

    Tang, Chao; Hu, Meiling; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Liu, Wenjuan; Wang, Meng; Huang, Zhaohui

    2015-07-01

    Titanium dioxide (TiO2) is one of the most common photocatalysts. In this study, TiO2-vermiculite composite nanofibers with a mesh structure and a diameter of approximately 300 nm were prepared via sol-gel approach combined with electrospinning technique. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, etc. The photocatalytic property was also evaluated. The TiO2-vermiculite composite nanofibers annealed at 550 °C for 3 h exhibited the best absorption and photo-degradation ability for the treatment of methylene blue. The results implied that the combination of mineral vermiculite powders with TiO2 enhanced the absorption-degradation performance of the as-prepared photocatalytic materials, consequently promoting the materials' ability to degrade methylene blue.

  19. Synthesis, characterization and activity of an immobilized photocatalyst: natural porous diatomite supported titania nanoparticles.

    PubMed

    Wang, Bin; de Godoi, Fernanda Condi; Sun, Zhiming; Zeng, Qingcong; Zheng, Shuilin; Frost, Ray L

    2015-01-15

    Diatomite, a porous non-metal mineral, was used as support to prepare TiO2/diatomite composites by a modified sol-gel method. The as-prepared composites were calcined at temperatures ranging from 450 to 950 °C. The characterization tests included X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with an energy-dispersive X-ray spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption/desorption measurements. The XRD analysis indicated that the binary mixtures of anatase and rutile exist in the composites. The morphology analysis confirmed the TiO2 particles were uniformly immobilized on the surface of diatom with a strong interfacial anchoring strength, which leads to few drain of photocatalytic components during practical applications. In further XPS studies of hybrid catalyst, we found the evidence of the presence of Ti-O-Si bond and increased percentage of surface hydroxyl. In addition, the adsorption capacity and photocatalytic activity of synthesized TiO2/diatomite composites were evaluated by studying the degradation kinetics of aqueous Rhodamine B under UV-light irradiation. The photocatalytic degradation was found to follow pseudo-first order kinetics according to the Langmuir-Hinshelwood model. The preferable removal efficiency was observed in composites by 750 °C calcination, which is attributed to a relatively appropriate anatase/rutile mixing ratio of 90/10. PMID:25454443

  20. Visible light photocatalytic disinfection of E. coli with TiO2-graphene nanocomposite sensitized with tetrakis(4-carboxyphenyl)porphyrin

    NASA Astrophysics Data System (ADS)

    Rahimi, Rahmatollah; Zargari, Solmaz; Yousefi, Azam; Yaghoubi Berijani, Marzieh; Ghaffarinejad, Ali; Morsali, Ali

    2015-11-01

    The present research deals with the development of a new heterogeneous photocatalysis system for disinfection of bacteria from wastewater by using TiO2-graphene (TG) nanocomposite sensitized with tetrakis(4-carboxyphenyl)porphyrin (TCPP). The disinfection of wastewater using this photocatalyst is not reported in the literature yet. All the synthesized materials were thoroughly characterized by Raman, XRD, DRS, BET, and SEM analysis. The optimum content of graphene in the TiO2-graphene nanocomposite was determined by photocurrent responses of prepared photocatalysts. Subsequently, the photocurrent measurements demonstrate that the TiO2-graphene nanocomposite with 3% graphene content has higher photoactivity. Furthermore, sensitization of the TiO2-graphene nanocomposite with porphyrin (TGP) is successfully capable to develop a new type of photocatalyst system for disinfection of bacteria with moderate to high yields in visible light irradiation.

  1. Synthesis of [111]- and {010}-faceted anatase TiO2 nanocrystals from tri-titanate nanosheets and their photocatalytic and DSSC performances

    NASA Astrophysics Data System (ADS)

    Chen, Changdong; Ikeuchi, Yasushi; Xu, Linfeng; Sewvandi, Galhenage A.; Kusunose, Takafumi; Tanaka, Yasuhiro; Nakanishi, Shunsuke; Wen, Puhong; Feng, Qi

    2015-04-01

    [111]- and {010}-faceted anatase nanocrystals with controllable crystal size and morphology were synthesized from tri-titanate H2Ti3O7 nanosheets by hydrothermal reaction. The nanostructures and the formation reaction mechanism of the obtained TiO2 nanocrystals were investigated using XRD, FE-SEM, and TEM. Furthermore, the photocatalytic and dye-sensitized solar cell (DSSC) performances of the synthesized anatase nanocrystals were also characterized. Two types of reactions occur in the formation process of the anatase nanocrystals. One is an in situ topochemical conversion reaction of the layered titanate structure to an anatase structure, and another is the dissolution-deposition reaction on the particle surface, which splits the formed nanosheet-like particles into small TiO2 nanocrystals. The surface photocatalytic activity and the DSSC performance of the anatase nanocrystals are dependent on the crystal facet exposed on the particle surface, which increases in the order of non-facet < [111]-facet < {010}-facet. The increasing order corresponds to the increasing order of the bandgap and energy level of the lowest valence band of the anatase nanocrystals. Furthermore, the facet of the anatase also affects the DSSC performance, which is enhanced in the order of non-facet < [111]-facet < {010}-facet.[111]- and {010}-faceted anatase nanocrystals with controllable crystal size and morphology were synthesized from tri-titanate H2Ti3O7 nanosheets by hydrothermal reaction. The nanostructures and the formation reaction mechanism of the obtained TiO2 nanocrystals were investigated using XRD, FE-SEM, and TEM. Furthermore, the photocatalytic and dye-sensitized solar cell (DSSC) performances of the synthesized anatase nanocrystals were also characterized. Two types of reactions occur in the formation process of the anatase nanocrystals. One is an in situ topochemical conversion reaction of the layered titanate structure to an anatase structure, and another is the dissolution-deposition reaction on the particle surface, which splits the formed nanosheet-like particles into small TiO2 nanocrystals. The surface photocatalytic activity and the DSSC performance of the anatase nanocrystals are dependent on the crystal facet exposed on the particle surface, which increases in the order of non-facet < [111]-facet < {010}-facet. The increasing order corresponds to the increasing order of the bandgap and energy level of the lowest valence band of the anatase nanocrystals. Furthermore, the facet of the anatase also affects the DSSC performance, which is enhanced in the order of non-facet < [111]-facet < {010}-facet. Electronic supplementary information (ESI) available: XRD patterns of the products obtained by hydrothermal treatment in the temperature range of 140-200 °C, the dependency of the (101) peak intensity of anatase on the pH values of nanosheet solution at different temperature, the EDS analysis results of the synthesized TiO2 samples, TEM images and the FFT diffraction pattern of the TMA-150-2.5 sample, I-V characteristics and FE-SEM images in the cross-section of the TiO2-film electrodes of the DSSC cells fabricated using TMA-200-3.6 and P25 samples, TEM images of TMA-200-3.6 anatase nanocrystal samples after the calcination at 480 °C for 1 h. See DOI: 10.1039/c5nr00069f

  2. Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts

    PubMed Central

    Qu, Yongquan; Liao, Lei; Cheng, Rui; Wang, Yue; Lin, Yung-chen; Huang, Yu; Duan, Xiangfeng

    2010-01-01

    Photocatalysts are of significant interest for solar energy harvesting and conversion into chemical energy. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here we report the rational design of a new generation of freestanding photoelectric nanodevices as highly efficient and stable photocatalysts by integrating a nanoscale photodiode with two redox catalysts in a single nanowire heterostructure. We show that a platinum-silicon-silver nanowire heterostructure can be synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. We further demonstrated that the Schottky diodes exhibited pronounced photovoltaic effect with nearly unity internal quantum efficiency, and that the integrated nanowire heterostructures could be used as highly efficient photocatalysts for a wide range of thermodynamically downhill and uphill reactions including photocatalytic degradation of organic dyes, reduction of metal ions and carbon dioxide using visible light. Our studies for the first time demonstrated the integration of multiple distinct functional components into a single nanostructure to form a standalone active nanosystem, and for the first time successfully realized a photoelectric nanodevice that is both highly efficient and highly stable throughout the entire solar spectrum. It thus opens a rational avenue to design and synthesize a new generation of photoelectric nanosystems with unprecedented efficiency and stability, and will impact broadly in areas including environmental remediation and solar fuel production. PMID:20373781

  3. Sonochemical synthesis of solar-light-driven Ag°-PbMoO4 photocatalyst.

    PubMed

    Gyawali, Gobinda; Adhikari, Rajesh; Joshi, Bhupendra; Kim, Tae Ho; Rodríguez-González, Vicente; Lee, Soo Wohn

    2013-12-15

    Ag°-PbMoO4 photocatalysts were synthesized by facile sonochemical method with different mol.% of Ag nanoparticles dispersed on the surface of PbMoO4. The synthesized powders were characterized by X-ray Diffraction (XRD) Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), and Diffuse Reflectance Spectroscopy (UV-vis DRS) to investigate the crystal structure, morphology, chemical composition, and optical properties of the photocatalyst. Photocatalytic activities of the Ag°-PbMoO4 samples were evaluated by the degradation of Indigo Carmine (IC) dye under simulated solar light irradiation. It has been observed that the sample containing 0.3 mol.% of Ag showed the best photocatalytic activity as compared to other samples. The results suggest that the dispersion of Ag nanoparticles on the surface of PbMoO4 significantly enhances the photocatalytic activity of PbMoO4. Increase in photocatalytic activity of Ag°-PbMoO4 photocatalyst has been explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the photocatalyst. PMID:23643197

  4. Synthesis of visible light-activated TiO{sub 2} photocatalyst via surface organic modification

    SciTech Connect

    Jiang Dong Xu Yao Hou Bo; Wu Dong; Sun Yuhan

    2007-05-15

    A visible light-activated TiO{sub 2} photocatalyst was successfully synthesized by the surface organic modification to sol-gel-hydrothermal synthesized TiO{sub 2}. The surface hydroxyls of TiO{sub 2} nanoparticles reacted with the active -NCO groups of tolylene diisocyanate (TDI) to form a surface complex that was confirmed by the FT-IR and XPS spectra. Due to the existence of surface complex, the absorption edge of as-prepared TDI-modified TiO{sub 2} nanomaterial extended well into visible region. Compared with unmodified TiO{sub 2} and Degussa P25, the TDI-modified TiO{sub 2} photocatalysts showed higher activity for the photocatalytic degradation of methylene blue under visible light irradiation. - Graphical abstract: A visible light-activated TiO{sub 2} photocatalyst was successfully synthesized by the surface organic modification to TiO{sub 2}. The surface hydroxyls of TiO{sub 2} nanoparticles reacted with the active -NCO groups of tolylene diisocyanate (TDI) to form a surface complex. The TDI-modified TiO{sub 2} photocatalysts showed higher activity for the photocatalytic degradation of methylene blue under visible light irradiation.

  5. Thermodynamically driven one-dimensional evolution of anatase TiO2 nanorods: one-step hydrothermal synthesis for emerging intrinsic superiority of dimensionality.

    PubMed

    Chen, Jiazang; Yang, Hong Bin; Miao, Jianwei; Wang, Hsin-Yi; Liu, Bin

    2014-10-29

    In photoelectrochemical cells, there exists a competition between transport of electrons through the porous semiconductor electrode toward the conducting substrate and back-reaction of electrons to recombine with oxidized species on the semiconductor-electrolyte interface, which determines the charge collection efficiency and is strongly influenced by the density and distribution of electronic states in band gap and architectures of the semiconductor electrodes. One-dimensional (1D) anatase TiO2 nanostructures are promising to improve charge transport in photoelectrochemical devices. However, the conventional preparation of 1D anatase nanostructures usually steps via a titanic acid intermediate (e.g., H2Ti3O7), which unavoidably introduces electronic defects into the host lattice, resulting in undesired shielding of the intrinsic role of dimensionality. Here, we manage to promote the 1D growth of anatase TiO2 nanostructures by adjusting the growth kinetics, which allows us to grow single-crystalline anatase TiO2 nanorods through a one-step hydrothermal reaction. The synthesized anatase nanorods possess a lower density of trap states and thus can simultaneously facilitate the diffusion-driven charge transport and suppress the electron recombination. Moreover, the electronically boundary free nanostructures significantly enhance the trap-free charge diffusion coefficient of the anatase nanorods, which enables the emergence of the intrinsic superiority of dimensionality. By virtue of these merits, the anatase nanorods synthesized in this work take obvious advantages over the conventional anatase counterparts in photoelectrochemical systems (e.g., dye-sensitized solar cells) by showing more efficient charge transport and collection and higher energy conversion efficiency. PMID:25290360

  6. Synthesis and characterization of maleimide-functionalized polystyrene-SiO2/TiO2 hybrid nanocomposites by sol-gel process

    NASA Astrophysics Data System (ADS)

    Ramesh, Sivalingam; Sivasamy, Arumugam; Kim, Joo-Hyung

    2012-06-01

    Maleimide-functionalized polystyrene (PSMA-SiO2/TiO2) hybrid nanocomposites were prepared by sol-gel reaction starting from tratraethoxysilane (TEOS) and titanium isopropoxide in the solution of polystyrene maleimide in 1,4-dioxane. The hybrid films were obtained by the hydrolysis and polycondensation of TEOS and titanium isopropoxide in maleimide-functionalized polystyrene solution followed by the Michael addition reaction. The transparency of polymer (PSMA-SiO2/TiO2) hybrid was prepared from polystyrene titanium isopropoxide using the ?-aminopropyltriethoxy silane as crosslinking agent by in situ sol-gel process via covalent bonding between the organic-inorganic hybrid nanocomposites. The maleimide-functionalized polystyrene was synthesized by Friedel-Crafts reaction from N-choloromethyl maleimide. The FTIR spectroscopy data conformed the occurrence of Michael addition reaction between the pendant maleimide moieties of the styrene and ?-aminopropyltriethoxysilane. The chemical structure and morphology of PSMA-SiO2/TiO2 hybrid nanocomposites were characterized by FTIR, nuclear magnetic resonance (NMR), 13 C NMR, SEM, XRD, and TEM analyses. The results also indicate that the inorganic particles are much smaller in the ternary systems than in the binary systems; the shape of the inorganic particles and compatibility for maleimide-functionalized polystrene and inorganic moieties are varied with the ratio of the inorganic moieties in the hybrids. Furthermore, TGA and DSC results indicate that the thermal stability of maleimide-functionalized polystyrene was enhanced through the incorporation of the inorganic moieties in the hybrid materials.

  7. Thermal evolution of structure and photocatalytic activity in polymer microsphere templated TiO2 microbowls

    NASA Astrophysics Data System (ADS)

    Erdogan, Deniz Altunoz; Polat, Meryem; Garifullin, Ruslan; Guler, Mustafa O.; Ozensoy, Emrah

    2014-07-01

    Polystyrene cross-linked divinyl benzene (PS-co-DVB) microspheres were used as an organic template in order to synthesize photocatalytic TiO2 microspheres and microbowls. Photocatalytic activity of the microbowl surfaces were demonstrated both in the gas phase via photocatalytic NO(g) oxidation by O2(g) as well as in the liquid phase via Rhodamine B degradation. Thermal degradation mechanism of the polymer template and its direct influence on the TiO2 crystal structure, surface morphology, composition, specific surface area and the gas/liquid phase photocatalytic activity data were discussed in detail. With increasing calcination temperatures, spherical polymer template first undergoes a glass transition, covering the TiO2 film, followed by the complete decomposition of the organic template to yield TiO2 exposed microbowl structures. TiO2 microbowl systems calcined at 600 °C yielded the highest per-site basis photocatalytic activity. Crystallographic and electronic properties of the TiO2 microsphere surfaces as well as their surface area play a crucial role in their ultimate photocatalytic activity. It was demonstrated that the polymer microsphere templated TiO2 photocatalysts presented in the current work offer a promising and a versatile synthetic platform for photocatalytic DeNOx applications for air purification technologies.

  8. Preparation and characterization of N-TiO2 photocatalyst with high crystallinity and enhanced photocatalytic inactivation of bacteria

    NASA Astrophysics Data System (ADS)

    Yu, Binyu; Lau, Woon Ming; Yang, Jun

    2013-08-01

    This study reports the synthesis, characterization and environmental applications of nitrogen doped TiO2 photocatalyst in the form of powder and film. N-TiO2 photocatalysts were synthesized via the hydrolysis of titanium tetraisopropoxide using urea as the nitrogen source. The crystalline structure, particle size and specific surface area of the resultant N-TiO2 nanoparticles were investigated by x-ray powder diffraction and the Brunauer-Emmett-Teller method. The results showed that a mixture of anatase and brookite phases was formed at pH 1 after annealing the powder at 450?° C for 4 h, in contrast to a pure anatase phase at pH 3. UV-vis spectral characterization showed that the absorption region of the as-prepared N-TiO2 was extended to the visible light region. Stable sols could be achieved by controlling the molar ratio of water-to-titanium precursor and pH of the sols. During the photocatalytic test, in comparison to the standard commercial photocatalyst Evonik-Degussa P25 and home-made bare TiO2 nanoparticles, the N-TiO2 particles exhibited enhanced photocatalytic performance for degradation of methylene blue (MB) dye. The visible light induced photocatalytic inactivation of the obtained nanopowders and nanofilms on bacteria (Escherichia coli) was evaluated. The N-TiO2 nanomaterials showed higher bactericidal activity under visible light irradiation.

  9. Synthesis and enhanced photocatalytic activity of a hierarchical porous flowerlike p-n junction NiO/TiO2 photocatalyst.

    PubMed

    Yu, Jiaguo; Wang, Wenguang; Cheng, Bei

    2010-12-01

    Hierarchical flowerlike ?-Ni(OH)(2) superstructures composed of intermeshed nanoflakes are synthesized by hydrothermal treatment with a mixed solution of C(2)H(4)(NH(2))(2), NaOH, and Ni(NO(3))(2). The as-prepared ?-Ni(OH)(2) superstructures could be easily changed into NiO superstructures without great morphology change by calcination at 400?°C for 5?h. Furthermore, the TiO(2) nanoparticles can be homogeneously deposited on the surface of NiO superstructures by dispersing ?-Ni(OH)(2) powders in Ti(OC(4)H(9))(4)-C(2)H(5)OH mixed solution and then vaporizing to remove the ethanol at 100?°C, and finally calcination at 400?°C for 5?h. The prepared NiO/TiO(2) p-n junction superstructures show much higher photocatalytic activity for photocatalytic degradation of p-chlorophenol aqueous solution than conventional TiO(2) powders and NiO superstructures prepared under the same experimental conditions. An obvious enhancement in the photocatalytic activity can be related to several factors, including formation of hierarchical porous structures, dispersion of TiO(2) particles on the surface of NiO superstructures, and production of a p-n junction. Further results show that NiO/TiO(2) composite superstructures can be more readily separated from the slurry system by filtration or sedimentation after photocatalytic reaction and re-used, compared with conventional powder photocatalysts. After many recycling experiments for the photodegradation of p-chlorophenol, the NiO/TiO(2) composite sample does not exhibit any great activity loss, confirming that NiO/TiO(2) sample is stable and not photocorroded. PMID:20941785

  10. Controllable hydrothermal synthesis of rutile TiO2 hollow nanorod arrays on TiCl4 pretreated Ti foil for DSSC application

    NASA Astrophysics Data System (ADS)

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-11-01

    Rutile TiO2 nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl4 pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO2 nanorod arrays (H-TNRs). The TiCl4 pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl4 concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ~1.5 ?m and diameter of ~200 nm, obtained on 0.15 M TiCl4 pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl4-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode.

  11. A simple low pressure method for the synthesis of TiO2 nanotubes and nanofibers and their application in DSSCs

    NASA Astrophysics Data System (ADS)

    Karimipour, Masoud; Mashhoun, Sara; Mollaei, Mohsen; Molaei, Mehdi; Taghavinia, Nima

    2015-07-01

    TiO2 nanotubes were synthesized using a modified autoclave-free thermal method from as-prepared initial powders. The size of initial powders (IP) was found to be critical in determining the morphology and crystal structure of the final product. Oleylamine (OA) was used as the polymer agent in the preparation of initial powders with different mol ratios of OA/Ti: 1, 5, and 10. X-ray diffraction analysis depicted that the increase of mole ratio up to 10 resulted in smaller nanoparticles with the sizes of about 8 nm. It was also deliberated that low temperature thermally treated IP showed the characteristic diffraction pattern of titanate phase of nanotubes. Scanning electron microscope images showed nanorods, short nanotubes, and single-phase long and uniform nanofibers produced from initial powders. SEM cross-section of the anode cell of TiO2 nanofibers demonstrated the presence of uniformly closed net long fibers in the cell. Open circuit voltage measurements of the nanofiber cell demonstrated a several hundreds of seconds in the electron transport decay, which was significantly higher than that of the nanoparticles. IMPS/IMVS measurements of the nanofibers and nanotube solar cells showed electron transport enhancement and long life time compared to their nanoparticle counterparts. [Figure not available: see fulltext.

  12. Synthesis, crystal structure, photodegradation kinetics and photocatalytic activity of novel photocatalyst ZnBiYO4.

    PubMed

    Cui, Yanbing; Luan, Jingfei

    2015-03-01

    ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a=b=11.176479Å and c=10.014323Å. The band gap of ZnBiYO4 was estimated to be 1.58eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min(-1) for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO4(2-) and NO3-, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography-mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems. PMID:25766013

  13. Synthesis, characterization and photocatalytic activity of new photocatalyst CdBiYO4

    NASA Astrophysics Data System (ADS)

    Du, Huiyang; Luan, Jingfei

    2012-09-01

    CdBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of CdBiYO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray spectrometry. CdBiYO4 crystallized with a tetragonal spinel structure by space group I41/amd. The lattice parameters for CdBiYO4 were a = b = 14.519 Å and c = 9.442 Å. The band gap of CdBiYO4 was estimated to be 2.41 eV. The photocatalytic degradation of methylene blue (MB) was realized under visible light irradiation with CdBiYO4 as catalyst. The results showed that CdBiYO4 owned higher photocatalytic activity compared with pure TiO2 or N-doped TiO2 for photocatalytic degradation of MB under visible light irradiation. The photocatalytic degradation of MB with CdBiYO4 or N-doped TiO2 as catalyst followed the first-order reaction kinetics, and the first-order rate constant was 0.0137 or 0.0033 min-1. After visible light irradiation for 225 min with CdBiYO4 as catalyst, complete removal and mineralization of MB were observed. The reduction of the total organic carbon, the formation of inorganic products, SO42- and NO3-, and the evolution of CO2 revealed the continuous mineralization of MB during the photocatalytic process. The possible photocatalytic degradation pathway of MB was obtained under visible light irradiation. CdBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be utilized to resolve other environmental chemical pollution problems.

  14. Enhancing selective decomposition of ibuprofen onto porous TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zakersalehi, Abolfazl

    Advanced oxidation technologies have gained tremendous attention for water treatment purposes after demonstration of insufficient efficiency of conventional systems for removal of many emerging chemicals of concern. Among AOTs, a TiO2-UV system is one of the most promising approaches due to its green properties and its effectiveness in generation of extremely oxidizing species such as hydroxyl radicals. However it has been demonstrated that non-selectivity of HRs in decomposition of organic compounds results in parallel decomposing of naturally abundant organic matter (NOM) along with toxic target contaminant, which significantly decreases the decomposition rate of target contaminants. Despite a great amount of researches conducted on TiO2 photocatalysts, limited success has been achieved in enhancing selectivity of TiO2 photocatalytic oxidation. In this study, a novel approach for suppressing the adverse effect of co-existing organics such as NOM has been proposed. Physical access of competing compounds was restrained through manipulation of the porous structure of TiO2 photocatalysts. An advanced templating method was employed to create a porous structure across TiO2 nanoparticles. In this study Ibuprofen as a target contaminant was decomposed in the presence of humic acid as competing NOM. Porous particles demonstrated significant improvement in selective decomposition of ibuprofen in the presence of humic acid as competing species. In the second phase of the study, a comprehensive study was conducted through changing the porous structure and size of co-existing organics in competing and non-competing conditions. The photocatalytic results, in correlation with material characterization demonstrated beneficial role of the controlled porous structure on adsorption followed by decomposition of organic species onto TiO2 photocatalysts.

  15. Direct Synthesis of Carbon-Doped TiO2-Bronze Nanowires as Anode Materials for High Performance Lithium-Ion Batteries.

    PubMed

    Goriparti, Subrahmanyam; Miele, Ermanno; Prato, Mirko; Scarpellini, Alice; Marras, Sergio; Monaco, Simone; Toma, Andrea; Messina, Gabriele C; Alabastri, Alessandro; Angelis, Francesco De; Manna, Liberato; Capiglia, Claudio; Zaccaria, Remo Proietti

    2015-11-18

    Carbon-doped TiO2-bronze nanowires were synthesized via a facile doping mechanism and were exploited as active material for Li-ion batteries. We demonstrate that both the wire geometry and the presence of carbon doping contribute to the high electrochemical performance of these materials. Direct carbon doping for example reduces the Li-ion diffusion length and improves the electrical conductivity of the wires, as demonstrated by cycling experiments, which evidenced remarkably higher capacities and superior rate capability over the undoped nanowires. The as-prepared carbon-doped nanowires, evaluated in lithium half-cells, exhibited lithium storage capacity of ?306 mA h g(-1) (91% of the theoretical capacity) at the current rate of 0.1C as well as excellent discharge capacity of ?160 mAh g(-1) even at the current rate of 10 C after 1000 charge/discharge cycles. PMID:26492841

  16. Enhanced photocatalytic activity of TiO2-impregnated with MgZnAl mixed oxides obtained from layered double hydroxides for phenol degradation

    NASA Astrophysics Data System (ADS)

    de Almeida, Marciano Fabiano; Bellato, Carlos Roberto; Mounteer, Ann Honor; Ferreira, Sukarno Olavo; Milagres, Jaderson Lopes; Miranda, Liany Divina Lima

    2015-12-01

    A series of TiO2/MgZnAl photocatalysts were successfully synthesized from ternary (Mg, Zn and Al) layered double hydroxides impregnated with TiO2 nanoparticles by the co-precipitation method at variable pH with different Zn2+/Mg2+ molar ratios. The composite photocatalysts were calcined at 500 °C resulting in the incorporation of oxide zinc, in the calcined MgZnAl LDH structure. Synergistic effect between ZnO and TiO2 lead to significant enhancement of TiO2/MgZnAl photocatalytic activity. Composite photocatalysts were characterized by ICP-MS, N2 adsorption-desorption, XRD, SEM, EDS, IR and UV-vis DRS. Phenol in aqueous solution (50 mg/L) was used as a model compound for evaluation of UV-vis (filter cut-off for ? > 300 nm) photocatalytic activity. The most efficient photocatalyst composite was obtained at a 5% Zn2+/Mg2+ molar ratio, in the catalyst identified as TiO2/MgZnAl-5. This composite catalyst had high photocatalytic activity, completely destroying phenol and removing 80% of total organic carbon in solution after 360 min. The TiO2/MgZnAl-5 catalyst remained relatively stable, presenting a 15% decrease in phenol degradation efficiency after five consecutive photocatalytic cycles.

  17. Doping of TiO2 for sensitized solar cells.

    PubMed

    Roose, Bart; Pathak, Sandeep; Steiner, Ullrich

    2015-11-21

    This review gives a detailed summary and evaluation of the use of TiO2 doping to improve the performance of dye sensitized solar cells. Doping has a major effect on the band structure and trap states of TiO2, which in turn affect important properties such as the conduction band energy, charge transport, recombination and collection. The defect states of TiO2 are highly dependent on the synthesis method and thus the effect of doping may vary for different synthesis techniques, making it difficult to compare the suitability of different dopants. High-throughput methods may be employed to achieve a rough prediction on the suitability of dopants for a specific synthesis method. It was however found that nearly every employed dopant can be used to increase device performance, indicating that the improvement is not so much caused by the dopant itself, as by the defects it eliminates from TiO2. Furthermore, with the field shifting from dye sensitized solar cells to perovskite solar cells, the role doping can play to further advance this emerging field is also discussed. PMID:26314371

  18. Fabrication of plasmonic AgBr/Ag nanoparticles-sensitized TiO2 nanotube arrays and their enhanced photo-conversion and photoelectrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Qingyao; Qiao, Jianlei; Jin, Rencheng; Xu, Xiaohui; Gao, Shanmin

    2015-03-01

    Plasmonic photosensitizer AgBr/Ag nanospheres supported on TiO2 nanotube arrays (TiO2 NTs) are prepared by successive ionic layer adsorption and reaction (SILAR) technique followed by photoreduction methods. The structural and surface morphological properties of AgBr/Ag nanoparticles sensitized TiO2 NTs and their photoelectrochemical performance are investigated and discussed. A detailed formation mechanism of the TiO2 NTs/AgBr/Ag is proposed. The TiO2 NTs/AgBr/Ag exhibit excellent photocurrent and photoelectrocatalytic activities under visible light irradiation. Efficient utilization of solar energy to create electron-hole pairs is attributed to the significant visible light response and surface plasmon resonance of Ag nanoparticles. This finding indicates that the high photosensitivity of the TiO2 NTs-based surface plasmon resonance materials could be applied toward the development of new plasmonic visible-light-sensitive photovoltaic fuel cells and photocatalysts.

  19. A comparative study of TiO2 nanoparticles synthesized in premixed and diffusion flames

    NASA Astrophysics Data System (ADS)

    Ma, Hsiao-Kang; Yang, Hsiung-An

    2010-12-01

    Previous studies have been shown that synthesis of titania (TiO2) crystalline phase purity could be effectively controlled by the oxygen concentration through titanium tetra-isopropoxide (TTIP) via premixed flame from a Bunsen burner. In this study, a modified Hencken burner was used to synthesize smaller TiO2 nanoparticles via short diffusion flames. The frequency of collisions among particles would decrease and reduce TiO2 nanoparticle size in a short diffusion flame height. The crystalline structure of the synthesized nanoparticles was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) measurements. The characteristic properties of TiO2 nanoparticles synthesized from a modified Hencken burner were compared with the results from a Bunsen burner and commercial TiO2 (Degussa P25). The results showed that the average particle size of 6.63 nm from BET method was produced by a modified Hencken burner which was smaller than the TiO2 in a Bunsen burner and commercial TiO2. Moreover, the rutile content of TiO2 nanoparticles increased as the particle collecting height increased. Also, the size of TiO2 nanoparticles was highly dependent on the TTIP loading and the collecting height in the flame.

  20. First-principles study on transition metal-doped anatase TiO2

    PubMed Central

    2014-01-01

    The electronic structures, formation energies, and band edge positions of anatase TiO2 doped with transition metals have been analyzed by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The model structures of transition metal-doped TiO2 were constructed by using the 24-atom 2?×?1?×?1 supercell of anatase TiO2 with one Ti atom replaced by a transition metal atom. The results indicate that most transition metal doping can narrow the band gap of TiO2, lead to the improvement in the photoreactivity of TiO2, and simultaneously maintain strong redox potential. Under O-rich growth condition, the preparation of Co-, Cr-, and Ni-doped TiO2 becomes relatively easy in the experiment due to their negative impurity formation energies, which suggests that these doping systems are easy to obtain and with good stability. The theoretical calculations could provide meaningful guides to develop more active photocatalysts with visible light response. PMID:24472374

  1. CORONA DISCHARGE REACTOR FOR SELECTIVE OXIDATION OF ALCOHOLS AND HYDROCARBONS USING OZONATION AND PHOTOXIDATION OF OVER TIO2

    EPA Science Inventory

    We have developed a process that combines the use of surface corona for the production of ozone by passing air or oxygen through a high voltage electrical discharge and the emitted UV is being used to activate a photocatalyst. A thin film of nanostructured TiO2 with primary part...

  2. Fabrication of TiO2 binary inverse opals without overlayers via the sandwich-vacuum infiltration of precursor.

    PubMed

    Cai, Zhongyu; Teng, Jinghua; Xiong, Zhigang; Li, Yanqiang; Li, Qin; Lu, Xianmao; Zhao, X S

    2011-04-19

    A sandwich-vacuum method was demonstrated for the fabrication of titania (TiO(2)) binary inverse opals with an open surface. In this method, a moisture-stable TiO(2) precursor was backfilled into the interstitial spaces of polystyrene binary colloidal crystals (PS bCCs), which served as a template. Removal of the template by calcination yielded TiO(2) binary inverse opals with a 3D-ordered macroporous (3DOM) structure. Optical reflectance spectra revealed the existence of a pseudostop band gap in the 3DOM TiO(2) samples. The position of the pseudostop band gap shifted to the low-wavelength region as the number ratio of small over large PS spheres was increased in the template. The sandwich-vacuum method proved to be simple and rapid for the fabrication of TiO(2) binary inverse opals without overlayers in large domains. The 3DOM TiO(2) materials were used as a photocatalyst for the degradation of benzoic acid. Results showed that in comparison to TiO(2) nanoparticles prepared under the same sintering conditions, the 3DOM TiO(2) materials displayed enhanced photocatalytic activity. PMID:21413750

  3. TiO2 embedded in carbon submicron-tablets: synthesis from a metal-organic framework precursor and application as a superior anode in lithium-ion batteries.

    PubMed

    Wang, Peiyu; Lang, Junwei; Liu, Dongxia; Yan, Xingbin

    2015-07-21

    Rutile TiO2 embedded in carbon submicron-tablets (TiO2/C) with a "blueberry muffin" morphology was fabricated via a two-step pyrolysis from a metal-organic framework precursor. Such a unique structure of the TiO2/C submicron-tablets provides the ideal anode characteristics (high reversible capacity, superior rate capability and excellent long-term cycling stability) for fast rechargeable lithium ion batteries. PMID:25813272

  4. TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.

    PubMed

    Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

    2009-10-01

    Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates. PMID:20355842

  5. Synthesis and characterization of ZnO-TiO2 nanocomposites and their application as photocatalysts

    NASA Astrophysics Data System (ADS)

    Habib, Md Ahsan; Shahadat, Md Tusan; Bahadur, Newaz Mohammed; Ismail, Iqbal M. I.; Mahmood, Abu Jafar

    2013-01-01

    Nanocomposite ZnO-TiO2 powders of varying ZnO/TiO2 molar ratios have been prepared from their salt/compound by heating at 600°C and 900°C and characterized using scanning electron microscope and X-ray diffraction techniques. The nanosized powders can decolorize/degrade brilliant golden yellow (BGY), an azo dye extensively used in textile industries, in water under solar irradiation. The effects of various parameters such as photocatalyst loading, molar ratio of ZnO/TiO2, pH of the solution, initial dye concentration, and irradiation time on the photodecolorization have been investigated. ZnO-TiO2 nanocomposite (6 g/L) in the molar ratio of 1:1 or 3:1, prepared at 900°C, can efficiently decolorize about 98% of 20 mg/L BGY at pH of about 7 by 2-h illumination in sunlight. The initial dye decolorization follows pseudo-first-order kinetics. Finally, trial experiments were done using real textile wastewater to find out the effectiveness of the photocatalysts to a more complex system.

  6. Carbon coating stabilized Ti(3+)-doped TiO2 for photocatalytic hydrogen generation under visible light irradiation.

    PubMed

    Fu, Gao; Zhou, Peng; Zhao, Meiming; Zhu, Weidong; Yan, Shicheng; Yu, Tao; Zou, Zhigang

    2015-07-28

    Self-doping by Ti(3+) is a useful method to expand the light response of TiO2 into the visible light region. However, to obtain a stable Ti(3+)-doped TiO2 seems to be a challenge due to the easy oxidation of Ti(3+) during the heterogeneous reaction. Here, we propose a simple carbon coating route to stabilize the Ti(3+)-doped TiO2, in which both the Ti(3+) and precursor of the carbon coating layer were in situ formed from the hydrothermal hydrolysis of titanium isopropoxide. The carbon coated Ti(3+)-doped TiO2 exhibited excellent stability for photocatalytic hydrogen production. Based on electron paramagnetic resonance (EPR) analysis, the proposed stabilizing mechanism is that the conductive carbon coating layer as a barrier layer prevents the H2O and O2 from diffusing into the surface of the photocatalyst, which can oxidize the surface O vacancies and Ti(3+) in TiO2. Our findings offer a simple route to prepare a highly stable TiO2-based photocatalyst with visible light response. PMID:26098384

  7. Photocatalytic reduction of carbon dioxide over ZnFe2O4/TiO2 nanobelts heterostructure in cyclohexanol.

    PubMed

    Song, Guixian; Xin, Feng; Yin, Xiaohong

    2015-03-15

    A series of ZnFe2O4/TiO2 heterostructure photocatalysts with different mass percentages of ZnFe2O4 were synthesized through hydrothermal deposition method. The photocatalysts were characterized by SEM, TEM, XRD, XPS, and UV-vis DRS techniques. It is observed that ZnFe2O4 nanoparticles grew on the TiO2 nanobelts, and the obtained nanocomposites have ordered nanobelt structure with a high crystallinity. The photocatalytic activities of the nanocomposites were tested by photocatalytic reduction of CO2 in cyclohexanol under UV light (main wave length at 360nm) irradiation. The experimental results showed that the main products were cyclohexanone (CH) and cyclohexyl formate (CF). Compared with pure TiO2 and ZnFe2O4 samples, the obtained ZnFe2O4/TiO2 nanocomposites showed much higher photocatalytic performance. The loading amount of ZnFe2O4 was an important factor affecting the generation yields of the products. When the loading amount of ZnFe2O4 reached 9.78%, the ZnFe2O4/TiO2 heterostructure sample displayed the highest activity. The Z-scheme system reaction mechanism was proposed to explain the photocatalytic activity of the ZnFe2O4/TiO2 heterostructure sample. PMID:25514648

  8. In situ synthesis of carbon incorporated TiO2 with long-term performance as anode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Ma, Xiaoqing; Cui, Xiaoli; Jiang, Zhiyu

    2016-01-01

    The carbon incorporated titanium dioxide (C-TiO2) has been in-situ synthesized via facile flame-assisted approach using tetrabutyl orthotitanate as a precursor. The as-prepared C-TiO2 samples are characterized by SEM, XRD, XPS, Raman spectroscopy, EDX, TGA and electrochemical measurements. It is found that carbon incorporated TiO2 microspheres can be directly obtained without any post annealing. Enhanced lithium storage performance is observed for the resultant sample after ball milling. The reversible capacity remains 159.8 mAh g-1 at a specific current of 335 mA g-1 even after 960 charge-discharge cycles. The high capacity reversibility and good long-term cycling capability are attributed to the inherently incorporated carbon species, which efficiently improve electronic conductivity. Meanwhile, the intrinsic crystal structure and enlarged contact area between electrode and electrolyte provide abundant channels for Li-ion transport. This work could not only make the prepared C-TiO2 a promising anode candidate, but also present an available strategy for developing other electrode materials.

  9. Photocatalysis and the origin of life: Synthesis of nucleoside bases from formamide on TiO2(001) single surfaces

    PubMed Central

    Senanayake, S. D.; Idriss, H.

    2006-01-01

    We report the conversion of a large fraction of formamide (NH2CHO) to high-molecular-weight compounds attributed to nucleoside bases on the surface of a TiO2 (001) single crystal in ultra-high vacuum conditions. If true, we present previously unreported evidence for making biologically relevant molecules from a C1 compound on any single crystal surface in high vacuum and in dry conditions. An UV light of 3.2 eV was necessary to make the reaction. This UV light excites the semiconductor surface but not directly the adsorbed formamide molecules or the reaction products. There thus is no need to use high energy in the form of photons or electrical discharge to make the carbon–carbon and carbon–nitrogen bonds necessary for life. Consequently, the reaction products may accumulate with time and may not be subject to decomposition by the excitation source. The formation of these molecules, by surface reaction of formamide, is proof that some minerals in the form of oxide semiconductors are active materials for making high-molecular-weight organic molecules that may have acted as precursors for biological compounds required for life in the universe. PMID:16423899

  10. Photocatalytic degradation of an azo dye Sunset Yellow under UV-A light using TiO2/CAC composite catalysts.

    PubMed

    Rajamanickam, D; Shanthi, M

    2014-07-15

    The photocatalytic activity and the promoting effect of titania (TiO2) by commercial activated carbon (CAC) for removing the pollutant in wastewater were investigated. The TiO2/CAC composite photocatalysts with various ratios of CAC to TiO2 were prepared by sol-gel method. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM), energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area measurement methods. The photocatalytic activity of TiO2/CAC was investigated for the degradation of Sunset Yellow (SY) in aqueous solution using UV-A light. The TiO2/CAC is found to be more efficient than prepared TiO2 and TiO2-P25 at pH 7 for the mineralization of SY. The synergism between TiO2 and CAC may increase the catalytic activity. The effects of operational parameters such as the amount of photocatalyst, dye concentration and initial pH on photo mineralization of SY have been analyzed. The mineralization of SY has been confirmed by COD measurements. The catalyst is found to be reusable. PMID:24662758

  11. Non-Band-Gap Photoexcitation of Hydroxylated TiO2

    PubMed Central

    2015-01-01

    The photochemistry of TiO2 has been studied intensively since it was discovered that TiO2 can act as a photocatalyst. Nevertheless, it has proven difficult to establish the detailed charge-transfer processes involved, partly because the excited states involved are difficult to study. Here we present evidence of the existence of hydroxyl-induced excited states in the conduction band region. Using two-photon photoemission, we show that stepwise photoexcitation from filled band gap states lying 0.8 eV below the Fermi level of rutile TiO2(110) excites hydroxyl-induced states 2.73 eV above the Fermi level that has an onset energy of ?3.1 eV. The onset is shifted to lower energy by the coadsorption of molecular water, which suggests a means of tuning the energy of the excited state. PMID:26267712

  12. TOF-SIMS study of photocatalytic decomposition reactions on nanocrystalline TiO 2 films

    NASA Astrophysics Data System (ADS)

    Gnaser, Hubert; Orendorz, Adam; Ziegler, Christiane; Rowlett, Elisabeth; Bock, Wolfgang

    2006-07-01

    Nanocrystalline TiO 2 is known to be a very efficient photocatalyst. In order to elucidate the details of reaction pathways occurring on the surface, nanocrystalline TiO 2 films (with 12 nm average crystallite size) were covered by methylene blue (MB) and studied, both in the pristine state and upon UV exposure, by TOF-SIMS. Distinct mass signals related to the MB parent molecule ( m = 284.1 amu) and from fragment ions are observed for the as-prepared samples. Upon irradiation with UV light under atmospheric conditions, the surface composition is pronouncedly changed, an observation ascribed to photocatalytic reactions induced by UV photons: the amount of the parent molecule is diminished whereas intermediate reaction products are identified to be present at the TiO 2 surfaces. Eventually, the parent molecule and the characteristic fragment species disappear completely upon extended exposure to UV light.

  13. Preparation and characterisation of TiO2 nanoparticle and titanate nanotube obtained from Ti-salt flocculated sludge with drinking water and seawater.

    PubMed

    Kim, J H; Okour, Y; Yang, H S; Kim, J B; Shon, H K

    2011-02-01

    This study aimed to prepare and characterise titanium dioxide (TiO2) nanoparticles and titanate nanotubes produced from Ti-sat flocculated sludge with drinking water (DW) and seawater (SW). The Ti-salt flocculated sludge from DW and SW was incinerated at 600 degrees C to produce TiO2 nanoparticles. XRD results showed that the anatase TiO2 structure was predominant for TiO2 from DW (TiO2-DW) and TiO2 from SW (TiO2-SW), which were mainly doped with carbon atoms. Titanate nanotubes (tiNT) were obtained when TiO2-DW and TiO2-SW were hydrothermally treated with NaOH solution. Structure phase, shape, crystallisation and photocatalytic activity of tiNT were affected by the incineration temperature and the amount of sodium present in different tiNT. The tiNT doped with thiourea incinerated at 600 degrees C presented anatase phase, showing a high increase of the degree of crystallisation with nanotube-like structures. The photocatalytic activity of these photocatalysts was evaluated using photooxidation of gaseous acetaldehyde. Thiourea doped tiNT-DW and tiNT-SW showed similar photocatalytic activity compared to commercially available TiO2-P25 under UV light and indicated a photocatalytic activity under visible light. PMID:21456256

  14. Fabrication of TiO2 Colloidal Crystal Films and Characterization of Their Photocatalytic Properties

    SciTech Connect

    Huang, Wei; Wang, Feng; Wang, Wei

    2011-01-01

    We have studied hydrolysis of organic alkyltitanate compounds and optimized reaction condition for synthesis of monodisperse titania (TiO2 colloidal particles with controlled size from nanometer to submicron. The synthesized TiO2 colloidal particles were further surface-modified with hydrophobic silane coupling agent. With the monodisperse hydrophobic particles, we fabricated TiO2 colloidal crystal thin films through transferring self-assembled colloidal crystal monolayer from water surface onto solid substrates. The TiO2 colloidal crystal films exhibit enhanced interaction with visible light. Consequently, in comparison with plain TiO2 particle thin film, the thin film with colloidal crystal structure shows enhanced photocatalytic activity, as evaluated through photodegradation of organic dye methyl orange in solution under simulated solar light.

  15. Effect of fluoride and water content on the growth of TiO2 nanotubes synthesized via ethylene glycol with voltage changes during anodizing process

    NASA Astrophysics Data System (ADS)

    Quiroz, Heiddy P.; Quintero, Francisco; Arias, Pedro J.; Dussan, A.; Zea, Hugo R.

    2015-07-01

    In this work, titanium foils were anodized in ethylene glycol solutions containing different amounts of water and fluoride to determine their effects on the top morphology and crystalline structure of the formed titania nanostructures. Anodizing was performed for 2 h by using titanium foils as both anode and cathode applying a squared-pulse voltage profile composed of one step at 80 V for 3 min followed by another at 20 V for 5 min; constant voltage conditions were also used to study the nanostructure formation on the surface. We found the formation of nanostructured titania on the surface of the anodized foil when small amounts of water and fluoride are present in the anodizing solution. The top of these nanostructures is irregular when no water is added, but is expected to change with different amounts of water and fluoride in the ranges of 1 - 9% and 0.05 - 0.5%, respectively. Synthesis parameters also change nanotube morphology. The morphology and structure properties of the samples were studied by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). Formation of TiO2 nanotubes by anodization method are strongly correlated to conditions like fluoride concentration and applied voltages. Tube length varying between 2 and 7 ?m, exhibiting different diameters and wall thicknesses were obtained. When an alternate voltage was applied, the wall of the nanotubes presented evenly spaced rings while nanotubes with smooth wall form were observed when constant voltage was applied. Reflection peaks corresponding to Brookite, Anatase, and Rutile of TiO2 phases were observed from XRD measurements. A correlation between the effects of synthesis parameters on nanotube formation and morphological properties is presented. TiO2 nanotubes prepared by electrochemical anodization have excellent performance in various applications such as photocatalysts, solar cells, gas sensors, and biomedical applications.

  16. Characterization of TiO2 and ZnO nanoparticles and their applications in photocatalytic degradation of azodyes.

    PubMed

    Gnanaprakasam, A; Sivakumar, V M; Sivayogavalli, P L; Thirumarimurugan, M

    2015-11-01

    TiO2 nanoparticles have been synthesized from the inorganic precursor Ti [OC3H7]4via sol-gel technique. Similarly, ZnO nanoparticles have also been synthesized from zinc sulfate precursor using precipitation method. The prepared nanoparticles was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques to study the morphology, structural configuration and its functionality. The average particle size for TiO2 and ZnO nanoparticles was 15.4nm and 17.9nm, respectively. The synthesized TiO2 and ZnO nanoparticles have been used for degradation of acid red 27 and coralene red F3BS dyes under the UV light. The regeneration of TiO2 photocatalyst was also tested. PMID:25937630

  17. Graphene-based hollow TiO2 composites with enhanced photocatalytic activity for removal of pollutants

    NASA Astrophysics Data System (ADS)

    Zhang, Lixin; Zhang, Jia; Jiu, Hongfang; Ni, Changhui; Zhang, Xia; Xu, Meiling

    2015-11-01

    Catalytically active graphene-based hollow TiO2 composites(TiO2/RGO) were successfully synthesized via the solvothermal method. Hollow TiO2 microspheres are uniformly dispersed on RGO. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) were used for the characterization of prepared photocatalysts. The mass of GO was optimized in the photocatalytic removal of rhodamine B (RhB) as a model dye pollutants. The results showed that graphene-based hollow TiO2 composites exhibit a significantly enhanced photocatalytic activity in degradation of RhB under either UV or visible light irradiation. The formation of the graphene-based hollow TiO2 composites and the photocatalytic mechanisms under UV and visible light were also discussed.

  18. Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

    PubMed

    Sharma, Ajit; Lee, Byeong-Kyu

    2016-01-01

    The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles. PMID:26386660

  19. TiO2 hollow spheres composed of highly crystalline nanocrystals exhibit superior lithium storage properties.

    PubMed

    Zhang, Genqiang; Wu, Hao Bin; Song, Taeseup; Paik, Ungyu; Lou, Xiong Wen David

    2014-11-10

    While the synthesis of TiO2 hollow structures is well-established, in most cases it is particularly difficult to control the crystallization of TiO2 in solution or by calcination. As a result, TiO2 hollow structures do not really exhibit enhanced lithium storage properties. Herein, we report a simple and cost-effective template-assisted method to synthesize anatase TiO2 hollow spheres composed of highly crystalline nanocrystals, in which carbonaceous (C)?spheres are chosen as the removable template. The release of gaseous species from the combustion of C?spheres may inhibit the growth of TiO2 crystallites so that instead small TiO2 nanocrystals are generated. The small size and high crystallinity of primary TiO2 nanoparticles and the high structural integrity of the hollow spheres gives rise to significant improvements in the cycling stability and rate performance of the TiO2 hollow spheres. PMID:25124735

  20. Photostability of wool fabrics coated with pure and modified TiO2 colloids.

    PubMed

    Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

    2015-02-15

    The surface of wool fabrics was coated with TiO2 and TiO2-based nanocomposite colloids and the impact of this coating on the photostability of wool was investigated. TiO2 along with TiO2/Metal and TiO2/Metal/SiO2 sols were synthesized through a low-temperature sol-gel method and applied to fabrics. Composite colloids were synthesized through integrating the silica and three noble metals of silver (Ag), gold (Au) and platinum (Pt) into the synthesis process of sols. Four different molar ratios of Metal to TiO2 (0.01%, 0.1%, 0.5% and 1%) were used to elucidate the role of metal type and amount on the obtained features. Photostability and UV protection features of fabrics were evaluated through measuring the photo-induced chemiluminescence (PICL), photoyellowing rate and ultraviolet protection factor (UPF) of fabrics. PICL and photoyellowing tests were carried out under UVA and UVC light sources, respectively. PICL profiles demonstrated that the presence of pure and modified TiO2 nanoparticles on fabrics reduced the intensity of PICL peak indicating a lower amount of polymer free radicals in coated wool, compared to that of pristine fabric. Moreover, a higher PICL peak intensity as well as photoyellowing rate was observed on fabrics coated with modified colloids in comparison with pure TiO2. The surface morphology of fabrics was further characterized using FESEM images. PMID:25460718

  1. Reprint of: photostability of wool fabrics coated with pure and modified TiO2 colloids.

    PubMed

    Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

    2015-06-01

    The surface of wool fabrics was coated with TiO2 and TiO2-based nanocomposite colloids and the impact of this coating on the photostability of wool was investigated. TiO2 along with TiO2/Metal and TiO2/Metal/SiO2 sols were synthesized through a low-temperature sol-gel method and applied to fabrics. Composite colloids were synthesized through integrating the silica and three noble metals of silver (Ag), gold (Au) and platinum (Pt) into the synthesis process of sols. Four different molar ratios of Metal to TiO2 (0.01%, 0.1%, 0.5% and 1%) were used to elucidate the role of metal type and amount on the obtained features. Photostability and UV protection features of fabrics were evaluated through measuring the photo-induced chemiluminescence (PICL), photoyellowing rate and ultraviolet protection factor (UPF) of fabrics. PICL and photoyellowing tests were carried out under UVA and UVC light sources, respectively. PICL profiles demonstrated that the presence of pure and modified TiO2 nanoparticles on fabrics reduced the intensity of PICL peak indicating a lower amount of polymer free radicals in coated wool, compared to that of pristine fabric. Moreover, a higher PICL peak intensity as well as photoyellowing rate was observed on fabrics coated with modified colloids in comparison with pure TiO2. The surface morphology of fabrics was further characterized using FESEM images. PMID:25746934

  2. TiO2 nanocomposites: Preparation, characterization, mechanical and biological properties

    NASA Astrophysics Data System (ADS)

    Ko?arsoy, Gözde; ?en, Elif Hilal; Aksöz, Nilüfer; ?de, Semra; Aksoy, Hüsnü

    2014-11-01

    Some novel nanocomposites, which contain different concentrations of TiO2 nanopowders, were firstly prepared by using marble dust with convenient chemical components. Their nano structures characterized and distributions of the nano-aggregations related with internal structural content of the samples have been determined by X-ray Scattering Methods (SAXS and WAXS) and mechanical properties were determined by using strain-stress measurements to increase their potential usage possibility as building materials in health and research centers. In the last and important part of the study, Candida albicans and Aspergillus niger which are a significant risk to medical patients were used to investigate originally prepared nanostructured samples' photocatalyst effect. During the last part of the study, effect of UV and visible light on photocatalyst nanocomposites were also researched. Heterogeneous photocatalysts can carry out advanced oxidation processes used for an antimicrobial effect on microorganisms. TiO2 nanoparticles as one of heterogeneous photocatalysts have been shown to exhibit strong cytotoxicity when exposed to UV and visible light.

  3. Tricrystalline TiO2 with enhanced photocatalytic activity and durability for removing volatile organic compounds from indoor air.

    PubMed

    Chen, Kunyang; Zhu, Lizhong; Yang, Kun

    2015-06-01

    It is important to develop efficient and economic techniques for removing volatile organic compounds (VOCs) in indoor air. Heterogeneous TiO2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline TiO2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3. The obtained samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline TiO2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline TiO2, due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline TiO2 prepared at RHNO3=0.8, containing 80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity, about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline TiO2 will enrich the chemistry of the TiO2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic. PMID:26040745

  4. Self-cleaning cotton functionalized with TiO2/SiO2: focus on the role of silica.

    PubMed

    Pakdel, Esfandiar; Daoud, Walid A

    2013-07-01

    This manuscript aims to investigate the functionalization of cotton fabrics with TiO2/SiO2. In this study, the sol-gel method was employed to prepare titania and silica sols and the functionalization was carried out using the dip-pad-dry-cure process. Titanium tetra isopropoxide (TTIP) and tetra ethyl orthosilicate (TEOS) were utilized as precursors of TiO2 and SiO2, respectively. TiO2/SiO2 composite sols were prepared in three different Ti:Si molar ratios of 1:0.43, 1:1, and 1:2.33. The self-cleaning property of cotton samples functionalized with TiO2/SiO2 was assessed based on the coffee stain removal capability and the decomposition rate of methylene blue under UV irradiation. FTIR study of the TiO2/SiO2 photocatalyst confirmed the existence of Si-O-Si and Ti-O-Si bonds. Scanning electron microscopy was employed to investigate the morphology of the functionalized cotton samples. The samples coated with TiO2/SiO2 showed greater ability of coffee stain removal and methylene blue degradation compared with samples functionalized with TiO2 demonstrating improved self-cleaning properties. The role of SiO2 in improving these properties is also discussed. PMID:23602671

  5. Solvothermal synthesis of Ce-doped tungsten oxide nanostructures as visible-light-driven photocatalysts.

    PubMed

    Chang, Xueting; Sun, Shibin; Zhou, Yun; Dong, Lihua; Yin, Yansheng

    2011-07-01

    Cerium (Ce)-doped tungsten oxide nanostructures have been generated by using a simple solvothermal method with cerium chloride salts and tungsten hexachloride as precursors. The as-synthesized samples were characterized by electron microscopy, x-ray diffraction and x-ray photoelectron spectrometry. The photocatalytic activities of the samples were evaluated by degradation of methyl orange in an aqueous solution under visible light irradiation. Results showed that the as-synthesized samples underwent morphological evolution with decreasing W/Ce molar ratio, from one-dimensional bundled nanowires through straighter, shorter and thicker bundled nanorods to two-dimensional bundled blocks, then to a mixture of bundled nanorods and agglomerated nanoparticles, and finally to particle agglomerates. The Ce-doped tungsten oxides exhibited better photocatalytic activities than that of the undoped tungsten oxide. The cerium-doped tungsten oxide bundled blocks synthesized with a W/Ce molar ratio of 15:1 possessed the most effective photocatalytic activity among the tested samples. These novel nanomaterials may find potential applications as visible-light-driven photocatalysts. PMID:21576793

  6. Solvothermal synthesis of Ce-doped tungsten oxide nanostructures as visible-light-driven photocatalysts

    NASA Astrophysics Data System (ADS)

    Chang, Xueting; Sun, Shibin; Zhou, Yun; Dong, Lihua; Yin, Yansheng

    2011-07-01

    Cerium (Ce)-doped tungsten oxide nanostructures have been generated by using a simple solvothermal method with cerium chloride salts and tungsten hexachloride as precursors. The as-synthesized samples were characterized by electron microscopy, x-ray diffraction and x-ray photoelectron spectrometry. The photocatalytic activities of the samples were evaluated by degradation of methyl orange in an aqueous solution under visible light irradiation. Results showed that the as-synthesized samples underwent morphological evolution with decreasing W/Ce molar ratio, from one-dimensional bundled nanowires through straighter, shorter and thicker bundled nanorods to two-dimensional bundled blocks, then to a mixture of bundled nanorods and agglomerated nanoparticles, and finally to particle agglomerates. The Ce-doped tungsten oxides exhibited better photocatalytic activities than that of the undoped tungsten oxide. The cerium-doped tungsten oxide bundled blocks synthesized with a W/Ce molar ratio of 15:1 possessed the most effective photocatalytic activity among the tested samples. These novel nanomaterials may find potential applications as visible-light-driven photocatalysts.

  7. Preparation and photocatalytic properties of nanometer-sized magnetic TiO2/SiO2/CoFe2O4 composites.

    PubMed

    Li, Hansheng; Zhang, Yaping; Wu, Qin; Wang, Xitao; Liu, Changhao

    2011-11-01

    Magnetic TiO2/SiO2/CoFe2O4 nanoparticles (TiO2/SCFs) were prepared by a sol-gel process in a reverse microemulsion combined with solvent-thermal technique. TiO2/SCFs were characterized by Fourier transform infrared spectrometry, thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Raman spectrometry, TEM, BET specific surface area measurement, and magnetic analysis. Structure analyses indicated that TiO2/SCFs presented a core-shell structure with TiO2 uniformly coating on SiO2/CoFe2O4 nanomagnets (SCFs) and typical ferromagnetic hysteresis. TiO2/SCFs showed larger specific surface area and better photocatalytic activities than TiO2 and TiO2/CoFe2O4 photocatalysts prepared by the same method. The doping interaction between TiO2 and CoFe2O4 reduced thanks to the inert SiO2 mesosphere. PMID:22413361

  8. In-situ aging microwave heating synthesis of LTA zeolite layer on mesoporous TiO2 coated porous alumina support

    NASA Astrophysics Data System (ADS)

    Baig, Mirza A.; Patel, Faheemuddin; Alhooshani, Khalid; Muraza, Oki; Wang, Evelyn N.; Laoui, Tahar

    2015-12-01

    LTA zeolite layer was successfully grown on a superhydrophilic mesoporous titania layer coated onto porous ?-alumina substrate. Mesoporous titania layer was formed as an intermediate bridge in the pore size variation between the macroporous ?-alumina support and micro-porous LTA zeolite layer. In-situ aging microwave heating synthesis method was utilized to deposit the LTA zeolite layer. Mesoporous titania layer was pre-treated with UV photons and this was observed to have played a major role in improving the surface hydrophilicity of the substrate leading to formation of increased number of Ti-OH groups on the surface. This increase in Ti-OH groups enhanced the interaction between the synthesis gel and the substrate leading to strong attachment of the amorphous gel on the substrate, thus enhancing coverage of the LTA zeolite layer to almost the entire surface of the 1-inch (25.4 mm) diameter membrane. LTA zeolite layer was developed via in-situ aged under microwave irradiation to study the effect of synthesis parameters such as in-situ aging time and synthesis time on the formation of the LTA zeolite layer. Optimized process parameters resulted in the formation of crack-free porous zeolite layer yielding a zeolite-titania-alumina multi-layer membrane with a gradient in porosity.

  9. Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans

    PubMed Central

    Yeniyol, Sinem; Mutlu, Ilven; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Ürgen, Mustafa; Karabuda, Zihni Cüneyt; Basegmez, Cansu; Ricci, John Lawrence

    2015-01-01

    Mixed-phase TiO2 nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The topology was assessed by White Light Optical Profiling (WLOP) in the Vertical Scanning Interferometer (VSI) mode. Representative height descriptive parameters of roughness Ra and Rz were calculated. The photocatalytic activity of the resulting TiO2 films was evaluated by the photodegradation of Rhodamine B (RhB) dye solution. The antibacterial ability of the photocatalyst was examined by??Aggregatibacter actinomycetemcomitans suspensions in a colony-forming assay. XRD showed that anatase/rutile mixed-phase TiO2 thin films were predominantly in anatase and rutile that were 54.6?wt% and 41.9?wt%, respectively. Craters (2–5?µm) and protruding hills (10–50?µm) on Ti substrates were produced after electrochemical anodization with higher Ra and Rz surface roughness values. Anatase/rutile mixed-phase TiO2 thin films showed 26% photocatalytic decolorization toward RhB dye solution. The number of colonizing bacteria on anatase/rutile mixed-phase TiO2 thin films was decreased significantly in vitro. The photocatalyst was effective against A. actinomycetemcomitans colonization. PMID:26576430

  10. Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans.

    PubMed

    Yeniyol, Sinem; Mutlu, Ilven; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Ürgen, Mustafa; Karabuda, Zihni Cüneyt; Basegmez, Cansu; Ricci, John Lawrence

    2015-01-01

    Mixed-phase TiO2 nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The topology was assessed by White Light Optical Profiling (WLOP) in the Vertical Scanning Interferometer (VSI) mode. Representative height descriptive parameters of roughness R a and R z were calculated. The photocatalytic activity of the resulting TiO2 films was evaluated by the photodegradation of Rhodamine B (RhB) dye solution. The antibacterial ability of the photocatalyst was examined by??Aggregatibacter actinomycetemcomitans suspensions in a colony-forming assay. XRD showed that anatase/rutile mixed-phase TiO2 thin films were predominantly in anatase and rutile that were 54.6?wt% and 41.9?wt%, respectively. Craters (2-5?µm) and protruding hills (10-50?µm) on Ti substrates were produced after electrochemical anodization with higher R a and R z surface roughness values. Anatase/rutile mixed-phase TiO2 thin films showed 26% photocatalytic decolorization toward RhB dye solution. The number of colonizing bacteria on anatase/rutile mixed-phase TiO2 thin films was decreased significantly in vitro. The photocatalyst was effective against A. actinomycetemcomitans colonization. PMID:26576430

  11. Enhanced TiO2 Photocatalytic Processing of Organic Wastes for Green Space Exploration

    NASA Technical Reports Server (NTRS)

    Udom, I.; Goswami, D. Y.; Ram, M. K.; Stefanakos, E. K.; Heep, A. F.; Kulis, M. J.; McNatt, J. S.; Jaworske, D. A.; Jones, C. A.

    2013-01-01

    The effect of transition metal co-catalysts on the photocatalytic properties of TiO2 was investigated. Ruthenium (Ru), palladium, platinum, copper, silver, and gold, were loaded onto TiO2 powders (anatase and mixed-phase P25) and screened for the decomposition of rhodamine B (RhB) under broad-band irradiation. The morphology and estimated chemical composition of photocatalysts were determined by scanning electron microscopy and energy dispersive spectroscopy, respectively. Brunhauer, Emmett and Teller (BET) analysis measured mass-specific surface area(s). X-ray diffraction analysis was performed to confirm the identity of titania phase(s) present. The BET surface area of anatase TiO2/Ru 1% (9.2 sq m/gm) was one of the highest measured of all photocatalysts prepared in our laboratory. Photolyses conducted under air-saturated and nitrogen-saturated conditions revealed photodegradation efficiencies of 85 and 2 percent, respectively, after 60 min compared to 58 percent with no catalyst. The cause of low photocatalytic activity under an inert atmosphere is discussed. TiO2/Ru 1% showed a superior photocatalytic activity relative to P25-TiO2 under broad-band irradiation. A potential deployment of photocatalytic technologies on a mission could be a reactor with modest enhancement in solar intensity brought about by a trough-style reactor, with reactants and catalyst flowing along the axis of the trough and therefore being illuminated for a controlled duration based on the flow rate.

  12. Photocatalytic comparison of Cu- and Ag-doped TiO2/GF for bioaerosol disinfection under visible light

    NASA Astrophysics Data System (ADS)

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2015-12-01

    Photocatalysts, TiO2/glass fiber (TiO2/GF), Cu-doped TiO2/glass fiber (Cu-TiO2/GF) and Ag-doped TiO2/glass fiber (Ag-TiO2/GF), were synthesized by a sol-gel method. They were then used to disinfect Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in bioaerosols under visible light irradiation. TiO2/GF did not show any significant disinfection effect. Both Cu and Ag acted as intermediate agents to enhance separation efficiency of electron-hole pairs of TiO2, leading to improved photocatalytic activity of Cu-TiO2/GF and Ag-TiO2/GF under visible light. Cu in Cu-TiO2/GF acted as a defective agent, increasing the internal quantum efficiency of TiO2, while Ag in Ag-TiO2/GF acted as a sensitive agent, enhancing the transfer efficiency of the electrons generated. The highest disinfection efficiencies of E. coli and S. aureus by Cu-TiO2/GF were 84.85% and 65.21%, respectively. The highest disinfection efficiencies of E. coli and S. aureus by Ag-TiO2/GF were 94.46% and 73.12%, respectively. Among three humidity conditions - 40±5% (dry), 60±5% (moderate), and 80±5% (humid) - the moderate humidity condition showed the highest disinfection efficiency for both E. coli and S. aureus. This study also showed that a Gram-negative bacterium (E. coli) were more readily disinfected by the photocatalysts than a Gram-positive bacterium (S. aureus).

  13. Photocatalytic performance of TiO2 catalysts modified by H3PW12O40, ZrO2 and CeO2.

    PubMed

    Cai, Tiejun; Liao, Yuchao; Peng, Zhenshan; Long, Yunfei; Wei, Zongyuan; Deng, Qian

    2009-01-01

    The binary composite photo-catalysts CeO2/TiO2, ZrO2/TiO2 and the ternary composite photo-catalysts H3PW12O40-CeO2/TiO2, H3PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalytic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas flow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystallization process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 also enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than un-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s(-1) over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law. PMID:19862969

  14. TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

    NASA Astrophysics Data System (ADS)

    Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

    2014-07-01

    A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

  15. Tailored Synthesis of Porous TiO2 Nanocubes and Nanoparallelepipeds with Exposed {111} Facets and Mesoscopic Void Space: A Superior Candidate for Efficient Dye-Sensitized Solar Cells.

    PubMed

    Amoli, Vipin; Bhat, Shekha; Maurya, Abhayankar; Banerjee, Biplab; Bhaumik, Asim; Sinha, Anil Kumar

    2015-12-01

    Anatase TiO2 nanocubes and nanoparallelepipeds, with highly reactive {111} facets exposed, were developed for the first time through a modified one pot hydrothermal method, through the hydrolysis of tetrabutyltitanate in the presence of oleylamine as the morphology-controlling capping-agent and using ammonia/hydrofluoric acid for stabilizing the {111} faceted surfaces. These nanocubes/nanoparallelepipeds were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and high angle annular dark-field scanning TEM (HAADF-STEM). Accordingly, a possible growth mechanism for the nanostructures is elucidated. The morphology, surface area and the pore size distribution of the TiO2 nanostructures can be tuned simply by altering the HF and ammonia dosage in the precursor solution. More importantly, optimization of the reaction system leads to the assembly of highly crystalline, high surface area, {111} faceted anatase TiO2 nanocubes/nanoparallelepipeds to form uniform mesoscopic void space. We report the development of a novel double layered photoanode for dye sensitized solar cells (DSSCs) made of highly crystalline, self-assembled faceted TiO2 nanocrystals as upper layer and commercial titania nanoparticles paste as under layer. The bilayered DSSC made from TiO2 nanostructures with exposed {111} facets as upper layer shows a much higher power conversion efficiency (9.60%), than DSSCs fabricated with commercial (P25) titania powder (4.67%) or with anatase TiO2 nanostructures having exposed {101} facets (7.59%) as the upper layer. The improved performance in bilayered DSSC made from TiO2 nanostructures with exposed {111} facets as the upper layer is attributed to high dye adsorption and fast electron transport dynamics owing to the unique structural features of the {111} facets in TiO2. Electrochemical impedance spectroscopy (EIS) measurements conducted on the cells supported these conclusions, which showed that the bilayered DSSC made from TiO2 nanostructures with exposed {111} facets as the upper layer possessed lower charge transfer resistance, higher electron recombination resistance, longer electron lifetime and higher collector efficiency characteristics, compared to DSSCs fabricated with commercial (P25) titania powder or with anatase TiO2 nanostructures having exposed {101} facets as the upper layer. PMID:26574644

  16. Photocatalytic activity of multielement doped TiO 2 in the degradation of congo red

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, R.; Kalaivani, S.; Amala Infant Joice, J.; Sivakumar, T.

    2012-01-01

    TiO2 although considered a promising photocatalyst for the degradation of aqueous pollutants, it suffers from poor absorption in the visible region and hence requires ultraviolet (UV) light for activation. To make TiO2 a visible active photocatalyst, multielement (C, N, B, and F) doping has been done. The synthesised CNBF/TiO2 catalysts were calcined at different temperatures and characterized by XRD, BET surface area, UV DRS, XPS, HRSEM-EDAX, and TEM techniques. These catalysts found to show less band gap values when compared to bare TiO2. These catalysts were tested for their catalytic activity towards the degradation of a textile dye - congo red (CR) under different reaction conditions. It was found that the photocatalytic activity was dependent on both doping of multielement and the calcination temperature of CNBF/TiO2. The co-doped catalysts which were calcined at 400 °C and 600 °C (100% intensity in anatase phase) were found to be the best catalysts (100% decolourisation of CR in 21/2 h and 2 h respectively). TOC analysis carried out for the samples at the reaction time of 5 h showed very high percentage (83%) degradation of CR over CNBF/TiO2 catalysts calcined at 600 °C when compared to the other catalysts calcined at different temperatures. CNBF/TiO2 (1000 °C) showed very less photocatalytic activity due to the formation of rutile phase.

  17. TiO2-graphene oxide nanocomposite as advanced photocatalytic materials

    PubMed Central

    2013-01-01

    Background Graphene oxide composites with photocatalysts may exhibit better properties than pure photocatalysts via improvement of their textural and electronic properties. Results TiO2-Graphene Oxide (TiO2 - GO) nanocomposite was prepared by thermal hydrolysis of suspension with graphene oxide (GO) nanosheets and titania peroxo-complex. The characterization of graphene oxide nanosheets was provided by using an atomic force microscope and Raman spectroscopy. The prepared nanocomposites samples were characterized by Brunauer–Emmett–Teller surface area and Barrett–Joiner–Halenda porosity, X-ray Diffraction, Infrared Spectroscopy, Raman Spectroscopy and Transmission Electron Microscopy. UV/VIS diffuse reflectance spectroscopy was employed to estimate band-gap energies. From the TiO2 - GO samples, a 300??m thin layer on a piece of glass 10×15 cm was created. The photocatalytic activity of the prepared layers was assessed from the kinetics of the photocatalytic degradation of butane in the gas phase. Conclusions The best photocatalytic activity under UV was observed for sample denoted TiGO_100 (k?=?0.03012?h-1), while sample labeled TiGO_075 (k?=?0.00774?h-1) demonstrated the best activity under visible light. PMID:23445868

  18. Enhanced photocatalytic activity of TiO2-C hybrid aerogels for methylene blue degradation

    NASA Astrophysics Data System (ADS)

    Shao, Xia; Lu, Wencong; Zhang, Rui; Pan, Feng

    2013-10-01

    Carbon-based TiO2 composites have many advantages as photocatalysts. However, they suffer from low light efficiency due to the low contrast of TiO2 with carbon. We synthesized a novel type of anatase-type TiO2-C hybrid aerogel by a one-pot sol-gel method, which shows a photocatalytic activity for methylene degradation up to 4.23 times that of P25, a commercial photocatalyst from Degussa Inc. The hybrid aerogels are prepared from TiCl4 and resorcinol-furfural, and have a tunable macropore size from 167 to 996 nm. They are formed of submicrometer particles that consist of interwoven anatase and carbon nanoparticles. The anatase nanoparticles have a size of 8-9 nm and a tunable oxygen vacancy from 7.2 to 18.0%. The extremely high activity is ascribed to the large light absorption caused by macropore scattering and oxygen vacancies in the anatase. These findings may open up a new avenue and stimulate further research to improve photocatalytic performance.

  19. A novel drug delivery of 5-fluorouracil device based on TiO2/ZnS nanotubes.

    PubMed

    Faria, Henrique Antonio Mendonça; de Queiroz, Alvaro Antonio Alencar

    2015-11-01

    The structural and electronic properties of titanium oxide nanotubes (TiO2) have attracted considerable attention for the development of therapeutic devices and imaging probes for nanomedicine. However, the fluorescence response of TiO2 has typically been within ultraviolet spectrum. In this study, the surface modification of TiO2 nanotubes with ZnS quantum dots was found to produce a red shift in the ultra violet emission band. The TiO2 nanotubes used in this work were obtained by sol-gel template synthesis. The ZnS quantum dots were deposited onto TiO2 nanotube surface by a micelle-template inducing reaction. The structure and morphology of the resulting hybrid TiO2/ZnS nanotubes were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. According to the results of fluorescence spectroscopy, pure TiO2 nanotubes exhibited a high emission at 380nm (3.26eV), whereas TiO2/ZnS exhibited an emission at 410nm (3.02eV). The TiO2/ZnS nanotubes demonstrated good bio-imaging ability on sycamore cultured plant cells. The biocompatibility against mammalian cells (Chinese Hamster Ovarian Cells-CHO) suggesting that TiO2/ZnS may also have suitable optical properties for use as biological markers in diagnostic medicine. The drug release characteristic of TiO2/ZnS nanotubes was explored using 5-fluorouracil (5-FU), an anticancer drug used in photodynamic therapy. The results show that the TiO2/ZnS nanotubes are a promising candidate for anticancer drug delivery systems. PMID:26249588

  20. LC/MS/MS structure elucidation of reaction intermediates formed during the TiO2 photocatalysis of microcystin-LR

    EPA Science Inventory

    Microcystin-LR (MC-LR), a cyanotoxin and emerging drinking water contaminant, was treated with TiO(2) photocatalysts immobilized on stainless steel plates as an alternative to nanoparticles in slurry. The reaction intermediates of MC-LR were identified with mass spectrometry (MS)...

  1. A novel magnetically separable TiO2/CoFe2O4 nanofiber with high photocatalytic activity under UVvis light

    E-print Network

    Gong, Jian Ru

    ,5]. The electrospinning technology has been recognized as an effective, versatile and mature method for the production electrospinning technology. In order to reclaim TiO2 photocatalysts effectively, we proposed a simple process combined with sol­gel method and electrospinning technology for fabricating magnetic photocatalytic

  2. Visible-Light-Sensitive Photocatalysts: Nanocluster-Grafted Titanium Dioxide for Indoor Environmental Remediation.

    PubMed

    Miyauchi, Masahiro; Irie, Hiroshi; Liu, Min; Qiu, Xiaoqing; Yu, Huogen; Sunada, Kayano; Hashimoto, Kazuhito

    2016-01-01

    Photocatalytic degradation of organic compounds requires photoexcited holes with strong oxidative power in the valence band (VB) of semiconductors. Although numerous types of doped semiconductors, such as nitrogen-doped TiO2, have been studied as visible-light-sensitive photocatalysts, the quantum yields of these materials were very low because of the limited oxidation power of holes in the nitrogen level above the VB. Recently, we developed visible-light-sensitive Cu(II) and Fe(III) nanocluster-grafted TiO2 using a facile impregnation method and demonstrated that visible-light absorption occurs at the interface between the nanoclusters and TiO2, as electrons in the VB of TiO2 are excited to the nanoclusters under visible-light irradiation. In addition, photogenerated holes in the VB of TiO2 efficiently oxidize organic contaminants, and the excited electrons that accumulate in nanoclusters facilitate the multielectron reduction of oxygen. Notably, Cu(II) and Fe(III) nanocluster-grafted TiO2 photocatalyst has the highest quantum yield among reported photocatalysts and has antiviral, self-cleaning, and air purification properties under illumination by indoor light fixtures equipped with white fluorescent bulbs or white light-emitting diodes. PMID:26654353

  3. Electron microscopy of Mg/TiO2 photocatalyst morphology for deep desulfurization of diesel

    NASA Astrophysics Data System (ADS)

    Yin, Yee Cia; Kait, Chong Fai; Fatimah, Hayyiratul; Wilfred, Cecilia

    2015-07-01

    A series of Mg/TiO2 photocatalysts were prepared and characterized using Field Emission Scanning Electron Microscopy (FESEM) and High-Resolution Transmission Electron Microscopy (HRTEM). The average particle sizes of the photocatalysts were ranging from 25.7 to 35.8 nm. Incorporation of Mg on TiO2 did not lead to any surface lattice distortion to TiO2. HRTEM data indicated the presence of MgO and Mg(OH)2 mixture at low Mg loading while at higher Mg loading, the presence of lamellar Mg-oxyhydroxide intermediates and Mg(OH)2.

  4. Facile aqueous synthesis of ?-AgI nanoplates as efficient visible-light-responsive photocatalyst.

    PubMed

    Jiang, Wen; An, Changhua; Liu, Junxue; Wang, Shutao; Zhao, Lianming; Guo, Wenyue; Liu, Jinxiang

    2014-01-01

    Owing to far-ranging industrial applications and theoretical researches, tailored synthesis of well-defined nanocrystals has attracted substantial research interest. Herein, ?-AgI nanoplates have been synthesized through a facile polyvinylpyrrolidone (PVP)-assisted-aqueous-solution (PAAS) method under mild conditions. The parametric studies on the effect of ratio of reactants, solvents and surfactants were performed, revealing that a molar ratio of I(-) to Ag(+) of 1.2 in deionized water and the presence of appropriate PVP as stabilizing agent can stimulate the preferred orientation growth of AgI nanoplates. The as-synthesized AgI nanoplates exhibit excellent photocatalytic activity and enhanced durability towards the degradation of organics, i.e., rhodamine B (RhB), under visible light illumination in comparison with corresponding bulk nanoparticles. A possible photocatalytic reaction mechanism was discussed, revealing O2?(-) and h(+) are main reactive species and free ?OH radicals in solution also contribute to the degradation reaction. The superior photocatalytic performance renders the as-achieved AgI nanoplates promising candidates for applications in the fields of environmental purification or water disinfection. The present work opens an avenue to the synthesis of other shaped silver halide nanophotocatalysts. PMID:24101116

  5. Noble-metal-free plasmonic photocatalyst: hydrogen doped semiconductors

    PubMed Central

    Ma, Xiangchao; Dai, Ying; Yu, Lin; Huang, Baibiao

    2014-01-01

    The unique capacity of localized surface plasmon resonance (LSPR) offers a new opportunity to overcome the limited efficiency of semiconductor photocatalyst. Here we unravel that LSPR, which usually occurs in noble metal nanoparticles, can be realized by hydrogen doping in noble-metal-free semiconductor using TiO2 as a model photocatalyst. Moreover, its LSPR is located in infrared region, which supplements that of noble metal whose LSPR is generally in the visible region, making it possible to extend the light response of photocatalyst to infrared region. The near field enhancement is shown to be comparable with that of noble-metal nanoparticles, indicating that highly enhanced light absorption rate can be expected. The present work can provide a key guideline for the creation of highly efficient noble-metal-free plasmonic photocatalysts and have a much wider impact in infrared bioimaging and spectroscopy where infrared LSPR is essential. PMID:24496400

  6. High-surface-area mesoporous TiO2 microspheres via one-step nanoparticle self-assembly for enhanced lithium-ion storage

    NASA Astrophysics Data System (ADS)

    Wang, Hsin-Yi; Chen, Jiazang; Hy, Sunny; Yu, Linghui; Xu, Zhichuan; Liu, Bin

    2014-11-01

    Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m2 g-1 were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity.Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m2 g-1 were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04729j

  7. Fabrication of In2S3 nanoparticle decorated TiO2 nanotube arrays by successive ionic layer adsorption and reaction technique and their photocatalytic application.

    PubMed

    Zhang, Zhenrong; Tang, Yanhong; Liu, Chengbin; Wan, Long

    2014-06-01

    In2S3 nanoparticle (NP) decorated self-organized TiO2 nanotube array (In2S3/TiO2 NT) hybrids were fabricated via simple successive ionic layer adsorption and reaction (SILAR) technique. The In2S3 NPs in a size of about 15 nm were found to deposit on the top surface of the highly oriented TiO2 NT while without clogging the tube entrances. The loading amount of In2S3 NPs on the TiO2 NT was controlled by the cycle number of SILAR deposition. Compared with the bare TiO2 NT, the In2S3/TiO2 NT hybrids showed stronger absorption in the visible light region and significantly enhanced photocurrent density. The photocatalytic activity of the In2S3/TiO2 NT photocatalyst far exceeds that of bare TiO2 NT in the degradation of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) under simulated solar light. After 160-min irradiation, almost 100% 2,4-D removal is obtained on the 7-In2S3/TiO2 NT prepared through seven SILAR deposition cycles, much higher than 26% on the bare TiO2 NT. After 10 successive cycles of photocatalytic process with total 1,600 min of irradiation, In2S3/TiO2 NT maintained as high 2,4-D removal efficiency as 95.1% with good stability and easy recovery, which justifies the potential of the photocatalytic system in application for the photocatalytic removal of organic pollutants such as herbicides or pesticides from water. PMID:24738366

  8. Novel adsorption and photocatalytic oxidation for removal of gaseous toluene by V-doped TiO2/PU under visible light.

    PubMed

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2015-12-30

    In this study, V was used as a dopant to defect into the TiO2 lattice, leading to formation of Ti(3+) and V(4+) in the lattice. The presence of Ti(3+) and V(4+) introduced into the TiO2 lattice increased the electron-hole pair generation capacity and electron-hole pair separation efficiency of the TiO2, leading to enhancement of the photocatalytic activity of the photocatalyst. Porous polyurethane (PU) was used to immobilize the V-doped TiO2 by creating chemical bonds. The use of porous substrate contributed to the increased adsorption ability of the enhanced photocatalyst, as well as expanded its application for the removal of toluene from aerosols. Under dark conditions, the V-TiO2/PU only exhibited adsorption ability for toluene treatment in aerosol. Under visible light conditions, the V-TiO2/PU exhibited high photocatalytic oxidation ability for the removal of toluene in aerosol. The photocatalytic oxidation ability was found to depend on the V to TiO2 ratio. The optimal V content in V/TiO2 for enhancing the photocatalytic activity of TiO2 was determined to be 6wt%. Even under visible light irradiation, the 6% V-TiO2/PU sample could photocatalytically remove 80% of the toluene in 200-ppmV inlet gas, while 89.3% of the removed amount was mineralized into CO2 and H2O. PMID:26247377

  9. Cu doped TiO2/GF for photocatalytic disinfection of Escherichia coli in bioaerosols under visible light irradiation: Application and mechanism

    NASA Astrophysics Data System (ADS)

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-03-01

    This study investigated the role of Cu as a doping agent to enhance photocatalytic activity of TiO2 in Cu-doped TiO2/glass fibers (Cu-TiO2/GF) used for disinfection of Escherichia coli (E. coli) in aerosols under visible light irradiation. Glass fiber was used as a substrate to immobilize TiO2 for disinfection of E. coli in bioaerosols. Cu in the prepared photocatalyst acted as an intermediate agent for the transfer of photo-generated electrons from the valence band to the conduction band of TiO2. Cu dopants increased the electron-hole pair separation efficiency, inhibited their recombination leading to a lifetime increase of the generated electrons, and thus improved photocatalytic activity even under visible light irradiation. Cu also defected the TiO2 lattice by producing Ti3+ ions, which can increase the electron-hole separation capacity of the photocatalyst, thereby increasing photocatalytic capacity. The optimal Cu content in Cu/TiO2 to enhance the photocatalytic activity of TiO2 was 5 wt.%. Among three humidity conditions (dry (40 ± 5%), moderate (60 ± 5%) and humid (80 ± 5%)), the moderate condition showed the highest disinfection efficiency of E. coli. When the 5% Cu-TiO2/GF was used under a moderate level of humidity, the highest disinfection efficiency and disinfection capacity of E. coli were identified as 87.8% and 23 CFU/s cm2, respectively.

  10. Phthalocyanine/chitosan-TiO2 photocatalysts: Characterization and photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Hamdi, A.; Boufi, S.; Bouattour, S.

    2015-06-01

    Chitosan (CS) was used as a template to prepare a hybrid chitosan-phthalocyanine-TiO2 (PC/CS-TiO2) photocatalyst at room temperature without any calcination treatment. The as-prepared hybrid photocatalyst (PC/CS-TiO2) was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-vis diffuse reflectance spectroscopy (DRS). The results of the photodegradation of aniline, used as a model pollutant, revealed that the hybrid photocatalyst (PC/CS-TiO2) exhibited a photocatalytic activity under visible-light irradiation. The enhanced activity of the hybrid catalyst is attributed to the cooperative role of the three components of the photocatalyst; chitosan as a template for the immobilization crystalline TiO2 nanoparticles, phthalocyanine that promote the light absorption in the visible range and TiO2 acting as an acceptor of electrons generated by the photons absorption to produce superoxide radicals.

  11. Photoassisted and photocatalytic degradation of sulfur mustard using TiO2 nanoparticles and polyoxometalates.

    PubMed

    Naseri, Mohammad Taghi; Sarabadani, Mansour; Ashrafi, Davood; Saeidian, Hamdollah; Babri, Mehran

    2013-02-01

    The decomposition of highly toxic chemical warfare agent, sulfur mustard (bis(2-chloroethyl) sulfide or HD), has been studied by homogeneous photolysis and heterogeneous photocatalytic degradation on titania nanoparticles. Direct photolysis degradation of HD with irradiation system was investigated. The photocatalytic degradation of HD was investigated in the presence of TiO(2) nanoparticles and polyoxometalates embedded in titania nanoparticles in liquid phase at room temperature (33 ± 2 °C). Degradation products during the treatment were identified by gas chromatography-mass spectrometry. Whereas apparent first-order kinetics of ultraviolet (UV) photolysis were slow (0.0091 min(-1)), the highest degradation rate is obtained in the presence of TiO(2) nanoparticles as nanophotocatalyst. Simultaneous photolysis and photocatalysis under the full UV radiation leads to HD complete destruction in 3 h. No degradation products observed in the presence of nanophotocatalyst without irradiation in 3 h. It was found that up to 90 % of agent was decomposed under of UV irradiation without TiO(2), in 6 h. The decontamination mechanisms are often quite complex and multiple mechanisms can be operable such as hydrolysis, oxidation, and elimination. By simultaneously carrying out photolysis and photocatalysis in hexane, we have succeeded in achieving faster HD decontamination after 90 min with low catalyst loading. TiO(2) nanoparticles proved to be a superior photocatalyst under UV irradiation for HD decontamination. PMID:22707206

  12. Efficient photocatalytic degradation of gaseous acetaldehyde by highly ordered TiO2 nanotube arrays.

    PubMed

    Liu, Zhaoyue; Zhang, Xintong; Nishimoto, Shunsuke; Murakami, Taketoshi; Fujishima, Akira

    2008-11-15

    Highly ordered TiO2 nanotube array prepared by electrochemical anodization generates considerable interest as a practical air purifier, since a nanotube array can form a TiO2 film with a porous surface and straight gas diffusion channel, simultaneously reserving enough geometric thickness. Here, we reported on the application of highly ordered TiO2 nanotube arrays with different lengths for degradation of gaseous acetaldehyde pollutants in air. The results showed that increasing the lengths of nanotube arrays within a certain range could significantly improve the degradation rate of acetaldehyde molecules. The main product of acetaldehyde degradation was detected to be CO2, which indicated that the mineralization of acetaldehyde molecules was the major process in this photocatalytic reaction. When compared with a P25 TiO2 nanoparticulate film with similar thickness and geometric area, in the initial degradation of acetaldehyde, the nanotube array did not show obvious superiority. However, in the subsequent degradation, the nanotube array demonstrated an enhanced photocatalytic activity. It was suggested that this enhancement resulted from the special infrastructure of the nanotube array, which was favorable for the diffusion of intermediates and the reduced deactivation of photocatalyst in the photocatalytic reaction. PMID:19068846

  13. Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst.

    PubMed

    Zavahir, Sifani; Zhu, Huaiyong

    2015-01-01

    Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase)-silicate under visible light irradiation of ? > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds. PMID:25629455

  14. Photocatalytic Degradation of DIPA Using Bimetallic Cu-Ni/TiO2 Photocatalyst under Visible Light Irradiation

    PubMed Central

    Bustam, Mohamad Azmi; Chong, Fai Kait; Man, Zakaria B.; Khan, Muhammad Saqib; Shariff, Azmi M.

    2014-01-01

    Bimetallic Cu-Ni/TiO2 photocatalysts were synthesized using wet impregnation (WI) method with TiO2 (Degussa-P25) as support and calcined at different temperatures (180, 200, and 300°C) for the photodegradation of DIPA under visible light. The photocatalysts were characterized using TGA, FESEM, UV-Vis diffuse reflectance spectroscopy, fourier transform infrared spectroscopy (FTIR) and temperature programmed reduction (TPR). The results from the photodegradation experiments revealed that the Cu-Ni/TiO2 photocatalysts exhibited much higher photocatalytic activities compared to bare TiO2. It was found that photocatalyst calcined at 200°C had the highest photocatalyst activities with highest chemical oxygen demand (COD) removal (86.82%). According to the structural and surface analysis, the enhanced photocatalytic activity could be attributed to its strong absorption into the visible region and high metal dispersion. PMID:25105158

  15. Photocatalytic degradation of DIPA using bimetallic Cu-Ni/TiO2 photocatalyst under visible light irradiation.

    PubMed

    Riaz, Nadia; Bustam, Mohamad Azmi; Chong, Fai Kait; Man, Zakaria B; Khan, Muhammad Saqib; Shariff, Azmi M

    2014-01-01

    Bimetallic Cu-Ni/TiO2 photocatalysts were synthesized using wet impregnation (WI) method with TiO2 (Degussa-P25) as support and calcined at different temperatures (180, 200, and 300°C) for the photodegradation of DIPA under visible light. The photocatalysts were characterized using TGA, FESEM, UV-Vis diffuse reflectance spectroscopy, fourier transform infrared spectroscopy (FTIR) and temperature programmed reduction (TPR). The results from the photodegradation experiments revealed that the Cu-Ni/TiO2 photocatalysts exhibited much higher photocatalytic activities compared to bare TiO2. It was found that photocatalyst calcined at 200°C had the highest photocatalyst activities with highest chemical oxygen demand (COD) removal (86.82%). According to the structural and surface analysis, the enhanced photocatalytic activity could be attributed to its strong absorption into the visible region and high metal dispersion. PMID:25105158

  16. Electron Energy Loss Spectroscopy Analysis of the Photocatalytic Activity of TiO2 Nanoparticles in Polymer Film

    NASA Astrophysics Data System (ADS)

    Pugachevskii, M. A.; Karpovich, N. F.

    2015-09-01

    Photocatalytic decomposition of a polymer film with TiO2 nanoparticles of different sizes and morphologies was investigated using transmission electron microscopy. Electron energy loss spectroscopy found that UV irradiation of the polymer-film-TiO2-nanoparticle composite decreased the carbon content in the polymer film. It was shown that this method could be used to study the activity of photocatalysts for decomposing organic matter.

  17. Photonic, and photocatalytic behavior of TiO2 mediated by Fe, CO, Ni, N doping and co-doping

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Zhao, Y. F.; Wang, T.; Li, H.; Li, C.

    2015-12-01

    Fe, Co, Ni, or N addition could modulate the photonic and catalytic responses of TiO2 for photocatalysts applications. Their morphologies, structures, compositions and photocatalytic performance in the degradation of methylene blue were characterized by scanning electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy, Raman spectra and X-ray photoelectron spectroscopy. The results showed that dopants affect the electronic transition energies by changing the optical band gap and the impurity absorption peaks of the specimens. Especially, co-doping enhances the visible-light photocatalytic activity of TiO2 by 4-10 times that of pure TiO2, and the Co and N co-doping derives 10-fold photocatalytic activity.

  18. Examination of interfacial charge transfer in photocatalysis using patterned CuO thin film deposited on TiO2

    NASA Astrophysics Data System (ADS)

    Osako, K.; Matsuzaki, K.; Hosono, H.; Yin, G.; Atarashi, D.; Sakai, E.; Susaki, T.; Miyauchi, M.

    2015-10-01

    We examined the interfacial charge transfer effect on photocatalysts using a patterned CuO thin film deposited on a rutile TiO2 (110) substrate. Photocatalytic activity was visualized based on the formation of metal Ag particles resulting from the photoreduction of Ag+ ions under visible-light illumination. Ag particles were selectively deposited near the edge of CuO film for several nanometer thick CuO film, indicating that interfacial excitation from the valence band maximum of TiO2 to the conduction band minimum of CuO plays a key role in efficient photocatalytic activity of CuO nanocluster-grafted TiO2 systems with visible-light sensitivity.

  19. Plasmon enhanced visible light photocatalysis for TiO2 supported Pd nanoparticles.

    PubMed

    Lacerda, A M; Larrosa, I; Dunn, S

    2015-08-01

    A photocatalyst consisting of nanostructured Pd photochemically deposited on 20 nm TiO2 displays a reaction half-life for rhodamine b decolourisation of 0.5 minute compared to the 9.4 minutes for unmodified P25 under identical reaction conditions. We associate this increased decolourisation rate to the increase in solar light harvesting which we have measured at 8% due to a significant red shift in the absorption profile of the catalyst. We relate the increased absorption of light with a visible active plasmon effect that is associated with the Pd nanostructures on the TiO2. This overall red-shift in the light harvesting for the catalyst leads to photocatalytic activity for excitations up to 600 nm. PMID:26149082

  20. Single-molecule, single-particle fluorescence imaging of TiO2-based photocatalytic reactions.

    PubMed

    Tachikawa, Takashi; Majima, Tetsuro

    2010-12-01

    Nanostructured metal oxide semiconductors, such as TiO(2) and ZnO, have attracted great attention as the promising material for photovoltaic devices, photocatalysts for water splitting and environmental purification, sensors, batteries, etc. In this critical review, we have focused on the on-site observation of interfacial chemical reactions involving charge carriers and reactive oxygen species (ROS), such as singlet oxygen and the hydroxyl radical, generated by the photoexcitation of TiO(2) nanoparticles using single-molecule, single-particle fluorescence spectroscopy. Advanced fluorescence imaging techniques enable us to determine the location of the photocatalytically active sites that are closely related to the defects heterogeneously distributed on the surface. Consequently, this review provides a great opportunity to understand the temporal and spatial heterogeneities within an individual catalyst particle, allowing for the potential use of single-molecule, single-particle approaches in the analysis of photocatalytic reactions (189 references). PMID:20824247

  1. Ni/Ti layered double hydroxide: synthesis, characterization and application as a photocatalyst for visible light degradation of aqueous methylene blue.

    PubMed

    Roy Chowdhury, Priyadarshi; Bhattacharyya, Krishna G

    2015-04-21

    Visible light responsive 2?:?1 Ni/Ti layered double hydroxide (LDH) was synthesized by a single step hydrothermal route using commercially available Ni(NO3)2·6H2O, TiCl4 and urea. The material exhibited significant absorption in the visible range with a very narrow band gap (2.68 eV). This could be attributed to structural defects as confirmed by diffuse reflectance spectroscopy (DRS), photoluminescence (PL), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. FT-IR, TGA, DTA, DSC, HR-TEM and SEM-EDX measurements yielded information about structural aspects, thermal stability and surface morphology. Surface and pore characteristics of the material were obtained from the BET isotherm for N2 adsorption at 77 K. Zeta potential measurements were used to characterize the electrical properties of the surface while XPS revealed changes in surface states and oxygen deficiencies. The material was found to be an excellent photocatalyst for the degradation of aqueous methylene blue in visible light. The photocatalytic properties of the material were explained on the basis of the narrow band gap, the high surface area and the presence of surface defects. The photocatalytic activity improved in alkaline media [pH 11.0, catalyst load 15 mg in 200 ml dye solution, dye concentration 1 × 10(-6) M (= 0.3198 mg L(-1))] due to the electrostatic attractions between the dye cations and the negative charges on the Ni/Ti LDH surface. The catalytic activity was found to be higher than the common commercial catalysts like ZnO, ZnS, NiO, TiO2 and Degussa P25. The catalytic activity was retained even after five methylene blue degradation cycles, demonstrating that the LDH could be an important addition to the field of wastewater treatment. PMID:25763803

  2. Interfacial band alignment for photocatalytic charge separation in TiO2 nanotube arrays coated with CuPt nanoparticles.

    PubMed

    Farsinezhad, Samira; Sharma, Himani; Shankar, Karthik

    2015-11-28

    n-Type anatase-phase one-dimensional TiO2 nanostructure arrays coated with nanoparticles of Cu or CuPt have emerged as high performance photocatalysts for both photooxidation and photoreduction. The properties of the catalyst-promoter interface are recognized to be critical to this high performance but are largely unknown. Using X-ray and ultraviolet photoelectron spectroscopies (XPS/UPS), we probed the electronic properties of the CuPt-TiO2 interface in transparent TiO2 nanotube arrays (TTNTAs) coated with photodeposited CuPt nanoparticles (CuPt-TTNTA hybrids) as well as those coated with sputtered CuPt (Sput-CuPt-TTNTA hybrids). XPS and UPS spectra provided the evidence of a Schottky barrier with a band-bending of 0.49-0.67 eV at the CuPt-TiO2 interface in CuPt-TTNTA hybrids due to which photoexcited electrons are expected to be retained in the TiO2 while photoexcited holes will be collected by the CuPt nanoparticles. For Sput-CuPt-TTNTA hybrids, no such band-bending was observed. These results point to the importance of the metal nanoparticle preparation technique on interfacial band-alignments and challenge the conventional understanding of the promoting action of noble metal nanoparticles on TiO2 photocatalysts as sinks for photoexcited electrons. PMID:26478516

  3. Photocatalytic activity of NH4F-doped TiO2 modified by noble metal nanoparticle deposition.

    PubMed

    Dozzi, Maria Vittoria; Saccomanni, Alessia; Altomare, Marco; Selli, Elena

    2013-04-01

    The effect of noble metal (Pt and Au) nanoparticle photodeposition on a series of NH4F-doped TiO2 photocatalysts calcined at 700 °C was investigated both in a thermodynamically down-hill reaction, i.e. the degradation of formic acid in aqueous suspension, and in an up-hill reaction, i.e. hydrogen production from methanol-water vapour mixtures. All photocatalysts were characterized by BET, XRD, UV-vis absorption and HRTEM analysis. Intriguing synergistic effects of simultaneous bulk and surface TiO2 modification were evidenced in both photocatalytic reactions, which can be interpreted in relation to the structural features of the materials. On one hand NH4F doping guarantees that the most active TiO2 anatase phase is stabilised up to high calcination temperature, ensuring high crystallinity and good photoinduced charge carriers production, on the other hand noble metal nanoparticles contribute in increasing the separation of photoproduced charge carriers, resulting in enhanced photocatalytic performances of the surface- and bulk-modified photocatalyst systems. PMID:22930393

  4. A new dielectric ta-C film coating of Ag-nanoparticle hybrids to enhance TiO2 photocatalysis

    NASA Astrophysics Data System (ADS)

    Liu, Fanxin; Tang, Chaojun; Wang, Zhenlin; Sui, Chenghua; Ma, Hongtao

    2014-03-01

    We have demonstrated a novel method to enhance TiO2 photocatalysis by adopting a new ultrathin tetrahedral-amorphous-carbon (ta-C) film coating on Ag nanoparticles to create strong plasmonic near-field enhancement. The result shows that the decomposition rate of methylene blue on the Ag/10 Å ta-C/TiO2 composite photocatalyst is ten times faster than that on a TiO2 photocatalyst and three times faster than that on a Ag/TiO2 photocatalyst. This can be ascribed to the simultaneous realization of two competitive processes: one that excites the surface plasmons (SPs) of the ta-C-film/Ag-nanoparticle hybrid and provides a higher electric field near the ta-C/TiO2 interface compared to Ag nanoparticles alone, while the other takes advantage of the dense diamond-like ta-C layer to help reduce the transfer of photogenerated electrons from the conduction band of TiO2 to the metallic surface, since any electron transfer will suppress the excitation of SP modes in the metal nanoparticles.

  5. Nanoporous TiO2 nanoparticle assemblies with mesoscale morphologies: nano-cabbage versus sea-anemone

    NASA Astrophysics Data System (ADS)

    Darbandi, Masih; Gebre, Tesfaye; Mitchell, Lucas; Erwin, William; Bardhan, Rizia; Levan, M. Douglas; Mochena, Mogus D.; Dickerson, James H.

    2014-05-01

    We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation.We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation. Electronic supplementary information (ESI) available: Synthesis and characterization procedures, TEM/XRD of samples prepared at different temperature and water content, table of nitrogen adsorption-desorption values of different samples. See DOI: 10.1039/c3nr06154j

  6. Synthesis and characterization of Cr-doped ZnO nanorod-array photocatalysts with improved activity

    SciTech Connect

    Chang, Chi-Jung Yang, Tsung-Lin; Weng, Yu-Ching

    2014-06-01

    Immobilized photocatalysts with high catalytic activity under UV light were prepared by growing Cr-doped ZnO nanorods on glass substrates by a hydrothermal method. The effects of Cr dopant on the surface texture, crystallinity, surface chemistry, and photoinduced charge separation and their relation with the photocatalytic degradation of Cr-doped ZnO were investigated by scanning electron microscopy, diffuse reflectance spectra, photoelectrochemical scanning electrochemical microscopy, and X-ray photoemission spectroscopy. Adding the appropriate amount of Cr dopant is a powerful way to enhance the separation of charge carriers in ZnO photocatalyst. The photocatalytic activity was improved due to the increase in surface oxygen vacancies, the separation of charge carriers, modification of the band gap, and the large surface area of the doped ZnO nanorod photocatalyst. - Graphical abstract: Photoinduced charge separation and its relation with the photocatalytic degradation activity of Cr-doped ZnO were investigated by photoelectrochemical scanning electrochemical microscopy. - Highlights: • Cr dopant enhances separation of charge carries in ZnO nanorod photocatalyst. • Photoinduced charge carries separation monitored by PEC-SECM. • The higher the photocurrent is, the higher the photocatalytic activity is. • Degradation of DB86 dye solutions under visible light finished within 50 min. • Higher activity due to more oxygen vacancy, tuned band gap and more surface area.

  7. Frontispiece: Mesoporous Foam TiO2 Nanomaterials for Effective Hydrogen Production.

    PubMed

    Krishnappa, Manjunath; Souza, Virgínia S; Ganganagappa, Nagaraju; Scholten, Jackson D; Teixeira, Sérgio R; Dupont, Jairton; Thippeswamy, Ramakrishnappa

    2015-12-01

    Photocatalysis The development of highly ordered porous materials has gained increased attention in scientific research. These multifunctional materials with controlled porosity can be applied to photocatalysis, photovoltaics, solar-energy conversion, sensors, textiles, paints, and cosmetics. In their Full Paper on page?17624?ff., J. Dupont, R. Thippeswamy, and co-workers describe a simple method for the preparation of large amounts of highly porous, novel, and spongy-type TiO2 materials, which were employed as efficient photocatalysts in the water-splitting process. PMID:26599875

  8. Investigations of near infrared reflective behaviour of TiO2 nanopowders synthesized by arc discharge

    NASA Astrophysics Data System (ADS)

    Fang, Fang; Kennedy, John; Carder, Damian; Futter, John; Rubanov, Sergey

    2014-05-01

    Titanium dioxide (TiO2) nanopowders with different polymorphic phases were successfully synthesized by an arc discharge method. Samples were characterized using synchrotron radiation X-ray diffraction, high resolution scanning electron microscopy, high resolution transmission electron microscope and near infrared diffuse reflectance spectroscopy. Spherical structures were obtained after arc discharge. A mixture of both anatase and rutile phases was discovered in TiO2 samples synthesized at an arc current of 50 A, showing a majority particle size of 34 nm with size distribution between 5 nm and 60 nm. Completed anatase to rutile phase transformation was observed when the arc current increased from 50 A to 74 A. The crystallite size of the TiO2 nanopowders was significant effected by the arc discharge current during synthesis. After the arc current increased from 74 A to 110 A, the majority particle size of the obtained TiO2 increased to 85 nm with a size distribution in the range between 50 nm and 1800 nm. Diffuse reflectance of the TiO2 nanopowders synthesized at different arc discharge currents was measured. Broadband near infrared reflection (800-950 nm) of up to 50% was observed for TiO2 nanopowders synthesized at an arc current of 74 A. It is considered that rutile phase together with an appropriate mean crystallite size of the TiO2 nanopowders synthesized at an arc current of 74 A contributes to the best near infrared reflectivity in this study. The developed TiO2 nanoppowders will be of immense use in NIR reflective pigment.

  9. Oxidative degradation of industrial wastewater using spray deposited TiO2/Au:Fe2O3 bilayered thin films.

    PubMed

    Mahadik, M A; Shinde, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2014-12-01

    The Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400 °C and 470 °C, respectively onto amorphous and F:SnO2 coated glass substrates. The effect of TiO2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 185 ?A and Voc = 450 mV) are at 38 nm thickness of TiO2. Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64 cm(2)) TiO2/Au:Fe2O3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO2/Au:Fe2O3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95 mg/L to 13 mg/L and 75 mg/L to 11 mg/L, respectively was also observed. PMID:25463684

  10. Cationic (V, Y)-codoped TiO2 with enhanced visible light induced photocatalytic activity: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Khan, Matiullah; Cao, Wenbin

    2013-11-01

    To employ TiO2 as an efficient photocatalyst, high reactivity under visible light and improved separation of photoexcited carriers are required. An effective co-doping approach is applied to modify the photocatalytic properties of TiO2 by doping vanadium (transition metal) and yttrium (rare earth element). V and/or Y codoped TiO2 was prepared using hydrothermal method without any post calcination for crystallization. Based on density functional theory, compensated and noncompensated V, Y codoped TiO2 models were constructed and their structural, electronic, and optical properties were calculated. Through combined experimental characterization and theoretical modeling, V, Y codoped TiO2 exhibited high absorption coefficient with enhanced visible light absorption. All the prepared samples showed pure anatase phase and spherical morphology with uniform particle distribution. Electronic band structure demonstrates that V, Y codoping drastically reduced the band gap of TiO2. It is found that both the doped V and Y exist in the form of substitutional point defects replacing Ti atom in the lattice. The photocatalytic activity, evaluated by the degradation of methyl orange, displays that the codoped TiO2 sample exhibits enhanced visible light photocatalytic activity. The synergistic effects of V and Y drastically improved the Brunauer-Emmett-Teller specific surface area, visible light absorption, and electron-hole pair's separation leading to the enhanced visible light catalytic activity.

  11. Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Bin; Park, Dong-Won; Jeun, Joon-Pyo; Oh, Seung-Hwan; Nho, Young-Chang; Kang, Phil-Hyun

    2012-08-01

    iO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20-100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films.

  12. Photocatalytic degradation of acephate in pak choi, Brassica chinensis, with Ce-doped TiO2.

    PubMed

    Liu, Xiangying; Wang, Lifeng; Zhou, Xiaomao; Liu, Kailin; Bai, Lianyang; Zhou, Xuguo

    2015-01-01

    The photocatalytic degradation of acephate was investigated using Ce-doped TiO2 (TiO2/Ce) hydrosol. In contrast to previous research conducted under artificial light in the laboratory, this study investigated the decomposition of acephate in a field trial. The results show that acephate can be efficiently degraded by the TiO2/Ce system under natural field conditions; the degradation efficiency was affected by the dosage of the photocatalyst and acephate. The optimum dosage of TiO2/Ce was 2400 g a.i.ha(-1), and the photodegradation efficiency of acephate reached 93.5% after 20 h at an acephate dosage of 675 g a.i.ha(-1). Ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) analysis detected and identified four degradation products-methamidophos, phosphorothioic acid O,O,S-trimethyl ester, S-methyl methanethiosulfonate and phosphorous acid-that were formed during the TiO2/Ce photodegradation of acephate. Based on the structural identification of the degradation products, a probable photodegradation pathway was proposed, and the first decomposition step may be the cleavage of the C?N bond of acephate. Subsequently, the P?S and P?O bonds may be oxidized gradually or simultaneously to complete the mineralization. PMID:25826101

  13. Atomic structure, electronic properties, and band offsets of SrRuO3/TiO2 heterojunctions

    NASA Astrophysics Data System (ADS)

    Ferdous, Naheed; Ertekin, Elif

    2015-03-01

    Photocatalytic water splitting by sunlight can in principle be an environmentally green approach to hydrogen fuel production, but at present photocatalytic conversion efficiencies remain too small. In titanium dioxide (TiO2) , the most commonly used photocatalyst, the biggest limitation arises from poor absorption of visible light. One way to increase the visible light absorption is to create a composite heterojunction by integrating TiO2 with a strongly light absorbing material. Inspired by experimental results demonstrating good light absorption in the correlated metal oxide Strontium Ruthenate (SrRuO3) , as well as enhanced photocatalytic activity of SrRuO3/TiO2 heterojunctions, we have carried out electronic structure calculations based on density functional theory to explain and improve on the observed properties of such heterojunctions. Our calculations present that this heterojunction exhibits type-II band alignment which is necessary to transport optically excited electrons from the SrRuO3 to the TiO2, with calculated work functions in good agreement with experimental measurements. Also, DFT calculations help to explain the origin of large light absorption in the correlated metal oxide, which arises from electronic excitations from O 2p levels into the Ru d-orbital quasiparticle states in the material. The use of correlated metal oxide/ TiO2 heterojunctions is a potentially interesting approach to improved photocatalytic activity.

  14. Optimization and characterization of transparent photocatalytic TiO2 thin films prepared by ion-assisted deposition

    NASA Astrophysics Data System (ADS)

    Boughaled, Redouan; Schlichting, Sebastian; Ehlers, Henrik; Ristau, Detlev; Bannat, Inga; Wark, Michael

    2008-09-01

    The term photocatalysis is used to describe a photon-driven catalytic process. Titanium dioxide is a well-known photocatalyst in such fields as self-cleaning material and anti-microbial effects. Besides these photocatalytic applications, TiO2 is a widely-used high index material for optical thin films. In the present investigation, the photocatalytic activity of transparent TiO2 thin films was optimized to achieve multifunctional high precision optical coatings. The films have been deposited by ion assisted deposition (IAD), applying a Leybold APS plasma source as well as a Denton CC-105 ion source. The cause-and-effect chain between the use of different parameters in the IAD process and optical properties of the TiO2 layers as well as their photocatalytic activities are described. As test reaction for the determination of the photocatalytic properties, the degradation of methylene blue (MB) was chosen. The used setup based on a high precision two-path laser measurement system was developed by the LZH in order to determine the kinetic performance of TiO2 catalysts under well-defined UV illumination conditions. Photonic efficiencies of the TiO2 thin films were calculated from the obtained data. Additionally, crystal structure analysis has been investigated for the identification of anatase and rutile modifications. The comparison of the results shows that ion assisted deposition is an appropriate technology for the preparation of photocatalytic active thin films for optical applications.

  15. Toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized Mn-doped TiO2.

    PubMed

    Ozmen, Murat; Güngördü, Abbas; Erdemoglu, Sema; Ozmen, Nesrin; Asilturk, Meltem

    2015-08-01

    The toxic effects of two selected xenobiotics, bisphenol A (BPA) and atrazine (ATZ), were evaluated after photocatalytic degradation using nano-sized, Mn-doped TiO2. Undoped and Mn-doped TiO2 nanoparticles were synthesized. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis-diffuse reflectance spectra (DRS), X-ray fluorescence spectroscopy (XRF), and BET surface area. The photocatalytic efficiency of the undoped and Mn-doped TiO2 was evaluated for BPA and ATZ. The toxicity of the synthesized photocatalysts and photocatalytic by-products of BPA and ATZ was determined using frog embryos and tadpoles, zebrafish embryos, and bioluminescent bacteria. Possible toxic effects were also evaluated using selected enzyme biomarkers. The results showed that Mn-doped TiO2 nanoparticles did not cause significant lethality in Xenopus laevis embryos and tadpoles, but nonfiltered samples caused lethality in zebrafish. Furthermore, Mn-doping of TiO2 increased the photocatalytic degradation capability of nanoparticles, and it successfully degraded BPA and AZT, but degradation of AZT caused an increase of the lethal effects on both tadpoles and fish embryos. Degradation of BPA caused a significant reduction of lethal effects, especially after 2-4h of degradation. However, biochemical assays showed that both Mn-doped TiO2 and the degradation by-products caused a significant change of selected biomarkers on X. laevis tadpoles; thus, the ecological risks of Mn-doped TiO2 should be considered due to nanomaterial applications and for spilled nanoparticles in an aquatic ecosystem. Also, the risk of nanoparticles should be considered using indicator reference biochemical markers to verify the environmental health impacts. PMID:26037099

  16. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  17. Facile Synthesis of Novel Redox-Mediator-free Direct Z-Scheme CaIn2S4 Marigold-Flower-like/TiO2 Photocatalysts with Superior Photocatalytic Efficiency.

    PubMed

    Jo, Wan-Kuen; Sivakumar Natarajan, Thillai

    2015-08-12

    Novel redox-mediator-free direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (CIS/TNP) photocatalysts with different CaIn2S4 weight percentages were synthesized using a facile wet-impregnation method. Uniform hierarchical marigold-flower-like CaIn2S4 (CIS) microspheres were synthesized using a hydrothermal method. Field-emission scanning electron microscopy and transmission electron microscopy analyses suggested that the formation and aggregation of nanoparticles, followed by the growth of petals or sheets and their subsequent self-assembly, led to the formation of the uniform hierarchical marigold-flower-like CIS structures. The photocatalytic degradation efficiency of the direct Z-scheme CIS/TNP photocatalysts was evaluated through the degradation of the pharmaceutical compounds isoniazid (ISN) and metronidazole (MTZ). The direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (1%-CIS/TNP) photocatalyst showed enhanced performance in the ISN (71.9%) and MTZ (86.5%) photocatalytic degradations as compared to composites with different CaIn2S4 contents or the individual TiO2 and CaIn2S4. A possible enhancement mechanism based on the Z-scheme formed between the CIS and TNP for the improved photocatalytic efficiency was also proposed. The recombination rate of the photoinduced charge carriers was significantly suppressed for the direct Z-scheme CIS/TNP photocatalyst, which was confirmed by photoluminescence analysis. Radical-trapping studies revealed that photogenerated holes (h+), •OH, and O2•- are the primary active species, and suggested that the enhanced photocatalytic efficiency of the 1%-CIS/TNP follows the Z-scheme mechanism for transferring the charge carriers. It was further confirmed by hydroxyl (•OH) radical determination via fluorescence techniques revealed that higher concentration of •OH radical were formed over 1%-CIS/TNP than over bare CIS and TNP. The separation of the charge carriers was further confirmed using photocurrent and electron spin resonance measurements. Kinetic and chemical oxygen demand analyses were performed to confirm the ISN and MTZ degradation. The results demonstrated that the direct Z-scheme CIS/TNP photocatalyst shows superior decomposition efficiency for the degradation of these pharmaceuticals under the given reaction conditions. PMID:26186618

  18. Visible light activated TiO2/microcrystalline cellulose nanocatalyst to destroy organic contaminants in water.

    EPA Science Inventory

    Hybrid TiO2/microcrystalline cellulose (MC) nanophotocatalyst was prepared in situ by a facile and simple synthesis utilizing benign precursors such as MC and TiCl4. The as-prepared nanocomposite was characterized by XRD, XPS, BET surface area analyzer, UV–vis DRS and TGA. Surfac...

  19. Completely <001> oriented anatase TiO2 nanoarrays: topotactic growth and orientation-related efficient photocatalysis

    NASA Astrophysics Data System (ADS)

    Yang, Jingling; Wu, Qili; He, Shiman; Yan, Jing; Shi, Jianying; Chen, Jian; Wu, Mingmei; Yang, Xianfeng

    2015-08-01

    A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their <001> direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001} facets on the anatase nanoarrays with super-hydrophilicity.A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their <001> direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001} facets on the anatase nanoarrays with super-hydrophilicity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03807c

  20. Role of Ti-O bonds in phase transitions of TiO2.

    PubMed

    Nosheen, Shaneela; Galasso, Francis S; Suib, Steven L

    2009-07-01

    A phase transition was achieved from TiO2 particles to titanate nanotubes by the breakage of Ti-O bonds without using expensive precursors, high temperatures, high chemical concentrations of alkaline solutions, and long synthesis times. The controlled preparation of one-dimensional nanostructures of titanates (H2Ti4O9.nH2O) has been conducted at a very low concentration of alkaline solution (1 M NaOH), and in a very short time (12 h) using TiO2 anatase and TiO2 P-25 (precursors) and a microwave enhanced soft chemical process. Temperature was used as a variable, and only low process temperatures (100-110 degrees C) were used. A combination of anatase nanoparticles/hydrogen tetratitanate nanotubes was synthesized using TiO2 (anatase) and a temperature of only 100 degrees C. When TiO2 (P-25) was used with the same concentration of alkaline solution (1 M NaOH), the same processing time of 12 h, and a higher temperature at 110 degrees C, only hydrogen tetratitanate nanotubes were observed. The linkages of "Ti-O" play a very important role in the structural features of different phases. X-ray diffraction (XRD) showed two crystalline phases (tetragonal and monoclinic) in the case of TiO2 (anatase) and one crystalline phase (monoclinic) for products of TiO2 (P-25). The role of Ti-O linkages is obvious in the Raman spectra as revealed by a shift in peak positions for a layered structure of the hydrogen tetratitanate and a nanosphere structure of the resulting TiO2. An X-ray photoelectron spectroscopy (XPS) study showed a shift to a lower binding energy of the 2p peaks (2p1/2, 3/2) in the Ti region for titanate and confirmed the formation of titanate nanostructures. Transmission electron microscopy (TEM) revealed nanotubes of hydrogen tetratitanates (H2Ti4O9.nH2O) in the form of bundles. High-resolution TEM (HRTEM) data supported findings of X-ray diffraction results of the products of TiO2 (anatase) and TiO2 (P-25). PMID:19453129

  1. Structure -- Magnetic Property Correlations in TiO 2 Nanotube Arrays

    NASA Astrophysics Data System (ADS)

    Mohammad Hosseinpour, Pegah

    TiO2 nanotube arrays are promising candidates for applications such as photocatalysis and for potential employment in spin-electronic (spintronic) devices. The functionality of TiO2-based nanotubes is highly dependent on their structure (microstructure and crystallographic symmetry) and magnetic properties. Unified understanding of the influence of these factors on the electronic structure of TiO2 is of paramount importance towards engineering these materials. This Dissertation aims at investigating the correlations of the morphology, crystallinity, crystal structure, electronic structure and magnetic properties of TiO2 nanotubes, with potential relevance to their functionality. Self-ordered arrays of amorphous TiO2 nanotubes (pure and Fe-doped with cationic concentration of ~2.1 at%) were synthesized by the electrochemical anodization technique, followed by subjecting them to thermal treatments up to 450 °C to crystallize these nanostructures. A variety of probes---morphological, structural, magnetic and spectroscopic---were used to characterize the properties of these nanostructures as functions of their processing conditions and the dopant content. Structure-functionality relationships in these nanostructures were verified by examining the photodegradation rate of methyl orange (a model water pollutant) in presence of TiO2 nanotubes under UV-Visible light irradiation. Results from this Dissertation research demonstrated that post-synthesis processing conditions---specifically, the nature of the annealing environment, as well as the presence of an external dopant, can alter the crystal structure and local electronic environment in TiO2 nanotubes, with subsequent effects on the magnetic properties of these nanostructures. The fundamental knowledge obtained in this research, on the interrelations of structural-magnetic properties and their potential influence on the functionality of TiO 2-based nanotubes, can be extended to the metal oxide semiconducting systems in general and is anticipated to provide avenues toward novel materials with enhanced functionality that originates from such tailored structural and magnetic characteristics. Despite the success achieved in this Dissertation, there are still open questions to be addressed in order to further enhance the fundamental knowledge of structure---magnetic property correlations in TiO2 nanotubes. In this regard, the concluding section of this Dissertation provides recommendations for additional experiments. Accomplishment of these recommendations is anticipated to provide enhanced insight into the various aspects of property-functionality relationships in TiO2-based nanomaterials, and provides paths to engineer novel multifunctional oxide-based materials for energy-related applications.

  2. TiO2 nanofibrous interface development for Raman detection of environmental pollutants

    NASA Astrophysics Data System (ADS)

    Maznichenko, D.; Selvaganapathy, P. R.; Venkatakrishnan, K.; Tan, B.

    2012-12-01

    Sensor development has been reliant on planar Au and Ag nanoparticle research. The current findings explored a unique 3-D network of crystalline TiO2 nanoparticles linked as nanofibers. In addition to the favorability of using TiO2 for chemical and bio-molecular sensing, the nanofiber network provides molecular diffusion control and an increased confocal volume signal. Controlled femtosecond laser synthesis is also demonstrated that directly impacts surface-enhanced Raman spectroscopy detection of two common environmentally harmful chemicals: bisphenol A and diclofenac sodium salt. These findings assert that 3-D nanofibrous network porosity optimization is crucial for Raman monitoring of drinking water.

  3. Visible Light Photocatalysis via CdS/ TiO 2 Nanocomposite Materials

    DOE PAGESBeta

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    Nanostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS- TiO 2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS- TiO 2 nanocomposites are determined using XRD and SEM-EDS techniques. Themore »visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension. « less

  4. Defect chemistry and defect engineering of TiO2-based semiconductors for solar energy conversion.

    PubMed

    Nowotny, Janusz; Alim, Mohammad Abdul; Bak, Tadeusz; Idris, Mohammad Asri; Ionescu, Mihail; Prince, Kathryn; Sahdan, Mohd Zainizan; Sopian, Kamaruzzaman; Mat Teridi, Mohd Asri; Sigmund, Wolfgang

    2015-12-01

    This tutorial review considers defect chemistry of TiO2 and its solid solutions as well as defect-related properties associated with solar-to-chemical energy conversion, such as Fermi level, bandgap, charge transport and surface active sites. Defect disorder is discussed in terms of defect reactions and the related charge compensation. Defect equilibria are used in derivation of defect diagrams showing the effect of oxygen activity and temperature on the concentration of both ionic and electronic defects. These defect diagrams may be used for imposition of desired semiconducting properties that are needed to maximize the performance of TiO2-based photoelectrodes for the generation of solar hydrogen fuel using photo electrochemical cells (PECs) and photocatalysts for water purification. The performance of the TiO2-based semiconductors is considered in terms of the key performance-related properties (KPPs) that are defect related. It is shown that defect engineering may be applied for optimization of the KPPs in order to achieve optimum performance. PMID:26446476

  5. Nanostructure and charge transfer in Bi2S3-TiO2 heterostructures.

    PubMed

    Yu, Haijing; Huang, Jing; Zhang, Hua; Zhao, Qingfei; Zhong, Xinhua

    2014-05-30

    Interfacial nanostructures in Bi2S3-TiO2 nanorod-nanoparticle heterostructures with a change of coupling mode have been engineered. The samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet-visual light absorption spectroscopy. By means of in situ growth of TiO2 nanoparticles on the surfaces of Bi2S3 nanorods in one pot, heterostructures with high-quality interfaces were obtained in which the {105} facet of anatase TiO2 selectively coupled with the {010} facet of orthorhombic Bi2S3 nanorods without any crystal defects, showing the epitaxial relationship of Bi2S3 {011} // TiO2 {101}. By means of a two-step method, TiO2 nanoparticles also could be grown on the {310} facet of the pre-prepared Bi2S3 nanorods to form heterostructures but with interfacial defects. Charge transfer in the interface-different heterostructures was evaluated by photodegradation of methyl orange under visible-light irradiation. The defect-free interfaces favored electron-hole separation and transfer, resulting in improved photocatalytic activity. The current structural characterization and interface engineering should be expanded to other heterostructures when studying the relationship between synthesis, interfacial structure, and photocatalytic or photovoltaic applications. PMID:24784772

  6. Photoinduced interaction between riboflavin and TiO 2 colloid

    NASA Astrophysics Data System (ADS)

    Kathiravan, A.; Renganathan, R.

    2008-12-01

    The adsorption of riboflavin on the surface of TiO 2 colloidal particles and the electron transfer process from its singlet excited state to the conduction band of TiO 2 were examined by absorption and fluorescence quenching measurements. The apparent association constants ( Kapp) were determined. The quenching mechanism is discussed involving electron transfer from riboflavin to TiO 2.

  7. Bifunctional-nanotemplate assisted synthesis of nanoporous SrTiO? photocatalysts toward efficient degradation of organic pollutant.

    PubMed

    Ouyang, Shuxin; Li, Peng; Xu, Hua; Tong, Hua; Liu, Lequan; Ye, Jinhua

    2014-12-24

    Nanoporous SrTiO3 photocatalysts were fabricated via a novel technique, the nanotemplate assisted sol-gel hydrothermal reaction. In the alkaline-environment hydrothermal reaction, the SiO2 nanotemplate not only served as pore generator but also worked on adjusting the local reaction environment around the SrTiO3 nanocrystals. This contributed to a continuous modulation between the surface area and the crystallinity of the photocatalyst. The photocatalytic activities of the nanoporous SrTiO3 samples were evaluated by the degradation of gaseous isopropyl alcohol (IPA). Due to an optimal equilibrium between surface area and crystallinity, a SrTiO3 sample synthesized via adding 40% template (STO-SiO2-40%) showed the highest activity, which achieves 40 and 8 times of enhancement of CO2 evolution in comparison with the sample prepared without template and a commercial nano-SrTiO3, respectively. The photodegradation mechanism of IPA over this sample was also investigated in detail. This synthetic technique is also available to prepare the other nanoporous titanates, such as doped SrTiO3 samples and alkali-metal titanates. PMID:25415827

  8. Soft chemistry synthesis of high-crystalline orthogermanate CeGeO{sub 4}: A new photocatalyst

    SciTech Connect

    Xing Jun; Yang Chen; Li Weikun; Gong Xueqing; Yang Huagui

    2013-01-15

    A new orthogermanate phase of CeGeO{sub 4} was studied and the corresponding nanocrystals have been successfully synthesized via a facile hydrothermal method without adding any capping agent. The pH value of the solution and the reaction time were also further investigated, respectively. The as-prepared CeGeO{sub 4} nanocrystals with a uniform size of 15 nm have been characterized by using XRD/TEM/TGA/UV-vis techniques, and their electronic structures and band gap were calculated based on a plane wave density function theory (DFT). The promising photocatalytic properties of CeGeO{sub 4} have been confirmed through monitoring reactive oxidative species generated in photocatalytic reactions of terephthalic acid as a fluorescence probe. - Graphical Abstract: A novel photocatalyst CeGeO{sub 4} was prepared. Highlights: Black-Right-Pointing-Pointer CeGeO{sub 4} as a novel photocatalyst was successfully synthesized by a hydrothermal method. Black-Right-Pointing-Pointer Electronic structure and band gap were calculated based on DFT. Black-Right-Pointing-Pointer CeGeO{sub 4} exhibited a promising photocatalytic performance.

  9. Novel-structured electrospun TiO2/CuO composite nanofibers for high efficient photocatalytic cogeneration of clean water and energy from dye wastewater.

    PubMed

    Lee, Siew Siang; Bai, Hongwei; Liu, Zhaoyang; Sun, Darren Delai

    2013-08-01

    It is still a challenge to photocatalytically cogenerate clean water and energy from dye wastewater owing to the relatively low photocatalytic efficiency of photocatalysts. In this study, novel-structured TiO2/CuO composite nanofibers were successfully fabricated via facile electrospinning. For the first time, the TiO2/CuO composite nanofibers demonstrated multifunctional ability for concurrent photocatalytic organic degradation and H2 generation from dye wastewater. The enhanced photocatalytic activity of TiO2/CuO composite nanofibers was ascribed to its excellent synergy of physicochemical properties: 1) mesoporosity and large specific surface area for efficient substrate adsorption, mass transfer and light harvesting; 2) red-shift of the absorbance spectra for enhanced light utilization; 3) long nanofibrous structure for efficient charge transfer and ease of recovery, 4) TiO2/CuO heterojunctions which enhance the separation of electrons and holes and 5) presence of CuO which serve as co-catalyst for the H2 production. The TiO2/CuO composite nanofibers also exhibited rapid settleability by gravity and uncompromised reusability. Thus, the as-synthesized TiO2/CuO composite nanofibers represent a promising candidate for highly efficient concurrent photocatalytic organic degradation and clean energy production from dye wastewater. PMID:23541306

  10. [Photocatalytic removing of a mustard gas analogue 2-CEES vapor over SO4(2-)/TiO2].

    PubMed

    Han, Shi-tong; Xi, Hai-ling; Wang, Xu-xu; Fu, Xian-zhi

    2005-05-01

    Disinfection with photocatalysis, compared to with the conventional cleanout, is both high efficient and non contaminative, but the simple TiO2 photocatalyst is showing to be of low activity and low active stability so to be hardly practical application. In the paper, SO4(2-)/TiO2 were papered by surface modification of TiO2 with dilute H2SO4, and the photocatalytic degradation of 2-chloroethyl ethyl sulfide (2-CEES) on the samples was examined in a fixed-bed microreactor. The examination show that the acidic modification enhanced both the activity and the active stability of TiO2, and the sample ST200 prepared by calcination at 200 degrees C was better than ST400 by calcination at 400 degrees C. The effect of water vapor content and reaction temperature on the photocatalytic degradation of 2-CEES was also tested, showing that the sample ST200 had high activity and stability at 90 degrees C, and kept a constant activity when adding 30.5 mL/L water vapor into the reactive system in which 2-CEES initial concentration was low to < 61 microL x L(-1). In addition, it was found that supporting SO4(2-)/TiO2 on gamma-Al2O3, SiO2 and active carbon could improve on the activity and stability of SO4(2-)/TiO2, and on supports SiO2 is the best one. PMID:16124485

  11. Visible light photoactivity of TiO2 loaded with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles

    NASA Astrophysics Data System (ADS)

    Go??biewska, Anna; Lisowski, Wojciech; Jarek, Marcin; Nowaczyk, Grzegorz; Zieli?ska-Jurek, Anna; Zaleska, Adriana

    2014-10-01

    TiO2 modified with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles have been prepared using a water-in-oil microemulsion system (water/AOT/cyclohexane) followed by calcination step. The effect of metal ratio, reducing agent type (NaBH4 or N2H4), TiO2 matrix type (P-25, ST-01, TiO-5, TiO2 nanotubes or TiO2 obtained by TIP hydrolysis) as well as calcination temperature (from 350 to 650 °C) were systematically investigated. Obtained photocatalysts were characterized by UV-vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning transmission microscopy (STEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity under visible light (? > 420 nm) has been estimated in phenol degradation reaction in aqueous phase. The results showed that phenol degradation rate under visible light in the presence of TiO2 loaded with Au/Pt nanoparticles differed from 0.7 to 2.2 ?mol dm-3 min-1 for samples prepared using different reducing agent. Sodium borohydride (NaBH4) favors formation of smaller Au/Pt nanoparticles and higher amount gold in Au/Pt is in the form of electronegative species (Au?-) resulted in higher photoactivity. TiO2 obtained by TIP hydrolysis in microemulsion system seems to be the best support for Au/Pt nanoparticles from all among investigated matrix. It was also observed that enhancement of calcination temperature from 450 to 650 °C resulted in rapid drop of Au/Pt-TiO2 photoactivity under visible light due to surface area shrinkage, crystal structure change and probably change in Au/Pt nanoparticles morphology.

  12. In Situ Formation of Disorder-Engineered TiO2(B)-Anatase Heterophase Junction for Enhanced Photocatalytic Hydrogen Evolution.

    PubMed

    Cai, Jinmeng; Wang, Yating; Zhu, Yingming; Wu, Moqing; Zhang, Hao; Li, Xingang; Jiang, Zheng; Meng, Ming

    2015-11-18

    Hydrogenation of semiconductors is an efficient way to increase their photocatalytic activity by forming disorder-engineered structures. Herein, we report a facile hydrogenation process of TiO2(B) nanobelts to in situ generate TiO2(B)-anatase heterophase junction with a disordered surface shell. The catalyst exhibits an excellent performance for photocatalytic hydrogen evolution under the simulated solar light irradiation (?580 ?mol h(-1), 0.02 g photocatalyst). The atomically well-matched heterophase junction, along with the disorder-engineered surface shell, promotes the separation of electron-hole and inhibits their recombination. This strategy can be further employed to design other disorder-engineered composite photocatalysts for solar energy utilization. PMID:26536137

  13. Synthesis, characteristics and sonocatalytic activities of calcined ?-Fe2O3 and TiO2 nanotubes/?-Fe2O3 magnetic catalysts in the degradation of Orange G.

    PubMed

    Pang, Yean Ling; Lim, Steven; Ong, Hwai Chyuan; Chong, Wen Tong

    2016-03-01

    In this work, ?-Fe2O3 and TiO2 NTs/?-Fe2O3 composites with good magnetism and sonocatalytic activity were prepared by a facile polyol method and utilize the principle of isoelectric point method, respectively. The structural and magnetic features of the prepared calcined ?-Fe2O3 and composite catalysts were investigated by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), surface analysis, UV-Vis diffuse reflectance spectra (UV-Vis DRS), vibrating sample magnetometry (VSM) and zeta potential analysis. The effects of calcination temperature on ?-Fe2O3 phase variation, physical properties and sonocatalytic properties were investigated. The porosity, specific surface area, band gap energy and sonocatalytic activity of ?-Fe2O3 were gradually decreased with calcination temperature increased. TiO2 NTs/?-Fe2O3 with appropriate composition and specific structural features possess synergetic effects such as efficient separation of charge carriers and hydroxyl radicals produced by heterogeneous fenton and fenton-like reactions. This enhanced the sonocatalytic activity for the degradation of Orange G under ultrasonic irradiation. The sonocatalytic reactions obeyed pseudo first-order kinetics. All these information provide insight into the design and development of high-efficiency catalyst for wastewater treatment. PMID:26585012

  14. Completely <001> oriented anatase TiO2 nanoarrays: topotactic growth and orientation-related efficient photocatalysis.

    PubMed

    Yang, Jingling; Wu, Qili; He, Shiman; Yan, Jing; Shi, Jianying; Chen, Jian; Wu, Mingmei; Yang, Xianfeng

    2015-09-01

    A TiO2 film has been facilely grown on a Ti foil via a general and simple acid vapor oxidation (AVO) strategy. Based on detailed characterization by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the TiO2 film was composed of anatase nanoarrays highly oriented along their <001> direction, resulting in a large exposed {001} top surface on the film. The growth mechanism based on a topotactic transformation was proposed according to a careful study of time-dependent experimental results. Resulting from the evaluation of photocatalytic performance compared with a commercial TiO2 photocatalyst (Degussa P25), the as-prepared oriented anatase TiO2 film showed higher efficiency for degradation of atrazine and acid orange II (AOII). The performance of photocatalysis is highly relevant to the preferential orientation. The efficient photocatalysis could be attributed to the highly reactive {001} facets on the anatase nanoarrays with super-hydrophilicity. PMID:26219743

  15. Enhanced photocatalytic generation of hydrogen by Pt-deposited nitrogen-doped TiO2 hierarchical nanostructures

    NASA Astrophysics Data System (ADS)

    Naik, Brundabana; Moon, Song Yi; Kim, Sang Hoon; Park, Jeong Young

    2015-11-01

    We report the photocatalytic activity of hydrogen generation on Pt nanoparticles deposited on hierarchically porous N-doped TiO2 nanostructures (Pt-NHPT). The photocatalysts are composed of Pt nanoparticles well dispersed throughout hierarchical macroporous TiO2 fibrous channels. The interstitial N doping extends light absorption toward the visible region. We found that the porosity of N-doped TiO2 nanostructures can be tuned using different annealing temperatures. While Pt-NHPT catalysts calcined at 300 °C (Pt-NHPT-300) have both macro- and mesoporosity, Pt-NHPT catalysts calcined at 800 °C (Pt-NHPT-800) exhibit only macroporosity. We found that Pt-NHPT-300 shows a two-fold higher H2 evolution activity than that of Pt-NHPT-800, and 30% higher activity than undoped hierarchical catalysts (Pt-HPT-300). The enhanced photoactivity is attributed to the synergistic effects of N doping, hierarchical porosity, and charge transfer between the TiO2 nanostructures and the Pt co-catalyst.

  16. Anomalous behavior of visible light active TiO2 for the photocatalytic degradation of different Reactive dyes.

    PubMed

    Kaur, Navneet; Shahi, Satwant Kaur; Singh, Vasundhara

    2015-10-28

    Nanocrystalline undoped, N-doped, N and metal codoped titania with different particle size, surface area, anatase phase content, crystallinity, band gap and zeta potential were synthesized by the sol-gel method. The photocatalytic activities of the synthesized TiO2 powders were compared by employing four different Reactive dyes. The order of photocatalytic activity observed for Reactive Red 198 dye (RR 198) was undoped = N,Cu codoped = N-doped > N,Fe codoped TiO2, Reactive Blue 4 dye (RB 4) was N,Cu codoped > N,Fe codoped > N-doped > undoped TiO2, Reactive Black 5 dye (RB 5) was N,Cu codoped* > undoped > N-doped > N,Fe codoped TiO2 and negligible degradation was observed for Reactive Orange 16 dye (RO 16). In this paper, the anomalous trend of the photocatalytic activity of various photocatalysts for the degradation of a particular class of dyes has been observed and accounted for based upon three parameters: mechanism of degradation, physicochemical properties of the catalyst and adsorption behavior based on the zeta potential. It was concluded that apart from these parameters, the substrate-specificity of the catalyst is also of equal importance in developing new catalysts for the photodegradation of dyes present in textile effluents. PMID:26303630

  17. Preparation of 13X from Waste Quartz and Photocatalytic Reaction of Methyl Orange on TiO2/ZSM-5, 13X and Y-Zeolite.

    PubMed

    Wang, Jia-Jie; Jing, You-Hai; Ouyang, Tong; Chang, Chang-Tang

    2015-08-01

    TiO2 photocatalytic reactions not only remove a variety of organic pollutants via complete mineralization, but also destroy the bacterial cell wall and cell membrane, thus playing an important bactericidal role. However, the post-filtration procedures to separate nanometer-levels of TiO2 and the gradual inactivity of photocatalyst during continuous use are defects that limit its application. In this case, we propose loading TiO2 on zeolite for easy separation and 13X is considered as a promising one. In our study, 13X-zeolite was prepared by a hydrothermal method and the source of Si was extracted from waste quartz sand. For comparison, commercial zeolite with different microporous and mesoporous diameters (ZSM-5 and Y-zeolites) were also used as TiO2 supports. The pore size of the three kinds of zeolites are as follows: Y-zeolite > 13X > ZSM-5. Different TiO2 loading content over ZSM-5, 13X and Y-zeolite were prepared by the sol-gel method. XRD, FTIR, BET, UV-vis, TGA and SEM were used for investigation of material characteristics. In addition, the efficiencies of mineralization and photodegradation were studied in this paper. The effects of the loading ratio of TiO2 over zeolites, initial pH, and concentration on photocatalytic performance are investigated. The relationship between best loading content of TiO2 and pore size of the zeolite was studied. The possible roles of the ZSM-5, 13X-zeolites and Y-zeolites support on the reactions and the possible mechanisms of effects were also explored. The best loading content of TiO2 over ZSM-5, 13X and Y-zeolite was found to be 50 wt%, 12.5 wt% and 7 wt%, respectively. The optimum pH condition is 3 with TiO2 over ZSM-5, 13X-zeolites and Y-zeolites. The results showed that the degradation and mineralization efficiency of 12.5 wt%GT13X (TiO2 over 13X) after 90 min irradiation reached 57.9% and 22.0%, which was better than that of 7 wt%GTYZ (TiO2 over Y-zeolites) while much lower than that of 50 wt%GTZ (TiO2 over ZSM-5). The materials were recycled four times while the degradation was remained at a higher level. PMID:26369215

  18. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    PubMed Central

    Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

    2014-01-01

    In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42? and NO3?, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

  19. Synthesis, characterization and photocatalytic activity of new photocatalyst ZnBiSbO4 under visible light irradiation.

    PubMed

    Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

    2014-01-01

    In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO4(2-) and NO3(-), and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

  20. Structural, morphological and local electric properties of TiO2 thin films grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    György, E.; Pérez del Pino, A.; Sauthier, G.; Figueras, A.; Alsina, F.; Pascual, J.

    2007-09-01

    Titanium dioxide (TiO2) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (? = 266 nm, ?FWHM cong 5 ns, ? = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO2 thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters.

  1. CO2 gas detection properties of a TIO2/Al2O3 heterostructure under UV light irradiation

    NASA Astrophysics Data System (ADS)

    Karaduman, Irmak; Demir, Mehmet; Y?ld?z, Dilber Esra; Acar, Selim

    2015-05-01

    Al/TiO2/p-Si and Al/T?O2/Al2O3/p-Si samples were prepared using the atomic layer deposition method (ALD) and their gas sensing properties were investigated. The electrical properties of the samples were studied using a two probe method in the temperature range 25-230 °C and at room temperature UV conditions. The TiO2/Al2O3 heterojunction sample exhibited an excellent gas sensing response to CO2 gas at room temperature and improved the effect of UV light irradiation. The results showed that heterostructures helped to improve the gas sensor properties, affected the sensing at room temperature and thus guided the design of photocatalysts. The TiO2/Al2O3 heterojunction prepared using this method can be used as a material for semiconductor gas sensors detecting poisonous gases like CO2 at room temperature with high sensitivity and selectivity.

  2. Development of Titanium Dioxide (TiO2 ) Nanocoatings on Food Contact Surfaces and Method to Evaluate Their Durability and Photocatalytic Bactericidal Property.

    PubMed

    Yemmireddy, Veerachandra K; Farrell, Glenn D; Hung, Yen-Con

    2015-08-01

    Titanium dioxide (TiO2 ) is a well-known photocatalyst for its excellent bactericidal property under UVA light. The purpose of this study was to develop physically stable TiO2 coatings on food contact surfaces using different binding agents and develop methods to evaluate their durability and microbicidal property. Several types of organic and inorganic binders such as polyvinyl alcohol, polyethylene glycol, polyurethane, polycrylic, sodium and potassium silicates, shellac resin, and other commercial binders were used at 1:1 to 1:16 nanoparticle to binder weight ratios to develop a formulation for TiO2 coating on stainless steel surfaces. Among the tested binders, polyurethane, polycrylic, and shellac resin were found to be physically more stable when used in TiO2 coating at 1:4 to 1:16 weight ratio. The physical stability of TiO2 coatings was determined using adhesion strength and scratch hardness tests by following standard ASTM procedures. Further, wear resistance of the coatings was evaluated based on a simulated cleaning procedure used in food processing environments. TiO2 coating with polyurethane at a 1:8 nanoparticle to binder weight ratio showed the highest scratch hardness (1.08 GPa) followed by coating with polycrylic (0.68 GPa) and shellac (0.14 GPa) binders. Three different techniques, namely direct spreading, glass cover-slip, and indented coupon were compared to determine the photocatalytic bactericidal property of TiO2 coatings against Escherichia coli 0157:H7 at 2 mW/cm(2) UVA light intensity. Under the tested conditions, the indented coupon technique was found to be the most appropriate method to determine the bactericidal property of TiO2 coatings and showed a reduction of 3.5 log CFU/cm(2) in 2 h. PMID:26189653

  3. Performance of photocatalytic reactors using immobilized TiO2 film for the degradation of phenol and methylene blue dye present in water stream.

    PubMed

    Ling, Chin Mei; Mohamed, Abdul Rahman; Bhatia, Subhash

    2004-11-01

    TiO2 thin film photocatalyst was successfully synthesized and immobilized on glass reactor tube using sol-gel method. The synthesized TiO2 coating was transparent, which enabled the penetration of ultra-violet (UV) light to the catalyst surface. Two photocatalytic reactors with different operating modes were tested: (a) tubular photocatalytic reactor with re-circulation mode and (b) batch photocatalytic reactor. A new proposed TiO2 synthesized film formulation of 1 titanium isopropoxide: 8 isopropanol: 3 acetyl acetone: 1.1 H2O: 0.05 acetic acid (in molar ratio) gave excellent photocatalytic activity for degradation of phenol and methylene blue dye present in the water. The half-life time, t1/2 of photocatalytic degradation of phenol was 56 min at the initial phenol concentration of 1000 microM in the batch reactor. In the tubular photocatalytic reactor, 5 re-circulation passes with residence time of 2.2 min (single pass) degraded 50% of 40-microM methylene blue dye. Initial phenol concentration, presence of hydrogen peroxide, presence of air bubbling and stirring speed as the process variables were studied in the batch reactor. Initial methylene blue concentration, pH value, light intensity and reaction temperature were studied as the process variables in the tubular reactor. The synthesized TiO2 thin film was characterized using SEM, XRD and EDX analysis. A comparative performance between the synthesized TiO2 thin film and commercial TiO2 particles (99% anatase) was evaluated under the same experimental conditions. The TiO2 film was equally active as the TiO2 powder catalyst. PMID:15488916

  4. Time- and energy-efficient solution combustion synthesis of binary metal tungstate nanoparticles with enhanced photocatalytic activity.

    PubMed

    Thomas, Abegayl; Janáky, Csaba; Samu, Gergely F; Huda, Muhammad N; Sarker, Pranab; Liu, J Ping; van Nguyen, Vuong; Wang, Evelyn H; Schug, Kevin A; Rajeshwar, Krishnan

    2015-05-22

    In the search for stable and efficient photocatalysts beyond TiO2 , the tungsten-based oxide semiconductors silver tungstate (Ag2 WO4 ), copper tungstate (CuWO4 ), and zinc tungstate (ZnWO4 ) were prepared using solution combustion synthesis (SCS). The tungsten precursor's influence on the product was of particular relevance to this study, and the most significant effects are highlighted. Each sample's photocatalytic activity towards methyl orange degradation was studied and benchmarked against their respective commercial oxide sample obtained by solid-state ceramic synthesis. Based on the results herein, we conclude that SCS is a time- and energy-efficient method to synthesize crystalline binary tungstate nanomaterials even without additional excessive heat treatment. As many of these photocatalysts possess excellent photocatalytic activity, the discussed synthetic strategy may open sustainable materials chemistry avenues to solar energy conversion and environmental remediation. PMID:26018624

  5. Antimicrobial materials for water disinfection based on visible-light photocatalysts

    NASA Astrophysics Data System (ADS)

    Wu, Pinggui

    Since the discovery of photocatalytic water-splitting on TiO2 in 1972, enormous effort has been devoted to the study of TiO2. Since the optical properties of TiO2 and e--h + recombination are essential to the photon-driven applications, these two areas have drawn tremendous research attention in the past few years. But there is no single optimal system to date that has visible-light activity, high photo-efficiency and easy recovery. In this study, chemical co-doping approach was adopted to achieve desirable properties of TiO2-based photocatalyst. Nitrogen and metal ions selected from the transition metal or the rare earth element group were incorporated into TiO2 to induce a red-shift to the visible-light absorption regime and to enhance photocatalytic activity. The anion and cation co-doped TiO2 was made into various forms, including thin film, fiber, and foam that circumvent the problems associated with catalyst recovery. Chemical composition, structure, microstructure, optical, and photocatalytic properties were investigated to characterize each type of the materials. Electronic structure calculation and electron paramagnetic resonance spectroscopy were conducted to understand the role of nitrogen and metal ions. The photocatalytic property of these visible-light-active photocatalysts were studied in the inactivation of bacteria and bacterial spores in water. Fast killing rate was obtained for the inactivation of E. coli, P. aeruginosa, S. aureus and B. subtilis endospores. The results of mechanistic study provided evidence of oxidative damages, and indicated that hydroxyl radicals are one of the key killing species. Atomic force microscopy and electron microscopy showed that the cell walls were attacked by photocatalytic inactivation. The potential application of the photocatalyst in water disinfection was demonstrated by flow-through tests.

  6. Analysis of benzylpenicillin in milk using MALDI-TOF mass spectrometry with top-down synthesized TiO2 nanowires as the solid matrix.

    PubMed

    Kim, Jo-Il; Park, Jong-Min; Noh, Joo-Yoon; Hwang, Seong-Ju; Kang, Min-Jung; Pyun, Jae-Chul

    2016-01-01

    In this work, the wet-corrosion process for the synthesis of titanium oxide (TiO2) nanowires in the anatase phase was optimized as the solid matrix in MALDI-TOF mass spectrometry, and the solid matrix of the TiO2 nanowires was applied to the detection of antibiotics in a daily milk sample. The influence of the alkali concentration and the heat treatment temperature on the crystal structure of the TiO2 nanowires was investigated. The ionization activity of the TiO2 nanowires was estimated for each synthetic condition using amino acids as model analytes with low molecular weights. For the detection of antibiotics in milk, benzylpenicillin was spiked in daily milk samples, and MALDI-TOF mass spectrometry with the TiO2 nanowires was demonstrated to detect the benzylpenicillin at the cut-off concentration of the EU directive. PMID:25896977

  7. Preparation of new magnetic nanocatalysts based on TiO2 and ZnO and their application in improved photocatalytic degradation of dye pollutant under visible light.

    PubMed

    Nabid, Mohammad Reza; Sedghi, Roya; Gholami, Saeede; Oskooie, Hossein Abdi; Heravi, Majid M

    2013-01-01

    Photocatalytic degradation of methyl orange (MO) as a model of an organic pollution was accomplished with magnetic and porous TiO(2)/ZnO/Fe(3)O(4)/PANI and ZnO/Fe(3)O(4)/PANI nanocomposites under visible light irradiation. The structures of nanocomposites were characterized by various techniques including UV-Vis absorption spectroscopy, XRD, SEM, EDS, BET and TGA. Optical absorption investigations show two ?(max) at 450 and 590 nm for TiO(2)/ZnO/Fe(3)O(4)/PANI nanocomposites respectively possessing optical band gaps about 2.75 and 2.1 eV smaller than that of the neat TiO(2) and ZnO nanoparticles. Due to these optical absorptions, the nanocomposites can be considered promising candidates as visible light photocatalysts to produce more electron-hole pairs. The degradation of MO, extremely increased using polymeric photocatalysts and decolorization in the presence of visible light achieved up to 90% in less than 20 min in comparison with the neat nanoparticles (about 10%). All these advantages promise a bright future for these composites as useful photocatalysts. The degradation efficiency of MO using stable nanocomposites was still over 70% after ten times reusing. The highest decolorizing efficiencies were achieved with 0.75 g L(-1) of catalyst and 10 mg L(-1) of MO at natural pH under visible light irradiation in less than 20 min. PMID:22817280

  8. A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Li, L. H.; Deng, Z. X.; Xiao, J. X.; Yang, G. W.

    2015-06-01

    Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

  9. A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

    PubMed

    Li, L H; Deng, Z X; Xiao, J X; Yang, G W

    2015-01-26

    Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity. PMID:26040400

  10. Dual cure photocatalyst systems

    SciTech Connect

    DeVoe, R.J.; Brown-Wensley, K.A.; Holmes, G.L.; Mathis, M.D.; McCormick, F.B.; Palazzotto, M.C.; Spurgeon, K.M. . Corporate Research Labs.)

    1990-01-01

    A family of dual cure photocatalyst systems is being developed to be used in the solventless processing of organic coatings. The photocatalyst systems consist of organometallic compounds often in combination with other agents. Upon photolysis, the photocatalyst system generates a Lewis acid and a free radical. The Lewis acid can initiate the polymerization of epoxies or the addition of isocyanates and polyols to form polyurethanes while the free radical can initiate the polymerization of acrylates. The performance of the various photocatalyst systems will be compared on the basis of the physical properties of the cured compositions they produce. 17 figs.

  11. CTAB-assisted synthesis of monoclinic BiVO4 photocatalyst and its highly efficient degradation of organic dye under visible-light irradiation.

    PubMed

    Yin, Wenzong; Wang, Wenzhong; Zhou, Lin; Sun, Songmei; Zhang, Ling

    2010-01-15

    A highly efficient monoclinic BiVO(4) photocatalyst (C-BVO) was synthesized by an aqueous method with the assistance of cetyltrimethylammonium bromide (CTAB). The structure, morphology and photophysical properties of the C-BVO were characterized by XRD, FE-SEM and diffuse reflectance spectroscopy, respectively. The photocatalytic efficiencies were evaluated by the degradation of rhodamine B (RhB) under visible-light irradiation, revealing that the degradation rate over the C-BVO was much higher than that over the reference BiVO(4) prepared by aqueous method and over the one prepared by solid-state reaction. The efficiency of de-ethylation and that of the cleavage of conjugated chromophore structure were investigated, respectively. The chemical oxygen demand (COD) values of the RhB were measured after the photocatalytic degradation over the C-BVO and demonstrated a 53% decrease in COD. The effects of CTAB on the synthesis of C-BVO were investigated, which revealed that CTAB not only changed the reaction process via the formation of BiOBr as an intermediate, but also facilitated the transition from BiOBr to BiVO(4). Comparison experiments were carried out and showed that the existence of impurity level makes significant contribution to the high photocatalytic efficiency of the C-BVO. PMID:19733435

  12. Facile synthesis of Ag@CeO2 core-shell plasmonic photocatalysts with enhanced visible-light photocatalytic performance.

    PubMed

    Wu, Linen; Fang, Siman; Ge, Lei; Han, Changcun; Qiu, Ping; Xin, Yongji

    2015-12-30

    Novel Ag@CeO2 core-shell nanostructures with well-controlled shape and shell thickness were successfully synthesized via a green and facile template-free approach in aqueous solution. As-prepared samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (DRS), electron spin resonance (ESR) and photoluminescence spectroscopy (PL). The structures with different core shapes and controllable shell thickness exhibited unique optical properties. It is found that the nanoscale Ag@CeO2 core-shell photocatalysts exhibit significantly enhanced photocatalytic activities in the O2 evolution and MB dye degradation compared to pure CeO2 nanoparticals. The enhancement in photocatalytic activities can be ascribed to the localized surface plasmon resonance (SPR) of Ag cores. Moreover, larger active interfacial areas and contact between metal/semiconductor in the core-shell structure facilitate transfer of charge carriers and prolong lifetime of photogenerated electron-hole pairs. It is expected that the Ag@CeO2 core-shell structure may have great potential in a wider range of light-harvesting applications. PMID:26163484

  13. Hydrogen production by Tuning the Photonic Band Gap with the Electronic Band Gap of TiO2

    PubMed Central

    Waterhouse, G. I. N.; Wahab, A. K.; Al-Oufi, M.; Jovic, V.; Anjum, D. H.; Sun-Waterhouse, D.; Llorca, J.; Idriss, H.

    2013-01-01

    Tuning the photonic band gap (PBG) to the electronic band gap (EBG) of Au/TiO2 catalysts resulted in considerable enhancement of the photocatalytic water splitting to hydrogen under direct sunlight. Au/TiO2 (PBG-357?nm) photocatalyst exhibited superior photocatalytic performance under both UV and sunlight compared to the Au/TiO2 (PBG-585?nm) photocatalyst and both are higher than Au/TiO2 without the 3 dimensionally ordered macro-porous structure materials. The very high photocatalytic activity is attributed to suppression of a fraction of electron-hole recombination route due to the co-incidence of the PBG with the EBG of TiO2 These materials that maintain their activity with very small amount of sacrificial agents (down to 0.5 vol.% of ethanol) are poised to find direct applications because of their high activity, low cost of the process, simplicity and stability. PMID:24108361

  14. High power TiO2 and high capacity Sn-doped TiO2 nanomaterial anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lübke, Mechthild; Johnson, Ian; Makwana, Neel M.; Brett, Dan; Shearing, Paul; Liu, Zhaolin; Darr, Jawwad A.

    2015-10-01

    A range of phase-pure anatase TiO2 (?5 nm) and Sn-doped TiO2 nanoparticles with the formula Ti1-xSnxO2 (where x = 0, 0.06, 0.11 and 0.15) were synthesized using a continuous hydrothermal flow synthesis (CHFS) reactor. Charge/discharge cycling tests were carried out in two different potential ranges of 3 to 1 V and also a wider range of 3 to 0.05 V vs Li/Li+. In the narrower potential range, the undoped TiO2 nanoparticles display superior electrochemical performance to all the Sn-doped titania crystallites. In the wider potential range, the Sn-doped samples perform better than undoped TiO2. The sample with composition Ti0.85Sn0.15O2, shows a capacity of ca. 350 mAh g-1 at an applied constant current of 100 mA g-1 and a capacity of 192.3 mAh g-1 at a current rate of 1500 mA g-1. After 500 charge/discharge cycles (at a high constant current rate of 382 mA g-1), the same nanomaterial anode retains a relatively high specific capacity of 240 mAh g-1. The performance of these nanomaterials is notable, particularly as they are processed into electrodes, directly from the CHFS process (after drying) without any post-synthesis heat-treatment, and they are made without any conductive surface coating.

  15. Growth and characterization of TiO2 nanotubes from sputtered Ti film on Si substrate

    PubMed Central

    2012-01-01

    In this paper, we present the synthesis of self-organized TiO2 nanotube arrays formed by anodization of thin Ti film deposited on Si wafers by direct current (D.C.) sputtering. Organic electrolyte was used to demonstrate the growth of stable nanotubes at room temperature with voltages varying from 10 to 60?V (D.C.). The tubes were about 1.4 times longer than the thickness of the sputtered Ti film, showing little undesired dissolution of the metal in the electrolyte during anodization. By varying the thickness of the deposited Ti film, the length of the nanotubes could be controlled precisely irrespective of longer anodization time and/or anodization voltage. Scanning electron microscopy, atomic force microscopy, diffuse-reflectance UV–vis spectroscopy, and X-ray diffraction were used to characterize the thin film nanotubes. The tubes exhibited good adhesion to the wafer and did not peel off after annealing in air at 350?°C to form anatase TiO2. With TiO2 nanotubes on planar/stable Si substrates, one can envision their integration with the current micro-fabrication technique large-scale fabrication of TiO2 nanotube-based devices. PMID:22788778

  16. In situ sonosynthesis of nano TiO2 on cotton fabric.

    PubMed

    Akhavan Sadr, Farid; Montazer, Majid

    2014-03-01

    Here, titanium dioxide nanoparticles (NPs) were sonosynthesized and loaded simultaneously onto the cotton fabric. Titanium tetra isopropoxide (TTIP) was used as precursor and ultrasonic irradiation was utilized as a tool for synthesis of TiO2 in low temperature with anatase structure and loading nanoparticles onto the cotton fabric. TiO2 loaded cotton fabric was characterized by XRD, FE-SEM, EDS, and XRF. Moreover, several properties of the treated cotton fabrics such as self-cleaning, UV protection, washing durability, and tensile strength were studied. The effect of variables, including TTIP concentration and sonication time, was investigated based on central composite design (CCD) and response surface methodology (RSM). The results confirmed formation of anatase TiO2 nanoparticles with 3-6 nm crystalline size loaded onto the cotton fabric at low temperature (75 °C) that led to good self-cleaning and UV-protection properties. The excellent UV-protection rating of the treated fabric maintained even after 25 home launderings indicating an excellent washing durability. Interestingly, sonochemical method had no negative influence on the cotton fabric structure. The statistical analysis indicated significant effect of both TTIP concentration and sonication time on the content of the loaded TiO2 on the fiber and self-cleaning properties of the fabric. PMID:24152573

  17. Electron traps and their effect on the surface chemistry of TiO2(110)

    PubMed Central

    Papageorgiou, Anthoula C.; Beglitis, Nikolaos S.; Pang, Chi L.; Teobaldi, Gilberto; Cabailh, Gregory; Chen, Qiao; Fisher, Andrew J.; Hofer, Werner A.; Thornton, Geoff

    2010-01-01

    Oxygen vacancies on metal oxide surfaces have long been thought to play a key role in the surface chemistry. Such processes have been directly visualized in the case of the model photocatalyst surface TiO2(110) in reactions with water and molecular oxygen. These vacancies have been assumed to be neutral in calculations of the surface properties. However, by comparing experimental and simulated scanning tunneling microscopy images and spectra, we show that oxygen vacancies act as trapping centers and are negatively charged. We demonstrate that charging the defect significantly affects the reactivity by following the reaction of molecular oxygen with surface hydroxyl formed by water dissociation at the vacancies. Calculations with electronically charged hydroxyl favor a condensation reaction forming water and surface oxygen adatoms, in line with experimental observations. This contrasts with simulations using neutral hydroxyl where hydrogen peroxide is found to be the most stable product. PMID:20133773

  18. Synthesis and photocatalytic activity of mesoporous cerium doped TiO{sub 2} as visible light sensitive photocatalyst

    SciTech Connect

    Aman, Noor; Satapathy, P.K.; Mishra, T.; Mahato, M.; Das, N.N.

    2012-02-15

    Graphical abstract: Cerium doped titania having optimum 5 wt% of cerium can decompose methylene blue and reduce selenium (IV) efficiently under visible light. Highlights: Black-Right-Pointing-Pointer Effect of cerium doping on the surface properties and visible light mediated photocatalytic reaction is studied. Black-Right-Pointing-Pointer Cerium doping increases the anatase phase stability, surface area (up to 137 m{sup 2}/g) and visible light absorption. Black-Right-Pointing-Pointer Importance of Ce{sup 3+}/Ce{sup 4+}, oxygen vacancy, surface area and crystallinity is correlated with improved catalytic activity. Black-Right-Pointing-Pointer Material with 5 wt% Ce is found to be most active photocatalyst for methylene blue decomposition and Se (IV) reduction. -- Abstract: Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N{sub 2} adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 Degree-Sign C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 Degree-Sign C shows better activity than that calcined at 400 Degree-Sign C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce{sup 4+}/Ce{sup 3+} rather than only visible light absorption.

  19. UV-curable nanocomposite based on methacrylic-siloxane resin and surface-modified TiO2 nanocrystals.

    PubMed

    Ingrosso, Chiara; Esposito Corcione, Carola; Striani, Raffaella; Comparelli, Roberto; Striccoli, Marinella; Agostiano, Angela; Curri, M Lucia; Frigione, Mariaenrica

    2015-07-22

    A novel UV-light-curable nanocomposite material formed of a methacrylic-siloxane resin loaded with 1 wt % oleic acid and 3-(trimethoxysilyl)propyl methacrylate silane (OLEA/MEMO)-coated TiO2 nanorods (NRs) has been manufactured as a potential self-curing structural coating material for protection of monuments and artworks, optical elements, and dental components. OLEA-coated TiO2 NRs, presynthesized by a colloidal chemistry route, have been surface-modified by a treatment with the methacrylic-based silane coupling agent MEMO. The resulting OLEA/MEMO-capped TiO2 NRs have been dispersed in MEMO; that is a monomer precursor of the organic formulation, used as a "common solvent" for transferring the NRs in prepolymer components of the formulation. Differential scanning calorimetry and Fourier transform infrared spectroscopy have allowed investigation of the effects of the incorporation of the OLEA/MEMO-capped TiO2 NRs on reactivity and photopolymerization kinetics of the nanocomposite, demonstrating that the embedded NRs significantly increase curing reactivity of the neat organic formulation both in air and inert atmosphere. Such a result has been explained on the basis of the photoactivity of the nanocrystalline TiO2 which behaves as a free-radical donor photocatalyst in the curing reaction, finally turning out more effective than the commonly used commercial photoinitiator. Namely, the NRs have been found to accelerate the cure rate and increase cross-linking density, promoting multiple covalent bonds between the resin prepolymers and the NR ligand molecules, and, moreover, they limit inhibition effect of oxygen on photopolymerization. The NRs distribute uniformly in the photocurable matrix, as assessed by transmission electron microscopy analysis, and increase glass transition temperature and water contact angle of the nanocomposite with respect to the neat resin. PMID:26151152

  20. Antimicrobial photodisinfection with Zn(II) phthalocyanine adsorbed on TiO2 upon UVA and red irradiation

    NASA Astrophysics Data System (ADS)

    Mantareva, Vanya; Eneva, Ivelina; Kussovski, Vesselin; Borisova, Ekaterina; Angelov, Ivan

    2015-01-01

    The light exposure on a daily basis has been well accepted as a competitive method for decontamination of wastewater. The catalytic properties of TiO2 offer a great potential to reduce the transmission of pathogens in the environment. Although the titanium dioxide shows high activity against pathogens, its general usage in water cleaning is limited due to the insufficient excitation natural light (about 3% of the solar spectrum). A hydrophobic dodecylpyridyloxy Zn(II)-phthalocyanine with four peripheral hydrocarbon chains of C12 (ZnPcDo) was immobilized on a photocatalyst TiO2 anatase (P25). The resulted greenish colored nanoparticles of phthalocyanine were characterized by the means of absorption, fluorescence and infrared spectroscopy. The laser scanning confocal fluorescence microscopy was used to visualize the phthalocyanine dye by the red fluorescence emission (650 - 740 nm). The intensive Q-band in the far red visible spectral region (~ 690 nm) suggested a monomeric state of phthalocyanine on TiO2 nanoparticles. Two pathogenic bacterial strains (methicillin-resistant Staphylococcus aureus - MRSA and Salmonella enteritidis) associated with wastewater were photoinactivated with the suspension of the particles. The effective photoinactivation was observed with 1 g.L-1 TiO2 anatase at irradiation with UVA 364 nm as with UVA 364 nm and LED 643 nm. The gram-negative Salmonella enteritidis was fully photoinactivated with ZnPcDo-TiO2 and TiO2 alone at UVA 346 nm and at irradiation with two light sources (364 nm + 643 nm). The proposed conjugate appears as an useful composite material for antibacterial disinfection.

  1. Porous immobilized C coated N doped TiO2 containing in-situ generated polyenes for enhanced visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sabri, N. A.; Nawi, M. A.; Nawawi, W. I.

    2015-10-01

    Carbon coated nitrogen-doped Degussa P25TiO2 (or C,N-P25TiO2) was successfully immobilized on a glass plate using epoxidized natural rubber (ENR-50) and polyvinyl chloride (PVC) as the organic binders. Photo-etching of the fabricated system for 10 h oxidized its PVC binder into polyenes as well as forming a highly porous surface. The band gap energy (Eg) of the photo-etched immobilized photocatalyst system (C,N-P25TiO2/ENR/PVC-10 h) was reduced from 2.91 to 2.86 eV. Its photocatalytic activity was studied via photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under a 45 W visible light fluorescent lamp. C,N-P25TiO2/ENR/PVC-10 h with polyenes performed better than its slurry counterpart under visible light irradiation where the conjugated double bonds acted as photo sensitizers. The immobilized C,N-P25TiO2/ENR/PVC-10 h has excellent reusability and sustainable with an average k value of 0.056 ± 0.011 min-1 and average percent removal of 99.18 ± 0.54%.

  2. Core-shell VO2@TiO2 nanorods that combine thermochromic and photocatalytic properties for application as energy-saving smart coatings

    PubMed Central

    Li, Yamei; Ji, Shidong; Gao, Yanfeng; Luo, Hongjie; Kanehira, Minoru

    2013-01-01

    Vanadium dioxide (VO2) is a Mott phase transition compound that can be applied as a thermochromic smart material for energy saving and comfort, and titanium dioxide (TiO2) is a well-known photocatalyst for self-cleaning coatings. In this paper, we report a VO2@TiO2 core-shell structure, in which the VO2 nanorod core exhibits a remarkable modulation ability for solar infrared light, and the TiO2 anatase shell exhibits significant photocatalytic degradation of organic dye. In addition, the TiO2 overcoating not only increased the luminous transmittance of VO2 based on an antireflection effect, but also modified the intrinsic colour of VO2 films from yellow to light blue. The TiO2 also enhanced the chemical stability of VO2 against oxidation. This is the first report of such a single nanoparticle structure with both thermochromic and photocatalytic properties that offer significant potential for creating a multifunctional smart coating. PMID:23546301

  3. Monitoring of TiO2-catalytic UV-LED photo-oxidation of cyanide contained in mine wastewater and leachate.

    PubMed

    Kim, Seong Hee; Lee, Sang Woo; Lee, Gye Min; Lee, Byung-Tae; Yun, Seong-Taek; Kim, Soon-Oh

    2016-01-01

    A photo-oxidation process using UV-LEDs and TiO2 was studied for removal of cyanide contained in mine wastewater and leachates. This study focused on monitoring of a TiO2-catalyzed LED photo-oxidation process, particularly emphasizing the effects of TiO2 form and light source on the efficiency of cyanide removal. The generation of hydroxyl radicals was also examined during the process to evaluate the mechanism of the photo-catalytic process. The apparent removal efficiency of UV-LEDs was lower than that achieved using a UV-lamp, but cyanide removal in response to irradiation as well as consumption of electrical energy was observed to be higher for UV-LEDs than for UV-lamps. The Degussa P25 TiO2 showed the highest performance of the TiO2 photo-catalysts tested. The experimental results indicate that hydroxyl radicals oxidize cyanide to OCN(-), NO2(-), NO3(-), HCO3(-), and CO3(2-), which have lower toxicity than cyanide. In addition, the overall efficacy of the process appeared to be significantly affected by diverse operational parameters, such as the mixing ratio of anatase and rutile, the type of gas injected, and the number of UV-LEDs used. PMID:26195431

  4. Synthesis and Microstructure Evolution of Nano-Titania Doped Silicon Coatings

    NASA Astrophysics Data System (ADS)

    Moroz, N. A.; Umapathy, H.; Mohanty, P.

    2010-01-01

    The Anatase phase of Titania (TiO2) in nanocrystalline form is a well known photocatalyst. Photocatalysts are commercially used to accelerate photoreactions and increase photovoltaic efficiency such as in solar cells. This study investigates the in-flight synthesis of Titania and its doping into a Silicon matrix resulting in a catalyst-dispersed coating. A liquid precursor of Titanium Isopropoxide and ethanol was coaxially fed into the plasma gun to form Titania nanoparticles, while Silicon powder was externally injected downstream. Coatings of 75-150 ?m thick were deposited onto flat coupons. Further, Silicon powder was alloyed with aluminum to promote crystallization and reduce the amorphous phase in the Silicon matrix. Dense coatings containing nano-Titania particles were observed under electron microscope. X-ray diffraction showed that both the Rutile and Anatase phases of the Titania exist. The influence of process parameters and aluminum alloying on the microstructure evolution of the doped coatings is analyzed and presented.

  5. Photoelectrocatalytic decomposition of ethylene using TiO2/activated carbon fiber electrode with applied pulsed direct current square-wave potential

    NASA Astrophysics Data System (ADS)

    Ye, Sheng-ying; Zheng, Sen-hong; Song, Xian-liang; Luo, Shu-can

    2015-06-01

    Removing ethylene (C2H4) from the atmosphere of storage facilities for fruits and vegetable is one of the main challenges in their postharvest handling for maximizing their freshness, quality, and shelf life. In this study, we investigated the photoelectrocatalytic (PEC) degradation of ethylene gas by applying a pulsed direct current DC square-wave (PDCSW) potential and by using a Nafion-based PEC cell. The cell utilized a titanium dioxide (TiO2) photocatalyst or ?-irradiated TiO2 (TiO2*) loaded on activated carbon fiber (ACF) as a photoelectrode. The apparent rate constant of a pseudo-first-order reaction (K) was used to describe the PEC degradation of ethylene. Parameters of the potential applied to the PEC cell in a reactor that affect the degradation efficiency in terms of the K value were studied. These parameters were frequency, duty cycle, and voltage. Ethylene degradation by application of a constant PDCSW potential to the PEC electrode of either TiO2/ACF cell or TiO2*/ACF cell enhanced the efficiency of photocatalytic degradation and PEC degradation. Gamma irradiation of TiO2 in the electrode and the applied PDCSW potential synergistically increased the K value. Independent variables (frequency, duty cycle, and voltage) of the PEC cell fabricated from TiO2 subjected 20 kGy ? radiation were optimized to maximize the K value by using response surface methodology with quadratic rotation-orthogonal composite experimental design. Optimized conditions were as follows: 358.36 Hz frequency, 55.79% duty cycle, and 64.65 V voltage. The maximum K value attained was 4.4 × 10-4 min-1.

  6. Effect of substrate on evaluation of the photocatalytic activity of TiO2 nanocrystals with exposed {0 0 1} facets

    NASA Astrophysics Data System (ADS)

    Ye, Hengpeng; Lu, Shaoming

    2013-04-01

    There are increasing debates on the high photocatalytic activity of TiO2 nanocrystals with exposed high-energy facets. In this paper, the effect of substrate on evaluation of the photocatalytic activity of anatase TiO2 nanocrystals with exposed {0 0 1} facets was studied. Surface-clean anatase TiO2 nanocrystals with exposed {0 0 1} facets were prepared by a microwave-assisted hydrothermal route in a Ti(OC4H9)4-HF-H2O mixed solution (both the amount of Ti(OC4H9)4 and HF were 60 mmol). It was found that the percentage of exposed {0 0 1} facets is negatively correlated with the molar ratio of water to titanium/or fluoride (x). With increasing x from 0 to 21, the percentage of exposed {0 0 1} facets steadily decreases from 81% to 36%. Anionic dye Brilliant Red X-3B (X3B) and cationic dye Methylene Blue (MB) were used as probes to evaluate the relative photocatalytic activity of the prepared TiO2 samples. TiO2 nanocrystals with exposed 40% {0 0 1} facets at x = 15 shows the highest photocatalytic activity in degradation of MB. However, an overwhelmingly better performance of TiO2 sample with exposed 49% {0 0 1} facets at x = 9 was found among all the photocatalysts in photocatalytic degradation of X3B, reflecting the importance of substrate on evaluation the photocatalytic activity of high-energy TiO2 nanocrystals.

  7. Enhanced visible-light photocatalytic performances of Ag3PO4 surface-modified with small amounts of TiO2 and Ag

    NASA Astrophysics Data System (ADS)

    Wang, Desong; Li, Lei; Luo, Qingzhi; An, Jing; Li, Xueyan; Yin, Rong; Zhao, Mangmang

    2014-12-01

    A novel approach has been developed to prepare an efficient visible-light photocatalyst using Ag3PO4 and TiO2 sol as precursors. First, Ag3PO4 particles were dipped into TiO2 sol for 5 min and were filtered quickly. Second, Ag3PO4 particles adsorbing a small amount of TiO2 sol were aged for 24 h to form TiO2 gel on their surface. Finally, Ag3PO4 particles covered by TiO2 gel were calcined at 450 °C for 2 h to obtain the surface-modified Ag3PO4 sample. The surface-modified Ag3PO4 was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The visible-light photocatalytic performances of the surface-modified Ag3PO4 were evaluated by the photodegradation of methyl orange or phenol solution. The results showed that the surface-modified Ag3PO4 exhibited much higher visible-light photocatalytic activity and stability than pure Ag3PO4. As the amount of TiO2 gel on the Ag3PO4 surface increased, the visible-light photocatalytic activity increased first and then decreased. The surface-modification of Ag3PO4 obviously decreased its solubility in water environment due to the protection of TiO2 and Ag nanocrystals on the surface. The visible-light photocatalytic mechanism of the surface-modified Ag3PO4 has been discussed.

  8. UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

    PubMed

    Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

    2014-10-01

    Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency. PMID:24217967

  9. Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11.

    PubMed

    Li, Zhao-Qian; Chen, Wang-Chao; Guo, Fu-Ling; Mo, Li-E; Hu, Lin-Hua; Dai, Song-Yuan

    2015-01-01

    Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells. PMID:26384004

  10. Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11%

    NASA Astrophysics Data System (ADS)

    Li, Zhao-Qian; Chen, Wang-Chao; Guo, Fu-Ling; Mo, Li-E.; Hu, Lin-Hua; Dai, Song-Yuan

    2015-09-01

    Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells.

  11. Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11%

    PubMed Central

    Li, Zhao-Qian; Chen, Wang-Chao; Guo, Fu-Ling; Mo, Li-E; Hu, Lin-Hua; Dai, Song-Yuan

    2015-01-01

    Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells. PMID:26384004

  12. Enhanced Photocatalytic Activity for H2 Evolution under Irradiation of UV–Vis Light by Au-Modified Nitrogen-Doped TiO2

    PubMed Central

    Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

    2014-01-01

    Background Purpose Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Methods Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV–vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. Results DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV–vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Conclusion Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV–vis light. PMID:25090093

  13. Enhancing the photocatalytic activity of TiO2 co-doping of graphene-Fe3+ ions for formaldehyde removal.

    PubMed

    Low, Wasu; Boonamnuayvitaya, Virote

    2013-09-30

    In the present work, graphene and Fe(3+) ions were doped to enhance the photocatalytic activity of a TiO2 photocatalyst with the expectation of synergistic effects on the specific surface area and electronic conductivity due to the formation of Ti-O-C bonds preventing charge recombination contributed by graphene and band gap energy narrowing by doping with Fe(3+) ions. GR/Fe(3+)-TiO2 was successfully synthesized by the refluxed peroxo titanic acid (PTA) method and was tested for gaseous formaldehyde removal. The results show that graphene contributed to formaldehyde adsorption since the equilibrium adsorption capacity increased with an increasing weight ratio of graphene. The GR/Fe(3+)-TiO2 photocatalyst with a weight ratio of graphene to TiO2 (PTA) of 1:50 and the Fe(3+) dopant at 0.12 wt% was optimal. An equilibrium formaldehyde adsorption capacity of 10.2 mg(HCHO) g(-1)catalyst and photodegradation efficiency of about 50.3% and 25.5% under UV and visible light irradiation for 90 min, respectively, were obtained. It was observed that the adsorption property of the catalyst was increased by adding graphene and the extendable absorption edge of light to longer wavelengths was attributed to the synergistic effect of graphene and Fe(3+) dopants on the band gap energy of the catalyst. The greater photocatalytic activity of GR/Fe(3+)-TiO2 compared to GR-TiO2 resulted from more hydroxyl (OH) and superoxide [Formula: see text] radicals produced via redox reactions with Fe ions. PMID:23694821

  14. Oxidation of S(IV) in Seawater by Pulsed High Voltage Discharge Plasma with TiO2/Ti Electrode as Catalyst

    NASA Astrophysics Data System (ADS)

    Gong, Jianying; Zhang, Xingwang; Wang, Xiaoping; Lei, Lecheng

    2013-12-01

    Oxidation of S(IV) to S(VI) in the effluent of a flue gas desulfurization(FGD) system is very critical for industrial applications of seawater FGD. This paper reports a pulsed corona discharge oxidation process combined with a TiO2 photocatalyst to convert S(IV) to S(VI) in artificial seawater. Experimental results show that the oxidation of S(IV) in artificial seawater is enhanced in the pulsed discharge plasma process through the application of TiO2 coating electrodes. The oxidation rate of S(IV) using Ti metal as a ground electrode is about 2.0×10-4 mol · L-1 · min-1, the oxidation rate using TiO2/Ti electrode prepared by annealing at 500°C in air is 4.5×10-4 mol · L-1 · min-1, an increase with a factor 2.25. The annealing temperature for preparing TiO2/Ti electrode has a strong effect on the oxidation of S(IV) in artificial seawater. The results of in-situ emission spectroscopic analysis show that chemically active species (i.e. hydroxyl radicals and oxygen radicals) are produced in the pulsed discharge plasma process. Compared with the traditional air oxidation process and the sole plasma-induced oxidation process, the combined application of TiO2 photocatalysts and a pulsed high-voltage electrical discharge process is useful in enhancing the energy and conversion efficiency of S(IV) for the seawater FGD system.

  15. Photo-Catalytic Properties of TiO2 Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites

    NASA Astrophysics Data System (ADS)

    Ramoraswi, Nteseng O.; Ndungu, Patrick G.

    2015-10-01

    Mesoporous silica, specifically SBA-15, acid-treated multi-walled carbon nanotubes and a hybrid nanocomposite of SBA-15 coated onto the sidewalls acid-treated multi-walled carbon nanotubes (CNTs) were prepared and used as supports for anatase TiO2. Sol-gel methods were adapted for the synthesis of selected supports and for coating the materials with selected wt% loading of titania. Physical and chemical properties of the supports and catalyst composite materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectroscopy and fluorescence spectroscopy. The photo-activity of the catalyst composites were evaluated on the decolorisation of methylene blue as a model pollutant. Coating CNTs with SBA-15 improved the thermal stability and textural properties of the nanotubes. All supported titania composites had high surface areas (207-301 m2/g), altered band gap energies and reduced TiO2 crystallite sizes. The TiO2/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO2/SBA-15 and TiO2/CNT composites. In addition, an interesting observation was noted with the TiO2/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO2/CNT nanocomposites in spite of the high electron-hole recombination phenomena observed with the photoluminescence results. Discussions in terms of morphological, textural and physical-chemical aspects to account for the result are presented.

  16. Photo-Catalytic Properties of TiO2 Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites.

    PubMed

    Ramoraswi, Nteseng O; Ndungu, Patrick G

    2015-12-01

    Mesoporous silica, specifically SBA-15, acid-treated multi-walled carbon nanotubes and a hybrid nanocomposite of SBA-15 coated onto the sidewalls acid-treated multi-walled carbon nanotubes (CNTs) were prepared and used as supports for anatase TiO2. Sol-gel methods were adapted for the synthesis of selected supports and for coating the materials with selected wt% loading of titania. Physical and chemical properties of the supports and catalyst composite materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectroscopy and fluorescence spectroscopy. The photo-activity of the catalyst composites were evaluated on the decolorisation of methylene blue as a model pollutant. Coating CNTs with SBA-15 improved the thermal stability and textural properties of the nanotubes. All supported titania composites had high surface areas (207-301 m(2)/g), altered band gap energies and reduced TiO2 crystallite sizes. The TiO2/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO2/SBA-15 and TiO2/CNT composites. In addition, an interesting observation was noted with the TiO2/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO2/CNT nanocomposites in spite of the high electron-hole recombination phenomena observed with the photoluminescence results. Discussions in terms of morphological, textural and physical-chemical aspects to account for the result are presented. PMID:26518026

  17. Single-Step Synthesis of SnS? Nanosheet-Decorated TiO? Anatase Nanofibers as Efficient Photocatalysts for the Degradation of Gas-Phase Diethylsulfide.

    PubMed

    Christoforidis, Konstantinos C; Sengele, Armelle; Keller, Valérie; Keller, Nicolas

    2015-09-01

    We report on a facile one-step soft hydrothermal process for synthesizing 1D anatase TiO2 nanofibers decorated with ultrathin SnS2 nanosheets. H-titanate nanofibers were used as preshaped Ti precursor. Under controlled conditions, the H-titanate structure was transformed into anatase maintaining the fibril morphology, while at the same time SnS2 nanosheets were grown in situ on the surface of the nanofibers. The successful formation of SnS2 nanosheets on the TiO2 nanofibers was confirmed by high-resolution TEM, and together with XPS spectroscopy, the tight interface formed between the SnS2 and the anatase TiO2 nanofibers was verified. The 1D SnS2/TiO2 hierarchical nanostructures with semiconductor heterojunction were proven to be very efficient under artificial solar irradiation in the photocatalytic degradation of gaseous diethylsulfide as simulant for live yperite chemical warfare agent as well as model substrate for malodorous organosulfide volatile organic compounds. SnS2 did not operate as a visible light sensitizer for TiO2 but rather as an oxidizing agent and charge-carrier separator. The semiconductor ratio in the heterostructure controlled the photoactivity. Samples with no or high content of SnS2 were less active than those with moderate SnS2 content. Enhanced reactivity was ascribed to an efficient separation of the photogenerated charge carriers driven by the differences in band edge positions and favored by the tight interface within the coupled heterostructure. PMID:26262595

  18. Photocatalytic degradation of 17?-ethinylestradiol (EE2) in the presence of TiO2-doped zeolite.

    PubMed

    Pan, Zhong; Stemmler, Elizabeth A; Cho, Hong Je; Fan, Wei; LeBlanc, Lawrence A; Patterson, Howard H; Amirbahman, Aria

    2014-08-30

    Current design limitations and ineffective remediation techniques in wastewater treatment plants have led to concerns about the prevalence of pharmaceutical and personal care products (PPCPs) in receiving waters. A novel photocatalyst, TiO2-doped low-silica X zeolite (TiO2-LSX), was used to study the degradation of the pharmaceutical compound, 17?-ethinylestradiol (EE2). The catalyst was synthesized and characterized using XRD, BET surface analysis, SEM-EDAX, and ICP-OES. The effects of different UV light intensities, initial EE2 concentrations, and catalyst dosages on the EE2 removal efficiency were studied. A higher EE2 removal efficiency was attained with UV-TiO2-LSX when compared with UV-TiO2 or UV alone. The EE2 degradation process followed pseudo-first-order kinetics. A comprehensive empirical model was developed to describe the EE2 degradation kinetics under different conditions using multiple linear regression analysis. The EE2 degradation mechanism was proposed based on molecular calculations, identification of photoproducts using HPLC-MS/MS, and reactive species quenching experiments; the results showed that oxidative degradation pathways initiated by hydroxyl radicals were predominant. This novel TiO2-doped zeolite system provides a promising application for the UV disinfection process in wastewater treatment plants. PMID:25036996

  19. Preparation and characterization of PVA-I complex doped mesoporous TiO2 by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Shi, Qian; Jiang, Caiyun; Wang, Yuping; Yang, Weiben; Yang, Chun

    2013-05-01

    Polyvinyl alcohol [PVA]-iodine complex doped mesoporous TiO2 (PIT) and iodine doped (IT) catalysts were prepared by hydrothermal method, using tetrabutyl titanate as precursor, potassium iodate and iodine as iodine sources. The as-prepared PIT and IT catalysts were characterized by UV-vis, XRD, FESEM, BET, TG/DTA, XPS and photoluminescence (PL) spectroscopy. Production of rad OH radicals on the surface of photocatalyst was detected by the PL technique using terephthalic acid as a probe molecule. The influences of calcinated temperature on the structure and properties of the catalysts were investigated. The photocatalytic activity of catalysts was evaluated through photocatalytic decolorization of methylene blue (MB) aqueous solution. The results showed that PIT samples were anatase mesoporous TiO2 and their iodine content and mesoporous structure were influenced by calcinated temperature. Particle size of PIT samples was smaller than that of IT as a result of the PVA skeleton and regular structure. Because of the complexation of iodine and PVA, thermostability of iodine is improved and the amount of iodine in PIT calcinated at 200 °C (PIT-200) is higher than that of IT calcinated at same temperature. Light absorption range and intensity of PIT-200 has been greatly improved due to the synergy of iodine and carbon. The efficiency of photocatalysis for MB is greatly improved with TiO2 modified by PVA-I complex under simulated sun light irradiation.

  20. Development and Progress in Enabling the Photocatalyst Ti02 Visible-Light-Active

    NASA Technical Reports Server (NTRS)

    Levine, Lanfang H.; Coutts, Janelle L.; Clausen, Christian A.

    2011-01-01

    Photocatalytic oxidation (PCO) of organic contaminants is a promising air and water quality management approach which offers energy and cost savings compared to thermal catalytic oxidation (TCO). The most widely used photocatalyst, anatase TiO2, has a wide band gap (3.2 eV) and is activated by UV photons. Since solar radiation consists of less than 4% UV, but contains 45% visible light, catalysts capable of utilizing these visible photons need to be developed to make peo approaches more efficient, economical, and safe. Researchers have attempted various approaches to enable TiO2 to be visible-light-active with varied degrees of success'. Strategies attempted thus far fall into three categories based on their electrochemical' mechanisms: 1) narrowing the band gap of TiO2 by implantation of transition metal elements or nonmetal elements such as N, S, and C, 2) modifying electron-transfer processes during PCO by adsorbing sensitizing dyes, and 3) employing light-induced interfacial electron transfer in the heteronanojunction systems consisting of narrow band gap semiconductors represented by metal sulfides and TiO2. There are diverse technical approaches to implement each of these strategies. This paper presents a review of these approaches and results of the photocatalytic activity and photonic efficiency of the end .products under visible light. Although resulting visible-light-active (VLA) photocatalysts show promise, there is often no comparison with unmodified TiO2 under UV. In a limited number of studies where such comparison was provided, the UV-induced catalytic activity of bare TiO2 is much greater than the visible-light-induced catalytic activity of the VLA catalyst. Furthermore, VLA-catalysts have much lower quantum efficiency compared to the approx.50% quantum efficiency of UV-catalysts. This stresses the need for continuing research in this area.

  1. Arrays of templated TiO2 nanofibres as improved photoanodes for water splitting under visible light.

    PubMed

    Ongaro, M; Mardegan, A; Stortini, A M; Signoretto, M; Ugo, P

    2015-04-24

    Arrays of TiO2 nanofibres (NFs) were successfully prepared by template sol-gel synthesis, using track-etched polycarbonate membranes as structure directing agent. The control of the sol-gel kinetic was crucial in order to homogeneously fill the pores with a continuous framework. For this reason acetylacetone was added to the sol-gel mixture as chelating agent. The band edge positions of TiO2 NFs were determined by a Mott-Schottky plot and diffuse reflectance analysis. The results support the presence of trace dopants which can act favorably with respect to the photoelectrochemical properties. The TiO2 NFs array showed enhanced photoelectrochemical activity both under UV light and visible light when used as photoanodes for the water splitting reaction. PMID:25824700

  2. P-doped TiO2 with superior visible-light activity prepared by rapid microwave hydrothermal method

    NASA Astrophysics Data System (ADS)

    Niu, Jinfen; Lu, Pan; Kang, Mei; Deng, Kunfa; Yao, Binghua; Yu, Xiaojiao; Zhang, Qian

    2014-11-01

    Phosphorous-doped anatase TiO2 powders (P-TiO2) were prepared by rapid microwave hydrothermal method. The resulting materials were characterized by XRD, SEM, XPS, DRS and N2 adsorption. P-doping decreased the band gap and enlarged the surface area of P-doped samples than that of undoped TiO2 samples. Therefore, the photocatalytic degradation of methyl blue (MB) and tetracycline hydrochloride (Tc) experiments showed that the P-TiO2 catalysts, especially the two-steps-controlling products P-TiO2-2, exhibited higher degradation efficiency than the undoped TiO2 and commercial P25 under visible-light irradiation. Hydroxyl radicals (rad OH) have been confirmed to be the active species during the photocatalytic oxidation reaction. The microwave hydrothermal method confirms to be very suitable for the synthesis of superior visible-light activity P-doped samples.

  3. Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells

    SciTech Connect

    Nie, Zimin; Zhou, Xiaoyuan; Zhang, Qifeng; Cao, Guozhong; Liu, Jun

    2013-11-01

    One-dimensional (1D) semiconducting oxides have attracted great attention for dye sensitized solar cells (DSCs), but the overall performance is still quite limited as compared to TiO2 nanocrystalline DSCs. Here, we report the synthesis of aggregated TiO2 based nanotubes with controlled morphologies and crystalline structures to obtain an overall power conversion efficiency of 9.9% using conventional dye without any additional chemical treatment steps. The high efficiency is attributed to the unique aggregate structure for light harvesting, optimized high surface area, and good crystallinity of the nanotube aggregates obtained through proper thermal annealing. This study demonstrates that high efficiency DSCs can be obtained with 1D nanomaterials, and provides lessons on the importance of optimizing both the nanocrystalline structure and the overall microscale morphology.

  4. Conductivity in transparent anatase TiO 2 films epitaxially grown by reactive sputtering deposition

    NASA Astrophysics Data System (ADS)

    Jeong, B.-S.; Norton, D. P.; Budai, J. D.

    2003-12-01

    The synthesis of semiconducting TiO 2 thin films deposited by reactive sputtering is discussed. In particular, defect doping of the anatase polymorph that is epitaxial stabilized on (0 0 1) LaAlO 3 was explored using either oxygen or water vapor as the oxidizing species. For films grown in oxygen, a transition from insulating to metallic conductivity of the films is observed as the O 2 pressure is reduced. X-ray diffraction measurements show the presence of the Ti nO 2 n-1 phase when the oxygen pressure is reduced sufficiently to induce conductive behavior. Hall measurements indicate that these materials are p-type. In contrast, the use of water vapor as the oxidizing species enabled the formation of n-type semiconducting TiO 2 with carrier density on the order of 10 18 cm -3 and mobility of 10-15 cm 2/V s.

  5. Effect of Aging Time on Crystalline Structure Evolution of TiO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Supothina, Sitthisuntorn; Juengsuwattananon, Kannikar; Panyathanmaporn, Thammarat; Jaroenworaluck, Angkhana; Jinawath, Supatra; Sooknoi, Tawan; Tawkaew, Sittinun

    It has been well realized that anatase TiO2 transforms to a more thermodynamically stable rutile phase by heat treatment at moderately high temperature, typically higher than 600 °C. However, by using suitable synthesis condition the anatast-to-rutitle phase transformation can occur at much lower temperature. In this present work, phase transformation during aging of TiO2 sol at room temperature was investigated. The sol was prepared based on hydrolysis and condensation of tetrabutyl orthotitanate precursor in the presence of small amount of water and hydrochloric acid. During aging time span of 50 days, the sol was sampled every 10 days for crystal structure and size analysis. It was found that aging time had a pronounced effect on anatase-to-rutile phase transformation accompanied by crystallite growth. Complete phase transformation was observed within 40 days of aging.

  6. The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance

    PubMed Central

    Cheng, Chia-Liang; Sun, Der-Shan; Chu, Wen-Chen; Tseng, Yao-Hsuan; Ho, Han-Chen; Wang, Jia-Bin; Chung, Pei-Hua; Chen, Jiann-Hwa; Tsai, Pei-Jane; Lin, Nien-Tsung; Yu, Mei-Shiuan; Chang, Hsin-Hou

    2009-01-01

    Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2. PMID:19272171

  7. Photogenerated charges transfer across the interface between NiO and TiO2 nanotube arrays for photocatalytic degradation: A surface photovoltage study.

    PubMed

    Hou, Libo; Li, Shuo; Lin, Yanhong; Wang, Dejun; Xie, Tengfeng

    2016-02-15

    To better understand the behavior of photogenerated charges in the composite photocatalyst interface is beneficial to the designing of effective photocatalyst for photocatalytic reaction. In our work, the separation and transfer process of photogenerated charges in NiO/TiO2 nanotube arrays (NiO/TiO2 NTAs) has been studied by surface photovoltage (SPV) spectroscopy and transient photovoltage (TPV) measurement. Through the experimental results analysis, we find that an interfacial electric field is formed at NiO/TiO2 NTAs interface, which is attributed to the work function difference between NiO and TiO2 NTAs. The photogenerated holes in TiO2 can transfer to the NiO layer along the interface electric field under the ultraviolet irradiation. A large amount of photogenerated holes can be separated effectively and then prolonged the holes lifetime to participate in the photocatalytic oxidation reaction. The above results show that the favorable hole-collecting process of NiO in the surface of TiO2 NTAs is the main factor being responsible for the increase the photocatalytic efficiency. PMID:26609928

  8. Fabrication of CdS/TiO 2 nano-bulk composite photocatalysts for hydrogen production from aqueous H 2S solution under visible light

    NASA Astrophysics Data System (ADS)

    Jang, Jum Suk; Li, Wei; Oh, Se Hyuk; Lee, Jae Sung

    2006-07-01

    CdS/TiO 2 nano-bulk composite (NBC) photocatalyst of a new configuration consisting of bulky CdS with high crystallinity decorated with nanosized TiO 2 particles exhibited an unprecedented high rate of hydrogen production under visible light irradiation ( ? ? 420 nm) from water containing sulfide and sulfite ions as hole scavengers. The fabrication method of the composite photocatalysts was critical for their performance. It was demonstrated that this active composite photocatalyst could be applied for practical processes of simultaneous hydrogen production and H 2S removal in the treatment of Claus plant tail gas streams or vents of hydrodesulfurization plants.

  9. Cobalt phosphate modified TiO2 nanowire arrays as co-catalysts for solar water splitting

    NASA Astrophysics Data System (ADS)

    Ai, Guanjie; Mo, Rong; Li, Hongxing; Zhong, Jianxin

    2015-04-01

    Cobalt phosphate (Co-Pi) is photo-electrodeposited on TiO2 nanowire arrays in Co2+ containing phosphate buffer. The resulting composite photoanode shows a generally enhanced photocurrent near the flat band potential region, and represents a 2.3 times improved photoconversion efficiency compared to that of pristine TiO2 in a neutral electrolyte. A negative effect on the photocurrent generation is also observed when loading TiO2 with a relatively thick Co-Pi layer, which is demonstrated to be due to the poor photohole transfer kinetics in the Co-Pi layer. Moreover, we find that Co-Pi can facilitate the photoelectrochemical performance of TiO2 over a wide pH range from 1-14. This improved activity is studied in detail by optical and electrochemical analyses. It is suggested that the mechanism of the overpotential-demanding water oxidation reaction is changed to a facile pathway by the Co-based electrocatalyst. At the same time, the more significant band bending is induced by the Co-Pi catalyst decreasing the charge recombination. This work provides a feasible route to reduce the external power needed to drive water splitting by coupling an electrocatalyst with a photocatalyst, as well as mechanistic insights important for other Co-Pi modified photoelectrodes for solar-driven water splitting.Cobalt phosphate (Co-Pi) is photo-electrodeposited on TiO2 nanowire arrays in Co2+ containing phosphate buffer. The resulting composite photoanode shows a generally enhanced photocurrent near the flat band potential region, and represents a 2.3 times improved photoconversion efficiency compared to that of pristine TiO2 in a neutral electrolyte. A negative effect on the photocurrent generation is also observed when loading TiO2 with a relatively thick Co-Pi layer, which is demonstrated to be due to the poor photohole transfer kinetics in the Co-Pi layer. Moreover, we find that Co-Pi can facilitate the photoelectrochemical performance of TiO2 over a wide pH range from 1-14. This improved activity is studied in detail by optical and electrochemical analyses. It is suggested that the mechanism of the overpotential-demanding water oxidation reaction is changed to a facile pathway by the Co-based electrocatalyst. At the same time, the more significant band bending is induced by the Co-Pi catalyst decreasing the charge recombination. This work provides a feasible route to reduce the external power needed to drive water splitting by coupling an electrocatalyst with a photocatalyst, as well as mechanistic insights important for other Co-Pi modified photoelectrodes for solar-driven water splitting. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00863h

  10. Photocatalytic characteristic and photodegradation kinetics of toluene using N-doped TiO2 modified by radio frequency plasma.

    PubMed

    Shie, Je-Lueng; Lee, Chiu-Hsuan; Chiou, Chyow-San; Chen, Yi-Hung; Chang, Ching-Yuan

    2014-01-01

    This study investigates the feasibility of applications of the plasma surface modification of photocatalysts and the removal of toluene from indoor environments. N-doped TiO2 is prepared by precipitation methods and calcined using a muffle furnace (MF) and modified by radio frequency plasma (RF) at different temperatures with light sources from a visible light lamp (VLL), a white light-emitting diode (WLED) and an ultraviolet light-emitting diode (UVLED). The operation parameters and influential factors are addressed and prepared for characteristic analysis and photo-decomposition examination. Furthermore, related kinetic models are established and used to simulate the experimental data. The characteristic analysis results show that the RF plasma-calcination method enhanced the Brunauer Emmett Teller surface area of the modified photocatalysts effectively. For the elemental analysis, the mass percentages of N for the RF-modified photocatalyst are larger than those of MF by six times. The aerodynamic diameters of the RF-modifiedphotocatalyst are all smaller than those of MF. Photocatalytic decompositions of toluene are elucidated according to the Langmuir-Hinshelwood model. Decomposition efficiencies (eta) of toluene for RF-calcined methods are all higher than those of commercial TiO2 (P25). Reaction kinetics ofphoto-decomposition reactions using RF-calcined methods with WLED are proposed. A comparison of the simulation results with experimental data is also made and indicates good agreement. All the results provide useful information and design specifications. Thus, this study shows the feasibility and potential use of plasma modification via LED in photocatalysis. PMID:24645445

  11. XAS study of TiO2-based nanomaterials

    NASA Astrophysics Data System (ADS)

    Schneider, K.; Zajac, D.; Sikora, M.; Kapusta, Cz.; Michalow-Mauke, K.; Graule, Th.; Rekas, M.

    2015-07-01

    X-Ray Absorption Spectroscopy studies of the W (0-1 at% W) and Mo-doped TiO2 (0-1 at% Mo) nanoparticle specimens at the K edges of titanium and molybdenum as well as at the L2 L3 edges of tungsten are presented. The materials were prepared with Flame Spray Synthesis process by oxidation of metal-organic precursors. The Ti:K edge spectra in the XANES range show pre-edge and post-edge features characteristic for anatase. A decrease of the amplitude of the EXAFS function with doping is observed and attributed to a softening of the crystal lattice. The Mo EXAFS functions show a considerable decrease of the second-neighbour-shell peak with increasing Mo content, which is attributed to an increased number of cation vacancies. For tungsten a less pronounced effect is observed. The Mo and W XANES spectra do not show noticeable changes with doping level, which indicates their unchanged oxidation states.

  12. Effect of solution combusted TiO2 nanopowder within commercial BaTiO3 dielectric layer on the photoelectric properties for AC powder electroluminescence devices.

    PubMed

    Park, Sung; Choi, Gil Rak; Kim, Youn Cheol; Lee, Jae Chun; Lee, Ju Hyeon

    2013-05-01

    A unique synthesis method was developed, which is called solution combustion method (SCM). TiO2 nanopowder was synthesized by this method. This SCM TiO2 nanopowder (-35 nm) was added to the dielectric layer of AC powder electroluminescence (EL) device. The dielectric layer was made of commercial BaTiO3 powder (-1.2 microm) and binding polymer. 0, 5, 10 and 15 wt% of SCM TiO2 nanopowder was added to the dielectric layer during fabrication of AC powder EL device respectively. Dielectric constant of these four kinds of dielectric layers was measured. The brightness and current density of AC powder EL device were also measured. When 10 wt% of SCM TiO2 nanopowder was added, dielectric constant and brightness were increased by 30% and 101% respectively. Furthermore, the current density was decreased by 71%. This means that the brightness was double and the power consumption was one third. PMID:23858874

  13. Root growth of TiO 2 nanorods by sputtering

    NASA Astrophysics Data System (ADS)

    Pradhan, Swati S.; Pradhan, Siddhartha K.; Bagchi, S.; Barhai, P. K.

    2011-09-01

    The growth of TiO 2 nanorods by a simple sputtering method is reported. Here we show that by sputtering of Ti target in argon-oxygen plasma it is possible to grow rutile core and anatase shell heterostructure TiO 2 nanorods on gold (Au) coated Si(1 0 0) substrate without external heating. It seems that the nanorods grow because of the stress assisted diffusion of under-laying Au atoms into the TiO 2 film followed by catalytic growth of the nanorods at the root.

  14. Adsorption-photodegradation of humic acid in water by using ZnO coupled TiO2/bamboo charcoal under visible light irradiation.

    PubMed

    Wang, Xuejiang; Wu, Zhen; Wang, Yin; Wang, Wei; Wang, Xin; Bu, Yunjie; Zhao, Jianfu

    2013-11-15

    ZnO coupled TiO2/bamboo charcoal (ZnO-TiO2/BC) was prepared using the sol-gel method combined with microwave irradiation. The ZnO-TiO2/BC and TiO2/BC were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption (BET), and UV-vis diffuse reflectance spectroscopy (UV-vis-DRS). The ZnO dopant promoted the transformation of anatase TiO2 to rutile phase, and a significant red shift of absorption edge was brought out due to the interfacial coupling effect between ZnO and TiO2 particles. The BET specific surface area and total pore volume decreased with ZnO doping, indicating that some micropores were blocked. SEM studies indicated that ZnO was almost uniformly deposited on the surface of the ZnO-TiO2/BC. The adsorption and photocatalytic degradation experiments showed that the photo-degrade efficiency for Zno-TiO2/BC was higher than that of TiO2/BC, and for both composites, the removal efficiency of HA increased as pH decreased from 10.0 to 2.0. The degradation of HA by ZnO-TiO2/BC and TiO2/BC fitted well with the Langmuir-Hinshelwood kinetics model, and HA degradation was achieved through a synergistic mechanism of adsorption and photocatalysis. ZnO-TiO2/BC could be used as an effective and alternative photocatalyst for the treatment of water contaminated by organic pollutants. PMID:24004575

  15. Degradation of Methyl Orange and Congo Red dyes by using TiO2 nanoparticles activated by the solar and the solar-like radiation.

    PubMed

    Ljubas, Davor; Smoljani?, Goran; Jureti?, Hrvoje

    2015-09-15

    In this study we used TiO2 nanoparticles as semiconductor photocatalysts for the degradation of Methyl Orange (MO) and Congo Red (CR) dyes in an aqueous solution. Since TiO2 particles become photocatalytically active by UV radiation, two sources of UV-A radiation were used - natural solar radiation which contains 3-5% UV-A and artificial, solar-like radiation, created by using a lamp. The optimal doses of TiO2 of 500 mg/L for the CR and 1500 mg/L for the MO degradation were determined in experiments with the lamp and were also used in degradation experiments with natural solar light. The efficiency of each process was determined by measuring the absorbance at two visible wavelengths, 466 nm for MO and 498 nm for CR, and the total organic carbon (TOC), i.e. decolorization and mineralization, respectively. In both cases, considerable potential for the degradation of CR and MO was observed - total decolorization of the solution was achieved within 30-60 min, while the TOC removal was in the range 60-90%. CR and MO solutions irradiated without TiO2 nanoparticles showed no observable changes in either decolorization or mineralization. Three different commercially available TiO2 nanoparticles were used: pure-phase anatase, pure-phase rutile, and mixed-phase preparation named Degussa P25. In terms of degradation kinetics, P25 TiO2 exhibited a photocatalytic activity superior to that of pure-phase anatase or rutile. The electric energy consumption per gram of removed TOC was determined. For nearly the same degradation effect, the consumption in the natural solar radiation experiment was more than 60 times lower than in the artificial solar-like radiation experiment. PMID:26160663

  16. Preparation, characterization, and photocatalytic activity of La-doped TiO2 supported on activated carbon at the decomposition of methylene orange

    NASA Astrophysics Data System (ADS)

    Xing, Jun; Sun, Xiaogang; Qiu, Jingping

    2015-06-01

    A composite photocatalyst (La/TiO2/AC) has been prepared by supporting photoactive La-doped TiO2 (La/TiO2) on activated carbon (AC) via hydrolysis of tetrabutyl titanate (Ti(OC4H9)4) with La(NO3)3 · 6H2O and Ti(OC4H9)4 as precursors in the presence of activated carbon. The prepared photocatalysts were characterized by BET surface area, scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The photocatalytic activities of the obtained photocatalysts under UV light are estimated by measuring the degradation rate of methylene orange in aqueous solution. The effect of La-doped content on the photocatalytic activity was studied and the result revealed that 0.2 mol % La/TiO2/AC exhibited highest photoactivity. In addition, the recyclability of the prepared photocatalyst was also confirmed, the photocatalytic activity of La/TiO2/AC remains about 86.5% of its activity as-prepared after being used four times. The photocatalyst therefore may be used as effective catalyst in photooxidation reactions and potentially applied for the treatment of water contaminated by organic pollutants.

  17. Heterojunction synergies in titania-supported gold photocatalysts: implications for solar hydrogen production.

    PubMed

    Jovic, Vedran; Smith, Kevin E; Idriss, Hicham; Waterhouse, Geoffrey I N

    2015-08-10

    The mixed-phase nature of P25?TiO2 (85?% anatase/15?% rutile) plays a key role in the high H2 production rates shown by Au/P25?TiO2 photocatalysts in alcohol/water systems. However, a full understanding of the synergistic charge transfer mechanisms between the TiO2 polymorphs that drive the high rates is yet to be realised. Here, we deconstruct P25?TiO2 into its component phases, functionalise the phases with Au nanoparticles and explore charge transfer in Au/TiO2 systems using EPR spectroscopy. EPR spectroscopy and photocatalytic data provide direct evidence that electrons excited across the rutile band gap move to anatase lattice traps through interfacial surface sites, which decreases electron-hole pair recombination and increases charge carrier availability for photoreactions. In particular, three-phase interfacial sites between Au, anatase and rutile appear to be H2 evolution "hot spots". The results isolate the origin of high photocatalytic H2 production rates seen in Au/P25?TiO2 systems. PMID:26105614

  18. Effective charge separation in the rutile TiO2 nanorod-coupled ?-Fe2O3 with exceptionally high visible activities

    PubMed Central

    Luan, Peng; Xie, Mingzheng; Liu, Dening; Fu, Xuedong; Jing, Liqiang

    2014-01-01

    Herein, we have fabricated rutile TiO2 nanorod-coupled ?-Fe2O3 by a wet-chemical process. It is demonstrated that the visible activities for photoelectrochemical water oxidation and for degrading pollutant of ?-Fe2O3 are greatly enhanced after coupling a proper amount of rutile nanorods. The enhanced activity is attributed to the prolonged lifetime and improved separation of photogenerated charges mainly by the transient surface photovoltage responses. Interestingly, the observed EPR signals (with g? = 1.963 and g|| = 1.948) of Ti3+ in the fabricated TiO2-Fe2O3 nanocomposite at ultra low temperature (1.8?k) after visible laser excitation, along with the electrochemical impedance spectra and the normalized photocurrent action spectra, testify evidently that the spacial transfers of visible-excited high-energy electrons of ?-Fe2O3 to TiO2 could happen. Moreover, it is confirmed that it is more favorable for the uncommon electron transfers of ?-Fe2O3 to rutile than to anatase. This is responsible for the much obvious enhancement of visible activity of Fe2O3 after coupling with rutile TiO2, compared with anatase and phase-mixed P25 ones. This work would help us to deeply understand the uncommon photophysical processes, and also provide a feasible route to improve the photocatalytic performance of visible-response semiconductor photocatalyst for water splitting and pollutant degradation. PMID:25154460

  19. SYNTHESIZING ORGANIC COMPOUNDS USING LIGHT-ACTIVATED TIO2

    EPA Science Inventory

    High-value organic compounds have been synthesized successfully from linear and cyclic hydrocarbons, by photocatalytic oxidation using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxgenated in both liquid and gaseous phase reactors usi...

  20. Continuous and nanostructured TiO2 films grown by dc sputtering magnetron.

    PubMed

    Sánchez, O; Vergara, L; Font, A Climent; de Melo, O; Sanz, R; Hernández-Vélez, M

    2012-12-01

    The growth of Anatase nanostructured films using dc reactive magnetron sputtering and post-annealing treatment is reported. TiO2 has been deposited on Porous Anodic Alumina Films used as templates which were previously grown in phosphoric acid solution and etched to modify their pore diameters. This synthesis via results in the formation of vertically aligned and spatially ordered TiO2 nanostructures replicating the underlying template. Previously, the growth optimization of TiO2 thin films deposited by dc magnetron sputtering on flat silicon substrates was done. The crystalline structure and Ti in-depth concentration profile were determined by grazing incidence X-ray diffraction and Rutherford backscattering spectrometry, respectively. The surface morphology of the samples was explored by mean of a Field Emission Gun scanning electron microscope. Optical properties of the nanostructured samples were studied by using the reflectance spectra received in the UV-visible range. In these spectra different band gap values and complex light absorption features were observed. PMID:23447970

  1. A Single-Atom-Thick TiO2 Nanomesh on an Insulating Oxide.

    PubMed

    Ohsawa, Takeo; Saito, Mitsuhiro; Hamada, Ikutaro; Shimizu, Ryota; Iwaya, Katsuya; Shiraki, Susumu; Wang, Zhongchang; Ikuhara, Yuichi; Hitosugi, Taro

    2015-09-22

    The electronic structures and macroscopic functionalities of two-dimensional (2D) materials are often controlled according to their size, atomic structures, and associated defects. This controllability is particularly important in ultrathin 2D nanosheets of transition-metal oxides because these materials exhibit extraordinary multifunctionalities that cannot be realized in their bulk constituents. To expand the variety of materials with exotic properties that can be used in 2D transition-metal-oxide nanosheets, it is essential to investigate fabrication processes for 2D materials. However, it remains challenging to fabricate such 2D nanosheets, as they are often forbidden because of the crystal structure and nature of their host oxides. In this study, we demonstrate the synthesis of a single-atom-thick TiO2 2D nanosheet with a periodic array of holes, that is, a TiO2 nanomesh, by depositing a LaAlO3 thin film on a SrTiO3(001)-(?13×?13)-R33.7° reconstructed substrate. In-depth investigations of the detailed structures, local density of states, and Ti valency of the TiO2 nanomesh using scanning tunneling microscopy/spectroscopy, scanning transmission electron microscopy, and density functional theory calculations reveal an unexpected upward migration of the Ti atoms of the substrate surface onto the LaAlO3 surface. These results indicate that the truncated TiO5 octahedra on the surface of perovskite oxides are very stable, leading to semiconducting TiO2 nanomesh formation. This nanomesh material can be potentially used to control the physical and chemical properties of the surfaces of perovskite oxides. Furthermore, this study provides an avenue for building functional atomic-scale oxide 2D structures and reveals the thin-film growth processes of complex oxides. PMID:26291512

  2. Heterojunctions in Composite Photocatalysts.

    PubMed

    Marschall, Roland

    2016-01-01

    Combining different light-absorbing materials for the formation of semiconductor heterojunctions is a very effective strategy for preparing highly active photocatalyst and photoelectrochemical systems. Moreover, the combination of solid state semiconductors with polymers or molecular absorbers expands the possible combinations of materials to alter light absorption and optimize charge carrier separation. In this chapter, different strategies to prepare such composites are presented, highlighting the necessity of intimate interfacial contact for optimum charge carrier transfer. Moreover, the most recent developments and improvements in the formation of heterojunctions and composite photocatalyst systems based on semiconductor solids are presented. PMID:26003562

  3. New synthesis of excellent visible-light TiO{sub 2-x}N{sub x} photocatalyst using a very simple method

    SciTech Connect

    Li Danzhen Huang Hanjie; Chen Xu; Chen Zhixin; Li Wenjuan; Ye Dong; Fu Xianzhi

    2007-09-15

    An excellent visible-light-responsive (from 400 to 550 nm) TiO{sub 2-x}N{sub x} photocatalyst was prepared by a simple wet method. Hydrazine was used as a new nitrogen resource in this paper. Self-made amorphous titanium dioxide precursor powders were dipped into hydrazine hydrate, and calcined at low temperature (110 deg. C) in the air. The TiO{sub 2-x}N{sub x} was successfully synthesized, following by spontaneous combustion. The photocatalyst was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), UV-Vis diffuse reflectance spectrometer (DRS), and X-ray photoelectron spectroscopy (XPS). Analysis of XPS indicated that N atoms were incorporated into the lattice of the titania crystal during the combustion of hydrazine on the surface of TiO{sub 2}. Ethylene was selected as a target pollutant under visible-light excitation to evaluate the activity of this photocatalyst. The newly prepared TiO{sub 2-x}N{sub x} photocatalyst with strong photocatalytic activity and high photochemical stability under visible-light irradiation was firstly demonstrated in the experiment. - Graphical abstract: The excellent visible-light-responsive (from 400 to 550 nm) TiO{sub 2-x}N{sub x} photocatalyst was prepared by a simple wet method. Hydrazine was used as a new nitrogen resource in this paper. In the experiment, a strong photocatalytic activity with high photochemical stability under visible-light irradiation was demonstrated.

  4. Photocatalytic decomposition of acephate in irradiated TiO2 suspensions.

    PubMed

    Han, ShiTong; Li, Jing; Xi, HaiLing; Xu, DaNian; Zuo, Yanjun; Zhang, JianHong

    2009-04-30

    In the present study, the photocatalytic degradation of acephate (O,S-dimethyl acetyl phosphoramidothioate ((CH(3)O)(CH(3)S)P(O)NHCOCH(3))) in aqueous TiO2 suspensions is extensively investigated, pertaining to the concentration of photocatalyst and substrate on degradation rate of acephate. It is found that the acephate can be degradated and mineralized. The high-degradation rate is obtained with 4 g/L concentration of TiO2. Moreover, Langmuir-Hinshelowood rate expression is employed for the degradation of acephate with adsorption constant and rate constant, i.e., 2.0 L/mmol and 0.6 mmol/(min L), respectively. The main target is to identify the products by a number of analytical techniques, such as HPLC, IC, ESR and GC-MS. Under acidic condition, the primary products are phosphorothioic acid, O,O',S-trimethyl ester (CH(3)O(CH(3)S)P(O)OCH(3)) and phosphoramidothioic acid, O,S-dimethyl ester (CH(3)O(CH(3)S)P(O)NH(2)), etc. It indicates that the decomposition of acephate begin from the destruction of C-N and P-N bonds. Subsequently, the P-S, P-O, P-C bonds may be oxidized gradually or simultaneously, and the final products such as CO(2), H(3)PO(4), were formed. About 100% sulfur atoms are transformed into SO(4)(2-) in 180 min, however; only 3% nitrogen atoms and 2% phosphorus atoms were transformed into NO(3)(-) and PO(4)(3-). PMID:18762373

  5. Well-organized meso-macroporous TiO2/SiO2 film derived from amphiphilic rubbery comb copolymer.

    PubMed

    Jeon, Harim; Lee, Chang Soo; Patel, Rajkumar; Kim, Jong Hak

    2015-04-15

    We report the facile synthesis of a well-organized meso-macroporous TiO2/SiO2 thin film with high porosity and good interconnectivity from a binary mixture (i.e., titania precursor and polymer template). Our process is based on self-assembly of the amphiphilic rubbery comb copolymer, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM) with titanium tetraisopropoxide (TTIP). SiO2 is self-provided by thermal oxidation of PDMS chains during calcination under air. The selective, preferential interaction between TTIP and the hydrophilic POEM chains was responsible for the formation of well-organized TiO2/SiO2 films, as supported by transmission electron microscopy, scanning electron microscopy, X-ray photospectroscopy, and X-ray diffraction analyses. We investigated in detail the effect of precursor content, solvent type, and polymer concentration on thin film morphology. Photodegradation of methyl orange by the well-organized meso-macroporous TiO2/SiO2 film was greater than that of a dense TiO2 film prepared without PDMS-g-POEM as well as a SiO2-etched TiO2 film. These results indicate that the well-organized structure and SiO2 doping of the TiO2 film play a pivotal role in enhancing its photocatalytic properties. PMID:25805232

  6. Selective preparation of zero- and one-dimensional gold nanostructures in a TiO2 nanocrystal-containing photoactive mesoporous template

    PubMed Central

    2012-01-01

    Nanocrystallized SiO2-TiO2 with tubular mesopores was prepared via the sol-gel technique. Gold was deposited in the tubular mesopores of the nanocrystallized SiO2-TiO2. The shape of the gold was varied from one-dimensional [1-D] to zero-dimensional [0-D] nanostructures by an increase in TiO2 content and ultraviolet [UV] irradiation during gold deposition. 1-D gold nanostructures [GNSs] were mainly obtained in the mesopores when a small amount of TiO2-containing mesoporous SiO2-TiO2 was used as a template, whereas the use of a template containing a large amount of TiO2 led to the formation of shorter 1-D or 0-D GNSs. UV irradiation also resulted in the formation of 0-D GNSs. PACS: 06.60.Jn (sample preparation); 81.07.Gf (nanowires); 81.16.Be (chemical synthesis methods). PMID:22221978

  7. Improving the photocatalytic reduction of CO2 to CO through immobilization of a molecular Re catalyst on TiO2

    E-print Network

    Windle, Christopher D.; Pastor, Ernest; Reynal, Anna; Whitwood, Adrian C.; Vaynzof, Yana; Durrant, James R.; Perutz, Robin N.; Reisner, Erwin

    2015-01-29

    the nitrogen content has increased. This observation can be ex- plained by coordination of DMF and/or TEOA to the Re, as in known photocatalytic intermediates for comparable Re com- plexes.[20] In addition, the three hydroxy groups in TEOA can also bind to TiO2... amount of inactive Re dimers is being formed in the catalytic cycle, which may also contribute to the higher activity of the ReP–TiO2 assembly. We have therefore shown that modification of the photochemical kinetics through photocatalyst immobilisation...

  8. TiO2/CdS porous hollow microspheres rapidly synthesized by salt-assistant aerosol decomposition method for excellent photocatalytic hydrogen evolution performance.

    PubMed

    Huang, Yu; Chen, Jun; Zou, Wei; Zhang, Linxing; Hu, Lei; He, Min; Gu, Lin; Deng, Jinxia; Xing, Xianran

    2016-01-01

    TiO2/CdS porous hollow microspheres have been one-pot rapidly synthesized by a salt-assisted aerosol decomposition method, and exhibit an excellent photocatalytic activity of 996 ?mol h(-1) (50 mg photocatalysts with loading Ru co-catalyst) for hydrogen evolution from aqueous solutions containing sacrificial reagents (SO3(2-) and S(2-)) under visible light (? ? 420 nm). Its high photocatalytic performance is attributed to the surface morphology, crystallinity and heterostructures. The present facile method can be extended to fabricate other heterostructures consisting of oxides or sulfides. PMID:26661031

  9. Synthesis, characterization and evaluation of the photocatalytic performance of Ag-CdMoO{sub 4} solar light driven plasmonic photocatalyst

    SciTech Connect

    Adhikari, Rajesh; Malla, Shova; Gyawali, Gobinda; Sekino, Tohru; Lee, Soo Wohn

    2013-09-01

    Graphical abstract: - Highlights: • Ag-CdMoO{sub 4} solar light driven photocatalyst was successfully synthesized. • Photocatalyst exhibited strong absorption in the visible region. • Photocatalytic activity was significantly enhanced. • Enhanced activity was caused by the SPR effect induced by Ag nanoparticles. - Abstract: Ag-CdMoO{sub 4} plasmonic photocatalyst was synthesized in ethanol/water mixture by photo assisted co-precipitation method at room temperature. As synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyzer. Photocatalytic activity was evaluated by performing the degradation experiment over methylene blue (MB) and indigo carmine (IC) as model dyes under simulated solar light irradiation. The results revealed that the Ag-CdMoO{sub 4} showed the higher photocatalytic performance as compared to CdMoO{sub 4} nanoparticles. Dispersion of Ag nanoparticles over the surface of CdMoO{sub 4} nanoparticles causes the surface plasmon resonance (SPR) and enhances the broad absorption in the entire visible region of the solar spectrum. Hence, dispersion of Ag nanoparticles over CdMoO{sub 4} nanoparticles could be the better alternative to enhance the absorption of visible light by scheelite crystal family for effective photocatalysis.

  10. Rutile TiO2 nano-branched arrays on FTO for dye-sensitized solar cells.

    PubMed

    Wang, Hua; Bai, Yusong; Wu, Qiong; Zhou, Wei; Zhang, Hao; Li, Jinghong; Guo, Lin

    2011-04-21

    Hierarchical TiO(2) nanostructures would be desirable for preparing dye-sensitized solar cells because of their large amount of dye adsorption and superior light harvesting efficiency, as well as efficient charge separation and transport properties. In this study, rutile TiO(2) nano-branched arrays grown directly on transparent conductive glass (FTO) were prepared by a facile two-step wet chemical synthesis process, using a simple aqueous chemical growth method involving immersing the TiO(2) nanorod arrays in an aqueous TiCl(4) solution as seeds, which were prepared by a hydrothermal method. The dye-sensitized solar cells based on the TiO(2) nano-branched arrays which were only about 3 ?m in length show a short-circuit current intensity of 10.05 mA cm(-2) and a light-to-electricity conversion efficiency of 3.75%, which is nearly three times as high as that of bare nanorod arrays, due to the preferable nanostructure, which not only retains the efficient charge separation and transport properties of the nanorod arrays, but also can improve the amount of dye adsorption due to the increased specific surface area from the nanobranches. PMID:21399795

  11. Facile preparation of TiO2-polyvinyl alcohol hybrid nanoparticles with improved visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Filippo, Emanuela; Carlucci, Claudia; Capodilupo, Agostina Lina; Perulli, Patrizia; Conciauro, Francesca; Corrente, Giuseppina Anna; Gigli, Giuseppe; Ciccarella, Giuseppe

    2015-03-01

    Hybrid inorganic/organic core/shell nanoparticles were prepared through a two step synthesis procedure. In the first step, pure anatase TiO2 nanoparticles were synthesized though a rapid microwave assisted non-aqueous route. Then, the obtained titania nanoparticles were coated with polyvinyl alcohol (PVA) using a simple solution method followed by relatively low temperature treatment. The PVA-coated titania nanoparticles samples were prepared at different TiO2-PVA weight ratio and they were characterized using X-Ray diffraction, transmission electron microscopy, infrared spectroscopy and Brunauer-Emmett-Teller (BET) analysis. Photocatalytic performance was also evaluated for all samples and the results indicated that TiO2:PVA weight ratio was a key factor to obtain an improvement of the photocatalytic activity with respect to bare TiO2 nanoparticles, since PVA concentration influenced the surface area and the aggregation of nanoparticles and the thickness of the coating layer. This inexpensive system provides a simple, quick and effective approach which allows to obtain core/shell hybrid nanostructures.

  12. Ultrathin films of TiO2 nanoparticles at interfaces.

    PubMed

    Choudhary, Keerti; Manjuladevi, V; Gupta, R K; Bhattacharyya, P; Hazra, A; Kumar, S

    2015-02-01

    The properties of a material change remarkably as a result of the scaling dimensions. The Langmuir-Blodgett (LB) film deposition technique is known to offer precise control over the film thickness and the interparticle separation. To form a well-ordered LB film, it is essential to form a stable Langmuir film at the air-water interface. Here, we report our studies on ultrathin films of TiO2 nanoparticles at air-water and air-solid interfaces. The Langmuir film of TiO2 nanoparticles at the air-water interface was found to be very stable, and it exhibits loose-packing and close-packing phases. The LB films were transferred onto solid substrates for characterization and application. The surface morphology of the LB film was obtained by a field emission scanning electron microscope. The optical and electronic properties of the LB films of TiO2 nanoparticles were studied using UV-vis spectroscopy and current-voltage measurements, respectively. The LB film of TiO2 nanoparticles was employed for ethanol gas sensing, and the sensing performance was compared to that of bulk material. Because of the enormous gain in the surface to volume ratio and the increase in crystalline defect density in the ultrathin LB film of TiO2 nanoparticles, the LB film is found to be a potential functional layer for ethanol sensing as compared to the bulk material. PMID:25557246

  13. Hydrogen Impurity Defects in Rutile TiO2

    PubMed Central

    Mo, Li-Bin; Wang, Yu; Bai, Yang; Xiang, Qing-Yun; Li, Qun; Yao, Wen-Qing; Wang, Jia-Ou; Ibrahim, Kurash; Wang, Huan-Hua; Wan, Cai-Hua; Cao, Jiang-Li

    2015-01-01

    Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO2 in gaseous H2 and atomic H. In gas-hydrogenated TiO2, the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO2, forming a weak O-H bond with the closest oxygen ion, and becomes positive. Both states of hydrogen affect the electronic structure of TiO2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy. PMID:26627134

  14. Hydrogen Impurity Defects in Rutile TiO2.

    PubMed

    Mo, Li-Bin; Wang, Yu; Bai, Yang; Xiang, Qing-Yun; Li, Qun; Yao, Wen-Qing; Wang, Jia-Ou; Ibrahim, Kurash; Wang, Huan-Hua; Wan, Cai-Hua; Cao, Jiang-Li

    2015-01-01

    Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO2 in gaseous H2 and atomic H. In gas-hydrogenated TiO2, the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO2, forming a weak O-H bond with the closest oxygen ion, and becomes positive. Both states of hydrogen affect the electronic structure of TiO2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy. PMID:26627134

  15. Thermal degradation of TiO2 nanotubes on titanium

    NASA Astrophysics Data System (ADS)

    Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

    2014-10-01

    The objective of this research was to study thermal degradation behavior of TiO2 nanotubes on titanium (Ti). TiO2 nanotubes were grown via anodization method on commercially pure Ti (Cp-Ti) discs using two different electrolytes, 1 vol. % HF in deionized (DI) water and 1 vol. % HF + 0.5 wt. % NH4F + 10 vol. % DI water in ethylene glycol, to obtain nanotubes with two different lengths, 300 nm and 950 nm keeping the nanotube diameter constant at 100 ± 20 nm. As grown TiO2 nanotubes were subjected to heat treatment to understand thermal degradation as a function of both temperature and hold time. The signs of degradation were observed mainly when amorphous nanotubes started to crystallize, however the crystallization temperature varied based on TiO2 nanotubes length and anodizing condition. Overall, 300 nm nanotubes were thermally stable at least up to 400 °C for 12 h, while the 950 nm long nanotubes show signs of degradation from 400 °C for 6 h only. Clearly, length of nanotubes, heat treatment temperature as well as hold times show influence toward degradation kinetics of TiO2 nanotubes on titanium.

  16. Photocatalytic Properties of TiO2 Porous Network Film.

    PubMed

    Yu, Lianqing; Zhi, Qianqian; Huang, Chengxing; Zhang, Yaping; Dong, Kaituo; Neppolian, B

    2015-09-01

    Three-dimensional porous network TiO2 film (PW-film) and nanoparticles film were synthesized on surface of the Ti foil by a facile method to investigate both the photoelectrochemical and photocatalytic properties. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction spectroscopy (XRD) techniques. Methylene blue was used as a target molecule to estimate the photocatalytic activity of the films. Results revealed that the hydrothermal temperature and time have great influence on the crystal type and film morphology of TiO2 catalysts. A higher hydrothermal temperature is benefit for the formation of anatase phase of TiO2 nanotubes with PW-film, which had a large number of nodes. After investigation of the photoelectrochemical properties, a maximum photoconversion efficiency of 4.79% is observed for nanoparticles film with rutile phase of TiO2 under UV light illumination, which was incredible 2 times higher than that of the PW-film with anatase phase. It was shown that the morphology of TiO2 film contributes more significant effect on photocatalytic and photoelectric performance than its crystal type. PMID:26716214

  17. Enhanced photocatalytic activity of Cl-residual rutile TiO2 nanorods after targeted co-modification with phosphoric and boric acids.

    PubMed

    Wu, Jing; Cui, Haiqin; Zhang, Xuliang; Luan, Yunbo; Jing, Liqiang

    2015-06-28

    The promotion of O2 adsorption on semiconductor surfaces for effectively capturing photogenerated electrons in the photocatalytic degradation of pollutants is highly desired. In this study, the targeted co-modification of residual chlorine rutile TiO2 nanorods with phosphoric and boric acids has been accomplished for the first time by simple wet chemical processes. The key to targeted co-modification is to connect -P-OH and -B-OH to the Cl-residual TiO2 surfaces by -Ti-OH and -Ti-Cl, respectively, consequently forming -Ti-O-P-OH and -Ti-Cl:B-OH ends. By means of the atmosphere-controlled surface photovoltage spectroscopy, the degrees for capturing photogenerated electrons by the adsorbed O2 as receptors on the resulting TiO2 nanorods are quantitatively analyzed. It is confirmed that the targeted co-modification could greatly promote the capture of the photogenerated electrons compared to the phosphate and borate modification alone. This is attributed to increased amounts of adsorbed O2 based on electrochemical O2 reduction and O2 temperature-programmed desorption measurements, further leading to the enhanced separation of photogenerated charges, characterized by an increase in the amount of produced hydroxyl radicals. This is responsible for the obviously enhanced photocatalytic activity of TiO2 nanorods towards the degradation of colorless gas-phase acetaldehyde and liquid-phase phenol. This work would provide us a feasible route for the co-modification with inorganic acids to synthesize efficient nanosized TiO2-based photocatalysts. PMID:26017969

  18. Innovative three-dimensional (3D) eco-TiO? photocatalysts for practical environmental and bio-medical applications.

    PubMed

    Lee, Hyun Uk; Lee, Soon Chang; Lee, Young-Chul; Son, Byoungchul; Park, So Young; Lee, Jae Won; Oh, You-Kwan; Kim, Yooseok; Choi, Saehae; Lee, Young-Seak; Lee, Jouhahn

    2014-01-01

    It is known that water purified by conventional TiO2 photocatalysts may not be safe enough for drinking, due to the toxicity by tiny existence of TiO2 nanoparticles after water treatment. We herein demonstrate a facile design of a three-dimensional (3D) TiO2 photocatalyst structure with which both the efficiency of purification and the safety level of the final purified water can be improved and ensured, respectively. The structure, consisting of 3D sulfur-doped TiO2 microtubes in nanotubes (eco-TiO2), is suitable for both environmental and bio-medical applications. Investigation of its formation mechanism reveals that anodic aluminum oxide (AAO), owing to a spatial constraint, causes a simple, nanoparticles-to-nanotubes structural rearrangement as a template for nanotube growth. It is found that eco-TiO2 can be activated under visible-light irradiation by non-metal (sulfur; S) doping, after which it shows visible-light photocatalytic activities over a range of solar energy. Importantly, an in vitro cytotoxicity test of well-purified water by eco-TiO2 confirms that eco-TiO2 satisfies the key human safety conditions. PMID:25338845

  19. Innovative three-dimensional (3D) eco-TiO2 photocatalysts for practical environmental and bio-medical applications

    PubMed Central

    Lee, Hyun Uk; Lee, Soon Chang; Lee, Young-Chul; Son, Byoungchul; Park, So Young; Lee, Jae Won; Oh, You-Kwan; Kim, Yooseok; Choi, Saehae; Lee, Young-Seak; Lee, Jouhahn

    2014-01-01

    It is known that water purified by conventional TiO2 photocatalysts may not be safe enough for drinking, due to the toxicity by tiny existence of TiO2 nanoparticles after water treatment. We herein demonstrate a facile design of a three-dimensional (3D) TiO2 photocatalyst structure with which both the efficiency of purification and the safety level of the final purified water can be improved and ensured, respectively. The structure, consisting of 3D sulfur-doped TiO2 microtubes in nanotubes (eco-TiO2), is suitable for both environmental and bio-medical applications. Investigation of its formation mechanism reveals that anodic aluminum oxide (AAO), owing to a spatial constraint, causes a simple, nanoparticles-to-nanotubes structural rearrangement as a template for nanotube growth. It is found that eco-TiO2 can be activated under visible-light irradiation by non-metal (sulfur; S) doping, after which it shows visible-light photocatalytic activities over a range of solar energy. Importantly, an in vitro cytotoxicity test of well-purified water by eco-TiO2 confirms that eco-TiO2 satisfies the key human safety conditions. PMID:25338845

  20. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    PubMed Central

    Che Ramli, Zatil Amali; Asim, Nilofar; Isahak, Wan N. R. W.; Emdadi, Zeynab; Ahmad-Ludin, Norasikin; Yarmo, M. Ambar; Sopian, K.

    2014-01-01

    This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC), TiO2/carbon (C), and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC) was obtained after treating TiO2/carbon with 1.0?M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TG-DTA), Brunauer-Emmet-Teller (BET), and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9?m2?g?1). The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples. PMID:25013855

  1. Bulk intermixing-type perovskite CH3NH3PbI3/TiO2 nanorod hybrid solar cells

    NASA Astrophysics Data System (ADS)

    Li, Shao-Sian; Wang, Ying-Chiao; Tsai, Chin-Ming; Wen, Cheng-Yen; Yu, Chia-Hao; Yang, Yu-Pei; Lin, Jou-Chun; Wang, Di-Yan; Chen, Chia-Chun; Yeh, Yun-Chieh; Chen, Chun-Wei

    2015-08-01

    To replace high-temperature sintered scaffold materials in conventional CH3NH3PbI3-based solar cells, this study demonstrates a new device structure of a bulk intermixing (BI)-type CH3NH3PbI3/TiO2 nanorod (NR) hybrid solar cell, where dispersed TiO2 NRs from chemical synthesis are intermixed with the perovskite absorbing layer to form a BI-type perovskite/TiO2 NR hybrid for device fabrication. Through interface engineering between the TiO2 NR surface and the photoactive perovskite material of CH3NH3PbI3 by ligand exchange treatment, a remarkable power conversion efficiency (PCE) of over 12% was achieved based on the simple BI-type CH3NH3PbI3/TiO2 NR hybrid device structure. The proposed hybrids not only provide great flexibility for deposition on various substrates through spin coating at low temperatures but also enable layer-by-layer deposition for the future development of perovskite-based multi-junction solar cells.To replace high-temperature sintered scaffold materials in conventional CH3NH3PbI3-based solar cells, this study demonstrates a new device structure of a bulk intermixing (BI)-type CH3NH3PbI3/TiO2 nanorod (NR) hybrid solar cell, where dispersed TiO2 NRs from chemical synthesis are intermixed with the perovskite absorbing layer to form a BI-type perovskite/TiO2 NR hybrid for device fabrication. Through interface engineering between the TiO2 NR surface and the photoactive perovskite material of CH3NH3PbI3 by ligand exchange treatment, a remarkable power conversion efficiency (PCE) of over 12% was achieved based on the simple BI-type CH3NH3PbI3/TiO2 NR hybrid device structure. The proposed hybrids not only provide great flexibility for deposition on various substrates through spin coating at low temperatures but also enable layer-by-layer deposition for the future development of perovskite-based multi-junction solar cells. Electronic supplementary information (ESI) available: TiO2 synthesis and ligand exchange process, device fabrication and characterization. See DOI: 10.1039/c5nr04076k

  2. Improved visible light photocatalytic activity of fluorine and nitrogen co-doped TiO2 with tunable nanoparticle size

    NASA Astrophysics Data System (ADS)

    Cheng, Junyang; Chen, Jin; Lin, Wei; Liu, Yandong; Kong, Yan

    2015-03-01

    Fluorine and nitrogen co-doped TiO2 (F-N-TiO2) photocatalysts with enhanced photocatalytic activities were facilely synthesized by a simple one-step hydrothermal method using Ti(SO4)2 as an economical precursor, and hydrofluoric acid and ammonia as F and N source, respectively. The structure, morphology, and optical properties of produced nanoparticles were characterized by X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectra (FT-IR) methods. The synergistic effects of F and N doping were systematically examined by changing the molar ratio of F/N. Compared with the un-doped F or N mono-doped TiO2, the co-doped samples exhibited significantly improved photocatalytic performance due to their synergistic effects under visible light. It was shown that F dopant promoted the crystal growth and crystallinity of samples, while N dopant hindered it to some extent, which resulted in the tunable particle size of obtained F-N-TiO2 materials. The effects of F and N dopants on the enhanced photocatalytic activity of modified TiO2 materials were also discussed. The degradation rate of methylene blue (MB) was achieved at 97.31% after 5 h reaction under visible light over the optimized sample of FN3.5T. The materials also showed excellent stability according to the recycling tests of the photodegradation of MB.

  3. Band Alignment and Controllable Electron Migration between Rutile and Anatase TiO2

    NASA Astrophysics Data System (ADS)

    Mi, Yang; Weng, Yuxiang

    2015-07-01

    TiO2 is the most promising semiconductor for photocatalytic splitting of water for hydrogen and degradation of pollutants. The highly photocatalytic active form is its mixed phase of two polymorphs anatase and rutile rather than their pristine compositions. Such a synergetic effect is understood by the staggered band alignment favorable to spatial charge separation. However, electron migration in either direction between the two phases has been reported, the reason of which is still unknown. We determined the band alignment by a novel method, i.e., transient infrared absorption-excitation energy scanning spectra, showing their conduction bands being aligned, thus the electron migration direction is controlled by dynamical factors, such as varying the particle size of anatase, putting electron or hole scavengers on either the surface of anatase or rutile phases, or both. A quantitative criterion capable of predicting the migration direction under various conditions including particle size and surface chemical reactions is proposed, the predictions have been verified experimentally in several typical cases. This would give rise to a great potential in designing more effective titania photocatalysts.

  4. Band Alignment and Controllable Electron Migration between Rutile and Anatase TiO2

    PubMed Central

    Mi, Yang; Weng, Yuxiang

    2015-01-01

    TiO2 is the most promising semiconductor for photocatalytic splitting of water for hydrogen and degradation of pollutants. The highly photocatalytic active form is its mixed phase of two polymorphs anatase and rutile rather than their pristine compositions. Such a synergetic effect is understood by the staggered band alignment favorable to spatial charge separation. However, electron migration in either direction between the two phases has been reported, the reason of which is still unknown. We determined the band alignment by a novel method, i.e., transient infrared absorption-excitation energy scanning spectra, showing their conduction bands being aligned, thus the electron migration direction is controlled by dynamical factors, such as varying the particle size of anatase, putting electron or hole scavengers on either the surface of anatase or rutile phases, or both. A quantitative criterion capable of predicting the migration direction under various conditions including particle size and surface chemical reactions is proposed, the predictions have been verified experimentally in several typical cases. This would give rise to a great potential in designing more effective titania photocatalysts. PMID:26169699

  5. Creating high quality Ca:TiO2-B (CaTi5O11) and TiO2-B epitaxial thin films by pulsed laser deposition.

    PubMed

    Zhang, Kui; Du, Xianfeng; Katz, Michael B; Li, Baihai; Kim, Sung Joo; Song, Kaixin; Graham, George W; Pan, Xiaoqing

    2015-05-21

    We demonstrate, in great detail, a completely waterless synthesis route to produce highly crystalline epitaxial thin films of TiO2-B and its more stable variant CaTi5O11, using pulsed laser deposition (PLD). PMID:25853927

  6. Improving the Photocatalytic Reduction of CO2 to CO through Immobilisation of a Molecular Re Catalyst on TiO2

    PubMed Central

    Windle, Christopher D; Pastor, Ernest; Reynal, Anna; Whitwood, Adrian C; Vaynzof, Yana; Durrant, James R; Perutz, Robin N; Reisner, Erwin

    2015-01-01

    The photocatalytic activity of phosphonated Re complexes, [Re(2,2?-bipyridine-4,4?-bisphosphonic acid) (CO)3(L)] (ReP; L=3-picoline or bromide) immobilised on TiO2 nanoparticles is reported. The heterogenised Re catalyst on the semiconductor, ReP–TiO2 hybrid, displays an improvement in CO2 reduction photocatalysis. A high turnover number (TON) of 48?molCO?molRe?1 is observed in DMF with the electron donor triethanolamine at ?>420?nm. ReP–TiO2 compares favourably to previously reported homogeneous systems and is the highest TON reported to date for a CO2-reducing Re photocatalyst under visible light irradiation. Photocatalytic CO2 reduction is even observed with ReP–TiO2 at wavelengths of ?>495?nm. Infrared and X-ray photoelectron spectroscopies confirm that an intact ReP catalyst is present on the TiO2 surface before and during catalysis. Transient absorption spectroscopy suggests that the high activity upon heterogenisation is due to an increase in the lifetime of the immobilised anionic Re intermediate (t50?%>1?s for ReP–TiO2 compared with t50?%=60?ms for ReP in solution) and immobilisation might also reduce the formation of inactive Re dimers. This study demonstrates that the activity of a homogeneous photocatalyst can be improved through immobilisation on a metal oxide surface by favourably modifying its photochemical kinetics. PMID:25639778

  7. Highly efficient, solar active, and reusable photocatalyst: Zr-loaded Ag-ZnO for Reactive Red 120 dye degradation with synergistic effect and dye-sensitized mechanism.

    PubMed

    Subash, B; Krishnakumar, B; Swaminathan, M; Shanthi, M

    2013-01-22

    The different wt % of Zr-codoped Ag-ZnO catalysts were prepared by the simple precipitation-thermal decomposition method and used for degradation of anionic azo dye Reactive Red 120 (RR 120) under natural sunlight. Highly efficient 4 wt % of Zr-codoped Ag-ZnO was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM) images, field emission scanning electron microscope (FE-SEM) images, energy-dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), and BET surface area measurements. Metal codopants increase the absorbance of ZnO to the entire visible region. XRD and XPS reveal that Ag is in the form of Ag(0) and Zr in the form of Zr(4+). The photocatalytic activity of 4 wt % Zr-codoped Ag-ZnO was compared with other single-metal-doped, undoped, and commercial catalysts. The quantum yields of all processes were determined and analyzed. Zr-Ag-ZnO was found to be more efficient than Ag-ZnO, Zr-ZnO, commercial ZnO, prepared ZnO, TiO(2)-P25, and TiO(2) at neutral pH for mineralization of RR 120 under solar light. To the best of our knowledge, this is the first report on the synthesis of Zr-codoped Ag-ZnO and its use in the degradation of RR 120 dye under natural sunlight illuminatioin. The influences of operational parameters such as the amount of photocatalyst, dye concentration, and initial pH on photomineralization of RR 120 have been analyzed. Mineralization of RR 120 has been confirmed by chemical oxygen demand (COD) measurements. A dual mechanism has been proposed for the higher efficiency of Zr-Ag-ZnO at neutral pH under solar light. This catalyst is found to be reusable. PMID:23234536

  8. Efficient ZnO-based visible-light-driven photocatalyst for antibacterial applications.

    PubMed

    Kumar, Raju; Anandan, Srinivasan; Hembram, Kaliyan; Rao, Tata Narasinga

    2014-08-13

    Herein, we report the development of a ZnO-based visible-light-driven photocatalyst by interfacial charge transfer process for the inactivation of pathogens under visible-light illumination. Surface modification by a cocatalyst on ZnO, prepared by flame spray pyrolysis process is carried out to induce the visible-light absorption in ZnO. Optical studies showed that surface modification of Cu(2+) induces the visible-light absorption in ZnO by interfacial charge transfer between ZnO and surface Cu(2+) ions upon light irradiation. The photocatalytic efficiency of pure and modified ZnO is evaluated for the inactivation of pathogens and the decomposition of methylene blue under visible-light illumination. The antibacterial activity of Cu(2+)-ZnO is several orders higher than pure ZnO and commercial Degussa-P25 and comparable with Cu(2+)-TiO2. Cu(2+)-ZnO nanorods show better photocatalytic activity than Cu(2+)-ZnO nanosphere, which is attributed to high surface area to volume ratio of former than later. The holes generated in the valence band and the Cu(1+) species generated during the interfacial charge transfer process may attribute for the inactivation of bacteria, whereas the strong oxidation power of hole is responsible for the decomposition of methylene blue. Besides the advantage of Cu(2+)-modified ZnO for visible-light-assisted photocatalytic applications, the method (FSP) used for the synthesis of ZnO in the present study is attractive for commercial application because the process has potential for the production of large quantities (2-3 kg/h) of semiconductors. PMID:25029041

  9. Protein Corona Prevents TiO2 Phototoxicity

    PubMed Central

    Garvas, Maja; Testen, Anze; Umek, Polona; Gloter, Alexandre; Koklic, Tilen; Strancar, Janez

    2015-01-01

    Background & Aim TiO2 nanoparticles have generally low toxicity in the in vitro systems although some toxicity is expected to originate in the TiO2-associated photo-generated radical production, which can however be modulated by the radical trapping ability of the serum proteins. To explore the role of serum proteins in the phototoxicity of the TiO2 nanoparticles we measure viability of the exposed cells depending on the nanoparticle and serum protein concentrations. Methods & Results Fluorescence and spin trapping EPR spectroscopy reveal that the ratio between the nanoparticle and protein concentrations determines the amount of the nanoparticles’ surface which is not covered by the serum proteins and is proportional to the amount of photo-induced radicals. Phototoxicity thus becomes substantial only at the protein concentration being too low to completely coat the nanotubes’ surface. Conclusion These results imply that TiO2 nanoparticles should be applied with ligands such as proteins when phototoxic effects are not desired - for example in cosmetics industry. On the other hand, the nanoparticles should be used in serum free medium or any other ligand free medium, when phototoxic effects are desired – as for efficient photodynamic cancer therapy. PMID:26083725

  10. Photocatalytic metamaterials: TiO2 inverse opals.

    PubMed

    Sordello, Fabrizio; Duca, Clara; Maurino, Valter; Minero, Claudio

    2011-06-01

    The study of the photocatalytic activity of TiO(2) inverse opals showed that these structures behave as metamaterials: their properties arise principally from the 3D periodic structure of the material and marginally from porosity, reflectivity and scattering. PMID:21519603

  11. Facile hydrothermal synthesis of novel Bi12TiO20-Bi2WO6 heterostructure photocatalyst with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Zhang, Lei; Hu, Jin-Song; Pan, Cheng-Ling; Hou, Chang-Min

    2015-08-01

    Novel Bi12TiO20-Bi2WO6 (denoted as BTO-BWO) heterostructure photocatalytic materials were constructed by a facile hydrothermal approach. Firstly, BWO nanosheets were fabricated via a solution-phase preparation route. Secondly, BTO-BWO composite photocatalysts could be readily obtained via a controllable partial precipitate conversion strategy, employing previously-prepared BWO nanosheets as precursors of Bi3+. Experiments revealed that BWO nanoflake was uniformly immobilized onto the exterior of the BTO tetrahedron. The visible-light activities of these products for the decomposition of rhodamine B (RhB) were evaluated. Compared to the single-component photocatalyst such as BTO and BWO, these sillenite-type BTO-BWO heterostructures exhibited higher photocatalytic ability. The effective separation of photo-induced carriers because of matching band positions and intimate interfacial contacts might account for the higher photo-activity of BTO-BWO hybrid structures. Furthermore, the influence of some trapping agents on the photocatalytic property was investigated and photo-induced holes and •O2- were verified to play more important roles than •OH. A possible photocatalytic degradation mechanism of RhB over BTO-BWO heterostructures was presented.

  12. Are TiO2 nanotubes worth using in photocatalytic purification of air and water?

    PubMed

    Pichat, Pierre

    2014-01-01

    Titanium dioxide nanotubes (TNT) have mainly been used in dye sensitized solar cells, essentially because of a higher transport rate of electrons from the adsorbed photo-excited dye to the Ti electrode onto which TNT instead of TiO2 nanoparticles (TNP) are attached. The dimension ranges and the two main synthesis methods of TNT are briefly indicated here. Not surprisingly, the particular and regular texture of TNT was also expected to improve the photocatalytic efficacy for pollutant removal in air and water with respect to TNP. In this short review, the validity of this expectation is checked using the regrettably small number of literature comparisons between TNT and commercialized TNP referring to films of similar thickness and layers or slurries containing an equal TiO2 mass. Although the irradiated geometrical area differed for each study, it was identical for each comparison considered here. For the removal of toluene (methylbenzene) or acetaldehyde (ethanal) in air, the average ratio of the efficacy of TNT over that of TiO2 P25 was about 1.5, and for the removal of dyes in water, it was around 1. This lack of major improvement with TNT compared to TNP could partially be due to TNT texture disorders as seems to be suggested by the better average performance of anodic oxidation-prepared TNT. It could also come from the fact that the properties influencing the efficacy are more numerous, their interrelations more complex and their effects more important for pollutant removal than for dye sensitized solar cells and photoelectrocatalysis where the electron transport rate is the crucial parameter. PMID:25244287

  13. Multiscale anode materials in lithium ion batteries by combining micro- with nanoparticles: design of mesoporous TiO2 microfibers@nitrogen doped carbon composites

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Rechberger, Felix; Primc, Darinka; Niederberger, Markus

    2015-08-01

    TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability.TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability. Electronic supplementary information (ESI) available: XRD patterns, SEM images, SEM-EDX element mapping, TEM images, TGA analysis, N2 gas sorption measurements and electrochemical characterizations. See DOI: 10.1039/c5nr03035h

  14. A Brown Mesoporous TiO2-x /MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution.

    PubMed

    Xing, Mingyang; Zhang, Jinlong; Qiu, Bocheng; Tian, Baozhu; Anpo, Masakazu; Che, Michel

    2015-04-24

    A brown mesoporous TiO2-x /MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record-breaking quantum yield (? = 46%) and a high photon-hydrogen energy conversion efficiency (? = 34%,) for solar photocatalytic H2 production, which are all higher than that of the black hydrogen-doped TiO2 (? = 35%, ? = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO2 /MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high-concentration F doping and the synergistic effect between lattice Ti(3+)-F and surface Ti(3+)-F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H2 for these catalysts. The as-prepared F-doped composite is an ideal solar light-driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H2 production. PMID:25511009

  15. Substrate-immobilized electrospun TiO2 nanofibers for photocatalytic degradation of pharmaceuticals: The effects of pH and dissolved organic matter characteristics.

    PubMed

    Maeng, Sung Kyu; Cho, Kangwoo; Jeong, Boyoung; Lee, Jaesang; Lee, Yunho; Lee, Changha; Choi, Kyoung Jin; Hong, Seok Won

    2015-12-01

    A substrate-immobilized (SI) TiO2 nanofiber (NF) photocatalyst for multiple uses was prepared through electrospinning and hot pressing. The rate of furfuryl alcohol degradation under UV irradiation was found to be the highest when the anatase to rutile ratio was 70:30; the rate did not linearly increase as a function of the NF film thickness, mainly due to diffusion limitation. Even after eight repeated cycles, it showed only a marginal reduction in the photocatalytic activity for the degradation of cimetidine. The effects of pH and different organic matter characteristics on the photodegradation of cimetidine (CMT), propranolol (PRP), and carbamazepine (CBZ) were investigated. The pH-dependence of the photocatalytic degradation rates of PRP was explained by electrostatic interactions between the selected compounds and the surface of TiO2 NFs. The degradation rates of CMT showed the following order: deionized water > l-tyrosine > secondary wastewater effluent (effluent organic matter) > Suwannee River natural organic matter, demonstrating that the characteristics of the dissolved organic matter (DOM) can affect the photodegradation of CMT. Photodegradation of CBZ was affected by the presence of DOM, and no significant change was observed between different DOM characteristics. These findings suggest that the removal of CMT, PRP, and CBZ during photocatalytic oxidation using SI TiO2 NFs is affected by the presence of DOM and/or pH, which should be importantly considered for practical applications. PMID:26025601

  16. CO2 Capture and Conversion on Rutile TiO2(110) in the Water Environment: Insight by First-Principles Calculations.

    PubMed

    Yin, Wen-Jin; Krack, Matthias; Wen, Bo; Ma, Shang-Yi; Liu, Li-Min

    2015-07-01

    The conversion of CO2 by the virtue of sunlight has the great potential to produce useful fuels or valuable chemicals while decreasing CO2 emission from the traditional fossil fuels. Here, we use the first-principles calculations combined with the periodic continuum solvation model (PCSM) to explore the adsorption and reactivity of CO2 on rutile TiO2(110) in the water environment. The results exhibit that both adsorption structures and reactivity of CO2 are greatly affected by water coadsorption on rutile TiO2(110). In particular, the solvation effect can change the most stable adsorption configuration of CO2 and H2O on rutile TiO2(110). In addition, the detailed conversion mechanism of CO2 reduction is further explored in the water environment. The results reveal that the solvation effect cannot only greatly decrease the energy barrier of CO2 reduction but also affect the selectivity of the reaction processes. These results presented here show the importance of the aqueous solution, which should be helpful to understand the detailed reaction processes of photocatalysts. PMID:26266731

  17. Preparation of AgInS2 nanocrystals and their application as sensitizers for TiO2 nanorod array photoelectrodes

    NASA Astrophysics Data System (ADS)

    Yin, Jianbo; Jia, Junhong

    2015-07-01

    This paper reports the controlled synthesis of AgInS2 nanocrystals and their application as sensitizers for TiO2 nanorod array photoelectrode. The analytical results of high resolution transmission electron microscope (TEM) and laser particle analyzer show that the as-prepared AgInS2 nanoparticles are highly crystallized with an average diameter of 16.67 nm. The results of ultraviolet (UV)-visible absorption spectra indicate that the as-prepared AgInS2 nanoparticles have strong absorption in the spectral range of 300 nm-700 nm. The photovoltaic detectable results of TiO2 nanorod array photoelectrode sensitized by AgInS2 nanocrystals reveal that the composite films red shift to visible light range with high photovoltaic conversion efficiency of 2.076%, which is 3 times higher than that of bare TiO2 photoelectrodes.

  18. The preparation of highly ordered TiO2 nanotube arrays by an anodization method and their applications.

    PubMed

    Jun, Yongseok; Park, Jong Hyeok; Kang, Man Gu

    2012-07-01

    The tubular-shaped nanostructure of TiO(2) is very interesting, and highly ordered arrays of TiO(2) nanotubes (TNTs) can be easily fabricated by anodization of the Ti substrate in specific electrolytes. Here in this feature article, we review synthesis methods for various TNTs including normal, alloy, and architectural forms such as bamboos, lace, and flowers. Specific nanosize architectures such as bamboo and lace types can be regulated by alternating voltage and further anodizing. In order to extend light response of TNTs to visible solar spectra, various dopings of specific elements have been discussed. The normal and modified TNTs are suggested for applications such as dye sensitized solar cells, water splitting, photocatalytic degradation of pollutants, CO(2) reduction, sensors, energy storage devices including Li ion batteries and supercapacitors, and other applications such as flexible substrate and biomaterials. PMID:22634750

  19. Enhanced photovoltaic performance of novel TiO2 photoelectrode on TCO substrates for dye-sensitized solar cells.

    PubMed

    Nam, Jung Eun; Kwon, Soon Jin; Jo, Hyo Jeong; Yi, Kwang Bok; Kim, Dae-Hwan; Kang, Jin-Kyu

    2014-12-01

    In this study, we report synthesis and growth of rutile-anatase TiO2 thin film on fluorine-doped tin oxide (FTO) glass by a two-step hydrothermal method. The effects of additional treatments (i.e., TiCl4 post-treatment and seed layer formation were also studied. Photocurrent-voltage (I-V) measurement of rutile-anatase TiO2 thin film was performed under 1.5 G light illumination. Photovoltaic performance was investigated by incident photon-to-electron conversion efficiency (IPCE), electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent/photovoltage spectroscopy (IMVS/IMPS) and open-circuit photovoltage decay (OCVD). PMID:25971044

  20. Photocatalytic degradation of diethyl phthalate using TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Singla, Pooja; Pandey, O. P.; Singh, K.

    2014-04-01

    TiO2 nanoparticles predominantly in rutile phase are synthesized by ultrasonication assisted sol-gel method. TiO2 powder is characterized using X-ray powder diffraction and UV-vis diffuse reflectance. TiO2 is used as catalyst in photocatalytic degradation of Diethyl Phthalate. TiO2 exhibits good photocatalytic activity for the degradation of diethyl phthalate.