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1

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

2

Synthesis of efficient TiO2-based photocatalysts by phosphate surface modification and the activity-enhanced mechanisms  

NASA Astrophysics Data System (ADS)

A simple strategy to greatly increase the thermal stability of nanocrystalline anatase has been put forward to fabricate efficient TiO2-based photocatalysts under ultraviolet irradiation, via the surface modification with phosphate anions. The results show that the increased anatase thermal stability is attributed to the roles of the phosphate modification effectively inhibiting the contacts among anatase nanocrystals. Compared to un-modified TiO2, the modified TiO2 calcined at high temperature (over 700 °C) exhibits much high photocatalytic activity for degrading Rhodamine B (or phenol) solution, even superior to the commercial P25 TiO2. The activity enhancement is mainly attributed to the increased separation rate of photogenerated charge carriers on the basis of the measurements of steady state- and transient state-surface photovoltage spectroscopy. This work would provide a practical route to reasonably design and synthesize high-performance TiO2-based nanostructured photocatalysts with high anatase thermal stability.

Jing, Liqiang; Qin, Xu; Luan, Yunbo; Qu, Yichun; Xie, Mingzheng

2012-02-01

3

Novel TiO2/C nanocomposites: synthesis, characterization, and application as a photocatalyst for the degradation of organic pollutants.  

PubMed

Novel TiO(2)/carbon nanocomposites were prepared through the pyrolysis of TiO(2)/poly(furfuryl alcohol) hybrid materials, which were obtained by the sol-gel method, starting from titanium tetraisopropoxide (TTIP) and furfuryl alcohol (FA) precursors. Six different TiO(2)/C samples were prepared based on different TiO(2) nanoparticle sizes and TiO(2)/FA ratios. All of the samples were characterized using X-ray diffraction, infrared, and Raman spectroscopy. The results indicated effective FA polymerization onto the TiO(2) (anatase) nanoparticles, polymer conversion to disordered carbon following the pyrolysis, and a simultaneous TiO(2) anatase-rutile phase transition. The resulting TiO(2)/carbon composites were used as photocatalysts in the advanced oxidative process (AOP) for the degradation of reactive organic dyes in aqueous solution. The results indicate excellent photocatalytic performance (degradation of 99% of the dye after 60 min) with several advantages over traditional TiO(2)-based photocatalysts. PMID:22056275

da Costa, Elias; Zamora, Patricio P; Zarbin, Aldo J G

2012-02-15

4

One-step synthesis of N- and F-codoped mesoporous TiO2 photocatalysts with high visible light activity  

NASA Astrophysics Data System (ADS)

We report on a novel approach to the synthesis of N- and F-codoped mesoporous TiO2 photocatalysts via a reproducible, rapid and single-step combustion method. TiF4 was used as the precursor to provide the source of Ti and F, while urea was used as the fuel as well as the source of the N dopant. The as-synthesized samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The specific surface areas of the samples were determined using a Quantachrome Nova 2200 for the N2 adsorption/desorption under liquid-nitrogen temperature. Our studies show that the fabricated N- and F-codoped TiO2 photocatalysts have mesoporous structure and a very large specific surface area (155.3 m2 g-1) and that the codoping of N and F significantly narrows the TiO2 bandgap energy from 3.2 to 2.45 eV. We further studied the photocatalytic activity of the synthesized N- and F-codoped mesoporous TiO2 through the decomposition of acetic acid, showing that the N- and F-codoped mesoporous TiO2 catalyst fabricated in this study exhibits superb photocatalytic activity and visible light response compared to one of the best commercially available TiO2 photocatalysts, P25.

Wu, Guosheng; Wen, Jiali; Nigro, Samantha; Chen, Aicheng

2010-02-01

5

One-step synthesis of N- and F-codoped mesoporous TiO2 photocatalysts with high visible light activity.  

PubMed

We report on a novel approach to the synthesis of N- and F-codoped mesoporous TiO2 photocatalysts via a reproducible, rapid and single-step combustion method. TiF4 was used as the precursor to provide the source of Ti and F, while urea was used as the fuel as well as the source of the N dopant. The as-synthesized samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The specific surface areas of the samples were determined using a Quantachrome Nova 2200 for the N2 adsorption/desorption under liquid-nitrogen temperature. Our studies show that the fabricated N- and F-codoped TiO2 photocatalysts have mesoporous structure and a very large specific surface area (155.3 m(2) g(-1)) and that the codoping of N and F significantly narrows the TiO2 bandgap energy from 3.2 to 2.45 eV. We further studied the photocatalytic activity of the synthesized N- and F-codoped mesoporous TiO2 through the decomposition of acetic acid, showing that the N- and F-codoped mesoporous TiO2 catalyst fabricated in this study exhibits superb photocatalytic activity and visible light response compared to one of the best commercially available TiO2 photocatalysts, P25. PMID:20097984

Wu, Guosheng; Wen, Jiali; Nigro, Samantha; Chen, Aicheng

2010-02-26

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 and characterization of visible light driven mesoporous nano-photocatalyst MoO3/TiO2.  

PubMed

A novel mesoporous-structured photocatalyst MoO3/TiO2 was synthesized through a modified sol-gel method by using P123 as the template, and the resulting nano-photocatalysts were characterized by X-ray diffraction (XRD), N2 adsorption measurements, transmission electron microscope (TEM), UV-vis spectroscopy, XPS and Raman techniques. Low-angle XRD and TEM images show the lack of long-range order in the as-prepared MoO3/TiO2, but the Mo species are homogenously dispersed on the anatase matrix. According to the results of N2 ads-desorption, the calcined products possess the high surface area and the pore size distribution centered between 4-7 nm. The calcined meso-MoO3/TiO2 materials exhibit the high photocatalytic activity for the degradation of MB (methylene blue) under visible light radiation. PMID:22755001

Kong, Fei; Huang, Li; Luo, Leilei; Chu, Sheng; Wang, Ying; Zou, Zhigang

2012-03-01

8

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....

9

Synthesis and characterization of the N-doped TiO2 photocatalyst for the photodegradation of methylene blue and phenol.  

PubMed

To extend the light absorption of TiO2-based photocatalysts towards the visible-light range and to eliminate the rapid recombination of excited electrons/holes during photoreaction, a new type of photocatalyst (N-doped TiO2) powder was prepared through a simple sol-gel process. The crystal phase composition, structure, and light absorption of the new photocatalyst were comprehensively examined via X-ray diffraction, ultraviolet-visible (UV-Vis) absorption spectroscopy, and atomic-absorption spectroscopy. The photo-oxidation efficiency of the photocatalyst was also evaluated in the photodegradation of methylene blue (MB) and of phenol in aqueous solutions under visible-light irradiation from a neon lamp (lambda > 400 nm). The results of the analyses that were performed in this study indicated that the N-doped TiO2 could eliminate the electron/holes recombination and could increase the light absorption in the visible range. The results of the analysis of the UV-Vis diffuse reflection and optical-absorption spectra indicated that a new energy level below 3.2 eV generated in the N-doped TiO2 promoted the optical absorption in the visible-light region and made visible-light excitation possible (E < 3.2 eV). The experiment demonstrated that the photo-oxidation efficiency of MB when N-doped TiO2 powder was used was significantly higher than that when the conventional TiO2 powders were used. The development of such photocatalyst may be considered a breakthrough in the large-scale utilization of solar energy to address the current and future environmental needs. PMID:22121743

Khang, Nguyen Cao; Van Minh, Nguyen; Yang, In-Sang

2011-07-01

10

Synthesis of C, Ag co-modified TiO2 photocatalyst and its application in waste water purification  

NASA Astrophysics Data System (ADS)

Monodispersed C, Ag co-modified TiO2 microspheres were successfully synthesized through a two-step method. Firstly, monodisperse spherical TiO2 particles were obtained via controlled hydrolysis of TBOT (tetrabutyltitanate) in ethanol. Secondly, the C, Ag co-modified TiO2 microspheres were prepared through a simple calcination process, in which the AgNO3 and citric acid was used as Ag and C source, respectively. The physical and chemical properties of C, Ag co-modified TiO2 microspheres were carefully studied by using XRD, SEM, TEM, Raman, PL spectra and UV-vis diffuse reflectance spectra (DRS), while the chemical states of C and Ag were discussed via EDS (energy dispersive spectrometer) and XPS. The photocatalytic activity of the as-prepared products was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under UV and visible-light irradiation. The photocatalytic activity research shows that, with the cooperation of two modified materials, C, Ag co-modified TiO2 microspheres exhibit enhanced photocatalytic activity both in ultraviolet and visible-light region compared with that of pure TiO2 and single Ag modified TiO2 microspheres.

Liu, Hui; Dong, Xiaonan; Li, Guangjun; Su, Xing; Zhu, Zhenfeng

2013-04-01

11

Structure, Synthesis, and Applications of TiO2 Nanobelts.  

PubMed

TiO2 semiconductor nanobelts have unique structural and functional properties, which lead to great potential in many fields, including photovoltaics, photocatalysis, energy storage, gas sensors, biosensors, and even biomaterials. A review of synthetic methods, properties, surface modification, and applications of TiO2 nanobelts is presented here. The structural features and basic properties of TiO2 nanobelts are systematically discussed, with the many applications of TiO2 nanobelts in the fields of photocatalysis, solar cells, gas sensors, biosensors, and lithium-ion batteries then introduced. Research efforts that aim to overcome the intrinsic drawbacks of TiO2 nanobelts are also highlighted. These efforts are focused on the rational design and modification of TiO2 nanobelts by doping with heteroatoms and/or forming surface heterostructures, to improve their desirable properties. Subsequently, the various types of surface heterostructures obtained by coupling TiO2 nanobelts with metal and metal oxide nanoparticles, chalcogenides, and conducting polymers are described. Further, the charge separation and electron transfer at the interfaces of these heterostructures are also discussed. These properties are related to improved sensitivity and selectivity for specific gases and biomolecules, as well as enhanced UV and visible light photocatalytic properties. The progress in developments of near-infrared-active photocatalysts based on TiO2 nanobelts is also highlighted. Finally, an outline of important directions of future research into the synthesis, modification, and applications of this unique material is given. PMID:25800706

Zhao, Zhenhuan; Tian, Jian; Sang, Yuanhua; Cabot, Andreu; Liu, Hong

2015-04-01

12

Preparation of N-doped TiO 2 photocatalyst by atmospheric pressure plasma process for VOCs decomposition under UV and visible light sources  

Microsoft Academic Search

The nitrogen doped (N-doped) titanium dioxide (TiO2) photocatalyst was prepared by the atmospheric-pressure plasma-enhanced nanoparticles synthesis (APPENS) process operated\\u000a under normal temperature, i.e. the dielectric barrier discharge plasma process. The N2 carrier gas is dissociated in the AC powered nonthermal plasma environment and subsequently doped into the TiO2 photocatalyst that was capable of being induced by visible light sources. The

Chienchih Chen; Hsunling Bai; Sue-min Chang; Chungliang Chang; Walter Den

2007-01-01

13

XAFS Study on TiO2 Photocatalyst Loaded on Zeolite Synthesized from Steel Slag  

SciTech Connect

The convenient route for the synthesis of Y-zeolites by utilizing steel slag as a material source was developed. Through hydrothermal treatment, well-crystallized Y-zeolite was obtained. We also synthesized TiO2-loaded Y-zeolites by an impregnation method. The structure of titanium oxide species highly dispersed on the zeolite, which couldn't be detected by XRD patterns, was investigated by XAFS analysis. Photocatalytic activity for decomposition of 2-propanol in liquid phase was found to be enhanced by the hydrophobic surface property of zeolite. It has been demonstrated that the zeolite synthesized from steel slag would be applicable as a promising support of TiO2 photocatalyst.

Kuwahara, Yasutaka; Ohmichi, Tetsutaro; Mori, Kosuke; Katayama, Iwao; Yamashita, Hiromi [Divisions of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka (Japan)

2007-02-02

14

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

PubMed

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

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

2013-07-22

15

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)

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.

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

2014-10-01

16

Characterization and photocatalytic activity of Zn 2+-TiO 2/AC composite photocatalyst  

NASA Astrophysics Data System (ADS)

Activated carbon (AC) supported Zn 2+-TiO 2 photocatalyst was prepared by sol-gel method. The prepared samples were characterized by X-ray diffraction, scanning electron micrograph, nitrogen absorption, diffuse reflectance UV/VIS and X-ray photoelectron spectroscopy. Using toluene as a pollution target, the photocatalytic activity of photocatalyst was evaluated. The results showed that prepared photocatalyst was obviously helpful for the removal of toluene in air. The photocatalytic degradation of toluene by Zn 2+-TiO 2/AC reached 100% for 40 min and remained 75% after 160 min, while degradation by TiO 2 was only 30%. It indicated that the photocatalytic activity of prepared photocatalyst was enhanced. It is due to Zn 2+-doping increased the oxidation and reduction of hole-electron pairs, which was the important factor in heterogeneous photocatalysis.

Lu, Xincheng; Jiang, Jianchun; Sun, Kang; Cui, Dandan

2011-12-01

17

Synthesis of mesoporous TiO2/SiO2 hybrid films as an efficient photocatalyst by polymeric micelle assembly.  

PubMed

Thermally stable mesoporous TiO2/SiO2 hybrid films with pore size of 50?nm have been synthesized by adopting the polymeric micelle-assembly method. A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide), which serves as a template for the mesopores, was utilized to form polymeric micelles. The effective interaction of titanium tetraisopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) with the polymeric micelles enabled us to fabricate stable mesoporous films. By changing the molar ratio of TEOS and TTIP, several mesoporous TiO2/SiO2 hybrid films with different compositions can be synthesized. The presence of amorphous SiO2 phase effectively retards the growth of anatase TiO2 crystal in the pore walls and retains the original mesoporous structure, even at higher temperature (650?°C). These TiO2/SiO2 hybrid films are of very high quality, without any cracks or voids. The addition of SiO2 phase to mesoporous TiO2 films not only adsorbs more organic dyes, but also significantly enhances the photocatalytic activity compared to mesoporous pure TiO2 film without SiO2 phase. PMID:24710980

Li, Yunqi; Bastakoti, Bishnu Prasad; Imura, Masataka; Hwang, Soo Min; Sun, Ziqi; Kim, Jung Ho; Dou, Shi Xue; Yamauchi, Yusuke

2014-05-12

18

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

19

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

PubMed Central

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

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

20

TiO2 Nanotubes/MWCNTs Nanocomposite Photocatalysts: Synthesis, Characterization and Photocatalytic Hydrogen Evolution Under UV-Vis Light Illumination  

SciTech Connect

Nanocomposite of TiO2 nanotubes (TiO2NTs) and multiwalled carbon nanotubes (MWCNTs) has been synthesized by a hydrothermal method and firstly used in photocatalytic hydrogen production. The obtained TiO2 NTs/MWCNTs composites were characterized by X-ray diffraction, transmission electron microscopy, Raman spectrum and ultraviolet-visible diffuse reflectance spectroscopy. The experimental results revealed that the MWCNTs were decorated with well dispersed anatase TiO2 nanotubes with a diameter of 8-15 nm. A slight blue shift and weak symmetry was observed for the strongest Raman peak which resulted from strain gradients originating from interface integration between TiO2 nanotubes and MWCNTs. The photocatalytic activity of the as-prepared samples was evaluated by hydrogen evolution from water splitting using Na2S and Na2SO3 as sacrificial reagents under UV-vis light irradiation. Enhanced photocatalytic activity compared with P25 has been observed for the resulted samples. The nanocomposite with optimized MWCNTs content of 1% displayed a hydrogen production rate of 161 u mol/h/g. Good photocatalytic stability of the as-synthesized samples was observed as well.

Li, Hao-Peng; Zhang, Xiao-Yan; Cui, Xiao-Li; Lin, Yuehe

2012-03-01

21

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

22

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

PubMed

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. PMID:25656872

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

2015-02-27

23

Development of TiO 2 photocatalyst reaction for water purification  

Microsoft Academic Search

A new type of tubular photocatalytic reactor was developed to realize practical application of TiO2 photocatalyst for water purification. The principal part of the reactor consists of the ceramic cylindrical tube whose inner surface is coated with Pt-loaded TiO2 film and the 30 W ultraviolet light lamp which is set longitudinally in the center of the tube. The water to

Lianfeng Zhang; Tatsuo Kanki; Noriaki Sano; Atsushi Toyoda

2003-01-01

24

One-pot approach for synthesis of N-doped TiO2/ZnFe2O4 hybrid as an efficient photocatalyst for degradation of aqueous organic pollutants.  

PubMed

N-doped TiO2/ZnFe2O4 catalysts were successfully prepared by coupling nitrogen modified TiO2 with ZnFe2O4 via a one-pot vapor-thermal method. The physicochemical properties of the as-prepared catalysts have been characterized using various spectroscopic and microscopic techniques. The UV-vis-light-driven photocatalytic activities of the hybrids were evaluated and the effects of the amount of photocatalyst, different types of dyes, catalyst stability on photodegradation of organic dyes were investigated. Moreover, degradation kinetics and mechanism as well as the roles of N doping, ZnFe2O4 and TiO2 have been analyzed. It was revealed that N-doped TiO2/ZnFe2O4 exhibited an improved performance compared with TiO2/ZnFe2O4 or ZnFe2O4 because of the formation of a heterostructure at the interface as well as the introduction of N species. Active species such as holes, electrons, hydroxyl radicals, and superoxide radicals involved in the photodegradation process were detected by using different types of scavengers. Because of ZnFe2O4 in the hybrid, the catalyst shows ferromagnetism, and thus, the hybrid catalyst is easily isolated from the reaction mixture after the photocatalytic experiments. This work not only offers a simple method for the fabrication of N doped TiO2/ZnFe2O4 hybrids, but also provides an effective and conveniently recyclable photocatalyst for the purification of water. PMID:25748999

Yao, Yunjin; Qin, Jiacheng; Chen, Hao; Wei, Fengyu; Liu, Xueting; Wang, Jianlong; Wang, Shaobin

2015-06-30

25

Cold Spraying of TiO2 Photocatalyst Coating With Nitrogen Process Gas  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) is a promising material for photocatalyst coatings. However, it is difficult to fabricate a TiO2 coating with anatase phase by conventional thermal spray processes due to a thermal transformation to rutile phase. In this paper, anatase TiO2 coatings were fabricated by the cold spray process. To understand the influence of process gas conditions on the fabrication of the coatings, the gas nature (helium or nitrogen) and the gas temperature are investigated. It was possible to fabricate TiO2 coatings with an anatase phase in all spraying conditions. The process gas used is not an important factor to fabricate TiO2 coatings. The thickness of the coatings increased with the process gas temperature increasing. It indicates that the deposition efficiency of the sprayed particles can be enhanced by controlling the spray conditions. The photocatalytic activity of the coatings is similar or better than the feedstock powder due to the formation of a large reaction area. Concludingly, cold spraying is an ideal process for the fabrication of a TiO2 photocatalyst coating.

Yamada, Motohiro; Isago, Hiroaki; Nakano, Hiromi; Fukumoto, Masahiro

2010-12-01

26

Utilization of TiO2 photocatalysts in green chemistry  

Microsoft Academic Search

Environmental pollution and destruction on a global scale have drawn attention to the vital need for totally new environmentally friendly, clean chemical technologies and processes, the most important challenge facing chemical scientists in the field of green chemistry. Strong contenders as environmentally harmonious catalysts are photocatalysts that operate at room temperature and in a clean manner, while applications of such

Masakazu Anpo

2000-01-01

27

Stabilization mechanism of TiO 2 on flexible fluorocarbon films as a functional photocatalyst  

Microsoft Academic Search

The repetitive discoloration kinetics of the azo-dye Methyl Orange (taken as a model organic compound) was followed under solar simulated radiation (90mW\\/cm2) to assess the performance of the TiO2\\/Tedlar® composite photocatalyst. The influence of solution parameters on the photo-discoloration process: pH, dye concentration, applied light intensity and concentration of H2O2 were systematically investigated. During the photocatalysis a modification occurs in

Yu Zhiyong; E. Mielczarski; J. A. Mielczarski; D. Laub; L. Kiwi-Minsker; A. Renken; J. Kiwi

2006-01-01

28

Photocatalyst TiO 2 supported on glass fiber for indoor air purification: effect of NO on the photodegradation of CO and NO 2  

Microsoft Academic Search

A synthetic photocatalyst TiO2 prepared using the sol–gel method showed a higher activity than commercial photocatalyst TiO2 (P25), for the photodegradation of NO and benzene, toluene, ethylbenzene, o-xylene (BTEX) at typical indoor air parts-per-billion (ppb) levels. The Brunauer–Emmett–Teller (BET) surface area was found to be the vital parameter for the increased activity of the photocatalyst. The photocatalyst was immobilized on

C. H. Ao; S. C. Lee; Jimmy C. Yu

2003-01-01

29

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

PubMed Central

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

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

2014-01-01

30

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

31

Plasmonic TiO2/AgBr/Ag ternary composite nanosphere with heterojunction structure for advanced visible light photocatalyst  

NASA Astrophysics Data System (ADS)

In this work, TiO2/AgBr/Ag ternary composite nanosphere photocatalyst has been synthesized by in situ deposition of AgBr onto hollow spherical TiO2 template and followed by sun light reduction of AgBr into AgBr/Ag. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images have shown that the diameter of hollow TiO2 nanospheres is 250-350 nm and AgBr/Ag nanoparticles are well dispersed on the outer surface of TiO2 nanosphere. UV-vis spectrum analysis has shown largely improved visible light absorption of this ternary composite, in comparison to pure TiO2 and AgBr. The building-in AgBr/Ag, TiO2/AgBr and TiO2/Ag junctions within the ternary composite enhanced the visible light absorption because of plasmonic resonance and narrow bandgap. The pseudo-first-order rate constant kapp of the TiO2/AgBr/Ag ternary composite for methylene blue photodegradation displays 24.5 times and 3.3 times than the pure TiO2 nanosphere and AgBr/Ag nanoparticles, respectively. Furthermore, the stability of TiO2/AgBr/Ag ternary composite is characterized through cyclic photocatalytic test. Results indicate that 92.7% of photocatalytic degradation can be achieved by TiO2/AgBr/Ag ternary composite even after five recycles.

Dai, Kai; Li, Dongpei; Lu, Luhua; Liu, Qi; Liang, Changhao; Lv, Jiali; Zhu, Guangping

2014-09-01

32

Local structure of Mo-doped TiO2 photocatalysts investigated by X-ray absorption fine structure  

NASA Astrophysics Data System (ADS)

The local structures of Mo-doped TiO2 photocatalysts are investigated by X-ray absorption fine structure spectroscopy (XAFS) combined with X-ray diffraction (XRD). The XRD patterns show that all the Mo-doped TiO2 samples maintain the high qualitative anatase TiO2 structure without any visible diffraction peak related to Mo. The detailed XANES and EXAFS analysis reveal that all of the Mo atoms substitute Ti atoms in the anatase lattice as Mo6+ with doping concentration as high as 6 atom %. Combined with theoretical calculation, we suggested that the high electron density of Mo-O causes the strong shrinkage of ~0.1 Å for Mo-O bond length in Mo-doped TiO2.

Feng, Y. J.; Wang, C.; Cheng, W. R.; Huang, J. H.; Zhao, T. X.; Liu, Q. H.; Xie, Z.; Pan, Z. Y.; Wei, S. Q.

2013-04-01

33

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)

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.

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

2014-12-01

34

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

35

Characterization and the photocatalytic activity of TiO2 immobilized hydrophobic montmorillonite photocatalystsDegradation of decabromodiphenyl ether (BDE 209)  

Microsoft Academic Search

A novel TiO2 immobilized hydrophobic montmorillonite photocatalysts were designed and prepared for the advanced oxidation of persistent organic pollutants in water, which combined the pre-adsorption and concentrated effects for aqueous micro-organic pollutants with the photocatalytic destruction of organic pollutants. The photocatalysts were synthesized by immobilizing TiO2 onto surfactant-pillared montmorillonite via ion exchange reaction between sodium montmorillonite with cation surfactant, cetyl

Taicheng An; Jiaxin Chen; Guiying Li; Xuejun Ding; Guoying Sheng; Jiamo Fu; Bixian Mai; Kevin E. O'Shea

2008-01-01

36

InVO 4-sensitized TiO 2 photocatalysts for efficient air purification with visible light  

Microsoft Academic Search

A visible-light-driven InVO4\\/TiO2 mesoporous photocatalyst was prepared by a sol–gel method. The catalyst was characterized by powder X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectra (XPS), ultraviolet photoelectron spectra (UPS), and spin-trapping electron paramagnetic resonance (EPR). Photocatalytic activity of the sample was evaluated by the degradation of volatile organic compounds (VOCs) in

Guangcan Xiao; Xinchen Wang; Danzhen Li; Xianzhi Fu

2008-01-01

37

Preparation and caracterization of TiO{2} powder photocatalysts. Comparative studies of photocatalytic activity in the degradation of ?-naphthol  

NASA Astrophysics Data System (ADS)

Titanium dioxide TiO{2} powder photocatalysts were prepared at the laboratory by two methods: hydrolysis of titanium tetraisopropoxide (TTIP) and the precipitation of a precursor starting from titanium tetrachloride TiCl{4} in basic medium. The products obtained are calcined at temperatures around 800° C. Their characterization was carried out by both diffraction X-ray (XRD) and thermogravimetric analysis (TGA). The photocatalytic activity of the elaborate solids (TiO{2}) is evaluated. It is compared with that given for commercial TiO{2} “Degussa P-25” in the degradation of ?-naphthol chosen as an model molecule in aqueous suspension. These reactions are done at room temperature in a photochemical reactor.

Qourzal, S.; Tamimi, M.; Assabbane, A.; Nounah, A.; Maroufi, N.; Bouamrane, A.; Ichou, Y. Ait

2005-03-01

38

Use of titanium dioxide (TiO2) photocatalysts as alternative means for Listeria monocytogenes biofilm disinfection in food processing.  

PubMed

The aim of this work was to study the photocatalytic activity of titanium dioxide (TiO(2)) against Listeria monocytogenes bacterial biofilm. Different TiO(2) nanostructured thin films were deposited on surfaces such as stainless steel and glass using the doctor-blade technique. All the surfaces were placed in test tubes containing Brain Heart (BH) broth and inoculated with L. monocytogenes. Test tubes were then incubated for 10 days at 16°C in order to allow biofilm development. After biofilm formation, the surfaces were illuminated by ultraviolet A light (UVA; wavelength of 315-400 nm). The quantification of biofilms was performed using the bead vortexing method, followed by agar plating and/or by conductance measurements (via the metabolic activity of biofilm cells). The presence of the TiO(2) nanoparticles resulted in a fastest log-reduction of bacterial biofilm compared to the control test. The biofilm of L. monocytogenes for the glass nanoparticle 1 (glass surface modified by 16% w/v TiO(2)) was found to have decreased by 3 log CFU/cm(2) after 90 min irradiation by UVA. The use of TiO(2) nanostructured photocatalysts as alternative means of disinfecting contaminated surfaces presents an intriguing case, which by further development may provide potent disinfecting solutions. Surface modification using nanostructured titania and UV irradiation is an innovative combination to enhance food safety and economizing time and money. PMID:21056789

Chorianopoulos, N G; Tsoukleris, D S; Panagou, E Z; Falaras, P; Nychas, G-J E

2011-02-01

39

Highly effective Fe-doped TiO2 nanoparticles photocatalysts for visible-light driven photocatalytic degradation of toxic organic compounds.  

PubMed

This paper reports the synthesis of various molar concentrations of iron (Fe)-doped TiO2 nanoparticles and their efficient use as potential photocatalysts for photocatalytic degradation of toxic and harmful chemical, paranitrophenol. The nanoparticles were synthesized by a novel and facile ultrasonic assisted hydrothermal method and characterized in detail by various analytical techniques in terms of their morphological, structural, compositional, thermal, optical, pore size distribution, etc properties. The photocatalytic activities of the as-prepared Fe-doped TiO2 nanoparticles were examined under visible light illumination using para-nitrophenol as target pollutant. By detailed experimental findings revealed that the Fe dopant content crucially determines the catalytic activity of TiO2 nanoparticles. The maximum degradation rate of para-nitrophenol observed was 92% in 5h when the Fe(3+) molar concentration was 0.05mol%, without addition of any oxidizing reagents. The prepared nanoparticles demonstrated excellent photocatalytic response because of their small size, excellent crystalline structure, increase in threshold wavelength response and maximum separation of photogenerated charge carriers. Further, the determination of reaction intermediates has also been carried out and plausible mechanism of photocatalytic degradation of para-nitrophenol has been proposed. PMID:25823725

Sood, Swati; Umar, Ahmad; Mehta, Surinder Kumar; Kansal, Sushil Kumar

2015-07-15

40

BiOI nanosheets decorated TiO2 nanofiber: Tailoring water purification performance of photocatalyst in structural and photo-responsivity aspects  

NASA Astrophysics Data System (ADS)

Microscopic structure and photo-responsive characters are two important facets that dominate the synthetic performance of photocatalysts in environment remediation. In the present investigation, we report the simultaneous tailoring of these two facets toward improving the water purification performance of TiO2 based photocatalyst. Electrospinning-derived TiO2 nanofibers were decorated with the visible-light responsive BiOI nanosheets via a simple hydrothermal reaction approach, constructing heterostructured composite fibers. The obtained hierarchical TiO2@BiOI fibers demonstrated improved reactivity toward decomposition of Rhodamine B in the visible-light range over the pristine TiO2 nanofibers, meanwhile possessed high recycling convenience. The mechanism for advancement of the photocatalytic reactivity of the TiO2@BiOI fibers was elucidated by analyzing the results of photoluminescence and transient photocurrent response.

Liao, Chenxing; Ma, Zhijun; Dong, Guoping; Qiu, Jianrong

2014-09-01

41

Photocatalytic synthesis of TiO(2) and reduced graphene oxide nanocomposite for lithium ion battery.  

PubMed

In this work, we synthesized graphene oxide (GO) using the improved Hummers' oxidation method. TiO2 nanoparticles can be anchored on the GO sheets via the abundant oxygen-containing functional groups such as epoxy, hydroxyl, carbonyl, and carboxyl groups on the GO sheets. Using the TiO2 photocatalyst, the GO was photocatalytically reduced under UV illumination, leading to the production of TiO2-reduced graphene oxide (TiO2-RGO) nanocomposite. The as-prepared TiO2, TiO2-GO, and TiO2-RGO nanocomposite were used to fabricate lithium ion batteries (LIBs) as the active anode materials and their corresponding lithium ion insertion/extraction performance was evaluated. The resultant LIBs of the TiO2-RGO nanocomposite possesses more stable cyclic performance, larger reversible capacity, and better rate capability, compared with that of the pure TiO2 and TiO2-GO samples. The electrochemical and materials characterization suggest that the graphene network provides efficient pathways for electron transfer, and the TiO2 nanoparticles prevent the restacking of the graphene nanosheets, resulting in the improvement in both electric conductivity and specific capacity, respectively. This work suggests that the TiO2 based photocatalytic method could be a simple, low-cost, and efficient approach for large-scale production of anode materials for lithium ion batteries. PMID:22738305

Qiu, Jingxia; Zhang, Peng; Ling, Min; Li, Sheng; Liu, Porun; Zhao, Huijun; Zhang, Shanqing

2012-07-25

42

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

PubMed

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

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

2005-05-12

43

The electronic and optical properties of Eu/Si-codoped anatase TiO2 photocatalyst  

NASA Astrophysics Data System (ADS)

The electronic and optical properties of Eu/Si-codoped anatase TiO2 are investigated using the density functional theory. The calculated results show that the synergistic effects of Eu/Si codoping can effectively extend the optical absorption edge, which can lead to higher visible-light photocatalytic activities than pure anatase TiO2. To verify the reliability of our calculated results, nanocrystalline Eu/Si-codoped TiO2 is prepared by a sol-gel-solvothermal method, and the experimental results also indicate that the codoping sample exhibits better absorption performance and higher photocatalytic activities than pure TiO2.

Lin, Yanming; Jiang, Zhenyi; Hu, Xiaoyun; Zhang, Xiaodong; Fan, Jun

2012-03-01

44

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

PubMed Central

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

Pham, Thanh-Dong; Lee, Byeong-Kyu

2014-01-01

45

Feasibility of silver doped TiO2/glass fiber photocatalyst under visible irradiation as an indoor air germicide.  

PubMed

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

Pham, Thanh-Dong; Lee, Byeong-Kyu

2014-03-01

46

Photocatalytic oxidation of methyl orange in water phase by immobilized TiO2-carbon nanotube nanocomposite photocatalyst  

NASA Astrophysics Data System (ADS)

We developed an immobilized carbon nanotube (CNT)-titanium dioxide (TiO2) heterostructure material for the photocatalytic oxidation of methyl orange in aqueous phase. The catalyst material was prepared via sol-gel method using multi-walled CNTs grown on graphite substrate as carriers. The multi-walled CNTs were synthesized from thermal decomposing of hydrocarbon gas directly on thin graphite plate, forming immobilized 3-dimensional network of CNTs. The nanophase TiO2 was synthesized coating on CNTs to form "coral"-shaped nanocomposite 3-dimensional network on graphite substrate, thus bringing effective porous structure and high specific surface area, and possessing the merit of dispersive powder photocatalysts, which is the fully available surface area, while adapting the requirement for clean and convenient manipulation as an immobilized photocatalyst. Moreover, the CNT-TiO2 heterostructure reduced the electron-hole pair recombination rate and enhanced the photoabsorption and the adsorption ability, resulting in elevating the photocatalysis efficiency. These synergistic effects due to the hybrid nature of the materials and interphase interaction greatly improved the catalytic activity, and demonstrated superior photocatalytic performances. Our work can be a significant inspiration for developing hybrid nano-phase materials to realize sophisticated functions, and bear tremendous significance for the development and applications of semiconductor nano-materials.

Dong, Yinmao; Tang, Dongyan; Li, Chensha

2014-03-01

47

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)

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.

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

2014-04-01

48

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...

49

The Role of the Relative Dye/Photocatalyst Concentration in TiO2 Assisted Photodegradation Process.  

PubMed

Despite photocatalytic degradation is studied generally focusing the catalyst, its interaction with the contaminant molecule plays a fundamental role in the efficiency of that process. Then, we proposed a comparative study about the photodegradation of two well-known dyes, with different acidity/basicity - Methylene Blue (MB) and Rhodamine B (RhB), catalyzed by TiO2 nanoparticles, varying both dye and photocatalyst concentrations. The results showed that the amphoteric character of MB molecules, even in a range of concentration of 5.0-10.0 mg L(-1) , did not imply in pH variation in solution. Therefore, it did not affect the colloidal behavior of TiO2 nanoparticles, independent of the relative dye/catalyst concentration. The acid-base character of RhB influenced the resultant pH of the solution, implicating in different colloidal behavior of the nanoparticles and consequently, in different degradation conditions according to dye concentration. As the isoelectric point of TiO2 is between the pH range of the RhB solutions used in this study, from 1.0 to 7.5 mg L(-1) , the resultant pH was the key factor for degradation conditions, from a well dispersed to an agglomerated suspension. PMID:24107092

de Mendonça, Vagner R; Mourão, Henrique A J L; Malagutti, Andréa R; Ribeiro, C

2013-09-24

50

Why is anatase a better photocatalyst than rutile? - Model studies on epitaxial TiO2 films  

PubMed Central

The prototypical photocatalyst TiO2 exists in different polymorphs, the most common forms are the anatase- and rutile-crystal structures. Generally, anatase is more active than rutile, but no consensus exists to explain this difference. Here we demonstrate that it is the bulk transport of excitons to the surface that contributes to the difference. Utilizing high –quality epitaxial TiO2 films of the two polymorphs we evaluate the photocatalytic activity as a function of TiO2-film thickness. For anatase the activity increases for films up to ~5?nm thick, while rutile films reach their maximum activity for ~2.5?nm films already. This shows that charge carriers excited deeper in the bulk contribute to surface reactions in anatase than in rutile. Furthermore, we measure surface orientation dependent activity on rutile single crystals. The pronounced orientation-dependent activity can also be correlated to anisotropic bulk charge carrier mobility, suggesting general importance of bulk charge diffusion for explaining photocatalytic anisotropies. PMID:24509651

Luttrell, Tim; Halpegamage, Sandamali; Tao, Junguang; Kramer, Alan; Sutter, Eli; Batzill, Matthias

2014-01-01

51

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...

52

[Preparation and catalytic activity for degradation of acidic fuchsine of TiO2 photocatalyst].  

PubMed

In the paper, undoped and Pr2O3 doped TiO2 nanoparticles were prepared by a sol-gel process using Ti(OC4H9)4 as raw material and characterized by means of XRD TG-DTA, AFM, UV-Vis and FTIR. The photocatalytic activity of Pr2O3/TiO2 was evaluated by the photocatalytic degradation of acidic fuchsine. The factors affecting on photocatalytic activity of Pr2O3/TiO2, such as the content of doped Pr2O3, the calcined temperature and added amount of the catalyst etc. were discussed. It was shown that Pr doping hampers the transformation of TiO2 crystal phase from anatase to rutile, and with Pr2O3 doping the particle diameter of Pr2O3/TiO2 samples decreased, the specific surface area increased and the photocatalytic activity improved. When doping amount of Pr is 0.8%, added amount of the catalyst is 0.03 g and the calcination temperature is 500 degrees C, the degradation efficiency of acidic fuchsine reaches 97%. The photocatalytic degradation of acidic fuchsine by Pr2O3/TiO2 is a quasi-first order dynamic reaction. PMID:18619330

Yang, Wu; Guo, Hao; Zhang, Wen-Hao; Xue, Zai-Lan; Cheng, Li-Yan; Bo, Li-Li; Gao, Jin-Zhang

2008-04-01

53

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

PubMed

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. PMID:25528508

Rajamanickam, D; Dhatshanamurthi, P; Shanthi, M

2015-03-01

54

Sandwich SrTiO3/TiO2/H-Titanate nanofiber composite photocatalysts for efficient photocatalytic hydrogen evolution  

NASA Astrophysics Data System (ADS)

SrTiO3/TiO2/H-Titanate nanofiber composites were synthesized through facile thermal treatment of Sr(OH)2 and H-titanate nanofibers in an ethanol/water solution and their photocatalytic activities for H2 evolution from a methanol/water solution under simulated solar irradiation were evaluated. TiO2/H-titanate nanofiber composites were acquired without Sr(OH)2 addition. At low Sr/Ti molar ratios, SrTiO3/TiO2/H-titanate nanofiber composites form. SrTiO3 nanoparticles were found to selectively grow on the surface of TiO2 nanoparticles, forming a unique SrTiO3-TiO2-H-titanate sandwich heterojunction. Upon increasing the Sr/Ti molar ratio, the fraction of TiO2 in the resultant composites decreases and eventually SrTiO3/H-titanate nanofiber composites form. SrTiO3/TiO2/H-titanate nanofiber composites are significantly more photocatalytically active than SrTiO3/H-titanate nanofiber and TiO2/H-titanate nanofiber composites due to the mitigated charge recombination and the accumulation of photo-excited electrons on the photocatalytically active TiO2 component. These results demonstrate an effective strategy of multi-heterojunctions with both appropriately-aligned band structures and appropriately-arranged composite structures to fabricate efficient composite photocatalysts.

Liu, Yuanxu; Wang, Zhonglei; Wang, Wendong; An, Xiaoqiang; Mi, Shiyang; Tang, Junwang; Huang, Weixin

2014-10-01

55

Microporous Ni-doped TiO2 film photocatalyst by plasma electrolytic oxidation.  

PubMed

Ni-doped TiO2 film catalysts were prepared by a plasma electrolytic oxidation (PEO) method and were mainly characterized by means of SEM, EDS, XRD, XPS, and DRS, respectively. The effects of Ni doping on the structure, composition and optical absorption property of the film catalysts were investigated along with their inherent relationships. The results show that the film catalyst is composed of anatase and rutile TiO2 with microporous structure. Doping Ni changes the phase composition and the lattice parameters (interplanar crystal spacing and cell volume) of the films. The optical absorption range of TiO2 film gradually expands and shifts to the red with increasing dosages. Both direct and indirect transition band gaps of the TiO2 films are deduced consequently. Moreover, the photocatalytic activity of the film catalysts for splitting Na2S+Na2SO3 solution into H2 is enhanced by doping with an appropriate amount of Ni. The as-prepared TiO2 film catalyst doping with 10 g/L of Ni(Ac)2 presents the highest photocatalytic reducing activity. PMID:20799710

Yao, Zhongping; Jia, Fangzhou; Tian, Shujun; Li, ChunXiang; Jiang, Zhaohua; Bai, Xuefeng

2010-09-01

56

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

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

57

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

PubMed

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

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

2009-01-01

58

Synthesis of TiO2 and TiO2-Pt and their application in photocatalytic degradation of humic acid.  

PubMed

The deposit of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this study, TiO2 nanoparticles were prepared using a sol-gel route followed by heat treatment at elevated temperatures (573 K, 773 K, and 973 K). TiO2-Pt catalyst (1 wt%) was prepared by depositing Pt on the surface of the prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were used as heterogeneous catalysts to remove humic acid with UV-light (120 W) illumination. TiO2 prepared at low temperature with smaller particle size and larger specific surface area had stronger activity on humic acid degradation. Deposit of Pt would favor separation of photogenerated charges and enhance the photocatalyst activity, but its coating of the active site also inhibited degradation of humic acid. The addition of H202 enhanced degradation of humic acid for more active oxygen produced. Low pH (pH = 4) was helpful to adsorb humic acid on the surface of TiO2 and, correspondingly, enhance degradation of humic acid (44.4%). PMID:24617110

Chen, Wenzhao; Ran, Xianqiang; Jiang, Xu; Min, Hongyang; Li, Dandan; Zou, Liyin; Fan, Jianwei; Li, Guangming

2014-01-01

59

Anatase TiO 2 nanolayer coating on cobalt ferrite nanoparticles for magnetic photocatalyst  

Microsoft Academic Search

TiO2\\/CoFe2O4 composite nanoparticles with a core–shell structure have been obtained. The core CoFe2O4 nanoparticles were synthesized via co-precipitation method, and the shell TiO2 nanocrystals were derived via sol–gel technology followed by heat-treatment at 450 °C. The morphology and the crystalline structure of composite nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction, respectively. The as-prepared composite particles can

Wuyou Fu; Haibin Yang; Minghua Li; Minghui Li; Nan Yang; Guangtian Zou

2005-01-01

60

Photocatalytic degradation of mixed gaseous carbonyl compounds at low level on adsorptive TiO2/SiO2 photocatalyst using a fluidized bed reactor.  

PubMed

An adsorptive silica-supported titania photocatalyst TiO(2)/SiO(2) was prepared by using nanosized titania (anatase) immobilized on silica gel by the sol-gel technique with the titanium tetra isopropoxide as the main raw material and acetic acid as the acid catalyst. Meanwhile the structure and properties of the TiO(2)/SiO(2) photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, and BET. Gas-solid heterogeneous photocatalytic decomposition of four carbonyl compounds mixture at low concentration levels over ultraviolet irradiated TiO(2)/SiO(2) photocatalyst were carried out with high degradation efficiencies in a coaxial triple-cylinder-type fluidized bed photocatalytic reactor, which provided efficient continuous contact of ultraviolet photons, silica-supported titania photocatalyst, and gaseous reactants. Experimental results showed that the photocatalyst had a high adsorption performance and a good photocatalytic activity for four carbonyl compounds mixture. Some factors influencing the photocatalytic decomposition of the mixed carbonyl compounds, i.e. the gas flowrate, relative humidity, concentration of oxygen, and illumination time, were discussed in detail. It is found that the photocatalytic reaction rate of four carbonyl compounds decreased in this order: propionaldehyde, acetone, acetaldehyde and formaldehyde. PMID:16412494

Zhang, Maolin; An, Taicheng; Fu, Jiamo; Sheng, Guoying; Wang, Xinming; Hu, Xiaohong; Ding, Xuejun

2006-06-01

61

Novel doping for synthesis monodispersed TiO2 grains filled into spindle-like hematite bi-component nanoparticles by ion implantation  

NASA Astrophysics Data System (ADS)

The synthesis of multifunctional nanoparticles (NPs) that combine some of the unique physical and chemical characteristics of two or more classes of materials is still a key goal in modern materials chemistry and has attracted substantial interests in recent years. In that context, magnetic monodispersed TiO2 grains filled into spindle-like hematite bi-component NPs were synthesized by ion implantation. The ?-Fe2O3/TiO2 bi-component NPs present superparamagnetism at room temperature, and its saturation magnetization was enhanced from 0.53 emu/g (?-Fe2O3 seeds) to 3.55 emu/g. The proposed doping synthesis method allows for fabricating the other bi- or multi-component NPs. The magnetic ?-Fe2O3/TiO2 would be acted as "nanoreactors" and provide a promising composite photocatalyst with narrow and wide bandgap semiconductors in the future.

Sun, L. L.; Wu, W.; Zhang, S. F.; Zhou, J.; Cai, G. X.; Ren, F.; Xiao, X. H.; Dai, Z. G.; Jiang, C. Z.

2012-09-01

62

Study of Visible Light Reactive Photocatalyst TIO2 Prepared with Thiourea  

NASA Astrophysics Data System (ADS)

Visible light reactive N-doped TiO2 samples were prepared with thiourea in the sol-gel method. They had the single anatase-type crystal structure. N-doped TiO2 synthesized with thiourea (T-TiO2) had a higher catalytic activity than that synthesized with urea (U-TiO2). The S2p peak observed on the surface of T-TiO2 was assigned to S6+ by XPS measurement. It was estimated that sulfuric acid species exist on the surface of T-TiO2. However, it was concluded that sulfuric acid species do not have the catalytic activity directly, but depress the crystallinity, the decrease of specific surface area and the decrease of visible light absorption.

Murai, Kei-Ichiro; Endo, Kazuki; Nakagawa, Taisuke; Yamahata, Akiko; Moriga, Toshihiro

63

Synthesis and photocatalytic activity of TiO2 nanoparticles prepared by chemical vapor condensation method with different precursor concentration and residence time.  

PubMed

Nanosized TiO(2) photocatalysts were synthesized using a chemical vapor condensation method under a range of synthesis conditions (precursor vapor concentration and residence time in a tubular electric furnace). X-ray diffraction showed that the prepared TiO(2) powders consisted mainly of anatase (>94%) with a small amount of rutile. The mean particle diameter from the Brunauer-Emmett-Teller surface area and transmission electron microscopy measurements ranged from 9.4 to 16.6 nm. The specific surface area (92.5-163.5 m(2) g(-1)) of the prepared TiO(2) powders was found to be dependent on the synthesis conditions. The content of hydroxyl groups on the surface of the prepared TiO(2) sample was higher than those on commercial TiO(2), resulting in increased photocatalytic oxidation. The photocatalytic activity of the TiO(2) samples prepared in a methylene blue solution was strongly dependent on the crystallinity and specific surface area, which were affected by the TTIP vapor concentration and residence time. PMID:21802692

Chin, Sungmin; Park, Eunseuk; Kim, Minsu; Bae, Gwi-Nam; Jurng, Jongsoo

2011-10-15

64

Heterogeneous photocatalytic treatment of simulated dyehouse effluents using novel TiO 2-photocatalysts  

Microsoft Academic Search

Heterogeneous photocatalytic treatment of two different synthetic dyehouse effluents called RI and RII, that were simulating textile wastewater from an integrated plant and a dyehouse mill and containing various reactive dyestuffs and associated auxiliary chemicals, was investigated by using different TiO2 types and reaction conditions. The effect of initial pH and effluent dilution ratio on treatment efficiency was examined and

Idil Arslan; Isil Akmehmet Balcioglu; Detlef W. Bahnemann

2000-01-01

65

Self-organized TiO2 nanotube layers as highly efficient photocatalysts  

Microsoft Academic Search

Self-organized high-aspect-ratio TiO2 nanotubular layers exhibit excellent photocatalytic properties that are significantly enhanced compared to nanoparticulate layers. These tubular layers have showed remarkable photocatalytic activity for the decomposition of organic azo dyes namely, Acid Organge 7 (AO7) and Methylene Blue (MB), which are non-biodegradable dyes used in the textile industry and often considered as standard dyes for testing photocatalytic activity.

Martin Zlamal; Josef Krysa; Patrik Schmuki

2007-01-01

66

Gel-hydrothermal synthesis of carbon and boron co-doped TiO 2 and evaluating its photocatalytic activity  

Microsoft Academic Search

Carbon and boron co-doped TiO2 photocatalysts were prepared firstly by the gel-hydrothermal method, that is, synthesized through sol–gel process followed by hydrothermal in the glucose solution. The prepared photocatalysts were characterized by XRD, Raman spectra, TEM, N2 physical adsorption, XPS, and UV–vis absorption spectra. It was found that the co-doped TiO2 has a larger BET surface areas and a narrower

Yongmei Wu; Mingyang Xing; Jinlong Zhang

2011-01-01

67

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

68

2+/TiO2-Codoped Zeolites: Synthesis, Characterization, and the Role of TiO2 in Electron Transfer Photocatalysis  

E-print Network

Ru(bpy)3 2+/TiO2-Codoped Zeolites: Synthesis, Characterization, and the Role of TiO2 in Electron developed which are able to transfer electrons from excited Ru(II) donors within the zeolite framework to Co consist of zeolite Y-encapsulated Ru(bpy)3 2+ (bpy ) 2,2- bipyridine) sensitizers in close proximity to Ti

Turro, Claudia

69

Steady hydrogen evolution from water on Eosin Y-fixed TiO 2 photocatalyst using a silane-coupling reagent under visible light irradiation  

Microsoft Academic Search

A chemical fixation of xanthene dyes on platinized TiO2 particles via silane-coupling reagent was attempted in order to construct a stable dye-sensitized photocatalyst system in water. The Eosin Y fixed Pt-TiO2 (E.Y-TiO2) exhibited steady H2 production from aqueous triethanolamine solution (TEOA aq.) under visible light irradiation for long time, and the H2 evolution reproduced even after the exchange of TEOA

Ryu Abe; Koujirou Hara; Kazuhiro Sayama; Kazunari Domen; Hironori Arakawa

2000-01-01

70

Nitrogen doping of TiO2 photocatalyst forms a second eg state in the Oxygen (1s) NEXAFS pre-edge  

Microsoft Academic Search

Close inspection of the pre-edge in oxygen near-edge x-ray absorption fine structure spectra of single step, gas phase synthesized titanium oxynitride photocatalysts with 20 nm particle size reveals an additional eg resonance in the VB that went unnoticed in previous TiO2 anion doping studies. The relative spectral weight of this Ti(3d)-O(2p) hybridized state with respect to and located between the

Artur Braun; Kranthi K. Akurati; Giuseppino Fortunato; Felix A. Reifler; Axel Ritter; Ashley S. Harvey; Andri Vital; Thomas Graule

2011-01-01

71

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

72

Effects of SO2 on selective catalytic reduction of NO with NH3 over a TiO2 photocatalyst  

NASA Astrophysics Data System (ADS)

The effect of SO2 gas was investigated on the activity of the photo-assisted selective catalytic reduction of nitrogen monoxide (NO) with ammonia (NH3) over a TiO2 photocatalyst in the presence of excess oxygen (photo-SCR). The introduction of SO2 (300 ppm) greatly decreased the activity of the photo-SCR at 373 K. The increment of the reaction temperature enhanced the resistance to SO2 gas, and at 553 K the conversion of NO was stable for at least 300 min of the reaction. X-ray diffraction, FTIR spectroscopy, thermogravimetry and differential thermal analysis, x-ray photoelectron spectroscopy (XPS), elemental analysis and N2 adsorption measurement revealed that the ammonium sulfate species were generated after the reaction. There was a strong negative correlation between the deposition amount of the ammonium sulfate species and the specific surface area. Based on the above relationship, we concluded that the deposition of the ammonium sulfate species decreased the specific surface area by plugging the pore structure of the catalyst, and the decrease of the specific surface area resulted in the deactivation of the catalyst.

Yamamoto, Akira; Teramura, Kentaro; Hosokawa, Saburo; Tanaka, Tsunehiro

2015-04-01

73

Effect of preparation methods on the structure and catalytic performance of TiO(2)/AC photocatalysts.  

PubMed

Activated carbon (AC)-supported TiO(2) catalysts were prepared by sol-gel and metal organic chemical vapor deposition (MOCVD) in order to investigate effect of preparation methods on the structure and catalytic performance of TiO(2)/AC catalysts. It was found that both methods yield "egg-shell" TiO(2)/AC catalysts, that is to say, the TiO(2) coatings were mainly on the surface of AC supports. The TiO(2) coating by sol-gel was only coated on the external surface of AC. In contrast, TiO(2) by MOCVD was deposited on the surface of AC through the heterogeneous reaction, forming a TiO(2)+AC hybrid film (about 3 microm) as evidenced by SEM and N(2) adsorption tests. The hybrid TiO(2)+AC film could capture the intermediates produced during the degradation of the target pollutant resulting in efficient mineralization. The TiO(2)/AC catalysts by MOCVD exhibited a Ti-O-C bond, which correlated with the good stability of TiO(2) as observed on the corresponding samples. These results indicate MOCVD is a better choice for the preparation of TiO(2)/AC catalysts. PMID:17950997

Zhang, Xingwang; Lei, Lecheng

2008-05-01

74

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

75

Degradation of microcystin-LR by highly efficient AgBr/Ag3PO4/TiO2 heterojunction photocatalyst under simulated solar light irradiation  

NASA Astrophysics Data System (ADS)

A novel photocatalyst AgBr/Ag3PO4/TiO2 was developed by a simple facile in situ deposition method and used for degradation of mirocystin-LR. TiO2 (P25) as a cost effective chemical was used to improve the stability of AgBr/Ag3PO4 under simulated solar light irradiation. The photocatalytic activity tests for this heterojunction were conducted under simulated solar light irradiation using methyl orange as targeted pollutant. The results indicated that the optimal Ag to Ti molar ratio for the photocatalytic activity of the resulting heterojunction AgBr/Ag3PO4/TiO2 was 1.5 (named as 1.5 BrPTi), which possessed higher photocatalytic capacity than AgBr/Ag3PO4. The 1.5 BrPTi heterojunction was also more stable than AgBr/Ag3PO4 in photocatalysis. This highly efficient and relatively stable photocatalyst was further tested for degradation of the hepatotoxin microcystin-LR (MC-LR). The results suggested that MC-LR was much more easily degraded by 1.5 BrPTi than by AgBr/Ag3PO4. The quenching effects of different scavengers proved that reactive h+ and •OH played important roles for MC-LR degradation.

Wang, Xin; Utsumi, Motoo; Yang, Yingnan; Li, Dawei; Zhao, Yingxin; Zhang, Zhenya; Feng, Chuanping; Sugiura, Norio; Cheng, Jay Jiayang

2015-01-01

76

Sol-gel synthesis of mesoporous anatase-brookite and anatase-brookite-rutile TiO2 nanoparticles and their photocatalytic properties.  

PubMed

TiO2 photocatalysts with a mixture of different TiO2 crystal polymorphs have customarily been synthesized hydrothermally at high temperatures using complicated and expensive equipment. In this study TiO2 nanoparticles with a mixture of TiO2 crystals were synthesized using a modified sol-gel method at low temperature. In order to form nanoparticles with different polymorphs a series of samples were obtained at pH 2, 4, 7 and 9. Raw samples were calcined at different temperatures ranging from 200 to 800°C to evaluate the effect of the calcination temperature on the physico-chemical properties of the samples. XRD results revealed that a mixture of anatase and brookite can be obtained in the as-synthesized samples and in those calcined up to 800°C depending on the pH used to obtain the final product. Indeed, a mixture of anatase brookite and rutile; or a sample with only rutile phase can be yielded through further calcination of the as-prepared samples at temperatures ?600°C due to phase transformation. The photocatalytic performance of the samples with a mixture of anatase-brookite; anatase-brookite-rutile; and anatase-rutile (Degussa P25 TiO2) was exquisitely investigated in the degradation of methylene blue solutions. The samples obtained at pH 2 and calcined at 200°C possessed the highest activity of all due to its superior properties. This study elucidates a facile method suitable for the synthesis of TiO2 with different mixtures of TiO2 polymorphs with desirable properties for various applications. PMID:25514642

Mutuma, Bridget K; Shao, Godlisten N; Kim, Won Duck; Kim, Hee Taik

2015-03-15

77

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

PubMed Central

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

2011-01-01

78

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

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

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

2014-01-01

79

Simple preparation of Mn-N-codoped TiO2 photocatalyst and the enhanced photocatalytic activity under visible light irradiation  

NASA Astrophysics Data System (ADS)

Mn-N-codoped TiO2 nanocrystal photocatalysts responsive to visible light were synthesized by a simple sol-gel method and calcined at different temperatures. The catalysts with different Mn contents were characterized by XRD, BET, UV-vis DRS, XPS and ESR analyses and their photocatalytic activities for Rhodamine B degradation were studied under visible light irradiation. The results showed that the codoping of Mn and N ions inhibited the growth of crystalline size and the transformation from anatase to rutile phase. The XPS results showed that the introduction of a small amount of Mn facilitated further N uptake. Mn-TiO2 and Mn-N-TiO2 exhibited strong visible light absorptions at 400-650 nm. Mn-TiO2 showed significant photocatalytic activity under visible light irradiation compared to pure TiO2, and the activity was further enhanced by codoping Mn and N into TiO2. The highest photocatalytic activity was achieved on 0.25%Mn-N-TiO2 calcined at 400 °C. The synergistic effect of Mn and N ions narrowed the band gap of TiO2 and inhibited the recombination of the photogenerated electrons and holes, leading to a great improvement in the photocatalytic activity in the visible light region.

Quan, Feng; Hu, Yun; Zhang, Xia; Wei, Chaohai

2014-11-01

80

Indoor air purification by photocatalyst TiO 2 immobilized on an activated carbon filter installed in an air cleaner  

Microsoft Academic Search

The enhancement effect of using TiO2 immobilized on activated carbon (TiO2\\/AC) filter for removing indoor air pollutant at parts-per-billion (ppb) levels has been previously reported. To further evaluate the TiO2\\/AC filter for practical application, it was installed in an air cleaner available in the commercial market and tested inside an environmental chamber. Nitrogen oxide (NO) and toluene were selected as

C. H. Ao; S. C. Lee

2005-01-01

81

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)

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.

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

2014-11-01

82

Characterization of a Heterostructure TiO2/SnO2:F/SUBSTRATE with Two Different Geometries, Prepared by Spray Pyrolysis to BE Used as Photocatalyst  

NASA Astrophysics Data System (ADS)

Two TiO2/SnO2:F/substrate hetero-structures (HS) with different geometry were deposited by spray pyrolysis. The thickness for the TiO2 and SnO2:F films was 3.8 ?m and 2.3 ?m, and the band gap energy 3.3 eV and 3.6 eV, respectively. Both films have a transmittance greater than 70% in most of the visible spectrum. The electrical resistivity of the SnO2:F film was ? = (1.7)×10-4? ? cm. The surface morphology of the TiO2 film shows hemispheric agglomerates formed by nano-metric needle/platy shaped particles that give them a porous texture much like a "ball of wool," the length of the needles is from 100 nm and its thickness close to 20 nm. The geometry of HS has an important influence on its efficiency as photocatalyst under low-powered UV radiation. One of the geometry for this HS, in which the TiO2/SnO2:F interface is exposed, showed greater efficiency than the TiO2 and SnO2:F films separately, or than the common "sandwich" type HS geometry. Specifically, a decrease by 62% of the initial concentration of a watery solution of methylene blue (mb) of 20 ppm in approximately 5 h of UV radiation is observed for the exposed interface HS compared with less than 30% reduction observed for the common sandwich type HS.

Velázquez-Cruz, E. I.; Anaya-Castillejos, K. M.; Martínez-Martínez, R.; Soto-Guzmán, A. B.; Falcony, C.

2013-08-01

83

Synthesis and characterisation of Gd 3+-doped mesoporous TiO 2 materials  

Microsoft Academic Search

Using multi-walled carbon nano-tubes (MWNTs) as the template, Gd3+-doped mesoporous TiO2 (M-TiO2) material was prepared by the homogeneous precipitation-assisted template method. The as-prepared photo-catalysts were characterised using X-ray diffraction, scanning electron microscopy, nitrogen adsorption\\/desorption and ultraviolet–visible (UV–vis) diffuse-reflection spectroscopy analyses. The photo-catalytic properties of Gd3+-doped M-TiO2 were primarily investigated by the photo-degradation of methyl orange under Xe-lamp irradiation and compared

Caixia Lv; Yi Zhou; Hong Li; Mingming Dang; Changchun Guo; Yancong Ou; Bin Xiao

2011-01-01

84

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

PubMed

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

Ragupathy, S; Raghu, K; Prabu, P

2015-03-01

85

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)

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.

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

2015-03-01

86

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

NASA Astrophysics Data System (ADS)

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).

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

2012-07-01

87

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

PubMed

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

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

2011-06-15

88

Bio-inspired artificial functional photocatalyst: biomimetic enzyme-like TiO2/reduced graphene oxide nanocomposite with excellent molecular recognition ability.  

PubMed

An enzyme-like TiO2/reduced graphene oxide (enzyme-TiO2/rGO) nanocomposite with molecular recognition ability was fabricated by biomimicking the geometrical and chemical complementation of the enzyme and substrate. The anatase TiO2 nanocrystals were densely dispersed on rGO nanosheets with close interfacial contacts. With geometrical and chemical matching of target molecules and memorized cavities, the adsorption capacity of enzyme-TiO2/rGO nanocomposites for 4-nitrophenol (4.71 mg g(-1)) is about six times that of control TiO2/rGO without the enzyme-like feature (0.79 mg g(-1)), and the enzyme-TiO2/rGO shows a relative selectivity coefficient of 7.24. Moreover, enzyme-TiO2/rGO exhibits molecular recognitive photocatalytic degradation for a particular contaminant. The results demonstrate that enzyme-substrate recognition provides a convenient and powerful basis on which to biomimic and construct efficient photocatalysts with high selectivity. PMID:25851067

Li, Wentao; Pei, Xule; Deng, Fang; Luo, Xubiao; Li, Fengcong; Xiao, Yong

2015-05-01

89

High Rate Reactive Sputter Deposition of TiO2 Films for Photocatalyst and Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

We fabricated dye-sensitized solar cells (DSCs) using TiO2 films deposited on various substrates by reactive magnetron sputtering with midfrequency pulsing and process control units, and evaluated their performance. Two pulse modes, i.e., unipolar pulse and pulse packet modes, were utilized to deposit TiO2. The highest conversion efficiency achieved was 3.7% when 10-µm-thick TiO2 films were deposited on glass substrates coated with fluorine-doped tin oxide (FTO) using the unipolar pulse mode in the oxide mode and postannealing in air. On the other hand, the conversion efficiency achieved was 2.7% for cells with 10-µm-thick TiO2 films deposited on glass substrates coated with FTO using the pulse packet mode without postannealing, and it dropped to 1.3% when the unipolar pulse mode was used. The relationships between the photocatalytic decomposition activity and the DSC characteristics with regard to the TiO2 films were investigated in detail. The reduction in the density of defects in the TiO2 films led to an improvement in both the photocatalytic activity and the DSC characteristics.

Sato, Yasushi; Hashimoto, Takahiro; Miyamura, Amica; Ohno, Singo; Oka, Nobuto; Suzuki, Koichi; Glöß, Daniel; Frach, Peter; Shigesato, Yuzo

2011-04-01

90

Synthesis and hydrophilic properties of Mo doped TiO2 thin films  

NASA Astrophysics Data System (ADS)

Amorphous undoped TiO2 and Mo-doped TiO2 thin films were obtained by spray pyrolysis. By heat treatment, they became polycrystalline consisting in anatase, or mixed anatase/rutile phases, if deposited on glass or silicon, respectively. Mo enters in the TiO2 matrix as Mo5+, determining a slight red shift of the absorption edge. Based on Fourier transmission infrared analysis, performed on the studied films, before and after irradiation, providing information on the relationship between hydrophilicity and the amount of the adsorbed hydroxyl groups, we certify once again that the anatase phase (present in proportion of 100% in the films deposited on glass) is superior concerning the hydrophilic properties. Mo enhances wettability for the films deposited on silicon, compared to the undoped one, even if determines a rise in the rutile weight percentage, as a combined effect with the substrate nature. The decomposition of the oleic acid confirms that titania films with higher hydrophilic performances are also good photocatalysts, confirming in fact that investigating the hydrophilic properties of these films constitutes a much simpler way to obtain information on their photocatalytic activity.

Mardare, Diana; Cornei, Nicoleta; Luca, Dumitru; Dobromir, Marius; Irimiciuc, ?tefan A.; Pung?, Luciana; Pui, Aurel; Adomniţei, C?t?lin

2014-06-01

91

TiO2 doped with nitrogen: synthesis and characterization.  

PubMed

In this study, nitrogen-doped titanium dioxide (TiO2) powders were synthesized in two ways: by heating of titanium hydroxide with urea and by direct hydrolysis of titanium tetraisopropoxide (TTIP) with ammonium hydroxide. The samples were characterized by structural (XRD), analytical (XPS), optical (UV/Vis absorption/reflection and Raman spectroscopy) and morphological (SEM, TEM) techniques. The characterization suggested that the doped materials have anatase crystalline form without any detectable peaks that correspond to dopants. The absorption threshold of titanium dioxide was moved in the visible range of optical spectrum from 3.2 eV to 2.20 eV. Particle sizes of synthesized powders were obtained from XRD measurements and from TEM data ranging from 6-20 nm. XPS and Raman spectroscopy were used for detection of nitrogen in doped samples. PMID:18464379

Abazovi?, Nadica D; Montone, Amelia; Mirenghi, Luciana; Jankovi?, Ivana A; Comor, Mirjana I

2008-02-01

92

In situ surface hydrogenation synthesis of Ti3+ self-doped TiO2 with enhanced visible light photoactivity  

NASA Astrophysics Data System (ADS)

A novel one-step, vapor-fed aerosol flame synthetic process (VAFS) has been developed to prepare Ti3+ self-doped titanium dioxide (TiO2). The freshly formed TiO2 was in situ surface hydrogenated during the condensation stage by introducing H2 above the flame, and Ti3+ ions were created near the surface of TiO2. The relative content of Ti3+ ions near the surface of TiO2 is estimated to be 8%. Because of the high absorption of visible light and suppression of charge recombination, the photocurrent density and decomposition of MB under visible light irradiation were remarkably enhanced. This study demonstrates a simple, potential method to produce Ti3+ self-doped TiO2 with effective photoactivity in visible light.A novel one-step, vapor-fed aerosol flame synthetic process (VAFS) has been developed to prepare Ti3+ self-doped titanium dioxide (TiO2). The freshly formed TiO2 was in situ surface hydrogenated during the condensation stage by introducing H2 above the flame, and Ti3+ ions were created near the surface of TiO2. The relative content of Ti3+ ions near the surface of TiO2 is estimated to be 8%. Because of the high absorption of visible light and suppression of charge recombination, the photocurrent density and decomposition of MB under visible light irradiation were remarkably enhanced. This study demonstrates a simple, potential method to produce Ti3+ self-doped TiO2 with effective photoactivity in visible light. Electronic supplementary information (ESI) available: Schematic setup for Ti3+ self-doped TiO2 nanoparticles is shown in Fig. S1. The BET specific surface and pore-size distribution of Ti3+ self-doped TiO2 is shown in Fig. S2. XRD patterns of pristine TiO2 and Ti3+ self-doped TiO2 are shown in Fig. S3. HRTEM image of Ti3+ self-doped TiO2 with mixture phase is shown in Fig. S4. The photographs of different colors of Ti3+ self-doped TiO2 with different flow rates of hydrogen are shown in Fig. S5. TEM images of Ti3+ self-doped TiO2 samples with different flow rates of carrier gas are shown in Fig. S6. XPS spectrum of O 1s is shown in Fig. S7. Photodegradation of MB in aqueous solutions using Ti3+ self-doped TiO2, pristine TiO2 and P25 as photocatalysts with irradiation of ultraviolet light is shown in Fig. S8. UV-vis spectra of MB aqueous solutions at different times by using Ti3+ self-doped TiO2 as a photocatalyst under the irradiation of visible light is shown in Fig. S9. See DOI: 10.1039/c4nr00972j

Huo, Junchao; Hu, Yanjie; Jiang, Hao; Li, Chunzhong

2014-07-01

93

Effect of preparation conditions on the characteristics and photocatalytic activity of TiO2/purified diatomite composite photocatalysts  

NASA Astrophysics Data System (ADS)

TiO2/purified diatomite composite materials were prepared through a modified hydrolysis-deposition method under low temperature using titanium tetrachloride as precursor combined with a calcination crystallization process. The microstructure and crystalline phases of the obtained composites prepared under different preparation conditions were characterized by high resolution scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The photocatalytic performance of TiO2/purified diatomite composites was evaluated by Rhodamine B as the target pollutant under UV irradiation, and the optimum preparation conditions of composites were obtained. The TiO2 crystal form in composites prepared under optimum conditions was anatase, the grain size of which was 34.12 nm. The relationships between structure and property of composite materials were analyzed and discussed. It is indicated that the TiO2 nanoparticles uniformly dispersed on the surface of diatoms, and the photocatalytic performance of the composite materials was mainly determined by the dispersity and grain size of loaded TiO2 nanoparticles.

Sun, Zhiming; Hu, Zhibo; Yan, Yang; Zheng, Shuilin

2014-09-01

94

Study the structure and performance of thermal/plasma modified Au nanoparticle-doped TiO2 photocatalyst  

NASA Astrophysics Data System (ADS)

This study describes the influence of thermal/plasma treatments on the structure and photocatalytic performance of the Au-doped TiO2 catalyst. Au (gold) nanoparticles were attached on TiO2 (Titania) nanoparticle surfaces by conventional deposition precipitation technique and the resulting catalysts were subsequently modified with thermal (at 450°C under vacuum) and plasma (at an ambient temperature under Argon atmosphere for 20 min) treatments. Structural characterization of the modified catalysts was performed by diverse analytical techniques and the photocatalytic activity was evaluated by assessing the degradation of the methylene blue (MB) in water under UV (ultra-violet) irradiations. Results showed that the thermal/plasma treatment significantly influenced the structural features of Au-doped TiO2 catalyst by altering the morphology, increasing the Au nanoparticles population, improving the Au/TiO2 catalytic activity, changing the textural properties and reducing the band gap energies thus tuned Au-doped TiO2 catalyst to higher efficiency. Thermal/plasma treated Au-doped TiO2 was found to exhibit higher photocatalytic activity than the as-synthesized (pristine sample). This improvement in photocatalytic activity might be due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

Mahmood, Asif; Ramay, Shahid M.; Al-Zaghayer, Yousef S.; Atiq, Shahid; Ahmad, Iftikhar; Shar, Muhammad Ali; Khan, Salah Din

2014-10-01

95

Controlled synthesis and facets-dependent photocatalysis of TiO2 nanocrystals  

NASA Astrophysics Data System (ADS)

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.

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

2015-04-01

96

Synthesis of chiral TiO2 nanofibre with electron transition-based optical activity  

PubMed Central

The optical chirality induced at the absorption bands due to electronic exciton coupling of the transition dipole moments between chromophores in close proximity is ubiquitous in helical organic materials. However, inorganic materials with optical activity resulting from electronic transitions have not been explored. Here we report the synthesis of chiral TiO2 fibres via transcription of the helical structure of amino acid-derived amphiphile fibres through coordination bonding interactions between the organics and the TiO2 source. Upon calcination, the as-prepared amorphous TiO2 double-helical fibres with a pitch length of ~100?nm were converted to double-helical crystalline fibres with stacks of anatase nanocrystals in an epitaxial helical relationship. Both the amorphous and anatase crystalline helical TiO2 fibres exhibited optical response to circularly polarized light at the absorption edge around ~350?nm. This was attributed to the semiconductor TiO2-based electronic transitions from the valence band to the conduction band under an asymmetric electric field. PMID:23169056

Liu, Shaohua; Han, Lu; Duan, Yingying; Asahina, Shunsuke; Terasaki, Osamu; Cao, Yuanyuan; Liu, Ben; Ma, Liguo; Zhang, Jialiang; Che, Shunai

2012-01-01

97

Preparation of visible-light-responsive TiO2-xNx photocatalyst by a sol-gel method: analysis of the active center on TiO2 that reacts with NH3.  

PubMed

Active reaction centers for ammonia on titanium oxyhydroxide were explored to direct the search for an efficient sol-gel method for the synthesis of a titanium oxynitride (TiO2-xNx) sample with an efficient responsiveness to the visible light constituting a main part of the solar spectrum. The results lead to the conclusion that the site giving IR bands at around 2195 cm(-1) for the adsorbed CO molecules at 300 K is a reactive site and behaves as Lewis acid site in the coordination environment of distorted five-coordinate Ti4+ ions. Ammonia molecules are adsorbed on such a site to form -NH2 and -OH species during the heat treatments at a temperature above 373 K, and they are ultimately incorporated into the TiO2 lattice as nitride through the dehydration at higher temperatures of up to 723 K, resulting in the formation of an anatase type of TiO2-xNx. PMID:16089416

Kuroda, Yasushige; Mori, Toshinori; Yagi, Kazunori; Makihata, Naoko; Kawahara, Yoichiro; Nagao, Mahiko; Kittaka, Shigeharu

2005-08-16

98

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

USGS Publications Warehouse

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.

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

2007-01-01

99

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

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

100

Synthesis of highly-ordered TiO2 nanotube arrays with tunable sizes  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

101

Surface complexation of the zwitterionic fluoroquinolone antibiotic ofloxacin to nano-anatase TiO2 photocatalyst surfaces.  

PubMed

The surface complexation behavior of ofloxacin (OFX), a zwitterionic fluoroquinolone antibiotic, to nano-anatase titanium dioxide (TiO(2)) was characterized. OFX adsorption in aqueous TiO(2) suspensions was measured as a function of pH, OFX concentration, and electrolyte type and concentration, and structural information was derived from in situ spectroscopic observations. An ultraviolet-visible spectral red shift upon OFX adsorption indicated formation of inner-sphere coordination complexes. Fourier transform infrared spectra of TiO(2)-adsorbed OFX were invariable over a wide concentration and pH range and were similar to measured spectra of dissolved species wherein the carboxylate group is deprotonated. A charge distribution surface complexation model constrained by spectroscopic observations was developed to describe macroscopic adsorption trends. A tridentate mode of adsorption involving bridging bidentate inner-sphere coordination of the deprotonated carboxylate group and hydrogen bonding through the adjacent carbonyl group on the quinoline ring resulted in successful predictions of observed adsorption trends. In NaClO(4) electrolyte, spectroscopic data and model fitting suggested that OFX ion pairing with ClO(4)(-) enhanced adsorption under acidic conditions. Moreover, comparison of OFX adsorption data with the pH trend in the kinetics of OFX degradation by visible light (? > 400 nm) photocatalysis suggested that adsorbed OFX-ClO(4)(-) ion pairs inhibit photodegradation. PMID:23078178

Paul, Tias; Machesky, Michael L; Strathmann, Timothy J

2012-11-01

102

TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties  

PubMed Central

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

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

2013-01-01

103

Combustion synthesis and EIS characterization of TiO 2–SnO 2 system  

Microsoft Academic Search

TiO2 is an insulator, but using specific dopants, can modify sharply its electronic structure towards semiconducting behavior. This type of response is widely applied in many electrochemical and electrocatalytical devices, namely chlorine production, hydrocarbon oxidation, CO and CO2 hydrogenation and as electroactive substrata for biological cell growth.Combustion synthesis is a very simple, rapid and clean method for material preparation, which

E. Chinarro; B. Moreno; J. R. Jurado

2007-01-01

104

Automated electrochemical synthesis and characterization of TiO2 supported Au nanoparticle electrocatalysts  

Microsoft Academic Search

Automated systems for electrochemical synthesis and high throughput screening of catalytic materials were developed and used to prepare a library of nanoparticulate gold supported on TiO2. A two-dimensional array (library) of Au was synthesized by pulsed cathodic electrodeposition onto a thermally oxidized titanium dioxide substrate. Variations in particle size across the library were created by changing the deposition time (number

Sung-Hyeon Baeck; Thomas F. Jaramillo; Alan Kleiman-Shwarsctein; Eric W. McFarland

2005-01-01

105

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

106

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

PubMed

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

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

2014-02-21

107

Preparation of AgI sensitized amorphous TiO2 as novel high-performance photocatalyst for environmental applications.  

PubMed

A novel visible-light-active material was prepared by dispersion of AgI on amorphous TiO2 through simple one-pot process (AgI/Am-TiO2-S). For comparison, AgI sensitized TiO2 (amorphous, anatase and P25) were also prepared via traditional deposition-precipitation method. The samples were characterized by XRD, XPS, TGA-DSC, UV-Vis-DRS, BET, and etc. Larger specific surface area, negative shift of flat band potential, as well as greatly reduced charge transfer resistance were observed for AgI/Am-TiO2-S comparing to other samples. Moreover, with the same molar of initial Ti and Ag, the weight of AgI/Am-TiO2-S obtained was the heaviest, due to large amount of surface titania hydrate. The photocatalytic activity of the as-prepared AgI/titania samples were evaluated by the reduction of Cr(VI) in the absence or presence of organic pollutants (dyes, phenol). AgI/Am-TiO2-S always presented the highest photocatalytic activity. The estimated kCr(VI) on AgI/Am-TiO2-S was about 2 times that on AgI/P25-TiO2 in the absence/presence of RhB. Superior stability was also observed in the cyclic runs indicating that the as-prepared AgI/Am-TiO2-S is highly desirable for the remediation of Cr(VI)-organic co-contaminated wastewaters. PMID:25746194

Wang, Qi; Chen, Meimei; Zhu, Naxin; Shi, Xiaodong; Jin, Huan; Zhang, Yi; Cong, Yanqing

2015-06-15

108

Hydrothermal doping method for preparation of Cr 3+-TiO 2 photocatalysts with concentration gradient distribution of Cr 3+  

Microsoft Academic Search

Cr3+-doped anatase titanium dioxide photocatalysts were prepared by the combination of sol–gel process with hydrothermal treatment. The samples were characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area (SBET), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), electron paramagnetic resonance (EPR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was confirmed that Cr substitutes

Jiefang Zhu; Zhigang Deng; Feng Chen; Jinlong Zhang; Haijun Chen; Masakazu Anpo; Jiazhen Huang; Lizhong Zhang

2006-01-01

109

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

PubMed

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. PMID:24710730

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

2014-05-21

110

Ultrasound with low intensity assisted the synthesis of nanocrystalline TiO2 without calcination.  

PubMed

A novel method has been developed for the preparation of nano-sized TiO(2) with anatase phase. Nanoparticles with diameter about 6 nm were prepared at a relatively low temperature (75 degrees C) and short time. The synthesis was carried out by the hydrolysis of titanium tetra-isopropoxide (TTIP) in the presence of water, ethanol, and dispersant under ultrasonic irradiation (500 kHz) at low intensity. The results show that variables such as water/ethanol ratio, irradiation time, and temperature have a great influence on the particle size and crystalline phases of TiO(2) nanoparticles. Characterization of the product was carried out by different techniques such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and UV-vis spectroscopy. PMID:20382553

Ghows, Narjes; Entezari, Mohamad H

2010-06-01

111

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

PubMed

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

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

2011-05-01

112

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

PubMed Central

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

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

2015-01-01

113

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

114

Facile synthesis of the Ti(3+) self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis.  

PubMed

This study developed a facile approach for preparing Ti(3+) 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 Ti(3+) 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 Ti(3+) 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

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

2015-01-01

115

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

PubMed

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

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

2015-03-21

116

Synthesis of Nanoscale TiO2 and Study of the Effect of Their Crystal Structure on Single Cell Response  

PubMed Central

To study the effect of nanoscale titanium dioxide (TiO2) on cell responses, we synthesized four modifications of the TiO2 (amorphous, anatase, brookite, and rutile) capable of keeping their physicochemical characteristics in a cell culture medium. The modifications of nanoscale TiO2 were obtained by hydrolysis of TiCl4 and Ti(i-OC3H7)4 (TIP) upon variation of the synthesis conditions; their textural, morphological, structural, and dispersion characteristics were examined by a set of physicochemical methods: XRD, BET, SAXS, DLS, AFM, SEM, and HR-TEM. The effect of synthesis conditions (nature of precursor, pH, temperature, and addition of a complexing agent) on the structural-dispersion properties of TiO2 nanoparticles was studied. The hydrolysis methods providing the preparation of amorphous, anatase, brookite, and rutile modifications of TiO2 nanoparticles 3–5?nm in size were selected. Examination of different forms of TiO2 nanoparticles interaction with MDCK cells by transmission electron microscopy of ultrathin sections revealed different cell responses after treatment with different crystalline modifications and amorphous form of TiO2. The obtained results allowed us to conclude that direct contact of the nanoparticles with cell plasma membrane is the primary and critical step of their interaction and defines a subsequent response of the cell. PMID:22623903

Ismagilov, Z. R.; Shikina, N. V.; Mazurkova, N. A.; Tsikoza, L. T.; Tuzikov, F. V.; Ushakov, V. A.; Ishchenko, A. V.; Rudina, N. A.; Korneev, D. V.; Ryabchikova, E. I.

2012-01-01

117

Hydrothermal synthesis of ordered single-crystalline rutile TiO2 nanorod arrays on different substrates  

NASA Astrophysics Data System (ADS)

We report the mild hydrothermal synthesis of single-crystalline rutile TiO2 nanorod arrays (NRAs). The method reported here shows great versatility and can be used to grow TiO2 NRAs on a large diversity of substrates including Si, Si/SiO2, sapphire, Si pillars, and fluorine doped tin oxide (FTO)-covered glass. The average diameter and length of the nanorods prepared at typical conditions are ˜60 nm and 400 nm, respectively. Dye-sensitized solar cells assembled with the TiO2 NRAs grown on the FTO-covered glass as photoanode were prepared with a photoconversion efficiency of ˜1.10%.

Wang, Hong-En; Chen, Zhenhua; Leung, Yu Hang; Luan, Chunyan; Liu, Chaoping; Tang, Yongbing; Yan, Ce; Zhang, Wenjun; Zapien, Juan Antonio; Bello, Igor; Lee, Shuit-Tong

2010-06-01

118

Simultaneous amination of TiO2 nanoparticles in the gas phase synthesis for bio-medical applications  

NASA Astrophysics Data System (ADS)

A simultaneous synthesis and surface amination method to effectively modify the surface of inorganic nanoparticles is discussed in this study. As a target material system and surface functional group, TiO2 nanoparticles and amine were selected. APTES (3-aminopropyltriethoxysilane), the source of amine group, was mixed with TTIP (titanium tetraisopropoxide) and used for the synthesis of aminated TiO2 nanoparticles. XRD (X-ray diffractometry) results showed TiO2 nanoparticles of pure anatase phase, 15 nm in crystallite size, were successfully synthesized at 700°C and 50 mbar. Fourier transformation infrared (FT-IR) spectroscopy measurement and confocal microscopy study using fluoresceine isothiocyanate (FITC) confirmed that amine groups were successfully deposited and activated on the surface of TiO2 nanoparticles.

Lee, Kyoung-No; Kim, Yangeon; Lee, Chang-Woo; Lee, Jai-Sung

2011-10-01

119

Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.  

PubMed

A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster. PMID:19863989

Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

2010-02-01

120

Hydrothermal synthesis of rutile-anatase TiO2 nanobranched arrays for efficient dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Rutile-anatase TiO2 nanobranched arrays were prepared in two sequential hydrothermal-synthesis steps. The morphologies and crystalline nanostructures of the samples were investigated by controlling growth time and the concentration of the titanium precursor. All samples were characterized by field-emission scanning electron microscopy and X-ray diffraction analysis. It was found that treating the surfaces of rutile TiO2 nanorods with aqueous TiCl4 solutions allows the anatase TiO2 nanobranches to grow perpendicular to the main rutile TiO2 nanorods attached to the FTO glass. Irregularly shaped, dense TiO2 structures formed in the absence of TiCl4 treatment. A light-to-electricity conversion efficiency of 3.45% was achieved using 2.3 ?m tall TiO2 nanobranched arrays in a dye-sensitized solar cell. This value is significantly higher than that observed for pure rutile TiO2 nanorods.

Kwon, Soon Jin; Im, Hyo Been; Nam, Jung Eun; Kang, Jin Kyu; Hwang, Taek Sung; Yi, Kwang Bok

2014-11-01

121

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

122

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

PubMed

In the present study, the biosynthesis of rutile TiO(2) nanoparticles (TiO(2) 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 TiO(2) NPs at lower temperature using agricultural waste. Rutile TiO(2) NPs were characterized by UV, XRD, SEM, TEM and EDS studies. The UV-Vis spectrophotometer results were promising and showed a rapid production of TiO(2) NPs with a surface plasmon resonance occurring at 284 nm. The formation of the TiO(2) NPs as observed from the XRD spectrum is confirmed to be TiO(2) 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. PMID:22983203

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

2012-12-01

123

Green synthesis of anatase TiO(2) nanocrystals with diverse shapes and their exposed facets-dependent photoredox activity.  

PubMed

The exposed facets of a crystal are known to be one of the key factors to its physical, chemical and electronic properties. Herein, we demonstrate the role of amines on the controlled synthesis of TiO2 nanocrystals (NCs) with diverse shapes and different exposed facets. The chemical, physical and electronic properties of the as-synthesized TiO2 NCs were evaluated and their photoredox activity was tested. It was found that the intrinsic photoredox activity of TiO2 NCs can be enhanced by controlling the chemical environment of the surface, i.e.; through morphology evolution. In particular, the rod shape TiO2 NCs with ?25% of {101} and ?75% of {100}/{010} exposed facets show 3.7 and 3.1 times higher photocatalytic activity than that of commercial Degussa P25 TiO2 toward the degradation of methyl orange and methylene blue, respectively. The higher activity of the rod shape TiO2 NCs is ascribed to the facetsphilic nature of the photogenerated carriers within the NCs. The photocatalytic activity of TiO2 NCs are found to be in the order of {101}+{100}/{010} (nanorods) > {101}+{001}+{100}/{010} (nanocuboids and nanocapsules) > {101} (nanoellipsoids) > {001} (nanosheets) providing the direct evidence of exposed facets-depended photocatalytic activity. PMID:25188808

Roy, Nitish; Park, Yohan; Sohn, Youngku; Leung, Kam Tong; Pradhan, Debabrata

2014-10-01

124

Synthesis of TiO 2 using different hydrolysis catalysts and doped with Zn for efficient degradation of aqueous phase pollutants under UV light  

Microsoft Academic Search

In this work, various TiO2 and TiO2 doped with 0.1, 1.0, and 5.0 mol% of Zn were prepared by the sol–gel method varying different hydrolysis catalysts (HNO3, OHAc, H3PO4) in order to be used as photocatalysts for environmental applications. The X-ray diffraction results showed that the different\\u000a TiO2 samples have presented the anatase as main phase, However, the acid nature has

O. Vázquez-Cuchillo; A. Cruz-López; L. M. Bautista-Carrillo; A. Bautista-Hernández; L. M. Torres Martínez; S. Wohn Lee

2010-01-01

125

Cost effective facile synthesis of TiO2 nanograins for flexible DSSC application using rose bengal dye  

NASA Astrophysics Data System (ADS)

Synthesis of titanium dioxide (TiO2) nanograins using economical successive ionic layer adsorption and reaction (SILAR) method has been carried out. TiO2 thin films are studied for their structural, compositional, optical and morphological properties. A layer by layer process leads to the formation of 2.4 ?m thick nanocrystalline TiO2 film. The heat treated TiO2 thin films are hydrophilic in nature with contact angle of 67°. The interconnected nanograins are employed for dye sensitized solar cells (DSSC) using inexpensive Rose Bengal (RB) dye. RB dye sensitization resulted into shifting of absorption peak from UV to visible region. The photoresponce of the dye sensitized solar cell is evaluated in the polyiodide electrolyte (0.1 M KI + 0.01 M I2) at 40 mWcm-2 illumination intensity. The TiO2 nanograins accompanied with RB sensitizer showed the conversion efficiency ( ?) of 0.89%. These results depict the strong assurance of TiO2 nanograins for DSSC application.

Jambure, Supriya Bapurao; Gund, Girish Sambhaji; Dubal, Deepak Prakash; Shinde, Sujata Sureshrao; Lokhande, Chandrakant Dnyandev

2014-09-01

126

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...

127

Synthesis of highly stable sub-8 nm TiO2 nanoparticles and their multilayer electrodes of TiO2/MWNT for electrochemical applications.  

PubMed

Next-generation electrochemical energy storage for integrated microsystems and consumer electronic devices requires novel electrode materials with engineered architectures to meet the requirements of high performance, low cost, and robustness. However, conventional electrode fabrication processes such as doctor blading afford limited control over the electrode thickness and structure at the nanoscale and require the incorporation of insulating binder and other additives, which can promote agglomeration and reduce active surface area, limiting the inherent advantages attainable from nanoscale materials. We have engineered a route for the synthesis of highly stable, sub-8 nm TiO2 nanoparticles and their subsequent incorporation with acid-functionalized multiwalled carbon nanotubes (MWNTs) into nanostructured electrodes using aqueous-based layer-by-layer electrostatic self-assembly. Using this approach, binder-free thin film electrodes with highly controllable thicknesses up to the micrometer scale were developed with well-dispersed, nonagglomerated TiO2 nanoparticles on MWNTs. Upon testing in an Li electrochemical half-cell, these electrodes demonstrate high capacity (>150 mAh/gel(ectrode) at 0.1 A/gel(ectrode)), good rate capability (>100 mAh/gel(ectrode) up to 1 A/g(electrode)) and nearly no capacity loss up to 200 cycles for electrodes with thicknesses up to 1480 nm, indicating their promise as thin-film negative electrodes for future Li storage applications. PMID:24003950

Hyder, Md Nasim; Gallant, Betar M; Shah, Nisarg J; Shao-Horn, Yang; Hammond, Paula T

2013-10-01

128

Optical and photocatalytic properties of nanocrystalline TiO 2 synthesised by solid-state chemical reaction  

Microsoft Academic Search

Nanoparticulate TiO2 is of interest for a variety of technological applications, including optically transparent UV-filters and photocatalysts for the destruction of chemical waste. The successful use of nanoparticulate TiO2 in such applications requires an understanding of how the synthesis conditions effect the optical and photocatalytic properties. In this study, we have investigated the effect of heat treatment temperature on the

Aaron Dodd; Allan McKinley; Takuya Tsuzuki; Martin Saunders

2007-01-01

129

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

130

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

PubMed Central

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

Banerjee, Arghya Narayan

2011-01-01

131

Nanomaterial synthesis and characterization for toxicological studies: TiO2 case study  

USGS Publications Warehouse

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.

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

2008-01-01

132

Influence of the size-controlled TiO 2 nanotubes fabricated by low-temperature chemical synthesis on the dye-sensitized solar cell properties  

Microsoft Academic Search

Titanium dioxide nanotubes (TiO2 NTs) with various sizes have been prepared by low-temperature chemical synthesis using commercial anatase TiO2 particles with different crystallite size in NaOH solution and used as a photoelectrode in a dye-sensitized solar cell (DSSC).\\u000a The relationship between the physicochemical properties of electrode materials and photovoltaic performance was investigated.\\u000a The electrodes made from modified TiO2 NTs showed

Jang-Yul Kim; Tohru Sekino; Shun-Ichiro Tanaka

2011-01-01

133

The synthesis of TiO2 and TiO2-Pt and their application in the removal of Cr (VI).  

PubMed

The deposition of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this paper, TiO2 nanoparticles were prepared via a sol-gel route, followed by heat treatment at elevated temperatures. TiO2-Pt catalyst was prepared by deposition of platinum (Pt) on the surface of as-prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, ultraviolet-visible differential reflectance spectra and infrared spectroscopy. TiO2 and TiO2-Pt were used as heterogeneous catalysts for the removal of Cr (VI) under ultraviolet-light illumination. TiO2 prepared at low temperature had smaller particle size and higher specific surface area, and consequently had higher activity on the removal of Cr (VI). The Pt deposited on the surface of TiO2 favoured the separation of photo-produced electrons (e-) and holes (h+), inhibited the recombination of e- and h+, and enhanced Cr (VI) removal. However, its blocking of active sites also inhibited the removal of Cr (VI). The deposition of 1% (wt.%) Pt to TiO2 produced the optimum activity for the removal of Cr (VI). A lower pH favoured the adsorption of Cr (VI) on the surface of TiO2, and correspondingly enhanced the removal of Cr (VI). PMID:21780710

Fan, Jian-Wei; Liu, Xiang-Hu; Zhang, Jie

2011-01-01

134

TiO2 Nanoparticles Are Phototoxic to Marine Phytoplankton  

Microsoft Academic Search

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

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

2012-01-01

135

Room temperature synthesis and Li insertion into nanocrystalline rutile TiO 2  

Microsoft Academic Search

Nanocrystalline rutile TiO2 is prepared at RT from acidic solution by sol–gel method using titanium tetraisopropoxide as precursor. Samples of varying crystallite sizes are prepared by post annealing the as synthesized rutile TiO2 at different temperatures. The absorption spectra of synthesized samples reveal a large blue shift (311nm) vis a vis bulk rutile TiO2 (394nm) indicating the nanocrystalline nature of

M. Anji Reddy; M. Satya Kishore; V. Pralong; V. Caignaert; U. V. Varadaraju; B. Raveau

2006-01-01

136

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)

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.

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

2014-11-01

137

Characteristics of excited-state intermediates of TiO 2 –Y-Zeolite and MCM41 encapsulating photosensitive molecules: design of new photocatalysts  

Microsoft Academic Search

Some photosensitive molecules, such as p-N,N?-dimethylaminobenzoic acid (DMABA), Nile Red, heteropolytungstic acid (H3PW12O40, HPA) and metalloporphyrins, have been entrapped onto nano-scale pores or channels of TiO2-modified Y-Zeolite (TiO2-Y-Zeolite) and MCM41 (TiO2-MCM41) and their excited-state intermediates have been characterized in terms of the excited-state dynamics by using laser spectroscopic techniques. Through these studies, it has been found that the photo-induced electrons

Minjoong Yoon; Su Young Ryu

2004-01-01

138

Light-storing photocatalyst  

NASA Astrophysics Data System (ADS)

Light-storing photocatalyst was prepared by coating light-storing phosphor and TiO2 photocatalyst in sequence on ceramic. The light-storing photocatalyst can store light irradiation and emit slowly. Consequently, the photocatalyst remains active when the irradiation source is cut off. Rhodamine B (RhB) can be decomposed efficiently by this photocatalyst in the dark after it absorbs light irradiation. This photocatalyst is photoreactive in an outdoor environment or can save energy by supplying irradiation intermittently for the photocatalyst.

Zhang, Junying; Pan, Feng; Hao, Weichang; Ge, Qi; Wang, Tianmian

2004-12-01

139

Electrospinning Synthesis and Photocatalytic Activity of Mesoporous TiO2 Nanofibers  

PubMed Central

Titanium dioxide (TiO2) nanofibers in the anatase structure were successfully prepared via electrospinning technique followed by calcination process. The morphologies, crystal structure, surface area, and the photocatalytic activity of resulting TiO2 nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen sorption, and UV-vis spectroscopy. The results revealed that calcination temperature had greatly influenced the morphologies of TiO2 nanofibers, but no obvious effect was noticed on the crystal structure of TiO2 nanofibers. The photocatalytic properties of TiO2 nanofibers were evaluated by photocatalytic degradation of rhodamine B (RhB) in water under visible light irradiation. It was observed that TiO2 nanofibers obtained by calcination at 500°C for 3 hours exhibited the most excellent photocatalytic activity. We present a novel and simple method to fabricate TiO2 nanofibers with high-photocatalytic activity. PMID:22619598

Li, Jing; Qiao, Hui; Du, Yuanzhi; Chen, Chen; Li, Xiaolin; Cui, Jing; Kumar, Dnt; Wei, Qufu

2012-01-01

140

Facile electrochemical synthesis of antimicrobial TiO2 nanotube arrays  

PubMed Central

Infection-related complications have been a critical issue for the application of titanium orthopedic implants. The use of Ag nanoparticles offers a potential approach to incorporate antimicrobial properties into the titanium implants. In this work, a novel and simple method was developed for synthesis of Ag (II) oxide deposited TiO2 nanotubes (TiNTs) using electrochemical anodization followed by Ag electroplating processes in the same electrolyte. The quantities of AgO nanoparticles deposited in TiNT were controlled by selecting different electroplating times and voltages. It was shown that AgO nanoparticles were crystalline and distributed throughout the length of the nanotubes. Inductively coupled plasma mass spectrometry tests showed that the quantities of released Ag were less than 7 mg/L after 30 days at 37°C. Antimicrobial assay results show that the AgO-deposited TiNTs can effectively kill the Escherichia coli bacteria. Although the AgO-deposited TiNTs showed some cytotoxicity, it should be controllable by optimization of the electroplating parameters and incorporation of cell growth factor. The results of this study indicated that antimicrobial properties could be added to nanotextured medical implants through a simple and cost effective method. PMID:25429214

Zhao, Yu; Xing, Qi; Janjanam, Jagadeesh; He, Kun; Long, Fei; Low, Ke-Bin; Tiwari, Ashutosh; Zhao, Feng; Shahbazian-Yassar, Reza; Friedrich, Craig; Shokuhfar, Tolou

2014-01-01

141

Bio-mediated synthesis of TiO2 nanoparticles and its photocatalytic effect on aquatic biofilm.  

PubMed

The nano-TiO(2) was synthesized biologically employing Bacillus subtilis (FJ460362). These nanoparticles were characterized by FTIR, TGA-DTA, UV-Visible spectroscopy, XRD and TEM. FTIR and TGA results confirm that the organic impurities were completely removed while calcinating the resultant products. Band gap value was estimated from the UV-Visible spectrum and anatase crystal phase was confirmed by XRD. TEM images reveal that these particles were agglomerated; mostly spherical in shape with an average particle size of 10-30nm. The synthesized nano-TiO(2) particles were coated on glass slides, biofilm were grown and subjected to irradiation of polychromatic light to understand photocatalytic activity in controlling the aquatic biofilm. The bacterial killing process was established by Epi-fluorescence microscopy. The results reveal that biogenic TiO(2) nanomaterial acts as good photocatalyst by the generation of H(2)O(2) in the vicinity of the TiO(2)-biofilm interfaces to suppress the growth of the aquatic biofilm. PMID:22483978

Dhandapani, Perumal; Maruthamuthu, Sundram; Rajagopal, Gopalakrishnan

2012-05-01

142

Template synthesis and luminescence properties of TiO2:Eu3+ nanotubes  

NASA Astrophysics Data System (ADS)

Uniform TiO2:Eu3+ nanotubes have been successfully synthesized through a simple solvothermal process with carbon nanotubes (CNTs) as templates, free of any surfactant or catalyst. X-ray diffraction (XRD) results demonstrate that the product is a pure anatase phase of TiO2. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicate that the as-obtained TiO2:Eu3+ nanotubes are uniform in size and distribution, and the thickness of the wall is about 8 nm. The possible formation mechanism has also been proposed. The luminescent spectrum shows that TiO2:Eu3+ nanotubes exhibit a red emission at 612 nm due to the 5D0?7F2 transition. Furthermore, this synthetic route is promising for the preparation of other one-dimensional inorganic nanomaterials because of its simplicity and the low cost of the starting reagents.

Zhao, Huan; Zheng, Keyan; Sheng, Ye; Li, Hongbo; Zhang, Hongguang; Qi, Xiaofei; Shi, Zhan; Zou, Haifeng

2014-02-01

143

Microwave-assisted synthesis of nanocrystalline TiO2 for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The main purposes of this study are replacing conventional hydro-thermal method by microwave heating using water as reaction medium to rapidly synthesize TiO2.Titanium tetraisopropoxide (TTIP) was hydrolyzed in water. The solution is subsequently processed with microwave heating for crystal growth. The reaction time could be shortened into few minutes. Then we chose different acids as dispersion agents to prepare TiO2 paste for investigating the effects of dispersion on the power conversion efficiency of dye-sensitized solar cells (DSCs). The photovoltaic performance of the microwave-assisted synthesized TiO2 achieved power conversion efficiency of 6.31% under AM 1.5 G condition (100 mW/cm2). This PCE value is compatible with that of the devices made from commercial TiO2.

Kuo, Ta-Chuan; Guo, Tzung-Fang; Chen, Peter

2012-09-01

144

A facile low temperature synthesis of TiO2 nanorods for high efficiency dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Titania (TiO2) nanorods have been synthesized with controlled size for dye-sensitized solar cells (DSSCs) via hydrothermal route at low hydrothermal temperature of 100 °C for 24 h. The titania nanorods were characterized using XRD, SEM, TEM/HRTEM, UV-vis Spectroscopy, FTIR and BET specific surface area ( S BET), as well as pore-size distribution by BJH. The results indicated that the bulk traps and the surface states within the TiO2 nanorods films have enhanced the efficiency of DSSCs. The size of the titania nanorods was 6.7 nm in width and 22 nm in length. The high surface area can provide more sites for dye adsorption, while the fast photoelectron-transfer channel can enhance the photogenerated electron transfer to complete the circuit. The specific surface area S BET was 77.14 m2 g-1 at the synthesis conditions. However, the band gap energy of the obtained titania nanorods was 3.2 eV. The oriented nanorods with appropriate lengths are beneficial in improving the electron transport property and thus leading to the increase of photocurrent, together enhancing the power conversion efficiency. A nearly quantitative absorbed photon-to-electrical current conversion achieved upon excitation at wave length of 550 nm and the power efficiency was enhanced from 5.6 % for commercial TiO2 nanoparticles Degussa (P25) cells to 7.2 % for TiO2 nanorods cells under AM 1.5 illumination (100 mW cm-2). The TiO2 cells performance was improved due to their high surface area, hierarchically mesoporous structures and fast electron-transfer rate compared with the Degussa (P25).

Shalan, A. E.; Rashad, M. M.; Yu, Youhai; Lira-Cantú, Mónica; Abdel-Mottaleb, M. S. A.

2013-01-01

145

Synthesis, characterization, and photoconductivity studies on nanocrystalline TiO2 films doped with gold nanoparticles  

Microsoft Academic Search

Nanocrystalline TiO2 films doped with gold nanoparticles were synthesized by the sol-gel process at room temperature. The TiO2 films were synthesized by using tetrabutyl orthotitanate as the inorganic precursor. The films were spin-coated on glass wafers. The samples were annealed at 100°C for 30 minutes and sintered at 520°C for 1 hour to generated anatase and rutile phases. The films

G. Valverde-Aguilar; J. A. García-Macedo; P. Galván-Ramírez; V. Rentería-Tapia

2009-01-01

146

Effect of synthesis conditions on photocatalytic activities of nanoparticulate TiO 2 thin films  

Microsoft Academic Search

In the present study, design of experiments (DOE) was used to find an optimal combination for the factors affecting the preparation, morphology and catalytic activity of nano-crystalline TiO2 thin films synthesized by sol–gel method. Nine TiO2 thin films were prepared onto indium–tin oxide (ITO) substrates by changing four operating parameters at three levels. The four operating parameters are the volume

Lei Sun; Taicheng An; Shungang Wan; Guiying Li; Ningzhong Bao; Xiaohong Hu; Jiamo Fu; Guoying Sheng

2009-01-01

147

CdS-sensitized TiO2 nanocorals: hydrothermal synthesis, characterization, application.  

PubMed

Cadmium sulfide (CdS) nanoparticle-sensitized titanium oxide nanocorals (TNC) were synthesized using a two-step deposition process. The TiO(2) nanocorals were grown on the conducting glass substrates (FTO) using A hydrothermal process and CdS nanoparticles were loaded on TNC using successive ionic layer adsorption and reaction (SILAR) method. The TiO(2), CdS and TiO(2)-CdS samples were characterized by optical absorption, X-ray diffraction (XRD), FT-Raman, FT-IR, scanning electron microscopy (SEM) and contact angle. Further, their photoelectrochemical (PEC) performance was tested in NaOH, Na(2)S-NaOH-S and Na(2)S electrolytes, respectively. When CdS nanoparticles are coated on TNCs, the optical absorption is found to be enhanced and band edge is red-shifted towards visible region. The TiO(2)-CdS sample exhibits improved photoelectrochemical (PEC) performance with maximum short circuit current of (J(sc)) 1.04 mA cm(-2). After applying these TiO(2)-CdS electrodes in photovoltaic cells, the photocurrent was found to be enhanced by 2.7 and 32.5 times, as compared with those of bare CdS and TiO(2) nanocorals films electrodes respectively. Also, the power conversion efficiency of TiO(2)-CdS electrodes is 0.72%, which is enhanced by about 16 and 29 times for TiO(2), CdS samples. PMID:21799995

Mali, S S; Desai, S K; Dalavi, D S; Betty, C A; Bhosale, P N; Patil, P S

2011-10-01

148

Nanocoral architecture of TiO 2 by hydrothermal process: Synthesis and characterization  

NASA Astrophysics Data System (ADS)

TiO2 thin films with novel nanocoral-like morphology were successfully grown directly onto the glass and conducting fluorine doped tin oxide coated glass substrates via multi-step hydrothermal (MSH) process. Titanium chloroalkoxide [TiCl2 (OEt)2 (HOEt)2)] precursor was used in an aqueous saturated NaCl in presence of 1 mM HCl catalyst and HNO3 peptizer at 120 °C. Reaction time varied from 3 to 12 h. The morphological features and physical properties of TiO2 films were investigated by field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform IR spectroscopy, Fourier transform Raman spectroscopy, room temperature photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The surface morphology revealed the formation of TiO2 corals having nanosized (30-40 nm) polyps. The photoelectrochemical properties of the TiO2 nanocoral electrodes were investigated in 0.1 M NaOH electrolyte under UV illumination. The results presented in this study highlight two major findings: (i) ability to tune the photoelectrochemical response and photoconversion efficiency via controlled thickness of TiO2 nanocorals and (ii) the substantial increase in short circuit photocurrent (Jsc) due to the improved charge transport through TiO2 nanocorals prepared via MSH process. This approach would be quite useful for the fabrication of nanocoral architecture that finds key applications in photocatalysis, dye-sensitized solar cells and hybrid solar cells.

Mali, Sawanta S.; Shinde, Pravin S.; Betty, C. A.; Bhosale, Popatrao N.; Lee, Won J.; Patil, Pramod S.

2011-09-01

149

Composite photocatalyst of Glass-Microspheres\\/TiO2:Synthesis and photocatalysis activity  

Microsoft Academic Search

Composite photocatalyst of Glass-Microspheres\\/TiO2 was successfully synthesized by sol-gel method using tetrabutyl titanate as raw materials and hollow Glass-Microspheres as the carrier. The samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM). It was present that a uniform film of anatase TiO2 was formed on the surface of GMS.In addition, The experiment of photocatalytic degradation of organophosphorus solution

Zhuo Luo; Shiying Zhang; Difa Xu; Yang You; Zhongxin Lin

2011-01-01

150

Preparation of visible-light nano-photocatalysts through decoration of TiO2 by silver nanoparticles in inverse miniemulsions.  

PubMed

Ag/TiO2 nanocomposites were prepared through combination of a sol-gel process of a titanium precursor in inverse miniemulsions and in situ reduction of silver ions in the "nanoreactors". The morphological investigation shows that Ag nanoparticles are mainly located on the surface of TiO2 nano-supports because of the fast reduction rate of Ag ions by hydrazine. Ag/TiO2 nanocomposites with amorphous or anatase TiO2 phase displayed high visible-light catalytic activity for degradation of Rhodamine B. The photoactivity of Ag/anatase TiO2 nanocomposites could be influenced by the Ag content that could be conveniently tuned by the loading of silver salts. The influence of the loading of silver salts on the particle properties of the Ag/TiO2 nanocomposites was investigated systematically. PMID:25217730

Cao, Zhihai; Zhu, Shudi; Qu, Hui; Qi, Dongming; Ziener, Ulrich; Yang, Liu; Yan, Yingjie; Yang, Haitang

2014-12-01

151

One-pot solvothermal synthesis of graphene-supported TiO2 (B) nanosheets with enhanced lithium storage properties.  

PubMed

A facile process was developed for the synthesis of graphene-supported TiO2 (B) nanosheets (GTBN) composite based on the hydrothermal treatment titanium (III) chloride and graphene oxide in an ethylene glycol. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy. The obtained GTBN show a high thermal stability and the phase transformation of TiO2 (B) to anatase can be prevented by graphene after pyrolysis of GTBN at 350°C for 2h. Furthermore, GTBN exhibited high rate performance and stability of lithium ion batteries, due to the enhanced conductivity of the electrode and accommodation to volume/strain changes during lithium insertion-extraction. PMID:23972503

Zhang, Zhe; Chu, Qingxin; Li, Huiyan; Hao, Jinhui; Yang, Wenshu; Lu, Baoping; Ke, Xi; Li, Jing; Tang, Jilin

2013-11-01

152

Synthesis and optical limiting studies of Au-doped TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

A series of Au-doped TiO2 nanoparticles with different Au concentrations were prepared by the sol–gel method using titanium (IV) isopropoxide and tetrachloroaurate (III) trihydrate as precursors. The framework substitution of Au in TiO2 nanoparticles was established by x-ray diffraction (XRD) and Fourier transform infrared (FT-IR) techniques. X-ray diffraction (XRD) and transmission electron microscopy (TEM) image results confirmed the anatase phase and nanocrystalline nature of TiO2–Au. The optical properties revealed an extended tailing of the absorption edge toward the visible region upon Au doping. The incorporation of Au in TiO2 was also confirmed by fluorescence quenching. The increase in Au doping enhanced the 'red-shift' in the UV-Vis absorption spectra. The spectral and nonlinear optical properties were studied using fluence-dependent transmittance measurements in order to reveal the optical limiting mechanism. The nonlinear optical response and optical limiting effects of TiO2–Au nanocomposites dispersed in ethylene glycol were studied at 532?nm using 5?ns Nd:YAG laser pulses. Effective three-photon absorption mechanisms play a major role for good optical limiting characteristics in these nanoparticles and it is seen that the optical nonlinearity enhances with lower threshold as the volume fraction of the Au concentration increased.

Mani Rahulan, K.; Ganesan, S.; Aruna, P.

2011-06-01

153

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

PubMed Central

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

Schweicher, Julien; Desai, Tejal A.

2014-01-01

154

Direct synthesis of a mesoporous TiO2-RuO2 composite through evaporation-induced polymeric micelle assembly.  

PubMed

Here we report a direct synthesis of a mesoporous TiO2-RuO2 composite. Titanium tetraisopropoxide (TTIP) and RuCl3 are used as inorganic precursors for TiO2 and RuO2, respectively. Evaporation-induced assembly of spherical micelles made of an asymmetric poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) triblock copolymer enables the fabrication of a mesoporous TiO2-RuO2 composite with a uniform pore size of 30 nm. PMID:24760227

Bastakoti, Bishnu Prasad; Salunkhe, Rahul R; Ye, Jinhua; Yamauchi, Yusuke

2014-06-14

155

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

E-print Network

, TiO2, Aqueously soluble, Direct liquid phase precipitation, Dynamic real-time measurement Background Titania (TiO2) is an important oxide with commercially exploitable physical and chemical properties. There are a variety of applications in, e.g., gas... and washed with absolute ethanol three times beforetated products were collected by centrifugation at a speed of 10,000 rpm for 20 min and washed withabsolute ethanol three times and dried overnight under vacuum at RT. Gallic acid-capped TiO2 NP synthesis...

Chen, Lan; Rahme, Kamil; Holmes, Justin D; Morris, Michael A; Slater, Nigel KH

2012-06-07

156

Radiation-induced synthesis of Fe-doped TiO 2: Characterization and catalytic properties  

NASA Astrophysics Data System (ADS)

Fe-doped TiO 2 catalyst was prepared by wet impregnation, using TiO 2 P25 Degussa as a precursor and Fe(NO 3) 3 as a dopant, followed by irradiation with an electron beam or ?-rays. Surface properties of Fe/TiO 2 samples were examined by BET, XRD, ToF-SIMS, and TPR methods. The photocatalytic activity towards destruction of the anionic surfactant, sodium dodecylbenzenesulfonate (SDBS), in aqueous solutions was higher for the irradiated Fe/TiO 2 catalysts than for bare TiO 2 P25 or that calcined at 500 °C. The results show that irradiated catalysts exhibit a more uniform texture with high dispersion of iron species. An enhancement of the activity of irradiated Fe/TiO 2 systems can be attributed to the synergetic effects of small crystallite size and homogenous distribution of iron species including FeTiO 3 phase.

Bzdon, Sylwia; Góralski, Jacek; Maniukiewicz, Waldemar; Perkowski, Jan; Rogowski, Jacek; Szadkowska-Nicze, Magdalena

2012-03-01

157

Uniform TiO2-SiO2 hollow nanospheres: Synthesis, characterization and enhanced adsorption-photodegradation of azo dyes and phenol  

NASA Astrophysics Data System (ADS)

TiO2-SiO2 hollow nanospheres with remarkable enhanced photocatalytic performance have been fabricated by sol-gel method. The hollow sphere possesses both high phototcatalytic activity and adsorption capability. The as-prepared samples were characterized by XRD, SEM, TEM, FTIR, XPS, BJH and TGA/DSC. The experiment results show that, the photocatalyst calcined at 500 °C with Ti/Si ratio of 5:1 (denoted as 5T/S-500) displayed superiorities in both textural and functional properties with the enhanced degradation efficiency on azo dyes (methylene blue, methyl orange) and phenol. The high adsorption capability of organic poisonous contaminants onto 5T/S-500 in aqueous solution demonstrated that the photocatalyst can remove the contaminants from water effectively even without illumination. The TEM and SEM morphologies demonstrated unique hollow and coarse structure of 5T/S-500. Structural analysis showed that Si was doped into the lattice of TiO2 and SiO2 nanoparticles can work as a surface modifier on TiO2. The surface area of 5T/S-500 is 1105 m2/g, 14.5 times as great as that of the pure hollow TiO2 nanosphere, confirms the effect of SiO2 on the improvement of specific surface area. The high photocatalytic activities and high adsorption ability for organic poisonous contaminants demonstrate that the nanocomposite of TiO2-SiO2 is a promising candidate material for future treatment of contaminated water.

Guo, Na; Liang, Yimai; Lan, Shi; Liu, Lu; Ji, Guijuan; Gan, Shucai; Zou, Haifeng; Xu, Xuechun

2014-06-01

158

Photodeposition-assisted synthesis of novel nanoparticulate In, S-codoped TiO2 powders with high visible light-driven photocatalytic activity  

NASA Astrophysics Data System (ADS)

In order to search for an efficient photocatalysts working under visible light illumination, we have investigated the effect of metal and nonmetal ions (In, S) codoping on the photocatalytic activity of TiO2 nanoparticles (TiO2 NPs) prepared by combining of sol-gel (SG) and photodeposition (PD) methods using titanium tetra isopropoxide (TTIP), indium nitrate (In(NO3)3) and thiourea as precursors. In this regard, at first three different percentage of S (0.05, 0.2 and 0.5) doped into the TiO2 by SG method, and then different amount of In(III) loaded on the surface of the prepared samples by PD technique. The results showed that the In, S-codoped TiO2 (In, S-TiO2) with a spheroidal shape demonstrates a smaller grain size than the pure TiO2. Meanwhile, the UV-vis DRS of In, S-TiO2 showed a considerable red shift to the visible region. Finally, the photocatalytic activity of In, S-TiO2 photocatalysts were evaluated by photooxidative degradation of methyl orange (MO) solution under UV and visible light illumination. As a result, it was found that 0.05%S-0.5%In/TiO2, 0.2%S-1.5%In/TiO2 and 0.5%S-0.5%In/TiO2 had the highest catalytic activity under visible light in each group and among these samples 0.2%S-1.5%In/TiO2 showed the best photocatalytic performance under visible light and decomposes more than 95% MO in only 90 min.

Hamadanian, M.; Reisi-Vanani, A.; Razi, P.; Hoseinifard, S.; Jabbari, V.

2013-11-01

159

Synthesis of metabolites of paracetamol and cocaine via photooxidation on TiO2 catalyzed by UV light.  

PubMed

Prediction and synthesis of drug metabolites generated by photodegradation using TiO(2)/UV system in aqueous solution was performed to monitor illicit drugs and to support legal actions against drug dealers. Metabolism of paracetamol and cocaine applied as exemplary compounds was monitored by liquid chromatography mass spectrometry (LC-MS/MS) and direct analysis by electrospray ionization mass spectrometry (ESI-MS/MS). The experiments proved that simulated metabolic pathways of the drug samples are efficient and lead to the formation of products that are observed using living organisms or hepatocyte microsomal preparations. Routinely, TiO(2) nanopowders are used for complete degradation of unwanted waste to protect environment. We applied such system for prediction of potential metabolites of harmful substances, such as cocaine. The results demonstrate that TiO(2)/UV oxidative system can be an efficient, complementary method to the in vivo approaches to obtain important metabolites for further studies. Investigations using such methodology may be helpful for toxicologists providing a vital knowledge on metabolites derived from e.g. newly introduced cognitive enhancers (designer drugs), and home-made substances prepared from the over-the-counter tablets (legal highs). PMID:23245731

Raoof, Hana; Mielczarek, Przemyslaw; Michalow, Katarzyna A; Rekas, Mieczyslaw; Silberring, Jerzy

2013-01-01

160

Highly dispersed platinum nanoparticles on TiO2 prepared by using the microwave-assisted deposition method: an efficient photocatalyst for the formation of H2 and N2 from aqueous NH3.  

PubMed

A simple and practical technique to synthesize nanosized platinum particles loaded on TiO(2) (Pt-TiO(2)) by using a microwave (Mw)-assisted deposition method has been exploited in the development of a highly efficient photocatalyst for the formation of H(2) and N(2) gases from harmful nitrogen-containing chemical wastes, for example, aqueous ammonia (NH(3)). Upon Mw irradiation, a platinum precursor can be deposited quickly on the TiO(2) surface from an aqueous solution of platinum and subsequent reduction with H(2) affords the nanosized platinum metal particles with a narrow size distribution (Mw-Pt-TiO(2)). Characterization by CO adsorption, platinum L(III)-edge X-ray absorption fine structure analysis, and TEM analysis revealed that the size of the metal nanoparticles strongly depended on the preparation methods. Smaller platinum nanoparticles were obtained by the Mw heating method than those obtained by conventional preparation techniques, such as photoassisted deposition (PAD), impregnation (Imp), and equilibrium adsorption (EA) deposition by conventional convective heating. The H(2) and N(2) formation rates increased with increasing dispersity of platinum. Pt-TiO(2) prepared by the Mw heating method exhibited a specifically high H(2) formation activity in the photocatalytic decomposition of aqueous NH(3) in a nearly stoichiometric 3:1 (H(2)/N(2)) molar ratio under inert conditions. The present Mw heating method is applicable to a variety of anatase-type TiO(2) species possessing different specific surface areas to provide small and highly dispersed platinum nanoparticles with a narrow size distribution. PMID:22315184

Fuku, Kojirou; Kamegawa, Takashi; Mori, Kohsuke; Yamashita, Hiromi

2012-06-01

161

Synthesis, pore texture and surface acid–base character of TiO 2\\/carbon composite xerogels and aerogels and their carbonized derivatives  

Microsoft Academic Search

Synthesis of TiO2\\/C composite xerogels and aerogels were obtained by polymerization of a mixture of resorcinol, formaldehyde and tetrabutyl orthotitanate. Samples so obtained were dried with supercritical CO2 (aerogel) or at 110°C in an oven (xerogel). The aerogel was prepared with two different initial TiO2 contents of 30 and 49%. Both aerogels and the xerogel were subsequently carbonized in an

Francisco José Maldonado-Hódar; Carlos Moreno-Castilla; José Rivera-Utrilla

2000-01-01

162

Impact of growth kinetics on morphology and pore structure of TiO2-one-pot synthesis of macroporous TiO2 microspheres.  

PubMed

Titanium dioxide was synthesized by the hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of acetic acid, 2-propanol, and organic amines (octylamine, aniline, and isobutylamine). H2O was supplied by an esterification reaction between acetic acid and 2-propanol (denoted as H2Oe), and/or by intentionally adding it (denoted as H2Oa). It was found that the quantity of H2Oa plays a crucial role in the morphology and porous structure of the final TiO2 product. Without the addition of H2Oa, 1D and porous TiO2 was synthesized. With the addition of H2Oa, and when the H2Oa:TiO2 molar ratio was in the range of 1:1 to 60:1, macroporous TiO2 microspheres possessing a large surface area and high thermal stability were obtained. When the H2Oa:TiO2 molar ratio exceeded 60:1, porous TiO2 with an irregular shape was formed. The variation in the morphology and porous structure is attributed to the manipulation of the growth kinetics by the addition of water. PMID:16749824

Zhong, Ziyi; Chen, Fengxi; Ang, Thiam-Peng; Han, Yifan; Lim, Weiqiang; Gedanken, Aharon

2006-06-12

163

Preparation and characterization of TiO 2 photocatalysts supported on various rigid supports (glass, quartz and stainless steel). Comparative studies of photocatalytic activity in water purification  

Microsoft Academic Search

In the present study TiO2 has been supported on several rigid substrates. Deposition on glass and quartz was carried out by a dip coating procedure and the deposition on stainless steel by an electrophoretic deposition process. The resulting materials have been characterized by XPS, SEM\\/EDX, XRD and UV-vis absorption spectroscopy. The materials were then tested for the photocatalytic degradation of

A. Fernández; G. Lassaletta; V. M. Jiménez; A. Justo; A. R. González-Elipe; J.-M. Herrmann; H. Tahiri; Y. Ait-Ichou

1995-01-01

164

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

PubMed Central

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

2012-01-01

165

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

PubMed

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

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

2010-01-01

166

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

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

167

A revised algorithm for calculating TiO2 from Clementine UVVIS data: A synthesis of rock, soil, and remotely sensed TiO2 concentrations  

NASA Astrophysics Data System (ADS)

Investigating mare basalt compositions, at both the sample and remote-sensing level for the Apollo and Luna mare sites, reveals the need for a more complex regression procedure than previously proposed in order to extract accurate TiO2 concentrations from Clementine spectral reflectance (CSR) data. The TiO2 algorithm of Lucey and coworkers is modified by using two different sets of regression parameters to relate measured regolith compositions from sampling locations to the CSR properties of these sites. One regression trend fits the majority of Apollo data, and the second regression is a fit to the Apollo 11, Luna 16, and Luna 24 data, which were considered to be anomalous in previous TiO2 calibrations. These three sites have unusually low albedo compared to other mare landing sites, and some 32% of nearside mare regions appear to share this characteristic. Possible reasons for these differences related to proximity of the other sites to mare-highland boundaries are discussed. Using the dual-regression method, we find (1) that TiO2 concentrations calculated for the basaltic landing sites faithfully reproduce a bimodal distribution as seen in the sample data, (2) that when coupled with the effects of other thermal neutron absorbers, Ti concentrations are more consistent with observed epithermal-to-thermal neutron-flux ratios than are previous Clementine-based derivations of TiO2 for basaltic regions, and (3) that basalts of intermediate-TiO2 concentrations occur most frequently in the Oceanus Procellarum region and that these intermediate concentrations appear to be inherent to the flows underlying the regolith and presumably to the basalt source regions.

Gillis, Jeffrey J.; Jolliff, Bradley L.; Elphic, Rick C.

2003-02-01

168

Low-temperature synthesis and characterization of anatase TiO(2) powders from inorganic precursors.  

PubMed

Nowadays, it is a great challenge to synthesize crystalline TiO(2) using low-temperature methods without a calcination step. In our study, the anatase TiO(2) powders were synthesized using titanium tetrachloride (TiCl(4)) as a precursor via the sol-gel method at low-temperature preparation conditions. Perchloric acid and nitric acid were used as peptizing mediators. The powders were obtained with consequent drying of the sols via evaporation of the solvent. The remaining acid in the powders prevented the aggregation of particles in the aqueous solution. The as-prepared catalysts were characterized by X-ray diffraction, thermal analysis, UV-Vis spectroscopy, BET surface area. The aggregate size of TiO(2) in the colloidal suspension solution was measured by dynamic light scattering. Material characteristics were correlated with photocatalytic activities of the prepared samples towards degradation of aqueous phenol solution under UVA radiation. Using HClO(4) instead of HNO(3) resulted in smaller colloidal particles of TiO(2) in the sol and in higher surface area of the powder, while the primary crystallite sizes for both types of powder were similar. The HClO(4)-based TiO(2) had approximately a 1.5 times higher catalytic activity than similar catalysts prepared by using HNO(3). Smaller aggregated colloidal particles, and consequently a larger surface area in HClO(4)-based powder, demonstrate the main reason for better photocatalytic activity compared to the HNO(3)-based powder. PMID:19424548

Tasbihi, Minoo; Stangar, Urska Lavrencic; Cernigoj, Urh; Kogej, Ksenija

2009-05-01

169

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

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

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

2014-01-01

170

Fabrication of hydroxyl group modified monodispersed hybrid silica particles and the h-SiO2/TiO2 core/shell microspheres as high performance photocatalyst  

E-print Network

core/shell microspheres as high performance photocatalyst for dye degradation Zhe-Ying Shen a , Long,4]. Many ef- forts have been made to encapsulate nano- or sub-micron size sil- ica microspheres of titania nanoparticles onto the silica or polymer microspheres through the layer-by-layer (LBL) technique

Li, Yat

171

Bamboo leaf-assisted formation of carbon/nitrogen co-doped anatase TiO2 modified with silver and graphitic carbon nitride: novel and green synthesis and cooperative photocatalytic activity.  

PubMed

We report a novel synthesis approach employing bamboo leaves as sources of both the C/N dopant and reductant to the formation of C/N co-doped TiO2 modified with Ag and g-C3N4 (Ag/CN-TiO2@g-C3N4). In this case, the ternary composite has a hierarchical structure and a large surface area, which increases the contact area of reactants. Degradation of rhodamine B (RhB) and hydrogen generation were carried out to evaluate the photocatalytic activity of as-prepared samples under visible light irradiation. It is found that with respect to single and binary catalysts, the Ag/CN-TiO2@g-C3N4 ternary composite shows the highest photocatalytic activity (degradation of RhB, H2 evolution from water splitting) as a result of the fast generation, separation and transportation of the photogenerated carriers, which was evidenced by photoluminescence measurements and free radical/hole scavenging experiments. At last, a possible photocatalytic mechanism under visible light irradiation was proposed. The novel and green synergistic approach presented here could provide a facile yet effective method for designing other visible light active non-metal co-doped TiO2 based photocatalysts with enhanced activity and high chemical stability. PMID:25102976

Jiang, Zhifeng; Liu, Dong; Jiang, Deli; Wei, Wei; Qian, Kun; Chen, Min; Xie, Jimin

2014-09-28

172

Facile synthesis of TiO2 nanocrystals using NH4F as morphology-controlling agent and its influences on photocatalytic activity.  

PubMed

Controllable synthesis of nanomaterials with different morphologies can significantly affect their properties. Here we report that the morphology and facet orientation of TiO2 nanocrystals can be readily modulated via a hydrothermal method using a simple morphology-controlling agent of NH4F. The photocatalytic activity of resultant TiO2 has been evaluated by photodegradation of methyl orange. The results indicate that the introduction of NH4F can be used to modulate the mophology and, thereby, the photocatalytic activity of TiO2. The obtained TiO2 with high-energy facet, small size, and large surface area can exhibit an improved photocatalytic efficiency, which may be promising for real application. PMID:23646738

Wang, Bin; Zhang, Xin; He, Meng; He, Tao

2013-01-01

173

Size controlled synthesis and photocatalytic activity of anatase TiO2 hollow microspheres  

NASA Astrophysics Data System (ADS)

Titanium oxide hollow microspheres were synthesized from organic precursor titanium tetraisopropoxide (TTIP) using continuous spray pyrolysis reactor. Effects of precursor concentration, applied voltage and annealing have been investigated. It was observed that the annealing of the as-synthesized TiO2 hollow microspheres at 250 °C, which had an average external diameter of 200 nm, leads to an increase in the size and also more spherical shape. The precursor concentration and applied voltage were found to have a direct impact on the size of the microspheres, which is also evident in the absorption spectrum. The as-prepared TiO2 hollow microspheres exhibited good photocatalytic activity for the degradation of MO.

Dwivedi, Charu; Dutta, V.

2012-10-01

174

Synthesis of monodisperse TiO2-paraffin core-shell nanoparticles for improved dielectric properties.  

PubMed

Core-shell structures of oxide nanoparticles having a high dielectric constant, and organic shells with large breakdown field are attractive candidates for large electrical energy storage applications. A high growth temperature, however, is required to obtain the dielectric oxide nanoparticles, which affects the process of core-shell formation and also leads to poor control of size, shape, and size-distribution. In this communication, we report a new synthetic process to grow core-shell nanoparticles by means of an experimental method that can be easily adapted to synthesize core-shell structures from a variety of inorganic-organic or inorganic-inorganic materials. Monodisperse and spherical TiO2 nanoparticles were produced at room temperature as a collimated cluster beam in the gas phase using a cluster-deposition source and subsequently coated with uniform paraffin nanoshells using in situ thermal evaporation, prior to deposition on substrates for further characterization and device processing. The paraffin nanoshells prevent the TiO2 nanoparticles from contacting each other and also act as a matrix in which the volume fraction of TiO2 nanoparticles was varied by controlling the thickness of the nanoshells. Parallel-plate capacitors were fabricated using dielectric core-shell nanoparticles having different shell thicknesses. With respect to the bulk paraffin, the effective dielectric constant of TiO2-paraffin core-shell nanoparticles is greatly enhanced with a decrease in the shell thickness. The capacitors show a minimum dielectric dispersion and low dielectric losses in the frequency range of 100 Hz-1 MHz, which are highly desirable for exploiting these core-shell nanoparticles for potential applications. PMID:20359188

Balasubramanian, Balamurugan; Kraemer, Kristin L; Reding, Nicholas A; Skomski, Ralph; Ducharme, Stephen; Sellmyer, David J

2010-04-27

175

Synthesis and characterization of Y3+-doped TiO2 nanocomposites for photocatalytic applications.  

PubMed

The TiO(2).[Y(2)O(3)](x) (x = 0.1-0.4) nanocomposites (NCs) with an average particle size of 74 nm were prepared by the method of chemical co-precipitation followed by hydrolysis (CPH). Their visible light photocatalytic activity was investigated for the degradation of congo red (CR) dye. All NCs showed improved degradation as compared to the polycrystalline samples of similar compositions prepared by the solid-state reaction (SSR) route (average particle size of a few micrometers), as well as to the pure TiO(2). The better photocatalytic activity of the NCs was attributed to their smaller particle size. Another comparison of the results with those obtained with Zn(2+)/Fe(3+) ions co-doped TiO(2) NCs, under similar experimental conditions, revealed that in the Y(3+)-doped NCs, particle size might not be the only factor responsible for the improved photocatalytic properties. It was concluded that the Y(3+) ion-mediated suppression of the unwanted e(-)/h(+) recombination could be the possible factor leading to additional enhancement. PMID:19491466

Narayan, Himanshu; Alemu, Hailemichael; Macheli, Lebohang; Thakurdesai, Madhavi; Rao, T K Gundu

2009-06-24

176

Synthesis of iron-doped TiO2 for degradation of reactive Orange16  

PubMed Central

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

2014-01-01

177

Synthesis and characterization of Fe3O4-TiO2 core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

Composite core-shell nanoparticles may have morpho-structural, magnetic, and optical (photoluminescence (PL)) properties different from each of the components considered separately. The properties of Fe3O4-TiO2 nanoparticles can be controlled by adjusting the titania amount (shell thinness). Core-shell nanoparticles were prepared by seed mediated growth of semiconductor (TiO2) through a modified sol-gel process onto preformed magnetite (Fe3O4) cores resulted from the co-precipitation method. The structure and morphology of samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), and high resolution-TEM respectively. X-ray photoelectron spectroscopy was correlated with ICP-AES. Magnetic measurements, optical absorption spectra, as well as PL spectroscopy indicate the presence of a charge/spin transfer from the conduction band of magnetite into the band gap of titania nanocrystals. The process modifies both Fe3O4 and TiO2 magnetic and optical properties, respectively.

Stefan, M.; Pana, O.; Leostean, C.; Bele, C.; Silipas, D.; Senila, M.; Gautron, E.

2014-09-01

178

Synthesis and photocatalytic performances of the TiO2 pillared montmorillonite.  

PubMed

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

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

2012-10-15

179

Intrinsic Au decoration of growing TiO2 nanotubes and formation of a high-efficiency photocatalyst for H2 production.  

PubMed

Electrochemical anodization of low-concentration (0.02-0.2 at% Au) TiAu alloys in a fluoride electrolyte leads to self-organized TiO2 nanotubes that show a controllable, regular in situ decoration with elemental Au nanoclusters of ?5 nm in diameter. The degree of self-decoration can be adjusted by the Au concentration in the alloy and the anodization time. Such Au particle decorated tubes show a high activity for photocatalytic H2 production from ethanol solutions. PMID:23963835

Lee, Kiyoung; Hahn, Robert; Altomare, Marco; Selli, Elena; Schmuki, Patrik

2013-11-13

180

Orthogonal synthesis, structural characteristics, and enhanced visible-light photocatalysis of mesoporous Fe2O3/TiO2 heterostructured microspheres  

NASA Astrophysics Data System (ADS)

In this paper, a facile solvothermal method assisted orthogonal experimental was applied to synthesis mesoporous Fe2O3/TiO2 heterostructured microsphere with the purpose of optimizing the preparation conditions. The as-prepared samples were characterized by TG, XRD, SEM, TEM, FT-IR, UV-vis DRS and N2 adsorption/desorption. On the basis of the above analysis, it was found that the mesoporous Fe2O3/TiO2 heterostructured microsphere has high crystallinity, ordered morphology, strong optical absorption, large surface area and enhanced catalytic activity. Furthermore, it also confirmed that orthogonal experimental design method was very efficient to optimize the preparation conditions for the synthesis of mesoporous Fe2O3/TiO2 heterostructured microspheres. The experimental results show that the reaction temperature and molar ratio of Fe to Ti have the most influence on the photocatalytic performance. The optimized preparation conditions for the synthesis of Fe2O3/TiO2 microspheres are reaction temperature at 140 °C, the amount of glucose of 3.4 g and the Fe:Ti molar ratio of 0.005:0.01. What's more, a tentative formation mechanism of mesoporous Fe2O3/TiO2 microspheres and charge transfer mechanism are proposed.

Wang, Ting; Yang, Guidong; Liu, Jia; Yang, Bolun; Ding, Shujiang; Yan, Zifeng; Xiao, Tiancun

2014-08-01

181

Influence of anions stabilizing the sols in synthesis of powders of highly dispersed titanium dioxide and three-dimensional nanocomposites based on SiO2/TiO2  

NASA Astrophysics Data System (ADS)

This paper reports on the results of investigations into the influence of anions (Cl-, SO{4/2-},NO{3/-}), which stabilize the sol-gel synthesis of highly dispersed titanium dioxide, on the crystallization and phase transition of TiO2 upon dehydration. The effect of the size factor on the phase composition of TiO2 in SiO2/TiO2 nanocomposites has been investigated using a three-dimensional opal matrix as a set of nanoreactors for the sol-gel synthesis of TiO2 · nH2O. It has been shown that there is a possibility of extending the region of the existence of a thermodynamically metastable modification of TiO2 (anatase) to the temperature of 1100°C due to the changes in the conditions of the sol-gel synthesis of TiO2 · nH2O.

Ivicheva, S. N.; Kargin, Yu. F.; Kutsev, S. V.; Shvorneva, L. I.; Yurkov, G. Yu.

2013-05-01

182

Al-doped TiO 2 mesoporous materials: synthesis and photodegradation properties  

Microsoft Academic Search

Aluminium-doped TiO2 mesoporous material was successfully fabricated by solid-state reaction with cetyltrimethylammonium bromide as a template\\u000a agent and tetrabutyl orthotitanate as a precursor. The characteristic results from low-angle and wide-angle X-ray diffraction,\\u000a high resolution transmission electron microscopy and energy dispersive spectroscopy, N2 absorption–desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet visible light spectroscopy\\u000a and X-ray photoelectron spectroscopy (XPS) clearly showed

Shaoyou Liu; Guocong Liu; Qingge Feng

2010-01-01

183

Synthesis of TiO2 Nanofluids by Wet Mechanochemical Process  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

184

Synthesis, characterization, and photoconductivity studies on nanocrystalline TiO2 films doped with gold nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocrystalline TiO2 films doped with gold nanoparticles were synthesized by the sol-gel process at room temperature. The TiO2 films were synthesized by using tetrabutyl orthotitanate as the inorganic precursor. The films were spin-coated on glass wafers. The samples were annealed at 100°C for 30 minutes and sintered at 520°C for 1 hour to generated anatase and rutile phases. The films were characterized using UV-Vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. An absorption peak located at around 651 nm is due to the surface plasmon resonance of the gold nanoparticles. Optical absorption spectrum was fitted by Gans model by using a high refractive index (nlocal = 2.6). This high index is related to the high content of anatase nanoparticles embedded in the film. Photoconductivity studies were performed on nanocrystalline (anatase phase) films. The experimental data were fitted with straight lines at darkness and under illumination at 515 nm and 645 nm. This indicates an ohmic behavior. Transport parameters were calculated. Results are discussed.

Valverde-Aguilar, G.; García-Macedo, J. A.; Galván-Ramírez, P.; Rentería-Tapia, V.

2009-08-01

185

Effects of various TiO2 nanostructures and graphene oxide on photocatalytic activity of TiO2.  

PubMed

The nanostructures of TiO2 significantly affect its photocatalytic activity. In this work, various TiO2 nanostructures have been successfully synthesized, including one-dimensional (1D) TiO2 nanotube, 1D TiO2 nanowire, three-dimensional (3D) TiO2 sphere assembled by nanoparticles (TiO2 sphere-P) and 3D TiO2 sphere assembled by nanosheets (TiO2 sphere-S). The results of photodegradation activity towards acid orange 7 (AO7) indicate that the photodegradation efficiency of TiO2 sphere-S is the highest among the investigated TiO2 nanostructures, even though the specific surface area of TiO2 sphere-S is lower than that of TiO2 nanotube. The best photodegradation activity of TiO2 sphere-S can be attributed to the highest light harvesting capacity resulted from multiple reflections of light, and hierarchical mesoporous structure. In addition, the combination of TiO2 sphere-S with graphene oxide (GO) sheets can further enhance the photodegradation efficiency of AO7 and disinfection activity of Escherichia coli (E. coli) under solar light, which is more energy efficient. The promising photocatalytic activity of GO-TiO2 composites is originated from the enhanced light absorption and efficient charge separation. Hence, this study paves a way for improving the performance of other photocatalysts. PMID:25038577

Gao, Peng; Li, Anran; Sun, Darren Delai; Ng, Wun Jern

2014-08-30

186

Sol-gel low-temperature synthesis of stable anatase-type TiO2 nanoparticles under different conditions and its photocatalytic activity.  

PubMed

In this work, TiO(2) nanoparticles in anatase phase was prepared by sol-gel low temperature method from titanium tetra-isopropoxide (TTIP) as titanium precursor in the presence of acetic acid (AcOH). The effects of synthesis parameters such as AcOH and water ratios, sol formation time, synthesis and calcination temperature on the photocatalytic activity of TiO(2) nanoparticles were evaluated. The resulting nanoparticles were characterized by X-ray diffraction, UV-Vis reflectance spectroscopy, transmission electron microscopy and Brunauer-Emmett-Teller techniques. Photocatalytic activity of anatase TiO(2) nanoparticles determined in the removal of C. I. Acid Red 27 (AR27) under UV light irradiation. Results indicate that with increasing AcOH/TTIP molar ratio from 1 to 10, sol formation time from 1 to 3 h and synthesis temperature from 0 to 25°C, increases crystallite size of synthesized nanoparticles. It was found that optimal conditions for low temperature preparation of anatase-type TiO(2) nanoparticles with high photocatalytic activity were as follows: TTIP:AcOH:water molar ratio 1:1:200, sol formation time 1 h, synthesis temperature 0°C and calcination temperature 450°C. PMID:21668867

Behnajady, Mohammad A; Eskandarloo, Hamed; Modirshahla, Nasser; Shokri, Mohammad

2011-01-01

187

Synthesis and application of TiO2 single-crystal nanorod arrays grown by multicycle hydrothermal for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned TiO2 nanorod arrays (NRs) are grown on the fluorine-doped tin oxide (FTO) substrates by a multicycle hydrothermal synthesis process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED). It is found that dye-sensitized solar cells (DSSCs) assembled by the as-prepared TiO2 single-crystal NRs exhibit different trends under the condition of different nucleation and growth concentrations. Optimum cell performance is obtained with high nucleation concentration and low growth cycle concentration. The efficiency enhancement is mainly attributed to the improved specific surface area of the nanorod.

Zhu, Jian-Jing; Zhao, Yu-Long; Zhu, Lei; Gu, Xiu-Quan; Qiang, Ying-Huai

2014-04-01

188

Synthesis of capped TiO2 nanocrystals of controlled shape and their use with MEH-PPV conjugated polymer to develop nanocomposite films for photovoltaic applications  

NASA Astrophysics Data System (ADS)

This study presents the synthesis details of titanium dioxide (TiO2) nanoparticles (NPs) of different shapes (nanospheres, nanorods and nanorhombics) using oleic acid (OA) and oleyl amine (OM) as capping agents. In order to develop nanocomposite thin films for photovoltaic cells, these TiO2 NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO2 NPs and MEH-PPV/TiO2 nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. It was found that the shape of NPs and the amount of OA and OM surfactants capped on their surface have an effect on their energy bandgap and also on the dispersion quality of MEH-PPV/TiO2 nanocomposites. Even though there was no evidence of chemical bonding between MEH-PPV matrix and TiO2 dispersed NPs, MEH-PPV/TiO2 nanocomposites showed very promising results for light absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO2 dispersed NPs, which are two main characteristics for photovoltaic materials.

Mighri, F.; Duong, Vu Thi Thuy; On, Do Trong; Ajji, A.

2014-05-01

189

Synthesis and characterization of polypyrrole/Sn-doped TiO 2 nanocomposites (NCs) as a protective pigment  

NASA Astrophysics Data System (ADS)

We have chemically polymerized pyrrole in the presence of Sn-doped TiO 2 nanoparticles (NPs) and TiO 2 (NPs) which act as a protective pigment. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results show a core-shell structure of pigments in which TiO 2 and Sn-doped TiO 2 NPs have a nucleus effect and caused a homogenous PPy core-shell type morphology leading to coverage of the TiO 2 and Sn-doped TiO 2 NPs by PPy deposit. The XRD results indicate that the crystalline size of polypyrrole/TiO 2 NCs and polypyrrole/Sn-doped TiO 2 NCs were approximately 93.46 ± 0.06 and 23.36 ± 0.06 nm respectively. The electrochemical impedance spectroscopy (EIS) results show that the performance of polypyrrole/Sn-doped TiO 2 NCs is better than polypyrrole/TiO 2 NCs. The results indicate that increasing the area of synthesized polypyrrole in the presence of Sn-doped TiO 2 NPs can increase its ability to interact with the ions liberated during the corrosion reaction of steel in the presence of NaCl. The UV-vis results show that the band gap of TiO 2 NPs increases with doped of Sn in lattice of TiO 2. The increase of the band gap of TiO 2 with doping of Sn can decrease the charge transfer through the coating.

Mahmoudian, M. R.; Basirun, W. J.; Alias, Y.; Ebadi, M.

2011-08-01

190

Synthesis and characterization of zinc doped nano TiO2 for efficient photocatalytic degradation of Eriochrome Black T  

NASA Astrophysics Data System (ADS)

Sol-gel method was used to synthesize undoped and zinc doped TiO2 with varied dopant concentrations using titanium tetraisopropoxide and zinc acetate as precursors. The synthesized catalyst samples were characterized by various techniques such as X-ray powder diffraction (XRD), UV-vis diffuse reflectance (DRS). The photocatalytic activity was determined by means of degradation of azo dye Eriochrome Black T. The results revealed that Zn doped TiO2 nanoparticles exhibited better results as compared to undoped TiO2 nanoparticles. Zn doped TiO2 (0.7mol %) nanoparticles exhibited the highest photocatalytic activity.

Singla, Pooja; Sharma, Manoj; Singh, Kulvir; Pandey, O. P.

2013-06-01

191

Synthesis of TiO2 nanoparticles utilizing hydrated reverse micelles in CO2.  

PubMed

Titanium dioxide nanoparticles were produced by the controlled hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of reverse micelles formed in CO2 with the surfactants ammonium carboxylate perfluoropolyether (PFPECOO-+NH4) (Mw = 587) and poly(dimethyl amino ethyl methacrylate-block-1H,1H,2H,2H-perfluorooctyl methacrylate) (PDMAEMA-b-PFOMA). Based on dynamic light scattering measurements, the amorphous TiO2 particles formed by injection of TTIP are larger than the reverse micelles, indicating surfactant reorganization. The size of the particles and the stability of dispersions in CO2 were affected by the molar ratio of water to surfactant headgroup (w(o)), precursor concentration, and injection rate. The amorphous particle size did not change upon depressurization and redispersion in CO2. PDMAEMA-b-PFOMA provided greater stability against particle aggregation at higher reactant concentration compared with PFPECOO-+NH4. The crystallite size after calcination, which was examined by X-ray diffraction and transmission electron microscopy, increased with w(o). PMID:15835711

Lim, Kwon Taek; Hwang, Ha Soo; Ryoo, Won; Johnston, Keith P

2004-03-16

192

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)

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.

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

2011-01-01

193

Self-cleaning properties of TiO2/palygorskite and TiO2/halloysite nanocomposite coatings  

NASA Astrophysics Data System (ADS)

Tubular halloysite and microfibrous palygorskite clay mineral combined with nanocrystalline TiO2 are involved in the preparation of nanocomposite films on glass substrates via sol-gel route at 450°C. The synthesis employing nonionic surfactant molecule as pore directing agent along with the acetic acid-based sol-gel route without addition of water molecules. Drying and thermal treatment of composite films ensure elimination of organic material lead to the formation of TiO2 nanoparticles homogeneously distributed on the palygorskite and halloysite surfaces. Nanocomposite films without cracks of active anatase crystal phase on palygorskite and halloysite surfaces are characterized by microscopy techniques, UV-Vis spectroscopy, and porosimetry methods in order to examine their structural properties. The composite palygorskite-TiO2 and halloysite/TiO2 films with variable quantities of palygorskite and halloysite were tested as photocatalysts in the photo-oxidation of Basic Blue 41 azo dye in water. These nanocomposite films proved to be most promising photocatalysts and highly effective to dye's decoloration in spite of small amount of palygorskite/TiO2 or halloysite/TiO2 catalyst immobilized onto glass substrates.

Panagiotaras, Dionisios; Kaplani, Eleni; Stathatos, Elias; Papoulis, Dimitrios

2014-10-01

194

Single-Step Synthesis of Al-Doped TiO2 Nanoparticles Using Non-Transferred Thermal Plasma Torch  

NASA Astrophysics Data System (ADS)

Al-doped TiO2 nanoparticles possessing visible-light photocatalytic activity were fabricated with an atmospheric-pressure thermal plasma system via a single-step direct combination of vaporized Ti, Al, and O2. Pure Ti and Al2O3 powders and ultrahigh-purity O2 were used as the precursors. The experimental results showed that the size of synthesized TiO2 was between 10 and 105 nm. Nevertheless, the nanoparticles with sizes smaller than 50 nm accounted for approximately 80% of the total number. The observed size reduction appeared to be the suppression on particle growth due to the introduction of Al species into TiO2 crystal. The largest specific surface area of the Al-doped TiO2 was 44 m2·g-1. The anatase phase was noticeably decreased with increasing the Al2O3 addition. The absorption spectra of Al-doped TiO2 shifted from UV to visible-light region with respect to an increase in Al2O3 addition. Oxygen in the formed TiO2 was found to be in TiO2 crystal lattice and in surface hydroxyl groups. Both Ti4+ and Ti3+ existed in the formed TiO2. However, the Ti3+ amount significantly increased with increasing Al2O3 addition due to Al/Ti substitution and the resulted oxygen vacancy.

Tsai, Cheng-Yen; Hsi, Hsing-Cheng; Bai, Hsunling; Fan, Kuo-Shuh; Sun, Hung-Dar

2012-01-01

195

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

PubMed

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

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

2014-10-01

196

Influence of vanadia content onto TiO 2-SiO 2 matrix for photocatalytic oxidation of trichloroethylene  

NASA Astrophysics Data System (ADS)

Direct synthesis of vanadia onto titania-silica matrices as photocatalysts was achieved by using simple sol-gel method. This synthetic strategy revealed that the vanadia species could be loaded into TiO 2-SiO 2 matrices up to 18.5 wt%. Results from FTIR indicated that at low loading amounts of vanadia species (i.e. ?1), the formation of monolayer vanadia species onto the matrices was successfully fabricated; however, a polymeric vanadate could be formed with high loading of vanadia species. On such heterogeneous photocatalytic systems, the oxidation affinity of trichloroethylene was substantially affected by the loading amount and the degree of dispersion V 2O 5 particles onto the TiO 2-SiO 2 support matrices, indicating the exclusive effect of the V 2O 5 nanoparticles on this photocatalytic reaction. Clearly evident is that this polymeric vanadate was a relatively inactive photocatalysts for the oxidation of trichloroethylene.

Ismail, Adel Ali; Matsunaga, Hideyuki

2007-10-01

197

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

PubMed

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

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

2013-06-01

198

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

PubMed

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

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

2014-11-17

199

Novel TiO2-Pt@SiO2 nanocomposites with high photocatalytic activity  

NASA Astrophysics Data System (ADS)

This article reports a facile and controllable two-step method to construct TiO2-Pt@SiO2 nanocomposites. TiO2 nanoparticles (NPs), with small size and high surface energy, were synthesized by a solvothermal reaction process. The TiO2-Pt@SiO2 nanocomposites were fabricated by a reverse micro-emulsion method. SiO2 shell coated NPs were adopted for further photocatalytic reaction. Because of their small size and high surface energy, TiO2@SiO2 and TiO2-Pt@SiO2 nanocomposites show higher photocatalytic activity than commercial Degussa P25. Compared with TiO2@SiO2, TiO2-Pt@SiO2nanocomposites have improved photocatalytic activity due to the Pt induced spatial separation of electrons and holes. The silica shells not only maintain the structure of the nanocomposites but also prevent their aggregation during the photocatalytic reactions, which is highly important for the good durability of the photocatalyst. This strategy is simple, albeit efficient, and can be extended to the synthesis of other composites of noble metals. It has opened a new window for the construction of hetero-nanocomposites with high activity and durability, which would serve as excellent models in catalytic systems of both theoretical and practical interest.This article reports a facile and controllable two-step method to construct TiO2-Pt@SiO2 nanocomposites. TiO2 nanoparticles (NPs), with small size and high surface energy, were synthesized by a solvothermal reaction process. The TiO2-Pt@SiO2 nanocomposites were fabricated by a reverse micro-emulsion method. SiO2 shell coated NPs were adopted for further photocatalytic reaction. Because of their small size and high surface energy, TiO2@SiO2 and TiO2-Pt@SiO2 nanocomposites show higher photocatalytic activity than commercial Degussa P25. Compared with TiO2@SiO2, TiO2-Pt@SiO2nanocomposites have improved photocatalytic activity due to the Pt induced spatial separation of electrons and holes. The silica shells not only maintain the structure of the nanocomposites but also prevent their aggregation during the photocatalytic reactions, which is highly important for the good durability of the photocatalyst. This strategy is simple, albeit efficient, and can be extended to the synthesis of other composites of noble metals. It has opened a new window for the construction of hetero-nanocomposites with high activity and durability, which would serve as excellent models in catalytic systems of both theoretical and practical interest. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30523b

Wu, Hao-Shuai; Sun, Ling-Dong; Zhou, Huan-Ping; Yan, Chun-Huan

2012-05-01

200

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

201

Synthesis and field emission properties of rutile TiO2 nanowires arrays grown directly on a Ti metal self-source substrate.  

PubMed

Large-area and uniform quasi-aligned titanium oxide (TiO2) nanowire arrays have been produced in situ on a titanium (Ti) foil by a simple high-temperature oxidation process with acetone as the oxidant. The products are characterized by X-ray diffraction, electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The TiO2 nanowires have a rutile single-crystalline structure. The typical diameters range from 20 to 50 nm and lengths are up to a few micrometers. Since the Ti foil serves as both the source of Ti and substrate, direct synthesis and assembly of TiO2 nanowire arrays on a conductive Ti substrate is accomplished in a single step. Consequently, good intrinsic adhesion and electrical contact are achieved naturally between the nanowires and metal substrate. Such TiO2 nanowire arrays exhibit good field emission properties with a low turn-on field of 4.1 V/microm boding well for applications in vacuum microelectronics. PMID:19453013

Huo, Kaifu; Zhang, Xuming; Fu, Jijiang; Qian, Guixiang; Xin, Yunchang; Zhu, Boquan; Ni, Hongwei; Chu, Paul K

2009-05-01

202

TiO2-SnO2 heterostructures applied to dye photodegradation: The relationship between variables of synthesis and photocatalytic performance  

NASA Astrophysics Data System (ADS)

This paper describes the synthesis of TiO2-SnO2 heterostructures and their application to water decontamination based on the photodegradation of Rhodamine B (RhB). The heterostructures were fabricated through two different routes, a hydrolytic sol gel and the polymeric precursor method, both of which induced the growth of SnO2 on commercial TiO2. The results show that the heterostructures presented higher photoactivity behaviors than commercial TiO2 nanopowders. The achievement of homogeneity during phase formation (i.e., of the SnO2 dispersion over the TiO2 nanoparticles) was a key parameter for obtaining higher photocatalytic activities per unit area. The main degradation mechanism was correlated with the process of rad OH radical generation, which was related to the concentration and nature of the surface hydroxyl groups. Accordingly, the polymeric precursor method was shown to be more adequate for dispersing higher amounts of SnO2 in comparison with the hydrolytic sol gel method. Additionally, the polymeric precursor method delivered higher proportions of bonded surface hydroxyl groups, which were responsible for radical formation; in contrast, the hydrolytic sol gel method demonstrated the highest amount of adsorbed water.

de Mendonça, Vagner R.; Lopes, Osmando F.; Fregonesi, Raul P.; Giraldi, Tania R.; Ribeiro, Caue

2014-04-01

203

Photocatalytic performance of TiO2-zeolite templated carbon composites in organic contaminant degradation.  

PubMed

TiO2 composites with zeolite templated carbon (TiO2-ZTC) and activated carbon (TiO2-AC) were prepared and used as the photocatalysts for comparative studies with pure TiO2. TiO2-ZTC exhibited the highest rate of methylene blue degradation with a rate approximately 4 and 400 times higher than those of TiO2-AC and pure TiO2, respectively. Moreover, the highest catalytic performance of TiO2-ZTC in gas-phase degradation of acetone was approximately 1.1 and 12.9 times higher than TiO2-AC and pure TiO2, respectively. These outstanding performances could be attributed to high surface area, pore volume, and hydrophobic surface properties, leading to improvement in the adsorption properties of organic molecules. PMID:25328126

Donphai, Waleeporn; Kamegawa, Takashi; Chareonpanich, Metta; Nueangnoraj, Khanin; Nishihara, Hirotomo; Kyotani, Takashi; Yamashita, Hiromi

2014-12-01

204

Anionic ligand assisted synthesis of 3-D hollow TiO2 architecture with enhanced photoelectrochemical performance.  

PubMed

Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties. We found that citric acid (CA) plays crucial roles in the formation of the 3-D hollow architecture. First, CA controls the hydrolysis rate of Ti ions and facilitates surface hydrolysis on templates during hydrothermal synthesis. Second, CA suppresses the growth of the carbon template at the initial reaction stage, resulting in the formation of comparatively small hollow fibers. More importantly, a prolonged hydrothermal reaction with CA enables a hollow sphere to grow into entangled hollow fibers via biomimetic swallowing growth. To demonstrate advantages of the 3-D hollow architecture for photoelectrochemical devices, we evaluated its photoelectrochemical performance, specifically the electrolyte diffusion and electron dynamics, by employing dye-sensitized solar cells as a model device. A systemic analysis reveals that the 3-D hollow architecture greatly improves both the electrolyte diffusion and electron transport compared to those of the nanoparticle and hollow sphere due to the elongated porous hollow morphology as well as the densely interconnected nanoparticles at the wall layer. PMID:25470414

Shin, Seong Sik; Kim, Dong Wook; Park, Jong Hoon; Kim, Dong Hoe; Kim, Ju Seong; Hong, Kug Sun; Cho, In Sun

2014-12-30

205

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

206

Synthesis and photonic band calculations of NCP face-centered cubic photonic crystals of TiO2 hollow spheres.  

PubMed

With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy. PMID:17097102

Zhu, Yong-zheng; Cao, Yan-ling; Li, Zhi-hui; Ding, Juan; Liu, Jun-song; Chi, Yuan-bin

2007-02-01

207

Hydrothermal preparation and characterization of TiO 2:AC composites  

Microsoft Academic Search

A new photocatalyst titania:activated carbon (TiO2:AC) composite was prepared by impregnating anatase type TiO2 nanoparticulates onto the activated carbon surface through a mild hydrothermal route. A varied ratio of TiO2 to AC was considered for impregnation. As-prepared TiO2:AC composite was characterized by various techniques such as powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), BET

A. K. Subramani; K. Byrappa; G. N. Kumaraswamy; H. B. Ravikumar; C. Ranganathaiah; K. M. Lokanatha Rai; S. Ananda; M. Yoshimura

2007-01-01

208

Sol-hydrothermal synthesis of inorganic-framework molecularly imprinted TiO2/SiO2 nanocomposite and its preferential photocatalytic degradation towards target contaminant.  

PubMed

Inorganic-framework molecularly imprinted TiO2/SiO2 nanocomposite (MIP-TiO2/SiO2) was successfully prepared by sol-hydrothermal method using 4-nitrophenol as template. The morphology, structure, optical property, zeta-potential and photocurrent of MIP-TiO2/SiO2 were characterized. The adsorption performance and photocatalytic selectivity were also studied. MIP-TiO2/SiO2 shows higher adsorption capacity and selectivity than the non-imprinted TiO2/SiO2 (NIP-TiO2/SiO2). Kinetics results show that the adsorption equilibrium of 4-nitrophenol on MIP-TiO2/SiO2 is established within 20 min, and the adsorption process obeys the pseudo-second-order model. Moreover, MIP-TiO2/SiO2 can completely degrade 4-nitrophenol within 30 min, while NIP-TiO2/SiO2 takes 110 min. It was found that the MIP-TiO2/SiO2 photocatalyst shows molecular recognition ability, leading to selective adsorption and molecular recognitive photocatalytic degradation of 4-nitrophenol. Furthermore, because of its inorganic framework, MIP-TiO2/SiO2 shows excellent reusability. PMID:24953942

Deng, Fang; Liu, Yin; Luo, Xubiao; Wu, Shaolin; Luo, Shenglian; Au, Chaktong; Qi, Ruoxi

2014-08-15

209

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

210

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

NASA Astrophysics Data System (ADS)

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%.

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

2014-07-01

211

Solvothermal synthesis and enhanced photocatalytic activity of flowerlike nanoarchitectures assembled from anatase TiO2 nanoflakes  

NASA Astrophysics Data System (ADS)

TiO2 nanoflakes assembled flowerlike nanoarchitectures with diameters of 1.70-2.20 ?m were synthesized by a solvothermal reaction of butyl titanate with isopropyl alcohol, HF and H2O at 180 °C for 12 h. The constituent nanoflakes have perfect rectangular shapes with the typical widths of 0.81-0.95 ?m, lengths of 1.04-1.20 ?m and thicknesses of 0.10-0.12 ?m. The constituent nanoflakes are formed due to the selective adsorption of isopropyl alcohol on (0 1 0) surface of anatase TiO2. These anatase TiO2 nanoflakes assemble into flowerlike structures driven by the electrostatic attraction. The as-prepared TiO2 flowerlike nanoarchitectures exhibit enhanced photocatalytic ability to degrade methyl orange dye in comparison with commercial TiO2 powders. The photodegradation of methyl orange dye catalyzed by the anatase TiO2 nanoflake assembled flowerlike nanostructures fits a pseudo first-order reaction.

Cui, Meng; Tian, Sha; Zhao, Hua; Jin, Rong; Chen, Yan; Liu, Bin; Yang, Heqing

2012-07-01

212

Surface Modification of TiO2 Nanocrystals by WOx Coating or Wrapping: Solvothermal Synthesis and Enhanced Surface Chemistry.  

PubMed

TiO2 anatase nanocrystals were prepared by solvothermal processing of Ti chloroalkoxide in oleic acid, in the presence of W chloroalkoxide, with W/Ti nominal atomic concentration (Rw) ranging from 0.16 to 0.64. The as-prepared materials were heat-treated up to 500 °C for thermal stabilization and sensing device processing. For R0.16, the as-prepared materials were constituted by an anatase core surface-modified by WOx monolayers. This structure persisted up to 500 °C, without any WO3 phase segregation. For Rw up to R0.64, the anatase core was initially wrapped by an amorphous WOx gel. Upon heat treatment, the WOx phase underwent structural reorganization, remaining amorphous up to 400 °C and forming tiny WO3 nanocrystals dispersed into the TiO2 host after heating at 500 °C, when part of tungsten also migrated into the TiO2 structure, resulting in structural and electrical modification of the anatase host. The ethanol sensing properties of the various materials were tested and compared with pure TiO2 and WO3 analogously prepared. They showed that even the simple surface modification of the TiO2 host resulted in a 3 orders of magnitude response improvement with respect to pure TiO2. PMID:25775118

Epifani, Mauro; Díaz, Raül; Force, Carmen; Comini, Elisabetta; Manzanares, Marta; Andreu, Teresa; Genç, Aziz; Arbiol, Jordi; Siciliano, Pietro; Faglia, Guido; Morante, Joan R

2015-04-01

213

Sol-gel synthesis and photocatalytic activity of B and Zr co-doped TiO2  

NASA Astrophysics Data System (ADS)

Effects of boron (B) and/or zirconium (Zr) doping on photocatalytic activity of sol-gel derived titania (TiO2) powders were investigated. A conventional, non-hydrous sol-gel technique was applied to synthesize the B, Zr doped/co-doped TiO2 powders. Doping was made at molar ratios of Ti/B=1 and Ti/Zr=10. Sol-gel derived xero-gels were calcined at 500 °C for 3 h. The crystal chemistry and the morphology of the undoped and B, Zr doped/co-doped TiO2 nanoparticles were investigated using X-ray diffractometer and scanning electron microscope. Nano-scale (9-46 nm) TiO2 crystallites were obtained after calcination. Doping and co-doping decreased the crystallite size. Photocatalytic activity was measured through the degradation of methylene blue (MB) under 1 h UV-irradiation using a UV-vis spectrophotometer. Results revealed that B doping into anatase caused the formation of oxygen vacancies, whereas Zr addition caused Ti substitution. Both B and Zr ions had a profound effect on the particle morphology and photocatalytic activity of TiO2. The photocatalytic activity of B and Zr doped TiO2 particles increased from 27% to 77% and 57%, respectively. The best activity (88.5%) was achieved by co-doping.

Kapusuz, Derya; Park, Jongee; Ozturk, Abdullah

2013-07-01

214

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites  

NASA Astrophysics Data System (ADS)

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO2-VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO2 nanoparticles serve two purposes, namely to prevent the TiO2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO2-VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO2-VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.

Balasubramanian, Balamurugan; Kraemer, Kristin L.; Valloppilly, Shah R.; Ducharme, Stephen; Sellmyer, David J.

2011-10-01

215

Low-frequency ultrasound induces oxygen vacancies formation and visible light absorption in TiO2 P-25 nanoparticles.  

PubMed

Low-frequency ultrasound (LFUS) irradiation induces morphological, optical and surface changes in the commercial nano-TiO(2)-based photocatalyst, Evonik-Degussa P-25. Low-temperature electron spin resonance (ESR) measurements performed on this material provided the first experimental evidence for the formation of oxygen vacancies (V(o)), which were also found responsible for the visible-light absorption. The V(o) surface defects might result from high-speed inter-particle collisions and shock waves generated by LFUS sonication impacting the TiO(2) particles. This is in contrast to a number of well-established technologies, where the formation of oxygen vacancies on the TiO(2) surface often requires harsh technological conditions and complicated procedures, such as annealing at high temperatures, radio-frequency-induced plasma or ion sputtering. Thus, this study reports for the first time the preparation of visible-light responsive TiO(2)-based photocatalysts by using a simple LFUS-based approach to induce oxygen vacancies at the nano-TiO(2) surface. These findings might open new avenues for synthesis of novel nano-TiO(2)-based photocatalysts capable of destroying water or airborne pollutants and microorganisms under visible light illumination. PMID:22192787

Osorio-Vargas, Paula A; Pulgarin, Cesar; Sienkiewicz, Andrzej; Pizzio, Luis R; Blanco, Mirta N; Torres-Palma, Ricardo A; Pétrier, Christian; Rengifo-Herrera, Julián A

2012-05-01

216

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

PubMed Central

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

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

2015-01-01

217

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

218

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

PubMed

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

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

2015-01-01

219

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

PubMed Central

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.

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

2015-01-01

220

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

PubMed Central

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

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

2014-01-01

221

Synthesis and characterization of a stable, label-free optical biosensor from TiO2-coated porous silicon.  

PubMed

A nanoscale layer of TiO2 is coated on the inner pore walls of a porous silicon (PSi) film by room-temperature infiltration of a TiO2 sol-gel precursor and firing at 500 °C. The PSi:TiO2 composite films are characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectral analysis (EDS), scanning electron microscopy (SEM) and reflective interferometric Fourier transform spectroscopy (RIFTS). The analysis indicates that TiO2 conformally coats the inner pore surfaces of the PSi film. The film displays greater aqueous stability in the pH range 2-12 relative to a PSi:SiO2 surface. A label-free optical interference immunosensor based on the TiO2-coated PSi film is demonstrated by real-time monitoring of the physical adsorption of protein A, followed by the specific binding of rabbit anti-sheep immunoglobulin (IgG) and then specific capture of sheep IgG. The time to achieve equilibrium for the physical adsorption of protein A on the surface of TiO2-coated PSi film is significantly greater than that of PSi film. The specificity of the protein A and rabbit anti-sheep IgG construct on the sensor is confirmed by tests with non-binding chicken IgG. The sensitivity of the immunosensor is shown to be 8210 ± 170 nm/refractive index unit (RIU). PMID:24419080

Li, Jianlin; Sailor, Michael J

2014-05-15

222

Low temperature synthesis and visible light driven photocatalytic activity of highly crystalline mesoporous TiO2 particles.  

PubMed

Mesoporous TiO2 powder materials with a high crystallinity have been prepared by evaporation induced self assembly (EISA) process using titanium tetraisopropoxide (TTIP) and pluronic P123 surfactant (EO20PO70EO20) as titanium source and structure-directing reagent, respectively. The prepared materials were characterized by low and wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical absorption, and N2 adsorption-desorption experiments. The crystallinity of the materials was controlled by varying the calcination temperature. The resulting TiO2 materials showed highly crystalline structure with uniform particle size which increases from 11.8 to 23.8 nm with increasing the calcination temperature from 400 to 600 degrees C, respectively, whereas the specific surface area decreases from 125 to 40 m2/g. TEM and XRD results revealed that the calcination temperature of 600 degrees C is the best condition to obtain highly crystalline mesoporous TiO2. The photocatalytic activity of the TiO2 mesoporous materials with different crystallinity and textural parameters has been studied in the decomposition of methylene blue (MB) dye molecules under visible light irradiation. Among the mesoporous TiO2 materials studied, the material with the highest crystallinity, prepared at 600 degrees C, showed the best photocatalytic performance in the decomposition of MB under visible light in a short time. PMID:21121305

Gujar, Tanaji P; Anand, Chokkalingam; Shinde, Vaishali R; Ye, Jinhua; Ariga, Katsuhiko; Vinu, Ajayan

2010-12-01

223

Solvothermal synthesis of TiO2 hollow nanospheres utilizing the Kirkendall effect and their photocatalytic activities  

NASA Astrophysics Data System (ADS)

Anatase TiO2 hollow nanospheres were prepared by solvothermal method, using polyethyleneimine (PEI) as an auxiliary agent, followed by calcination at 400, 500 and 700 °C, respectively. The samples were characterized by XRD, SEM, TEM, HRTEM, thermal gravimetric-differential thermal analysis (TG-DTA) and N2 adsorption-desorption isotherm. The optical properties and photocatalytic reaction mechanism were investigated by means of UV-Vis diffuse reflectance spectra, radical-trapping experiments and fluorescent technique. The effect of the PEI quantity on morphologies of the products and the formation mechanism of the TiO2 nanospheres were explored on the basis of series of control experiments. The photocatalytic activities of the samples were evaluated by degradation of rhodamine B (RhB) solutions and compared with that of the commercial TiO2 (P25). The results clearly show that the TiO2 hollow nanospheres were formed via the Kirkendall effect. For the first time, we find that the morphologies of the products change dramatically with slightly increasing the PEI quantity. The photocatalytic activity of the TiO2 nanospheres calcined at 500 °C is higher than those of the other two samples and P25. The active species for the photocatalytic reactions is not ·OH.

Chen, Sifeng; Wang, Huiqun; Zhu, Lianjie; Li, Jianfa; Sun, Jingfeng

2014-12-01

224

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

PubMed Central

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

2013-01-01

225

The Effect of Adding TiO2 on Synthesis of Al4SiC4 powders  

NASA Astrophysics Data System (ADS)

Three powders of aluminum, silicon and graphite were mixed with the molar ratio corresponding to the chemical composition of Al4SiC4, and then a small amount of titanium oxide was added into the mixture. The mixtures were heated at 1973 K in argon, and the Al4SiC4 phase was obtained. Conversely, the two phases, Al4O4C and TiC, were detected when the increasing of additive amount of TiO2 was made, and the grain sizes of Al4SiC4 were refined from 10~20 ?m to 1~5 ?m at the same time. Further, the morphology of Al4SiC4 without addition of TiO2 is irregular shape, but changes into tabular structure after adding TiO2.

Yu, Chao; Deng, Chengji; Yuan, Wenjie; Zhu, Hongxi

2013-12-01

226

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

227

Synthesis of Au/TiO2 Core-Shell Nanoparticles from Titanium Isopropoxide and Thermal Resistance Effect of TiO2 Shell  

NASA Astrophysics Data System (ADS)

On the synthesis of Au/TiO2 core-shell structure nanoparticles, the effect of the concentration of Ti4+ on the morphology and optical property of Au/TiO2 core-shell nanoparticles was examined. A gold colloid was prepared by mixing HAuCl4\\cdot4H2O and C6H5Na3\\cdot2H2O. Titanium stock solution was prepared by mixing solutions of titanium(IV) isopropoxide (TTIP) and triethanolamine (TEOA). The concentration of the Ti4+ stock solution was adjusted to 0.01-0.3 mM, and then the gold colloid was added to the Ti4+ stock solution. Au/TiO2 core-shell structure nanoparticles could be prepared by the hydrolysis of the Ti4+ stock solution at 80 °C. The size of the as-prepared Au nanoparticles was 15 nm. The thickness of the TiO2 shell on the surface of gold particles was about 10 nm. The absorption peak of the Au/TiO2 core-shell nanoparticles shifted towards the red end of the spectrum by about 3 nm because of the formation of the TiO2 shell on the surface of the gold particles. The crystal structure of the TiO2 shell showed an anatase phase. The increase in the Au crystallite size of the Au/TiO2 nanoparticles with increasing heat treatment temperature is smaller than that in the pure Au nanoparticles. This may be due to the encapsulation of Au particles with the TiO2 shell that prevents the growth of the nanoparticle nucleation.

Kwon, Hyun-Woo; Lim, Young-Min; Tripathy, Suraj Kumar; Kim, Byoung-Gyu; Lee, Min-Sang; Yu, Yeon-Tae

2007-04-01

228

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

NASA Astrophysics Data System (ADS)

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.

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

2008-10-01

229

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

NASA Astrophysics Data System (ADS)

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).

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

2014-07-01

230

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

NASA Astrophysics Data System (ADS)

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).

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

2015-04-01

231

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

NASA Astrophysics Data System (ADS)

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.

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

232

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

PubMed

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 24h) 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 (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 24h) was studied. PMID:23659950

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

233

Synthesis, phase to phase deposition and characterization of rutile nanocrystalline titanium dioxide (TiO2) thin films  

NASA Astrophysics Data System (ADS)

In this work the preparation, deposition and structural properties of titanium oxide (TiO2) thin films were investigated. The films were deposited by means of the e-beam physical vapor deposition (EBPVD) method in high vacuum (10-7 Torr). A controlled deposition rate in the range of 0.1-0.3 Å/s was monitored in situ employing quartz crystal. The films were deposited on the oxidized Si (1 0 0) wafer, glass micro slides. These films were analyzed using Grazing Angle X-ray diffraction (GA-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM) and UV-visible Spectroscopy (UV-vis). Structural characterization results showed mainly presence of the crystalline rutile phase, however an interfacial SiO2 layer between TiO2 and the substrate and the minor anatase crystalline phase of TiO2 was also identified in FTIR analysis. Grain size was found to be in the range of 100-125 nm while grain boundary was estimated to be 20 nm. Direct and indirect optical band gap was estimated to be 3.64 and 3.04 eV, respectively. A process induced self annealing of deposited film shows a strong effect on the structural, morphological and optical properties. Furthermore, low deposition rate and high vacuum allows rutile to rutile phase transformation from indigenously prepared TiO2 target to thin film.

Gupta, Sanjeev K.; Singh, Jitendra; Anbalagan, K.; Kothari, Prateek; Bhatia, Ravi Raj; Mishra, Pratima K.; Manjuladevi, V.; Gupta, Raj K.; Akhtar, J.

2013-01-01

234

Facile synthesis, structure and visible light photocatalytic activity of recyclable ZnFe2O4/TiO2  

NASA Astrophysics Data System (ADS)

A kind of sponge-like ZnFe2O4/TiO2 composite was facilely synthesized by a solution combustion method. The physicochemical properties, including the crystalline phase, surface morphology, spectral response, photogenerated charge carriers' separation and transfer efficiency, were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption isotherms, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and photoluminescence spectroscopy techniques and analyzed to interpret the relationship between the structure and photocatalytic activity. The sponge-like morphology promotes the adsorption of reaction species as well as functions as a good light harvesting structure for the enhancement of spectral utilization. The heterojunction effectively inhibited the recombination of photogenerated charge carriers. With these synergistic effects, the degradation rate of methylene blue on ZnFe2O4/TiO2 was up to 93.2% under visible light irradiation and remained stable even after five consecutive reaction runs. Moreover, owing to the magnetic property, ZnFe2O4/TiO2 can be recycled easily. Additionally, a photocatalytic mechanism of ZnFe2O4/TiO2 was proposed.

Zhu, Xiaodi; Zhang, Fan; Wang, Mengjiao; Ding, Jianjun; Sun, Song; Bao, Jun; Gao, Chen

2014-11-01

235

Synthesis of SUB-10 NM TiO2 Nanowires for the Application of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Highly oriented single-crystalline rutile TiO2 nanowires on transparent conductive fluorine-doped tin oxide (FTO) substrates are prepared by low-temperature hydrothermal method. The small lattice mismatch between FTO substrate and rutile TiO2 promote the epitaxial nucleation and growth of rutile TiO2 nanowires on FTO, with the diameter of 4-6 nm. Due to Van der waals force, the ultrafine nanowires tend to gather together, forming nanowire bundles. Using the ultrafine nanowire bundle array as the photoanode and ruthenium complex (N719) as the sensitizer, dye-sensitized solar cells (DSSCs) are assembled. The effect of the TiO2 nanowire gathering on the power conversion of the DSSCs has been investigated. Experimental result shows that the light-to-electricity conversion efficiency is increased by reducing the gathering of the nanowires through introducing toluene into reactant precursors. The DSSCs based on the bundles with smallest average width (i.e., least nanowire gathering) show the highest power conversion efficiency of 3.70%. The relatively high energy conversion efficiency is contributed to the large surface area, which enhances the adsorption of dye molecules.

Liu, Jun; Liu, Zhen; Lin, Kangbao; Wei, Aixiang

2013-04-01

236

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...

237

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)

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.

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

2014-06-01

238

Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility  

NASA Astrophysics Data System (ADS)

To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry.

Liu, Wenwen; Su, Penglei; Chen, Su; Wang, Na; Ma, Yuanping; Liu, Yiran; Wang, Jinshu; Zhang, Zhenting; Li, Hongyi; Webster, Thomas J.

2014-07-01

239

Effect of ZnFe 2O 4 doping on the photocatalytic activity of TiO 2  

Microsoft Academic Search

The photocatalytic oxidation of the organic pollutants with the TiO2 as photocatalyst has been widely studied in the world, and many achievements have been got. The degradation of pollutants is highly related with the photocatalytic activity of TiO2. It is demonstrated that doping ions or oxides to TiO2 is one way to enhance the photocatalytic activity of TiO2. In this

Guo-guang Liu; Xue-zhi Zhang; Ya-jie Xu; Xin-shu Niu; Li-qing Zheng; Xue-jun Ding

2004-01-01

240

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

241

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

242

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

SciTech Connect

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.

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

2013-03-13

243

Sol-gel synthesis and characterization of nanostructured TiO2/gamma-Al2O3 composite membranes.  

PubMed

Nanostructured TiO2/gamma-Al2O3 composite membranes with various compositions were prepared by sol-gel method. The structural and textural properties of the composite membranes could be modified by the mixing ratio of boehmite sol and titania sol, and calcination temperature. The existence of alumina in the composite membranes retarded anatase-to-rutile phase transformation, resulting in stabilization of textural properties. Defect-free composite membranes were confirmed by gas permeation test. PMID:22103175

Kwon, Hyuk Taek; Kim, Jinsoo

2011-08-01

244

Synthesis, structural and magnetic behavior of undoped and Mn-doped anatase TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Ti1-xMnxO2 (x = 0, 0.05) nanoparticles have been synthesized using chemically derived self-propagating combustion reaction method. X-ray diffraction studies demonstrate the formation of anatase phase of TiO2 belonging to 141/amd space group in both samples without the formation of any impurity phase. The incorporation of 5 at.% Mn content does not produce any changes in crystal structure which reveals the exact substitution of Mn atoms at Ti sites. Some change in lattice parameters and crystallite size is observed in Mn-doped composition, attributed to the difference in ionic radii. The size of grains obtained using scanning electron micrographs shows the consistent trend with the crystallite size evaluated from X-ray diffraction analysis. Energy dispersive X-ray analysis confirms the incorporation of Mn content in TiO2 structure. Ferromagnetic behavior detected only in Mn-doped TiO2 composition correspond to the strong Mn d-shell contribution.

Mahmood, Asif; Ramay, Shahid M.; Al-Zaghayer, Yousef S.; Atiq, Shahid; Saleem, Murtaza; Al Masary, Waheed A.; Haider, Sajjad

2015-02-01

245

Synthesis and photoelectrochemical response of CdS quantum dot-sensitized TiO2 nanorod array photoelectrodes  

PubMed Central

A continuous and compact CdS quantum dot-sensitive layer was synthesized on TiO2 nanorods by successive ionic layer adsorption and reaction (SILAR) and subsequent thermal annealing. The thickness of the CdS quantum dot layer was tuned by SILAR cycles, which was found to be closely related to light absorption and carrier transformation. The CdS quantum dot-sensitized TiO2 nanorod array photoelectrodes were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet–visible absorption spectroscopy, and photoelectrochemical property measurement. The optimum sample was fabricated by SILAR in 70 cycles and then annealed at 400°C for 1 h in air atmosphere. A TiO2/CdS core-shell structure was formed with a diameter of 35 nm, which presented an improvement in light harvesting. Finally, a saturated photocurrent of 3.6 mA/cm2 was produced under the irradiation of AM1.5G simulated sunlight at 100 mW/cm2. In particular, the saturated current density maintained a fixed value of approximately 3 mA/cm2 without decadence as time passed under the light conditions, indicating the steady photoelectronic property of the photoanode. PMID:23663590

2013-01-01

246

CuInS2 quantum dot-sensitized TiO2 nanorod array photoelectrodes: synthesis and performance optimization  

PubMed Central

CuInS2 quantum dots (QDs) were deposited onto TiO2 nanorod arrays for different cycles by using successive ionic layer adsorption and reaction (SILAR) method. The effect of SILAR cycles on the light absorption and photoelectrochemical properties of the sensitized photoelectrodes was studied. With optimization of CuInS2 SILAR cycles and introduction of In2S3 buffer layer, quantum dot-sensitized solar cells assembled with 3-?m thick TiO2 nanorod film exhibited a short-circuit current density (Isc) of 4.51 mA cm?2, an open-circuit voltage (Voc) of 0.56 V, a fill factor (FF) of 0.41, and a power conversion efficiency (?) of 1.06%, respectively. This study indicates that SILAR process is a very promising strategy for preparing directly anchored semiconductor QDs on TiO2 nanorod surface in a straightforward but controllable way without any complicated fabrication procedures and introduction of a linker molecule. PMID:23181940

2012-01-01

247

The layered double hydroxide route to Bi-Zn co-doped TiO2 with high photocatalytic activity under visible light.  

PubMed

In this work, a co-doped Bi-Zn-TiO2 photocatalist is synthesized by an original synthesis route of layered double hydroxide followed by heat treatment at 670°C. After characterization the photocatalyst efficiency is estimated by the photo-discoloration of an anionic dye (indigo carmine) under visible light and compare to TiO2-P25 as reference material. In this new photocatalyst, anatase and ZnO wurtzite are the only identified crystalline phase, rutile and Bi2O3 being undetected. Moreover, the binding energy of Bi determined (XPS analysis) is different from the one of Bi in Bi2O3. Compared to TiO2-P25, the absorption is red shifted (UV-vis DRS) and the Bi-Zn-TiO2 photocatalyst showed sorption capacity toward indigo carmine higher than that TiO2-P25. The kinetics of the photo-discoloration is faster with Bi-Zn-TiO2 than with TiO2-P25. Indeed, a complete discoloration is obtained after 70min and 120min in the presence of Bi-Zn-TiO2 and TiO2-P25 respectively. The identification of the responsible species on photo-discoloration was carried out in the presence of different scavengers. The study showed that the first responsible is h(+) specie with a moderate contribution of superoxide anion radical and a minor contribution of the hydroxyl radical. The material showed high stability after five uses with the same rate of photo-discoloration. PMID:25699677

Benalioua, Bahia; Mansour, Meriem; Bentouami, Abdelhadi; Boury, Bruno; Elandaloussi, El Hadj

2015-05-15

248

Tuning TiO2 nanoparticle morphology in graphene-TiO2 hybrids by graphene surface modification  

NASA Astrophysics Data System (ADS)

We report the hydrothermal synthesis of graphene (GNP)-TiO2 nanoparticle (NP) hybrids using COOH and NH2 functionalized GNP as a shape controller. Anatase was the only TiO2 crystalline phase nucleated on the functionalized GNP, whereas traces of rutile were detected on unfunctionalized GNP. X-Ray Photoelectron spectroscopy (XPS) showed C-Ti bonds on all hybrids, thus confirming heterogeneous nucleation. GNP functionalization induced the nucleation of TiO2 NPs with specific shapes and crystalline facets exposed. COOH functionalization directed the synthesis of anatase truncated bipyramids, bonded to graphene sheets via the {101} facets, while NH2 functionalization induced the formation of belted truncated bipyramids, bonded to graphene via the {100} facets. Belted truncated bipyramids formed on unfunctionalized GNP too, however the NPs were more irregular and rounded. These effects were ascribed to pH variations in the proximity of the functionalized GNP sheets, due to the high density of COOH or NH2 groups. Because of the different reactivity of anatase {100} and {101} crystalline facets, we hypothesize that the hybrid materials will behave differently as photocatalysts, and that the COOH-GNP-TiO2 hybrids will be better photocatalysts for water splitting and H2 production.We report the hydrothermal synthesis of graphene (GNP)-TiO2 nanoparticle (NP) hybrids using COOH and NH2 functionalized GNP as a shape controller. Anatase was the only TiO2 crystalline phase nucleated on the functionalized GNP, whereas traces of rutile were detected on unfunctionalized GNP. X-Ray Photoelectron spectroscopy (XPS) showed C-Ti bonds on all hybrids, thus confirming heterogeneous nucleation. GNP functionalization induced the nucleation of TiO2 NPs with specific shapes and crystalline facets exposed. COOH functionalization directed the synthesis of anatase truncated bipyramids, bonded to graphene sheets via the {101} facets, while NH2 functionalization induced the formation of belted truncated bipyramids, bonded to graphene via the {100} facets. Belted truncated bipyramids formed on unfunctionalized GNP too, however the NPs were more irregular and rounded. These effects were ascribed to pH variations in the proximity of the functionalized GNP sheets, due to the high density of COOH or NH2 groups. Because of the different reactivity of anatase {100} and {101} crystalline facets, we hypothesize that the hybrid materials will behave differently as photocatalysts, and that the COOH-GNP-TiO2 hybrids will be better photocatalysts for water splitting and H2 production. Electronic supplementary information (ESI) available: Statistical analysis of the D : G intensity ratio, additional XPS analysis and TEM micrographs. See DOI: 10.1039/c4nr01322k

Sordello, Fabrizio; Zeb, Gul; Hu, Kaiwen; Calza, Paola; Minero, Claudio; Szkopek, Thomas; Cerruti, Marta

2014-05-01

249

Synthesis, characterization and photocatalytic evaluation of visible light activated C-doped TiO2 nanoparticles.  

PubMed

We have demonstrated heterogeneous photocatalytic degradation of microcystin-LR (MC-LR) by visible light activated carbon doped TiO(2) (C-TiO(2)) nanoparticles, synthesized by a modified sol-gel route based on the self-assembly technique exploiting oleic acid as a pore directing agent and carbon source. The C-TiO(2) nanoparticles crystallize in anatase phase despite the low calcination temperature of 350 °C and exhibit a highly porous structure that can be optimized by tuning the concentration of the oleic acid surfactant. The carbon modified nanomaterials exhibited enhanced absorption in the broad visible light region together with an apparent red shift in the optical absorption edge by 0.5 eV (2.69 eV), compared to the 3.18 eV of reference anatase TiO(2). Carbon species were identified by x-ray photoelectron spectroscopy analysis through the formation of both Ti-C and C-O bonds, indicative of substitution of carbon for oxygen atoms and the formation of carbonates, respectively. Electron paramagnetic resonance spectroscopy revealed the formation of two carbon related paramagnetic centers in C-TiO(2), whose intensity was markedly enhanced under visible light illumination, pointing to the formation of localized states within the anatase band gap, following carbon doping. The photocatalytic activity of C-TiO(2) nanomaterials was evaluated for the degradation of MC-LR at pH 3.0 under visible light (? > 420 nm) irradiation. The doped materials showed a higher MC-LR degradation rate than reference TiO(2), behavior that is attributed to the incorporation of carbon into the titania lattice. PMID:22743554

Liu, Guanglong; Han, Changseok; Pelaez, Miguel; Zhu, Duanwei; Liao, Shuijiao; Likodimos, Vlassis; Ioannidis, Nikolaos; Kontos, Athanassios G; Falaras, Polycarpos; Dunlop, Patrick S M; Byrne, J Anthony; Dionysiou, Dionysios D

2012-07-27

250

Synthesis, characterization and photocatalytic evaluation of visible light activated C-doped TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

We have demonstrated heterogeneous photocatalytic degradation of microcystin-LR (MC-LR) by visible light activated carbon doped TiO2 (C-TiO2) nanoparticles, synthesized by a modified sol-gel route based on the self-assembly technique exploiting oleic acid as a pore directing agent and carbon source. The C-TiO2 nanoparticles crystallize in anatase phase despite the low calcination temperature of 350?°C and exhibit a highly porous structure that can be optimized by tuning the concentration of the oleic acid surfactant. The carbon modified nanomaterials exhibited enhanced absorption in the broad visible light region together with an apparent red shift in the optical absorption edge by 0.5 eV (2.69 eV), compared to the 3.18 eV of reference anatase TiO2. Carbon species were identified by x-ray photoelectron spectroscopy analysis through the formation of both Ti-C and C-O bonds, indicative of substitution of carbon for oxygen atoms and the formation of carbonates, respectively. Electron paramagnetic resonance spectroscopy revealed the formation of two carbon related paramagnetic centers in C-TiO2, whose intensity was markedly enhanced under visible light illumination, pointing to the formation of localized states within the anatase band gap, following carbon doping. The photocatalytic activity of C-TiO2 nanomaterials was evaluated for the degradation of MC-LR at pH 3.0 under visible light (? > 420 nm) irradiation. The doped materials showed a higher MC-LR degradation rate than reference TiO2, behavior that is attributed to the incorporation of carbon into the titania lattice.

Liu, Guanglong; Han, Changseok; Pelaez, Miguel; Zhu, Duanwei; Liao, Shuijiao; Likodimos, Vlassis; Ioannidis, Nikolaos; Kontos, Athanassios G.; Falaras, Polycarpos; Dunlop, Patrick S. M.; Byrne, J. Anthony; Dionysiou, Dionysios D.

2012-07-01

251

Synthesis and characterization of sol–gel derived PVA-titanium dioxide (TiO 2 ) nanocomposite  

Microsoft Academic Search

Novel PVA\\/TiO2 polymer nanocomposites have been prepared at low temperature via sol–gel route. XRD analysis showed the particles to be elongated\\u000a along a- and b-direction but contracted along c-direction. PVA-assisted TiO2 nanocomposite samples dried at a temperature of 35 °C were found to have ~12 nm particle size. It was found that the composite\\u000a nanoparticles had an increased degree of crystallinity in

Archana Maurya; Pratima Chauhan

252

Photocatalytic properties of Small Sized TiO2 Supported on Clays for the Degradation of Indoor Pollutants: Toluene and Limonene.  

NASA Astrophysics Data System (ADS)

Novel materials for the degradation of hydrophobic organic pollutants by photocatalytic oxidation were developed. Intercalation of TiO2 on clays provide favorable properties to the photocatalyst due to the adsorption properties of the clay, its content of mesopores that enables pollutant trapping and its further interaction with TiO2, leading to mineralization. Particularly, we are interested in hydrophobic pollutants for which bare TiO2 had been shown less effective than for polar species. Synthesis was carried out by the sol-gel method using titanium isopropoxide (Ti(OC3H7)4 ) as precursor; the formation of anatase phase was achieved by hydrothermal treatment. Clays used were Hectorite [SHCa-1, Na0.4Mg2.7Li0.3Si4O10(OH)2 ] from San Bernardino Country, California, USA and Kaolinite [KGa-1b, Al2Si2O5(OH)4 ] from Washington Country, Georgia, USA. Samples characterization was conducted using XRD, SEM, XPS, ICP-OES. Our results showed a strong intercalation of TiO2 on hectorite and a poor one on kaolinite. Nanoparticle size obtained on hectorite was of 9.6 nm compared to 17.39 nm of commercial TiO2 (Degussa P25). Photocatalytic experiments were realized by the FTIR-ATR technique monitoring the concentration of the organic compound on the surface of the material. Results were compared with commercial TiO2 (Degussa P25). For limonene bare TiO2 showed better degradation rates, while for toluene, degradation rates using TiO2 supported on clays were higher.

Kibanova, D.; Trejo, M.; Destaillats, H.; Cervini-Silva, J.

2007-12-01

253

Development of air purification device through application of thin-film photocatalyst  

Microsoft Academic Search

TiO2 photocatalyst was prepared by hydrothermal method using titanium isopropoxide as a precursor. This photocatalyst had higher content of anatase structure and larger surface area than commercial P-25 photocatalyst. The air purification device with a filter coated with photocatalyst film was excellent in its capabilities to decompose organic materials and to kill germs. When the device was installed in hospitals,

Jong-Ho Kim; Gon Seo; Dong-Lyun Cho; Byung-Chul Choi; Jong-Beom Kim; Hee-Ju Park; Myung-Wan Kim; Sun-Jung Song; Geon-Joong Kim; Shigekazu Kato

2006-01-01

254

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

PubMed

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 (1)H and (13)C 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 1000mVs(-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. PMID:25804509

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

2015-07-01

255

Low-temperature synthesis of soluble and processable organic-capped anatase TiO2 nanorods.  

PubMed

We demonstrate the controlled growth of high aspect ratio anatase TiO2 nanorods by hydrolysis of titanium tetraisopropoxide (TTIP) in oleic acid (OLEA) as surfactant at a temperature as low as 80 degrees C. Chemical modification of TTIP by OLEA is proven to be a rational strategy to tune the reactivity of the precursor toward water. The most influential factors in shape control of the nanoparticles are investigated by simply manipulating their growth kinetics. The presence of tertiary amines or quaternary ammonium hydroxides as catalysts is essential to promote fast crystallization under mild conditions. The novelty of the present approach relies on the large-scale production of organic-capped TiO2 nanocrystals to which standard processing of colloidal nanocrystals, such as surface ligand exchange, can be applied for the first time. Concentrated colloidal titania dispersions can be prepared for a number of fundamental studies in homogeneous solutions and represent a new source of easily processable oxide material for many technological applications. PMID:14624603

Cozzoli, P Davide; Kornowski, Andreas; Weller, Horst

2003-11-26

256

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

NASA Astrophysics Data System (ADS)

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 %.

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

2015-01-01

257

Photocatalytic degradation of omethoate using NaY zeolite-supported TiO 2  

Microsoft Academic Search

The degradation of omethoate was conducted using H2O2 as oxidant, TiO2 supported on NaY zeolite as photocatalyst and a 300W lamp as light source. The effect of the calcination temperature of the\\u000a photocatalyst, the amount of TiO2 loaded on NaY zeolite, the photocatalyst amount, the pH value and the radiation time on the degradation ratio of omethoate\\u000a were investigated. The

Dishun Zhao; Jialei Wang; Zhigang Zhang; Juan Zhang

2009-01-01

258

Synthesis of mesoporous TiO(2-x)N(x) spheres by template free homogeneous co-precipitation method and their photo-catalytic activity under visible light illumination.  

PubMed

The article presents preparation, characterization and catalytic activity evaluation of an efficient nitrogen doped mesoporous titania sphere photo-catalyst for degradation of methylene blue (MB) and methyl orange (MO) under visible light illumination. Nitrogen doped titania was prepared by soft chemical route i.e. template free, slow and controlled homogeneous co-precipitation from titanium oxysulfate sulfuric acid complex hydrate, urea, ethanol and water. The molar composition of TiOSO(4) to urea was varied to prepare different atomic % nitrogen doped titania. Mesoporous anatase TiO(2-x)N(x) spheres with average crystallite size of 10 nm and formation of titanium oxynitride center were confirmed from HRTEM, XRD and XPS study. UV-vis DRS showed a strong absorption in the range of 400-500 nm which supports its use in visible spectrum of light. Nitrogen adsorption-desorption study supports the porous nature of the doped material. All the TiO(2-x)N(x) samples showed higher photo-catalytic activity than Degussa P(25) and undoped mesoporous titania. Sample containing around one atomic % nitrogen showed highest activity among the TiO(2-x)N(x) samples. PMID:19264320

Parida, K M; Naik, Brundabana

2009-05-01

259

Adsorption properties and photocatalytic activity of TiO2/activated carbon fiber composite  

NASA Astrophysics Data System (ADS)

Photocatalysts of titanium dioxide (TiO2) and TiO2/activated carbon fiber (TiO2/ACF) composite were prepared by sol-gel method, followed by calcining the pure TiO2 sols and the TiO2/ACF sols at 500°C for 2 h in a N2 atmosphere, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms measurement. Batch experiments were conducted to study the adsorption property of TiO2/ACF composite using methylene blue as adsorbate. The adsorption data obtained from different batch experiments were analyzed using pseudo-second-order kinetic model, the experimental data can be adequately described by the pseudo-second-order equation. The photodecomposition behavior of TiO2/ACF was investigated in aqueous solution using methylene blue as target pollutant. It was found that methylene blue could be removed rapidly from water by TiO2/ACF, the photocatalytic decomposition was obviously improved when the photocatalyst was used. Kinetics analysis revealed that the photocatalytic decomposition reaction can be described well by a first-order rate equation.

Yao, Shuhua; Song, Shuangping; Shi, Zhongliang

2014-06-01

260

Synthesis and characterization of high photocatalytic activity and stable Ag3PO4/TiO2 fibers for photocatalytic degradation of black liquor  

NASA Astrophysics Data System (ADS)

The TiO2 fiber was prepared by using cotton fiber as a template, and then Ag3PO4/TiO2 fibers were synthesized via in situ Ag3PO4 particles onto the surface of TiO2 fiber. Their structure and physical properties were characterized by means of scanning electron microscopy (SEM), specific surface analyzer, X-ray diffraction (XRD), UV-vis absorption spectra and photoluminescence spectra (PL). SEM analysis indicated that the well-defined surface morphology of natural cotton fiber was mostly preserved in TiO2 and Ag3PO4/TiO2 fibers. Compared with TiO2 fiber, the absorbance wavelengths of Ag3PO4/TiO2 fibers were apparently red shifted and the PL intensities revealed a significant decrease. By using the photocatalytic degradation of black liquor as a model reaction, the visible light and ultraviolet light catalytic efficiencies of TiO2, Ag3PO4 and Ag3PO4/TiO2 fibers were evaluated. The reaction results showed that Ag3PO4/TiO2 fibers had stronger photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared Ag3PO4/TiO2 fibers could act as an efficient catalyst for the photocatalytic degradation of black liquor, which suggested their promising applications. It was proposed that the •OH radicals played the leading role in the photocatalytic degradation of the black liquor by Ag3PO4/TiO2 fibers system.

Cai, Li; Long, Qiyi; Yin, Chao

2014-11-01

261

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

PubMed

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

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

2013-01-01

262

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)

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.

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

2013-12-01

263

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

PubMed Central

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

2013-01-01

264

Comparison of Ag deposition effects on the photocatalytic activity of nanoparticulate TiO 2 under visible and UV light irradiation  

Microsoft Academic Search

We investigated the photocatalytic degradation of rhodamine B (RB) dye in the aqueous suspensions of TiO2 (?17nm) and Ag-deposited TiO2 nanoparticles under visible and UV light irradiation in order to evaluate and distinguish various effects of the Ag deposition on the TiO2 photocatalytic activity. The TiO2 and Ag–TiO2 photocatalysts were characterized by XRD, TEM, XPS, UV-visible absorption and photon correlation

Hyung Mi Sung-Suh; Jae Ran Choi; Hoe Jin Hah; Sang Man Koo; Young Chan Bae

2004-01-01

265

High-temperature hydrothermal synthesis of crystalline mesoporous TiO2 with superior photo catalytic activities  

NASA Astrophysics Data System (ADS)

Mesoporous titanium dioxide with crystalline mesopore walls (M-TiO2-ns) have been successfully synthesized through the self-assembly of poly 4-Vinylpyridine template and tetrabutyl titanate precursor based on their complex bond interaction under high temperature (180 °C) hydrothermal conditions. X-ray diffraction shows that M-TiO2-ns have highly crystalline mesopore walls with anatase phase characters; N2 sorption-desorption isotherms, SEM and TEM images show that M-TiO2-ns have high BET surface areas (85 and 120 m2/g, respectively), large pore volumes (0.32 and 0.34 cm3/g, respectively) and crystalline mesopore walls, which exhibit monolithic morphology with crystal sizes around 3-5 ?m. Interestingly, M-TiO2-ns exhibit much higher catalytic activities and good recyclability in both induced reduction of decabromodiphenyl and oxidation of Rhodamine B under UV light than those of nonporous crystalline TiO2 and M-TiO2 templated by hydrocarbon surfactant of F127, which is even comparable with that of commercial P25. Combination of the unique characters such as crystallinity, stable mesostructure, large BET surface areas and superior photo catalytic activities make M-TiO2-ns a kind of potentially important material for removing of organic pollutions in environment through green photo irradiation processes.

Liu, Fujian; Liu, Chun-Lin; Hu, Baowei; Kong, Wei-Ping; Qi, Chen-Ze

2012-07-01

266

Synthesis and characterization of nano TiO2-SiO2: PVA composite - a novel route  

NASA Astrophysics Data System (ADS)

A novel, simple, less time consuming and cost-effective sol-gel method has been developed to synthesize nano titania-silica with polyvinyl alcohol (PVA) composite relatively at low temperature in acidic pH. Titania sol is prepared by hydrolysis of titanium tetrachloride 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 with the addition of PVA solution. The resulting powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FT-IR), UV-visible spectroscopy and thermal techniques. The grain size of the particles was calculated by X-ray diffraction; surface morphology and chemical composition were determined from scanning electron microscopy-energy dispersive spectroscopy; metal oxide stretching was confirmed from FT-IR spectroscopy; bandgap was calculated using UV-visible spectroscopy, and thermal stability of the prepared composite was determined by thermogravimetric/differential thermal analysis. Since TiO2 got agglomerated on the surface of SiO2, effective absorptive sites increase which in turn increase the photocatalytic efficiency of the resulting composite.

Venckatesh, Rajendran; Balachandaran, Kartha; Sivaraj, Rajeshwari

2012-07-01

267

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

268

Tuning TiO2 nanoparticle morphology in graphene-TiO2 hybrids by graphene surface modification.  

PubMed

We report the hydrothermal synthesis of graphene (GNP)-TiO2 nanoparticle (NP) hybrids using COOH and NH2 functionalized GNP as a shape controller. Anatase was the only TiO2 crystalline phase nucleated on the functionalized GNP, whereas traces of rutile were detected on unfunctionalized GNP. X-Ray Photoelectron spectroscopy (XPS) showed C-Ti bonds on all hybrids, thus confirming heterogeneous nucleation. GNP functionalization induced the nucleation of TiO2 NPs with specific shapes and crystalline facets exposed. COOH functionalization directed the synthesis of anatase truncated bipyramids, bonded to graphene sheets via the {101} facets, while NH2 functionalization induced the formation of belted truncated bipyramids, bonded to graphene via the {100} facets. Belted truncated bipyramids formed on unfunctionalized GNP too, however the NPs were more irregular and rounded. These effects were ascribed to pH variations in the proximity of the functionalized GNP sheets, due to the high density of COOH or NH2 groups. Because of the different reactivity of anatase {100} and {101} crystalline facets, we hypothesize that the hybrid materials will behave differently as photocatalysts, and that the COOH-GNP-TiO2 hybrids will be better photocatalysts for water splitting and H2 production. PMID:24821216

Sordello, Fabrizio; Zeb, Gul; Hu, Kaiwen; Calza, Paola; Minero, Claudio; Szkopek, Thomas; Cerruti, Marta

2014-06-21

269

The synthesis of nanostructure TiO2 co-doped with N and Fe and their application for micro-polluted source water treatment.  

PubMed

The doping of titanium dioxide (TiO2) with various metal or nonmetal elements has been considered as an effective strategy to extend the photoactive wavelength region to include visible light. In this paper, TiO2 nanoparticles co-doped with N and Fe were prepared via a sol-gel route, followed by a heat treatment at elevated temperatures. The co-doped TiO2 nanoparticles showed a strong visible light absorption and exhibited an enhanced photocatalytic activity for the degradation of methylene blue as compared with pure TiO2 nanoparticles. Polypropylene packings, coated with the prepared N-Fe co-doped TiO2 nanoparticles, were used as a heterogeneous catalyst for the treatment of micro-polluted source water. Under the illumination of sunlight, when the water was treated with the coated polypropylene packings, the reduction of COD(Mn) was about 60%, whereas it was just 10% and 30% when the water was treated with pure polypropylene packings and polypropylene packings coated with pure TiO2, respectively. The NH3-N could also be decreased dramatically on the co-doped TiO2-coated polypropylene packings. The results showed that N-Fe co-doped TiO2-coated polypropylene packings still had a strong activity after three months of operation. PMID:20088210

Fan, Jian-Wei; Liu, Jia-Yu; Hong, Jie; Zhang, Jie

2009-12-01

270

Band gap engineered, oxygen-rich TiO2 for visible light induced photocatalytic reduction of CO2.  

PubMed

A facile and dopant-free strategy was employed to fabricate oxygen-rich TiO2 (O2-TiO2) with enhanced visible light photoactivity. Such properties were achieved by the in situ generation of oxygen through the thermal decomposition of the peroxo-titania complex. The O2-TiO2 photocatalyst exhibited high photoactivity towards CO2 reduction under visible light. PMID:24841282

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

2014-07-01

271

Photocatalytic oxidation of nitrogen monoxide using TiO 2 thin films under continuous UV light illumination  

Microsoft Academic Search

An apparent deactivating behavior of TiO2 photocatalysts in NO (1ppm) oxidation in air was examined using TiO2 nanoparticulate thin films (0.5–1.4?m thick) under continuous UV light illumination (1mWcm?2). The rate of NO oxidation decreased with HNO3 accumulation on the TiO2 surface. At the final steady state, the rate of NO oxidation was one-third of the initial one, and NO2 was

Yoshihisa Ohko; Yuri Nakamura; Nobuaki Negishi; Sadao Matsuzawa; Koji Takeuchi

2009-01-01

272

Bactericidal Performance of Visible-Light Responsive Titania Photocatalyst with Silver Nanostructures  

Microsoft Academic Search

BackgroundTitania dioxide (TiO2) photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved.Methodology\\/Principal FindingsUsing thermal reduction method, here we synthesized silver-nanostructures coated TiO2 thin films that contain a

Ming-Show Wong; Der-Shan Sun; Hsin-Hou Chang; Stefan Bereswill

2010-01-01

273

Synthesis of BiOCl photocatalyst by a low-cost, simple hydrolytic technique and its excellent photocatalytic activity  

NASA Astrophysics Data System (ADS)

A novel photocatalyst, bismuth oxychloride (BiOCl) micro-nano particles with a fine ferrite plate structure, was prepared by a low-cost, simple hydrolytic method. The as-prepared BiOCl was characterized by scanning electron microscopy (SEM), thermogravimetric analysis-differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectra (DRS). The effects of preparation conditions such as sodium dodecyl benzene sulfonate (SDBS) dispersant, HCl concentration, and heat treatment temperature on BiOCl performances were investigated. Moreover, its photocatalytic activity was evaluated on the degradation of methylene orange (MO) and was compared with that of TiO2 (P25). The experimental results confirmed that BiOCl micro-nano particles prepared with SDBS, the HCl concentration of 1.5 mol/L, and the heat treatment temperature of 80°C exhibited the best performance for the photodegradation of MO solution, and they showed good stability and better photocatalytic activity than P25 photocatalyst.

Wang, Yan; Shi, Zhu-qing; Fan, Cai-mei; Hao, Xiao-gang; Ding, Guang-yue; Wang, Yun-fang

2012-05-01

274

Synthesis of surface plasmon resonance (SPR) triggered Ag/TiO2 photocatalyst for degradation of endocrine disturbing compounds  

NASA Astrophysics Data System (ADS)

Surface deposition of silver nanoparticles (Ag NPs) onto the 100% anatase titania (Ag/TiO2) for evolution of surface plasmon resonance (SPR) was achieved sustainably with the assistance of solar energy. The preparation resulted in Ag/TiO2 photocatalyst with varied Ag depositions (0.5 wt%, 1.0 wt%, 3.0 wt% and 5.0 wt%). All obtained photocatalysts were characterized for the evolution of SPR via crystalline phase analysis, morphology, lattice fringes, surface area and pore size characteristics, chemical composition with chemical and electronic state, Raman scattering, optical and photoluminescence properties. The deposition of synthesized Ag NPs exhibited high uniformity and homogeneity and laid pathway for effective utilization of the visible region of electromagnetic spectrum through SPR. The depositions also lead for suppressing recombination rates of electron-hole. The photocatalytic evaluation was carried out by adopting two different class of endocrine disturbing compound (EDC) i.e., amoxicillin (pharmaceutical) and 2,4-dichlorophenol (pesticide) excited with artificial visible light source. Ag/TiO2 with Ag > 0.5 wt% exhibited significant degradation efficiency for both amoxicillin and 2,4-dichlorophenol. Thus synthesized Ag/TiO2 revealed the implication of plasmonics on TiO2 for the enhanced visible light photocatalytic activity.

Leong, Kah Hon; Gan, Bee Ling; Ibrahim, Shaliza; Saravanan, Pichiah

2014-11-01

275

Electrochemical characterization of TiO2/WOx nanotubes for photocatalytic application  

PubMed Central

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

2014-01-01

276

Porous TiO2 microspheres with tunable properties for photocatalytic air purification Alberto Naldoni a,  

E-print Network

Porous TiO2 microspheres with tunable properties for photocatalytic air purification Alberto 2012 Keywords: TiO2 Nanostructured microsphere Silica Photocatalysis NOx a b s t r a c t The synthesis of highly-crystalline porous TiO2 microspheres is reported using ultrasonic spray pyrolysis (USP

Suslick, Kenneth S.

277

TiO2 nanoparticles induce DNA double strand breaks and cell cycle arrest in human alveolar cells.  

PubMed

TiO2 nanoparticles (NPs) have the second highest global annual production (?3000 tons) among the metal-containing NPs. These NPs are used as photocatalysts for bacterial disinfection, and in various other consumer products including sunscreen, food packaging, therapeutics, biosensors, surface cleaning agents, and others. Humans are exposed to these NPs during synthesis (laboratory), manufacture (industry), and use (consumer products, devices, medicines, etc.), as well as through environmental exposures (disposal). Hence, there is great concern regarding the health effects caused by exposure to NPs and, in particular, to TiO2 NPs. In the present study, the genotoxic potential of TiO2 NPs in A549 cells was examined, focusing on their potential to induce ROS, different types of DNA damage, and cell cycle arrest. We show that TiO2 NPs can induce DNA damage and a corresponding increase in micronucleus frequency, as evident from the comet and cytokinesis-block micronucleus assays. We demonstrate that DNA damage may be attributed to increased oxidative stress and ROS generation. Furthermore, genomic and proteomic analyses showed increased expression of ATM, P53, and CdC-2 and decreased expression of ATR, H2AX, and Cyclin B1 in A549 cells, suggesting induction of DNA double strand breaks. The occurrence of double strand breaks was correlated with cell cycle arrest in G2/M phase. Overall, the results indicate the potential for genotoxicity following exposure to these TiO2 NPs, suggesting that use should be carefully monitored. Environ. Mol. Mutagen. 56:204-217, 2015. © 2014 Wiley Periodicals, Inc. PMID:25524809

Kansara, Krupa; Patel, Pal; Shah, Darshini; Shukla, Ritesh K; Singh, Sanjay; Kumar, Ashutosh; Dhawan, Alok

2015-03-01

278

Applications of TiO 2 Photocatalysis for Air Purification  

Microsoft Academic Search

\\u000a A system consisting of TiO2 and cement has recently been studied within the framework of a strategy for alleviating environmental pollution through the\\u000a use of construction materials containing photocatalysts. This technology for the photocatalytic degradation of organic pollutants\\u000a is aimed at maintaining the aesthetic characteristics of concrete structures, particularly those based on white cement. The\\u000a main reason for the discoloration

Anne Beeldens; Luigi Cassar; Yoshihiko Murata

279

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)

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.

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

2014-05-01

280

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

PubMed

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 15mol/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 15mol/L CH3COOH solution was more tolerant to moisture than the other TiO2 nanocrystals and P25. PMID:25597682

Chen, Kunyang; Zhu, Lizhong; Yang, Kun

2015-01-01

281

Synthesis and characterization of TiO 2/Fe 2O 3 core-shell nanocomposition film and their photoelectrochemical property  

NASA Astrophysics Data System (ADS)

TiO 2/Fe 2O 3 core-shell nanocomposition film has been fabricated via two-step method. TiO 2 nanorod arrays are synthesized by a facile hydrothermal method, and followed by Fe 2O 3 nanoparticles deposited on TiO 2 nanorod arrays through an ordinary chemical bath deposition. The phase structures, morphologies, particle size, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and ultraviolet-visible (UV-vis) spectrophotometer. The results confirm that Fe 2O 3 nanoparticles of mean size ca. 10 nm coated on the surface of TiO2 NRs. After depositing Fe 2O 3, UV-vis absorption property is induces the shift to the visible-light range, the annealing temperature of 600 °C is the best condition for UV-vis absorption property of TiO 2/Fe 2O 3 nanocomposite film, and increasing Fe content, optical activity are enhanced one by one. The photoelectrochemical (PEC) performances of the as-prepared composite nanorods are determined by measuring the photo-generated currents under illumination of UV-vis light. The TiO 2 NRs modified by Fe 2O 3 show the photocurrent value of 1.36 mA/cm 2 at 0 V vs Ag/AgCl, which is higher than those of unmodified TiO 2 NRs.

Zhao, Hui; Fu, Wuyou; Yang, Haibin; Xu, Yang; Zhao, Wenyan; Zhang, Yanyan; Chen, Hui; Jing, Qiang; Qi, Xuefeng; Cao, Jing; Zhou, Xiaoming; Li, Yixing

2011-08-01

282

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

PubMed Central

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

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

2014-01-01

283

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

284

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

PubMed

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

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

2014-01-01

285

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...

286

Enhanced photocatalytic activity of In2O3-decorated TiO2  

NASA Astrophysics Data System (ADS)

Titania (TiO2)-based photocatalysts decorated with different amounts of indium oxide (In2O3) were prepared by a pore impregnating method and characterized by the Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The separation efficiency of photogenerated charges was investigated using benzoquinone (BQ) as scavenger. The activities of the photocatalysts were evaluated by decolorization of methyl orange (MO) aqueous solution under ultraviolet-light irradiation. Compared to TiO2, In2O3/TiO2 composites show improved photocatalytic performance due to the coupling effect of TiO2 and In2O3, which greatly improves the separation of photogenerated electrons and holes.

Zhong, Junbo; Li, Jianzhang; Zeng, Jun; He, Xiyang; Huang, Shengtiang; Jiang, Weidong; Li, Minjiao

2014-06-01

287

Experimental Study of Nanometer TiO2 Photocatalysis Material in Air Purification  

Microsoft Academic Search

With the enhancement of environmental awareness, controlling oil mist in machinery processing workshop has become more and more important. Nanometer titanium dioxide (TiO2) photocatalysis material can treat with manifold pollutants, which is widely applied with its merits of decomposing products sufficiently and no secondary pollution. The nanometer TiO2 photocatalyst was prepared by using the sol-gel method on the optimum formulation

Wang Nan; Wu Zhijiang; Zhu Gongsheng

2009-01-01

288

Photocatalytic degradation of phenolic syntan using TiO 2 impregnated activated carbon  

Microsoft Academic Search

Investigations were carried out to study the photocatalytic degradation of phenolic syntan (PS), a widely used environmentally polluting chemical in the leather tanning industry. Photocatalytic inactive commercial TiO2 was used as the precursor for the preparation of TiO2 impregnated activated carbon (Ti-AC) photocatalyst. Experiments were conducted by varying the concentrations of PS solution (50–1000mg\\/l), pH (2.5–10) and time intervals to

Udaya Aruldoss; L. John Kennedy; J. Judith Vijaya; G. Sekaran

2011-01-01

289

Facile one-step synthesis of inorganic-framework molecularly imprinted TiO2/WO3 nanocomposite and its molecular recognitive photocatalytic degradation of target contaminant.  

PubMed

Inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites with molecular recognitive photocatalytic activity were first prepared successfully by a facile one-step sol-gel method using 2-nitrophenol and 4-nitrophenol as template molecules, and tetrabutyl orthotitanate as titanium source as well as the precursor of functional monomer which could complex with template molecules. The template molecules could be completely removed by means of high-temperature calcination, avoiding the traditional extraction procedures that are time- as well as solvent-consuming. Compared to nonimprinted TiO2/WO3, the molecularly imprinted TiO2/WO3 shows a much higher adsorption capacity and selectivity toward the template molecules. The enhancement in terms of adsorption capacity and selectivity can be attributed to the chemical interaction between target molecules and imprinted cavities, as well as size matching between imprinted cavities and target molecules. The photocatalytic activity of molecularly imprinted TiO2/WO3 toward the target molecules is more than two times that of non-imprinted TiO2/WO3, a result of selective adsorption of target molecules on molecularly imprinted TiO2/WO3. The formation pathway of intermediate products in 2-nitrophenol and 4-nitrophenol degradation process was provided. Moreover, molecularly imprinted TiO2/WO3 exhibits high stability. The results indicate that inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites have a promising prospect in the treatment of wastewater for irrigation. PMID:23746077

Luo, Xubiao; Deng, Fang; Min, Lujuan; Luo, Shenglian; Guo, Bin; Zeng, Guisheng; Au, Chaktong

2013-07-01

290

Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications.  

PubMed

Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min(-1) and turnover frequency is 5457 h(-1). PMID:25665732

Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

2015-03-01

291

Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications  

NASA Astrophysics Data System (ADS)

Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min?1 and turnover frequency is 5457 h?1.

Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

2015-03-01

292

Synthesis and characterization of Zr4+, La3+ and Ce3+ doped mesoporous TiO2: evaluation of their photocatalytic activity.  

PubMed

Sol-gel method was used to synthesize Zr(4+), La(3+) and Ce(3+) doped mesoporous TiO(2) materials with different weight percentage (0.5, 1.0, 2.0 and 3.0 wt%) using triblock copolymer as the structure directing template in ethanol/water medium. Characterization revealed the isomorphic substitution of Zr(4+) ion into the lattice of TiO(2), and surface binding nature of La(3+) and Ce(3+) ions on mesoporous TiO(2). Microscopic examination confirmed the surface adsorption of foreign ion which could alter the particle morphology. The size of the particles was less than 20 nm. Photocatalytic activity of metal ions doped mesoporous TiO(2) was evaluated using aqueous alachlor as a model pollutant. It was found that 1 wt% Ce(3+) doped mesoporous TiO(2) exhibited higher activity than pure and other metal ions doped mesoporous TiO(2). The change of oxidation state of Ce(3+) is suggested to be the cause for enhanced photocatalytic activity. PMID:21237564

Kumaresan, L; Prabhu, A; Palanichamy, M; Arumugam, E; Murugesan, V

2011-02-28

293

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

PubMed Central

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

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

2013-01-01

294

Sol-gel synthesis, characterization and optical properties of mercury-doped TiO 2 thin films deposited on ITO glass substrates  

NASA Astrophysics Data System (ADS)

The Hg-doped and undoped nano-crystalline TiO 2 films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO 2 were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO 2, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 °C. The average crystallite size of the undoped TiO 2 films was about 8.17 nm and was increased with Hg-doping in the TiO 2 films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO 2 films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 ?m and the optical gap of the Hg-doped TiO 2 thin films.

Mechiakh, R.; Ben Sedrine, N.; Chtourou, R.

2011-08-01

295

An on-line measurement and control system for submerged arc spray synthesis of TiO2 nanoparticles.  

PubMed

This article presents the development of an on-line measurement and control system for process characterization and optimization of the nanoparticle manufacturing process, called the submerged arc-spray nanoparticle synthesis system (SANSS). To achieve optimized control of particle uniformity, this research investigates the feasibility of employing optical fiber probe and the dynamic light scattering (DLS) technique to monitor and control particle sizes. According to the theory of DLS, an on-line nanoparticle sampling and measurement system was developed and integrated with the SANSS as an important step to verify the measurement performance of the proposed method. To examine the measurement accuracy of the developed system, calibrated polystyrene latex particles with known accurate sizes were employed to verify the particle sizing accuracy of the proposed system. The data conformity between the measurement results of TiO, nanoparticles obtained by various methods, including TEM, a calibrated commercial particle sizing system and the on-line measurement system, has indicated that the developed method was feasible and effective. PMID:18464363

Chen, Liang-Chia; Ji, Bao-Hong

2008-02-01

296

Hydrothermal synthesis of a novel BiErWO6 photocatalyst with wide spectral responsive property  

NASA Astrophysics Data System (ADS)

To overcome the drawback of low solar energy utilization rate brought by general photocatalysts, a novel BiErWO6 photocatalyst with wide spectral responsive property was designed and synthesized by a hydrothermal method. The effects of hydrothermal temperature on the phase structure and the photocatalytic activities of the products were investigated. Due to the wide spectral absorption range, the as-prepared BiErWO6 photocatalyst showed good photocatalytic performance in degradation of rhodamine B (RhB) under simulated solar light. Moreover, the BiErWO6 photocatalyst also exhibited high photocatalytic activity under a green LED (? = 520 nm) irradiation. This work provided a new concept for rational design and development of high-performance photocatalysts.

Zhang, Zhijie; Wang, Wenzhong; Zhou, Yu

2014-11-01

297

Mechanism of simulated solarlight-induced photocatalytic oxidation of 5-hydroxynaphthalene-1-sulphonic acid on sulfur doped TiO2  

Microsoft Academic Search

The photodegradation of 5-hydroxynaphthalene-1-sulphonic acid (HNSA) was investigated with the TiO2 and sulfur doped TiO2 (S\\/TiO2) photocatalysts under the irradiation of the ultraviolet light (UV) and the simulated solar light. The S\\/TiO2 photocatalyst was found to be highly effective for the HNSA photodegradation both under the UV light or the simulated solar light irradiation. Especially, using various analysis methods, the

Jiankun Ren; Guoqing Liu; Panying Peng; Yuping Wang

2011-01-01

298

Interface actions between TiO2 and porous diatomite on the structure and photocatalytic activity of TiO2-diatomite  

NASA Astrophysics Data System (ADS)

TiO2-diatomite photocatalysts were prepared by sol-gel process with various pre-modified diatomite. In order to obtain diatomite with different surface characteristics, two modification approaches including calcination and phosphoric acid treatment on the micro-structure of diatomite are introduced. The photocatalysts were characterized by XRD, XPS, nitrogen adsorption-desorption isotherms and micromorphology analysis. The results indicate that, compared with pure TiO2, the anatase-to-rutile phase transition temperature of TiO2 loaded on diatomite carrier is significantly increased to nearly 900 °C, depending on the different pretreatment method of diatomite. The photocatalytic activities of different samples were evaluated by their degradation rate of methyl orange (MO) dye under UV and visible-light irradiation. The samples prepared by phosphoric acid pretreatment method exhibit the highest photocatalytic activity. After 90 min of UV irradiation, about 90% of MO is decomposed by the best effective photocatalyst. And after 8 h visible-light irradiation, nearly 60% of MO is decomposed by the same sample. Further mechanism investigation reveals that the H3PO4 pretreatment process can obviously change the surface features of diatomite carrier, cause the formation of Si-O-Ti bond, increase the binding strength between TiO2 and diatomite, restrain crystal growth of loaded TiO2, and thus form thermal-stable mesoporous structure at the granular spaces. It helps to build micro-, meso- and macro-porous hierarchical porous structure in TiO2-diatomite, and improves the charge and mass transfer efficiency during catalyzing process, resulting in the significantly increased photocatalytic activity of TiO2-diatomite pretreated by phosphoric acid.

Xia, Yue; Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Xue, Bing; Li, Yanjuan

2014-06-01

299

CCMR: Synthesis of Nanosized Titanium-Chromium nitride Powders by Ammonolysis of Co-precipitated TiO2/Cr2O3 Precursors  

NSDL National Science Digital Library

Nanocrystalline bimetallic metal nitride, Ti0.5Cr0.5N was synthesized by ammonolysis at 800°C for 14 hours of the nanozide TiO2/Cr2O3 precursor powder. TiO2/Cr2O3 nanopowder resulting from the coprecipitation method. The precursor and the resulting nitrides were characterized by X-Ray diffraction analysis and scanning electron microscope (SEM). The corrosion stability was analyzed by the thermal gravimetric analysis (TGA). The results indicated that the precursor solution contains TiO2 and K2CrO7. The final product is TiN and CrN with an average particle size of 30nm.

Hernández Rivera, Mayra

2010-08-15

300

Synthesis of Mesoporous Wall-Structured TiO2 on Reduced Graphene Oxide Nanosheets with High Rate Performance for Lithium-Ion Batteries.  

PubMed

Mesoporous wall-structured TiO2 on reduced graphene oxide (RGO) nanosheets were successfully fabricated through a simple hydrothermal process without any surfactants and annealed at 400?°C for 2?h under argon. The obtained mesoporous structured TiO2 -RGO composites had a high surface area (99?0307?m(2) ?g(-1) ) and exhibited excellent electrochemical cycling (a reversible capacity of 260?mAh?g(-1) at 1.2?C and 180?mAh?g(-1) at 5?C after 400?cycles), demonstrating it to be a promising method for the development of high-performance Li-ion batteries. PMID:25704456

Zhen, Mengmeng; Sun, Meiqing; Gao, Guandao; Liu, Lu; Zhou, Zhen

2015-03-27

301

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

SciTech Connect

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.

Adhikari, Rajesh; Gyawali, Gobinda [Research Center for Eco-Multifunctional Nano Materials, Sun Moon University (Korea, Republic of); Sekino, Tohru [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University (Japan); Wohn Lee, Soo, E-mail: swlee@sunmoon.ac.kr [Department of Environmental Engineering, Sun Moon University (Korea, Republic of)

2013-01-15

302

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

PubMed

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

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

2015-03-21

303

Photodegradation of oxytetracycline in aqueous by 5A and 13X loaded with TiO2 under UV irradiation.  

PubMed

The photocatalysis degradation, mineralization and detoxification of oxytetracycline (OTC) in aqueous were investigated by 5A and 13X zeolite with nano-TiO(2) loaded under UV light. The composite photocatalysts are characterized by X-ray diffraction (XRD) and field emission scanning (FESEM) technologies. The adsorption isotherms of OTC by 5A and 13X with different pH are evaluated. The results show that 654 and 1497 mg/g OTC of saturation adsorption capacity is reached by 5A and 13X at pH 7, respectively. Then the effect of TiO(2) with 5A and 13X support and different wt% of TiO(2) over the support on the resultant OTC removal, net photocatalytic degradation and influence factors such as TiO(2) loading, initial pH, concentration of OTC and adding anion on degradation are investigated. The 15 wt% TiO(2)/5A and 10 wt% TiO(2)/13X photocatalysts are found optimum for OTC removal and degradation in aqueous. The mineralization was measured by total organic carbon (TOC) while combined toxicity change during OTC degradation was tested with standardized bioluminescence assay of inhibition rate on Vibrio qinghaiensis sp.-Q67 (Q67). The results suggest that TiO(2)/5A and TiO(2)/13X composite systems are effective photocatalysts for treatment of OTC in aqueous. PMID:20034739

Zhao, Chun; Deng, Huiping; Li, Yuan; Liu, Zhenzhong

2010-04-15

304

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...

305

Synthesis of Z-scheme g-C3N4-Ti(3+)/TiO2 material: an efficient visible light photoelectrocatalyst for degradation of phenol.  

PubMed

In this study, a photocatalytic material g-C3N4-Ti(3+)/TiO2 nanotube arrays was prepared by a facile and viable approach involving a heat treatment followed by an electrochemical reduction step, and it was characterized using instrumental techniques such as X-ray diffraction pattern, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytic efficiency of the as-prepared samples towards treating aqueous solution contaminated with phenol was systematically evaluated by a photoelectrocatalytic method and found to be highly dependent on the content of the g-C3N4. At the optimal content of g-C3N4, the apparent photocurrent density of g-C3N4-Ti(3+)/TiO2 was four times higher than that of the pristine TiO2 under visible-light illumination. The enhanced photoelectrocatalytic behavior observed for g-C3N4-Ti(3+)/TiO2 was ascribed to a cumulative impact of both g-C3N4 and Ti(3+), which enhances the photoresponsive behavior of the material into the visible region and facilitates the effective charge separation of photoinduced charge carriers. PMID:25744448

Liao, Wenjuan; Murugananthan, Muthu; Zhang, Yanrong

2015-04-14

306

Structural and optoelectronic characterization of TiO2 films prepared using the sol gel technique  

Microsoft Academic Search

TiO2 is a versatile material that makes for fascinating study in any of its several physical forms: monocrystal, polycrystal, powder or thin film. Its enhanced photosensitivity to UV radiation and excellent chemical stability in acidic and aqueous media point to its excellent potential for use in a variety of applications, such as solar cells, electronic devices, chemical sensors and photocatalysts.

A. E. Jiménez González; S. Gelover Santiago

2007-01-01

307

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

ERIC Educational Resources Information Center

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)

Giglio, Kimberly D.; And Others

1995-01-01

308

Synthesis of Nanostructured and Nanoporous TiO2-AgO Mixed Oxide Derived from a Particulate Sol-Gel Route: Physical and Sensing Characteristics  

NASA Astrophysics Data System (ADS)

Nanocrystalline TiO2-AgO thin films and powders were prepared by an aqueous particulate sol-gel route at the low temperature of 573 K (300 °C). Titanium tetraisopropoxide and silver nitrate were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the phase composition of the mixed oxide depends upon the annealing temperature, being a mixture of TiO2 and AgO in the range 573 K to 773 K (300 °C to 500 °C) and a mixture of TiO2, AgO, and Ag2O at 973 K (700 °C). Furthermore, one of the smallest crystallite sizes was obtained for TiO2-AgO mixed oxide, being 4 nm at 773 K (500 °C). Field emission-scanning electron microscopic (FE-SEM) and atomic force microscopic (AFM) images revealed that the deposited thin films had nanostructured and nanoporous morphology with columnar topography. Thin films produced under optimized conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response toward low concentrations of CO gas ( i.e., 25 ppm) at low operating temperature of 473 K (200 °C), resulting in an increase of the thermal stability of sensing films as well as a decrease in their power consumption. Furthermore, TiO2-AgO sensors follow the power law for the detection of CO gas.

Mohammadi, M. R.; Fray, D. J.

2011-08-01

309

Vectorial doping-promoting charge transfer in anatase TiO2 {0 0 1} surface  

NASA Astrophysics Data System (ADS)

Doping-induced visible-light adsorption is often considered as the main reason for the enhanced photocatalytic activity of TiO2. However, this work provides a new understanding on the effect of doping on the photocatalytic activity of TiO2. The investigation on the C-F codoped anatase TiO2 {0 0 1} surface reveals that the impurity C and F atoms prefer to substitute for the outmost O atoms in the TiO2 {0 0 1} surface rather than those in the bulk TiO2. The exhibited vectorial doping of C and F atoms in TiO2 {0 0 1} surface produces a conducting layer with low electric resistance, which can promote the charge transfer in the photocatalytic reaction. This effectively inhibits the undesirable bulk recombination of photogenerated electron and hole. Hence, the optimized charge transfer in the C-F codoped TiO2 {0 0 1} surface makes a great contribution to the enhanced photocatalytic activity of TiO2. Further, the surface doping treatment is a potential method to improve the performance of photocatalyst.

Zhou, Peng; Wu, Jionghua; Yu, Weilai; Zhao, Guanghui; Fang, Guojia; Cao, Shaowen

2014-11-01

310

A bio-inspired inner-motile photocatalyst film: a magnetically actuated artificial cilia photocatalyst  

NASA Astrophysics Data System (ADS)

A new type of inner-motile photocatalyst film is explored to enhance photocatalytic performance using magnetically actuated artificial cilia. The inner-motile photocatalyst film is capable of generating flow and mixing on the microscale because it produces a motion similar to that of natural cilia when it is subjected to a rotational magnetic field. Compared with traditional photocatalyst films, the inner-motile photocatalyst film exhibits the unique ability of microfluidic manipulation. It uses an impactful and self-contained design to accelerate interior mass transfer and desorption of degradation species. Moreover, the special cilia-like structures increase the surface area and light absorption. Consequently, the photocatalytic activity of the inner-motile photocatalyst film is dramatically improved to approximately 3.0 times that of the traditional planar film. The inner-motile photocatalyst film also exhibits high photocatalytic durability and can be reused several times with ease. Furthermore, this feasible yet versatile platform can be extended to other photocatalyst systems, such as TiO2, P25, ZnO, and Co3O4 systems, to improve their photocatalytic performance.A new type of inner-motile photocatalyst film is explored to enhance photocatalytic performance using magnetically actuated artificial cilia. The inner-motile photocatalyst film is capable of generating flow and mixing on the microscale because it produces a motion similar to that of natural cilia when it is subjected to a rotational magnetic field. Compared with traditional photocatalyst films, the inner-motile photocatalyst film exhibits the unique ability of microfluidic manipulation. It uses an impactful and self-contained design to accelerate interior mass transfer and desorption of degradation species. Moreover, the special cilia-like structures increase the surface area and light absorption. Consequently, the photocatalytic activity of the inner-motile photocatalyst film is dramatically improved to approximately 3.0 times that of the traditional planar film. The inner-motile photocatalyst film also exhibits high photocatalytic durability and can be reused several times with ease. Furthermore, this feasible yet versatile platform can be extended to other photocatalyst systems, such as TiO2, P25, ZnO, and Co3O4 systems, to improve their photocatalytic performance. Electronic supplementary information (ESI) available: Additional data including details of the fabrication scheme, TEM images of TiO2 deposited on G-COOH, optical microscopy images and mechanical properties of the artificial cilia, details of the mixing performance of actuated cilia, schematic drawing of the experimental setup for the photocatalytic test, photocatalytic kinetics curves, and the efficiency and generality of the new inner-motile photocatalyst film. See DOI: 10.1039/c4nr00644e

Zhang, Dunpu; Wang, Wei; Peng, Fengping; Kou, Jiahui; Ni, Yaru; Lu, Chunhua; Xu, Zhongzi

2014-04-01

311

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

312

TiO2 Photocatalytic Degradation of Phenylarsonic Acid  

PubMed Central

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

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

2010-01-01

313

Photochemical activity of TiO2 nanotubes  

NASA Astrophysics Data System (ADS)

TiO2 is well known as a low-cost, highly active photocatalyst showing good environmental compatibility. Recently it was found that TiO2 nanotubes promise to enable for high photocatalytic activity (PCA). In our experiments, we studied the PCA and spectroscopic properties of TiO2 nanotube arrays formed by the anodization of Ti. The PCA efficiency related to the decomposition of methylene-blue was measured. To obtain reliable data, the results were calibrated by comparing with standard materials like Pilkington Activ™ which is a commercially available self cleaning glass. The studies included a search strategy for finding optimum conditions for the nanotube formation and the investigation of the relationship between PCA and annealing temperature. TiO2 nanotubes of different shapes and sizes were prepared by an anodization of Ti foil in different electrolytes, at variable applied voltages and concentrations. The photo-dissociation of methylene-blue was detected spectroscopically. For the optimized material, an enhancement factor of 2 in comparison to the standard reference material was found. Furthermore, femtosecond-laser induced photoluminescence and nonlinear absorption of the material were investigated. Possibilities for further enhancements of the PCA are discussed.

Pfuch, A.; Güell, F.; Toelke, T.; Das, S. K.; Messaoudi, H.; McGlynn, E.; Seeber, W.; Fábrega, C.; Andreu, T.; Morante, J. R.; Grunwald, R.

2013-03-01

314

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

PubMed

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

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

2015-06-01

315

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

316

Synthetic precursor to vertical TiO2 nanowires  

NASA Astrophysics Data System (ADS)

An easy protocol for improvement in formation of the photoanode in a dye sensitized solar cell is addressed. Specifically, a novel synthesis for the formation of a TiO2 precursor: titanium butanediolate, is detailed. This precursor is found to have higher thermal and temporal stability than commercially available TiO2 precursors and it has successfully been employed in the one-pot synthesis of rutile nanowires grown directly on a conducting substrate: fluorine doped tin oxide (FTO). This synthesis has been further extended to directly form a mixed phase TiO2 film consisting of rutile nanowires along with anatase spherical particles on FTO and this assembly has been used as the photoanode in a dye-sensitized solar cell. The synergistic effect of the two phases has provided a net DSSC efficiency of 4.61% with FF = 61%.

Mishra, B.; Ghildiyal, P.; Agarkar, S.; Khushalani, D.

2014-04-01

317

Sonication-assisted synthesis of CdS quantum-dot-sensitized TiO2 nanotube arrays with enhanced photoelectrochemical and photocatalytic activity.  

PubMed

A sonication-assisted sequential chemical bath deposition (S-CBD) approach is presented to uniformly decorate CdS quantum dots (QDs) on self-organized TiO2 nanotube arrays (TNTAs). This approach avoids the clogging of CdS QDs at the TiO2 nanotube mouth and promotes the deposition of CdS QDs into the nanotubes as well as on the tube walls. The photoelectrochemical and photocatalytic properties of the resulting CdS-decorated TNTAs were explored in detail. In comparison with a classical S-CBD approach, the sonication-assisted technique showed much enhancement in the photoelectrochemical and photocatalytic activities of the CdS QDs-sensitized TNTAs. PMID:20849087

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

2010-10-01

318

Synthesis of Nanostructured and Nanoporous TiO2AgO Mixed Oxide Derived from a Particulate Sol-Gel Route: Physical and Sensing Characteristics  

Microsoft Academic Search

Nanocrystalline TiO2-AgO thin films and powders were prepared by an aqueous particulate sol-gel route at the low temperature of 573 K (300 °C). Titanium tetraisopropoxide and silver nitrate were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed

M. R. Mohammadi; D. J. Fray

2011-01-01

319

Formation of Active Sites for Selective Toluene Oxidation during Catalyst Synthesis via Solid-State Reaction of V 2O 5 with TiO 2  

Microsoft Academic Search

Interaction of V2O5 with TiO2 during the preparation of V\\/Ti-oxide catalysts via solid-state reaction has been studied by means of in situ FT-Raman spectroscopy, HRTEM and XPS. This interaction results in the formation of monomeric vanadia species with vanadium in tetrahedral coordination. The bridging oxygen in the V–O–Ti bond is suggested to be responsible for the catalytic activity during the

Dmitri A. Bulushev; Lioubov Kiwi-Minsker; Vladimir I. Zaikovskii; Albert Renken

2000-01-01

320

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

PubMed Central

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

2014-01-01

321

Hydrothermal Synthesis of TiO2 Porous Hollow Nanospheres for Coating on the Photoelectrode of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Various sizes of TiO2 hollow nanosphers were synthesized by a hydrolysis followed by the hydrothermal treatment using different water content and titanium isopropoxide (TTIP) while the remaining components such as methylamine, ethanol and acetonitrile were kept as a constant. We synthesized the various sizes of spheres, 150, 250, 400, 450, and 600 nm in diameter; those are represented as SP150, SP250, SP400, SP450, and SP600. The prepared spheres diameters were confirmed by scanning electron microscopy (SEM). These spheres were coated by using a simple spray technique with the TiO2 colloidal solution as a scattering layer for the TiO2 photoelectrode of dye-sensitized solar cells. Optical absorption measurements did not find a difference in the dye adsorption amount with and without the scattering layer. The scattering effect was observed by incident photon to current conversion efficiency (IPCE) measurements especially in the wavelength region of 550-700 nm. The current-voltage (I-V) measurements show that the scattering layer with 450 nm spheres coated on the photoelectrode gave the improved photovoltaic performances compared to other diameters of the spheres. In the present study, the best energy conversion efficiency of 9.56% was obtained for the photoelectrode with the scattering layer, while the pure photoelectrode without the layer gave 8.4%.

Madhu Mohan, Varishetty; Murakami, Kenji

2012-02-01

322

Facile synthesis of Fe3O4@mesoporous TiO2 microspheres for selective enrichment of phosphopeptides for phosphoproteomics analysis.  

PubMed

Protein phosphorylation is one of the most important post-translational modifications. Due to the dynamic nature and low stoichiometry of the protein phosphorylation, enrichment of phosphopeptides from proteolytic mixtures is necessary prior to their characterization by mass spectrometry. In this work, we synthesized Fe3O4@mesoporous TiO2 magnetic microspheres with core-shell structure and large surface area for selective enrichment of phosphopeptides. To demonstrate its ability for selective enrichment of phosphopeptides, we applied Fe3O4@mesoporous TiO2 magnetic microspheres to isolation and enrichment of the phosphopeptides from tryptic digestion of standard proteins and real samples, and then the enriched peptides were analyzed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) or liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS). Due to that the as-made Fe3O4@mesoporous TiO2 microspheres have large surface area, good dispersivity and biocompatibility, they have been demonstrated as a powerful tool for phosphoproteomics research. PMID:23597982

Lu, Jin; Wang, Mengyi; Deng, Chunhui; Zhang, Xiangmin

2013-02-15

323

Photocatalytic oxidation of NOx gases using TiO2: a surface spectroscopic approach.  

PubMed

The bandgap of solid-state TiO2 (3.2 eV) enables it to be a useful photocatalyst in the ultraviolet (lambda < 380 nm) region of the spectrum. A clean TiO2 surface in the presence of sunlight therefore enables the removal of harmful NOx gases from the atmosphere by oxidation to nitrates. These properties, in addition to the whiteness, relative cheapness and non-toxicity, make TiO2 ideal for the many de-NOX catalysts that are currently being commercially exploited both in the UK and Japan for concrete paving materials in inner cities. There is need, however, for further academic understanding of the surface reactions involved. Hence, we have used surface specific techniques, including X-ray photoelectron spectroscopy and Raman spectroscopy, to investigate the NOx adsorbate reaction at the TiO2 substrate surface. PMID:12395856

Dalton, J S; Janes, P A; Jones, N G; Nicholson, J A; Hallam, K R; Allen, G C

2002-01-01

324

Investigation of photocatalytic degradation of phenol by Fe(III)-doped TiO2 and TiO2 nanoparticles  

PubMed Central

In this study Fe (III)-doped TiO2 nanoparticles were synthesized by sol–gel method at two atomic ratio of Fe/Ti, 0.006 and 0.034 percent. Then the photoactivity of them was investigated on degradation of phenol under UV (<380 nm) irradiation and visible light (>380 nm). Results showed that at appropriate atomic ratio of Fe to Ti (% 0.034) photoactivity of Fe(III)–doped TiO2 nanoparticles increased. In addition, the effects of various operational parameters on photocatalytic degradation, such as pH, initial concentration of phenol and amount of photocatalyst were examined and optimized. At all different initial concentration, highest degradation efficiency occurred at pH =?3 and 0.5 g/L Fe(III)–doped TiO2 dosage. With increase in initial concentration of phenol, photocatalytic degradation efficiency decreased. Photoactivity of Fe (III)-doped TiO2 under UV irradiation and visible light at optimal condition (pH =?3 and catalyst dosage =?and 0.5 g/L) was compared with P25 TiO2 nanoparticles. Results showed that photoactivity of Fe(III)-doped TiO2 under visible light was more than P25 TiO2 photoactivity, but it was less than P25 TiO2 photoactivity under UV irradiation. Also efficiency of UV irradiation alone and amount of phenol adsorption on Fe(III)-doped TiO2 at dark condition was investigated. PMID:25105016

2014-01-01

325

Application of Atmospheric-Pressure Plasma for Enhancing Photoelectrochemical Properties of TiO2 Electrodes  

Microsoft Academic Search

A synergistic combination of nanostructure synthesis and surface engineering was used to enhance photoelectrochemical activity of TiO2 photoanodes. Titania (TiO2) nanotubular arrays were synthesized by electrochemical anodization of Ti thin foils. A combination of atmospheric-pressure helium plasma and nitrogen exposure was used to modify the surface properties of TiO2 nanotubes. The photocurrent from plasma treated samples was approximately 25% higher

R. Sharma; J. Bock; A. S. Biris; M. K. Mazumder; P. P. Das; M. Misra; V. Mahajan

2008-01-01

326

Photocatalytic degradation of Chromium (VI) from wastewater using nanomaterials like TiO2, ZnO, and CdS  

NASA Astrophysics Data System (ADS)

The photocatalytic degradation of Cr(VI) from wastewater by using nanomaterials TiO2, ZnO, and CdS. All the experiments were carried out in the batch process. The wastewater obtained from various industries. The amount of chromium was removed using photocatalyst with UV light and in the dark at different pH range. The maximum removal of Cr(VI) was observed at pH 2; out of these photocatalyst TiO2 showed highest capacity for Cr(VI) removal than TiO2 thin film. The removal of chromium has been studied by considering influent concentration, loading of photocatalyst, pH, and contact time as operating variables. The degradation was characterized by FTIR, XRD, SEM, and EDX analysis before and after application of photocatalysts.

Joshi, K. M.; Shrivastava, V. S.

2011-09-01

327

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

PubMed

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

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

2015-01-15

328

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

PubMed Central

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

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

2010-01-01

329

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

330

Facile synthesis of carbon doped TiO2 nanowires without an external carbon source and their opto-electronic properties  

NASA Astrophysics Data System (ADS)

The present study demonstrates a simple protocol for the preparation of one dimensional (1D) oxidized titanium carbide nanowires and their opto-electronic properties. The oxidized titanium carbide nanowires (Ox-TiC-NW) are prepared from TiC nanowires (TiC-NW) that are in turn synthesized from micron sized TiC particles using the solvothermal technique. The Ox-TiC-NW is characterized by X-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman spectroscopy. Thermal oxidation of TiC-NW yields carbon doped TiO2-NW (C-TiO2-NW), a simple methodology to obtain 1D C-TiO2-NW. Temperature dependent Raman spectra reveal characteristic bands for TiO2-NW. Electrical characterization of individual C-TiO2-NW is performed by fabricating a device structure using the focused ion beam deposition technique. The opto-electronic properties of individual C-TiO2-NW demonstrate visible light activity and the parameters obtained from photoconductivity measurements reveal very good sensitivity. This methodology opens up the possibility of using C-TiO2-NW in electronic and opto-electronic device applications.The present study demonstrates a simple protocol for the preparation of one dimensional (1D) oxidized titanium carbide nanowires and their opto-electronic properties. The oxidized titanium carbide nanowires (Ox-TiC-NW) are prepared from TiC nanowires (TiC-NW) that are in turn synthesized from micron sized TiC particles using the solvothermal technique. The Ox-TiC-NW is characterized by X-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman spectroscopy. Thermal oxidation of TiC-NW yields carbon doped TiO2-NW (C-TiO2-NW), a simple methodology to obtain 1D C-TiO2-NW. Temperature dependent Raman spectra reveal characteristic bands for TiO2-NW. Electrical characterization of individual C-TiO2-NW is performed by fabricating a device structure using the focused ion beam deposition technique. The opto-electronic properties of individual C-TiO2-NW demonstrate visible light activity and the parameters obtained from photoconductivity measurements reveal very good sensitivity. This methodology opens up the possibility of using C-TiO2-NW in electronic and opto-electronic device applications. Electronic supplementary information (ESI) available: SEM image of a hydrothermally treated TiC sample (S1), spectral output of a commercial halogen lamp (S2), preparation and characterization of C-TiO2-NW (prepared at 800 °C) and pristine TiO2-NW, comparison of the optical response between various TiO2-NWs (S3-S6), procedure for measuring Potical, photocurrent growth and decay transients (S7). See DOI: 10.1039/c3nr03309k

Kiran, Vankayala; Sampath, Srinivasan

2013-10-01

331

The effect of operational parameters and TiO 2-doping on the photocatalytic degradation of azo-dyes  

Microsoft Academic Search

The photocatalytic degradation of Acid Orange 7 (AO7), a non-biodegradable azo-dye, has been investigated over TiO2 photocatalysts irradiated with a light source simulating solar light. The effect of operational parameters, i.e., dye concentration, photocatalyst content, pH of the solution and incident light energy on the degradation rate of aqueous solutions of AO7 has been examined. The effect of incorporating cations

Fotini Kiriakidou; Dimitris I. Kondarides; Xenophon E. Verykios

1999-01-01

332

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

PubMed

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

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

2014-10-29

333

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

PubMed Central

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. PMID:22738226

2012-01-01

334

Tuning the band gap of mesoporous Zr-doped TiO2 for effective degradation of pesticide quinalphos.  

PubMed

This paper has focused on the synthesis and modification of TiO2 nanomaterial via an acid modified sol-gel process. ZrOCl2 was used as a source of Zr for doping titania. The nanomaterials were characterized by electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption isotherms, UV-visible diffuse reflectance spectroscopy, etc. Changes in the band gap of the synthesized nanomaterials were studied with respect to the dopant amount, and the performance of the synthesized nanomaterials was evaluated as a photocatalyst to degrade pesticide quinalphos in aqueous solution under UV light. Anatase TiO2 nanocrystallites with an average size of ca. 8-11 nm were obtained depending on the amount of dopant. The results showed that the amount of dopant significantly altered the band gap as well as the surface properties of the hybrid nanomaterials which resulted in high photocatalytic activity. PMID:23970021

Goswami, Pallabi; Ganguli, Jatindra Nath

2013-10-28

335

Synthesis of Nanostructured and Nanoporous TiO 2 AgO Mixed Oxide Derived from a Particulate Sol-Gel Route: Physical and Sensing Characteristics  

Microsoft Academic Search

Nanocrystalline TiO2-AgO thin films and powders were prepared by an aqueous particulate sol-gel route at the low temperature of 573 K (300 °C).\\u000a Titanium tetraisopropoxide and silver nitrate were used as precursors, and hydroxypropyl cellulose was used as a polymeric\\u000a fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy\\u000a (FTIR) revealed that the

M. R. Mohammadi; D. J. Fray

2011-01-01

336

In Situ Synthesis of TiC-Fe Composite Overlays from Low Cost TiO2 Precursors Using Plasma Transferred Arc Deposition  

NASA Astrophysics Data System (ADS)

A direct conversion of TiO2 into TiC during plasma transferred arc deposition is a cheap and novel approach to produce wear resistant coatings. The present study explored the use of a low cost titanium ore as precursor for titanium carbide in metal matrix composite overlays. The deposited layers were characterized using optical microscopy, scanning electron microscopy, x-ray diffraction and microhardness testing. A carbothermic reduction of the titanium oxides took place during the deposition of the coating by plasma transferred arc. The overlays produced in this way consisted of fine titanium carbides evenly dispersed in an iron matrix. The opportunities and limitations of this approach are discussed.

Corujeira Gallo, Santiago; Alam, Nazmul; O'Donnell, Robert

2014-02-01

337

Remediation of 17-?-ethinylestradiol aqueous solution by photocatalysis and electrochemically-assisted photocatalysis using TiO2 and TiO2/WO3 electrodes irradiated by a solar simulator.  

PubMed

TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L(-1) (34 ?mol L(-1)) of 17-?-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 ?m thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 (°)C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L(-1) (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution. PMID:25238917

Oliveira, Haroldo G; Ferreira, Leticia H; Bertazzoli, Rodnei; Longo, Claudia

2015-04-01

338

Enhancing selective decomposition of ibuprofen onto porous TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

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.

Zakersalehi, Abolfazl

339

Review of the progress in preparing nano TiO2: an important environmental engineering material.  

PubMed

TiO2 nanomaterial is promising with its high potential and outstanding performance in photocatalytic environmental applications, such as CO2 conversion, water treatment, and air quality control. For many of these applications, the particle size, crystal structure and phase, porosity, and surface area influence the activity of TiO2 dramatically. TiO2 nanomaterials with special structures and morphologies, such as nanospheres, nanowires, nanotubes, nanorods, and nanoflowers are thus synthesized due to their desired characteristics. With an emphasis on the different morphologies of TiO2 and the influence factors in the synthesis, this review summarizes fourteen TiO2 preparation methods, such as the sol-gel method, solvothermal method, and reverse micelle method. The TiO2 formation mechanisms, the advantages and disadvantages of the preparation methods, and the photocatalytic environmental application examples are proposed as well. PMID:25458670

Wang, Yan; He, Yiming; Lai, Qinghua; Fan, Maohong

2014-11-01

340

Simple synthesis and size-dependent surface-enhanced Raman scattering of Ag nanostructures on TiO2 by thermal decomposition of silver nitrate at low temperature.  

PubMed

A low-temperature dry-process was proposed to synthesize silver nanoparticles, nanorods, and nanoplates on TiO(2) films via thermal decomposition of silver nitrate. X-ray diffraction (XRD) shows only silver crystals were synthesized on the substrate without other byproducts remaining. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal the Ag nanoparticles are single-crystalline face-centered cubic (FCC) structures and their average diameters decrease from 100 to 15 nm with the increase in distance from the source, which corresponds to a decrease of substrate temperature from 350 to 110 degrees C. The Ag nanorods are also single-crystalline FCC structures growing along the [110] direction with diameter and length around 40 and 500 nm, respectively. The morphology of silver nanostructures could be adjusted by varying the working pressure as well as the roughness of the substrates. An obvious size-dependent SERS effect on the TiO(2) substrate with silver nanoparticles was observed for the first time. The enhancement factor increases as the size of the Ag nanoparticles decreases, which is attributed to the increase of hot spots. In addition, fractional brookite in the anatase films could be detected only after being loaded with Ag nanoparticles, which demonstrates the application of SERS in detecting fractional and important features of semiconductors. PMID:19706939

Wang, Ruey-Chi; Gao, Yong-Siang; Chen, Shu-Jen

2009-09-16

341

Simple synthesis and size-dependent surface-enhanced Raman scattering of Ag nanostructures on TiO2 by thermal decomposition of silver nitrate at low temperature  

NASA Astrophysics Data System (ADS)

A low-temperature dry-process was proposed to synthesize silver nanoparticles, nanorods, and nanoplates on TiO2 films via thermal decomposition of silver nitrate. X-ray diffraction (XRD) shows only silver crystals were synthesized on the substrate without other byproducts remaining. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal the Ag nanoparticles are single-crystalline face-centered cubic (FCC) structures and their average diameters decrease from 100 to 15 nm with the increase in distance from the source, which corresponds to a decrease of substrate temperature from 350 to 110 °C. The Ag nanorods are also single-crystalline FCC structures growing along the [110] direction with diameter and length around 40 and 500 nm, respectively. The morphology of silver nanostructures could be adjusted by varying the working pressure as well as the roughness of the substrates. An obvious size-dependent SERS effect on the TiO2 substrate with silver nanoparticles was observed for the first time. The enhancement factor increases as the size of the Ag nanoparticles decreases, which is attributed to the increase of hot spots. In addition, fractional brookite in the anatase films could be detected only after being loaded with Ag nanoparticles, which demonstrates the application of SERS in detecting fractional and important features of semiconductors.

Wang, Ruey-Chi; Gao, Yong-Siang; Chen, Shu-Jen

2009-09-01

342

Synthesis of hierarchical TiO2 flower-rod and application in CdSe/CdS co-sensitized solar cell  

NASA Astrophysics Data System (ADS)

A hierarchical double-layered TiO2 flower-rod structure composed of three-dimensional (3D) TiO2 flowers and one-dimensional (1D) nanorods on transparent fluorine-doped tin oxide (FTO) conducting glass has been synthesized by a facile hydrothermal method. The possible formation mechanism of the hierarchical architecture is also proposed. When used in CdSe/CdS quantum dots co-sensitized solar cells (QDSSCs), the 1D ordered rutile nanorods at bottom can accelerate the electron transfer rate by providing direct electrical pathway for photogenerated electrons, while the 3D flowers formed on the top of nanorods can increase the adsorption of QDs due to the enlarged areas, and can also be used as a scattering layer. The performance of the CdSe/CdS/TiO2 flower-rod solar cell can achieve a short-circuit current density (Jsc) of 13.46 mA cm-2, and a open-circuit voltage (Voc) of 0.42 V, with a maximum power conversion efficiency of 2.31% under one sun illumination (AM 1.5 G, 100 mW cm-2), which is greatly higher than that of CdSe/CdS/TiO2 nanorod solar cell (1.63%).

Yu, Libo; Li, Zhen; Liu, Yingbo; Cheng, Fa; Sun, Shuqing

2014-12-01

343

In-situ synthesis of TiO2 network nanoporous structure on Ti wire substrate and its application in fiber dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this paper, we explore a two-step treatment method to modify the Ti wires which are used as anode substrates of fiber dye sensitized solar cells (FDSSCs). A special kind of network nanoporous structure is formed on the surface of Ti wire substrates through sodium hydroxide hydrothermal reaction and titanium tetrachloride (TiCl4) assistant treatment. Nanoporous structures with different sizes are in-situ grown on the Ti wire substrates by changing the hydrothermal reaction condition. Then, TiO2 network nanoporous structures with branch-like nano-structure or 2D nanoflakes are obtained after TiCl4 treatment. The effects of these network nanoporous structures on the FDSSC performances are investigated intensively. It is found that these special network nanoporous structures between TiO2 nanoparticle active layer and Ti wire substrate are beneficial to the connection of the nanoparticle layer and fiber-shaped substrate, thus improving the electron transport rate and prolonging electron lifetime. As a result, the power conversion efficiency of this parallel assembled FDSSC increases to 4.64% from 2.56% after this two-step treatment.

Tao, Hong; Fang, Guo-jia; Ke, Wei-jun; Zeng, Wei; Wang, Jing

2014-01-01

344

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

345

Current Progress on Persistent Fluorescence-Assisted Composite Photocatalysts  

NASA Astrophysics Data System (ADS)

Long afterglow phosphors-assisted novel photocatalysts appear to be a series of promising functional materials, which have high utilization efficiency of solar light in practical application of environmental purifications. In this review paper, the recent progress on fluorescence-assisted composite type photocatalysts includes TiO2-based and Ag3PO4-based fluorescence photocatalyst composites with full-time active photocatalytic properties is reviewed. This fundamental understanding shows that excellent visible light induced photocatalysts coupled with an appropriate amount of long afterglow phosphors could continuously degrade pollutants in air and solution not only under light irradiation, but also after turning off the lamp irradiation for several hours, indicating the possibility of a full-time-active highly efficient photocatalysts system. A promising strategy involving coupling of a highly efficient visible light responsive photocatalyst with an appropriate long afterglow phosphor might be established.

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

2013-12-01

346

Synthesis, characterization and photocatalytic activity of new photocatalyst CdBiYO4  

NASA Astrophysics Data System (ADS)

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.

Du, Huiyang; Luan, Jingfei

2012-09-01

347

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

PubMed

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 0.00416min(-1) for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220min 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

Cui, Yanbing; Luan, Jingfei

2015-03-01

348

Synthesis and characterization of hard magnetic composite photocatalyst—Barium ferrite\\/silica\\/titania  

Microsoft Academic Search

Hard magnetic composite photocatalytic particles—barium ferrite (magnetic core)\\/silica (intermediate layer)\\/titania (photoactive shell) (B\\/S\\/T) were prepared by wet-chemical methods. Anatase titania nanoparticles were directly coated on the silica-coated barium ferrite forming photoactive titania shell by hydrolysis and condensation of titanium n-butoxide. The prepared hard magnetic composite photocatalyst can be magnetically fluidized and recovered by an applied magnetic field enhancing both the

Seung-woo Lee; Jack Drwiega; David Mazyck; Chang-Yu Wu; Wolfgang M. Sigmund

2006-01-01

349

Band alignment of rutile and anatase TiO2  

NASA Astrophysics Data System (ADS)

The most widely used oxide for photocatalytic applications owing to its low cost and high activity is TiO2. The discovery of the photolysis of water on the surface of TiO2 in 1972 launched four decades of intensive research into the underlying chemical and physical processes involved. Despite much collected evidence, a thoroughly convincing explanation of why mixed-phase samples of anatase and rutile outperform the individual polymorphs has remained elusive. One long-standing controversy is the energetic alignment of the band edges of the rutile and anatase polymorphs of TiO2 (ref. ). We demonstrate, through a combination of state-of-the-art materials simulation techniques and X-ray photoemission experiments, that a type-II, staggered, band alignment of ~ 0.4?eV exists between anatase and rutile with anatase possessing the higher electron affinity, or work function. Our results help to explain the robust separation of photoexcited charge carriers between the two phases and highlight a route to improved photocatalysts.

Scanlon, David O.; Dunnill, Charles W.; Buckeridge, John; Shevlin, Stephen A.; Logsdail, Andrew J.; Woodley, Scott M.; Catlow, C. Richard A.; Powell, Michael. J.; Palgrave, Robert G.; Parkin, Ivan P.; Watson, Graeme W.; Keal, Thomas W.; Sherwood, Paul; Walsh, Aron; Sokol, Alexey A.

2013-09-01

350

Structural and optoelectronic characterization of TiO2 films prepared using the sol gel technique  

NASA Astrophysics Data System (ADS)

TiO2 is a versatile material that makes for fascinating study in any of its several physical forms: monocrystal, polycrystal, powder or thin film. Its enhanced photosensitivity to UV radiation and excellent chemical stability in acidic and aqueous media point to its excellent potential for use in a variety of applications, such as solar cells, electronic devices, chemical sensors and photocatalysts. Of late, thin films of TiO2 have permitted the study of physical and chemical properties that are almost impossible to examine in powders. Using the sol-gel technique, it was possible to prepare TiO2 films, and to specifically modify their characteristic properties by means of annealing treatments. Optical measurements carried out on sol-gel derived films produced results similar to those found in films prepared using the sputtering technique. The use of TiO2 films facilitates the study of the behaviour of crystalline structure, grain size, photoresponse, electrical conductivity in both darkness and light and energy band gap (Eg) as a function of treatment temperature. For the first time, it has been demonstrated that the photoconductivity of TiO2 becomes apparent at a treatment temperature of 350 °C, which means that below this temperature the material is not photosensitive. The photosensitivity (S) of TiO2 films prepared by the sol-gel technique reaches values between 100 and 104, surpassing by more than two orders of magnitude the photosensitivity of TiO2 in powder form. In addition, it was possible to study the surface crystalline structure, where TEM studies clearly revealed both the polycrystalline order and the atomic arrangements of the TiO2 films. Our findings will afford us an opportunity to better study the nature of TiO2 and to enhance its performance with respect to the above-mentioned applications.

Jiménez González, A. E.; Gelover Santiago, S.

2007-07-01

351

Facile one-pot hydrothermal synthesis of B/N-codoped TiO2 hollow spheres with enhanced visible-light photocatalytic activity and photoelectrochemical property  

NASA Astrophysics Data System (ADS)

B/N-codoped TiO2 hollow spheres (B/N-THs) were synthesized by facile one-pot hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, UV-vis diffuse reflectance spectrum (DRS) and X-ray photoelectron spectroscopy (XPS). The B/N-THs have large surface areas (up to 172.1 m2 g-1). The photocatalytic activities of as-prepared THs were evaluated by degradation of Reactive Brilliant Red dye X-3B solution under visible light irradiation. The results showed that B/N-THs exhibited the highest photocatalytic activity due to their high surface area and synergetic effect of B/N-codoped. A photocurrent-time spectrum was examined by anodic photocurrent response to characterize the electron-transferring efficiency in the process of photocatalysis reaction.

Lin, Xiaoxia; Fu, Degang

2014-08-01

352

Structural and optoelectronic characterization of TiO2 films prepared using the sol–gel technique  

Microsoft Academic Search

TiO2 is a versatile material that makes for fascinating study in any of its several physical forms: monocrystal, polycrystal, powder or thin film. Its enhanced photosensitivity to UV radiation and excellent chemical stability in acidic and aqueous media point to its excellent potential for use in a variety of applications, such as solar cells, electronic devices, chemical sensors and photocatalysts.

S Gelover Santiago

2007-01-01

353

Pathways of solar light-induced photocatalytic degradation of azo dyes in aqueous TiO 2 suspensions  

Microsoft Academic Search

The photocatalytic degradation of aqueous solutions of Acid Orange 7 in TiO2 suspensions has been investigated with the use of a solar light simulating source. The photoreaction was followed by monitoring the degradation of the dye and the formation of intermediates and final products, as functions of time of irradiation, both in solution and on the photocatalyst surface. It has

Maria Stylidi; Dimitris I. Kondarides; Xenophon E. Verykios

2003-01-01

354

Photocatalytic disinfection of phytopathogenic bacteria by dye-sensitized TiO 2 thin film activated by visible light  

Microsoft Academic Search

Synthetic pesticides have been used to control plant diseases or pests for a long time. The public has been affected by many problems such as environmental pollution and health issues from synthetic pesticide use in agriculture. It has consequently become necessary to develop alternative methods for the control of plant diseases. The TiO2 photocatalyst technique has potential for agricultural application

K. S. Yao; D. Y. Wang; C. Y. Chang; K. W. Weng; L. Y. Yang; S. J. Lee; T. C. Cheng; C. C. Hwang

2007-01-01

355

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...

356

Optical properties and structure of the TiN-nitrogen-doped TiO2 nanocomposite  

NASA Astrophysics Data System (ADS)

As one of the most versatile photocatalysts, TiO2 is suitable for numerous environmental and energy-related applications, however its efficiency is limited by its wide band gap. Doping with anions such as nitrogen has been successful in extending the TiO2 solar absorption into the visible spectrum, although the exact nature and optimal level of N doping are still debated. Present study shows that excessive and mostly substitutional N doping can result in an in situ formation of nanocomposite structure consisting of TiN nano-crystals embedded in the N-doped anatase TiO2, in addition to effectively doping TiO2 by adding electronic states at the valence band edge thereby narrowing its band gap, as reported before. The metal-semiconductor interfaces in the thin film induce local band bending in the N-doped TiO2 phase and this may assist in separating the photogenerated charge carriers. The possible interplay between the two phases is discussed. Very low levels of N doping were found not to have any impact on the band gap of TiO2.

Buha, J.

2014-12-01

357

First-principles study on transition metal-doped anatase TiO2  

PubMed Central

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

2014-01-01

358

Photodecomposition of volatile organic compounds using TiO2 nanoparticles.  

PubMed

This study examined the photodecomposition of volatile organic compounds (VOCs) using TiO2 catalyst fabricated by the Submerged Arc Nanoparticle Synthesis System (SANSS). TiO2 catalyst was employed to decompose volatile organic compounds and compare with Degussa-P25 TiO2 in terms of decomposition efficiency. In the electric discharge manufacturing process, a Ti bar, applied as the electrode, was melted and vaporized under high temperature. The vaporized Ti powders were then rapidly quenched under low-temperature and low-pressure conditions in deionized water, thus nucleating and forming nanocrystalline powders uniformly dispersed in the base solvent. The average diameter of the TiO2 nanoparticles was 20 nm. X-ray diffraction analysis confirmed that the nanoparticles in the deionized water were Anatase type TiO2. It was found that gaseous toluene exposed to UV irradiation produced intermediates that were even harder to decompose. After 60-min photocomposition, Degussa-P25 TiO2 reduced the concentration of gaseous toluene to 8.18% while the concentration after decomposition by SANSS TiO2 catalyst dropped to 0.35%. Under UV irradiation at 253.7 +/- 184.9 nm, TiO2 prepared by SANSS can produce strong chemical debonding energy, thus showing great efficiency, superior to that of Degussa-P25 TiO2, in decomposing gaseous toluene and its intermediates. PMID:17654970

Jwo, Ching-Song; Chang, Ho; Kao, Mu-Jnug; Lin, Chi-Hsiang

2007-06-01

359

TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.  

PubMed

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

Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

2009-10-01

360

Photocatalytic process of simultaneous desulfurization and denitrification of flue gas by TiO2-polyacrylonitrile nanofibers.  

PubMed

TiO2 nanoparticles were successfully fabricated on electrospun polyacrylonitrile (PAN) nanofibers via the coupling of electrospinning and hydrothermal pathway. A straightforward photocatalysis oxidation process has been developed for simultaneous desulfurization and denitrification of flue gas using the TiO2-PAN photocatalyst. Also, the influences of some important operating parameters, such as titanium loading content of catalyst, flue gas humidity, flue gas flow, and inlet flue gas temperature on removal efficiencies of SO2 and NO were investigated. The results demonstrated that removal efficiencies of 99.3% for SO2 and 71.2% for NO were attained under the following optimal experiment conditions: titanium loading content, 6.78 At %; gas flow rate, 200 mL/min; flue gas humidity, 5%; inlet flue gas temperature, 40 °C. Furthermore, the presumed reaction mechanism of SO2 and NO removal using TiO2-PAN photocatalyst under UV light was proposed. PMID:24024677

Su, Chunyan; Ran, Xu; Hu, Jianglei; Shao, Changlu

2013-10-15

361

Ag3PO4/TiO2 composite for efficient photodegradation of organic pollutants under visible light  

NASA Astrophysics Data System (ADS)

Photocatalytic degradation of organic pollutants attracts much attention in environment remediation, and it is still a challenge to develop highly efficient and stable visible-light-response photocatalyst. Herein, we synthesized Ag3PO4/TiO2 (P-25) composite via a facile in situ precipitation method to enhance the activity and stability of Ag3PO4. SEM and TEM characterizations indicate TiO2 particles are dispersed on Ag3PO4 surface, resulting in heterojunction interfaces. UV-vis DRS spectra show that TiO2 in the composite does not interfere the absorption of visible light, while the photoluminescence spectra confirm TiO2 inhibits the recombination of photo-induced charges. Therefore, during the photodegradation of organic pollutants under visible light, the composites are much more active than pure Ag3PO4. Moreover, XPS and XRD analysis show the reduction of Ag3PO4 to Ag0 is retarded during the photoreaction. Furthermore, the effect of TiO2 amount in the composites was studied, and AP12 is the most active with the reaction rate being 1.43 times higher than pure Ag3PO4. The strategy of using TiO2 as activity and stability promoter to construct the composite may be useful in developing highly active and stable visible-light photocatalyst for pollutants removal.

Zhao, Feng-Min; Pan, Lun; Wang, Siwen; Deng, Qinyi; Zou, Ji-Jun; Wang, Li; Zhang, Xiangwen

2014-10-01

362

Solar light induced and TiO 2 assisted degradation of textile dye reactive blue 4  

Microsoft Academic Search

Aqueous solutions of reactive blue 4 textile dye are totally mineralised when irradiated with TiO2 photocatalyst. A solution containing 4×10?4 M dye was completely degraded in 24 h irradiation time. The intensity of the solar light was measured using Lux meter. The results showed that the dye molecules were completely degraded to CO2, SO42?, NO3?, NH4+ and H2O under solar

B. Neppolian; H. C. Choi; S. Sakthivel; B. Arabindoo; V. Murugesan

2002-01-01

363

Photocatalytic degradation of organophosphate and phosphonoglycine pesticides using TiO 2 immobilized on silica gel  

Microsoft Academic Search

The photocatalytic degradation of the three pesticides acephate, dimethoate, and glyphosate in water has been investigated using UV light and TiO2 immobilized on silica gel as photocatalyst. Results show that the pesticides can be efficiently degraded by the UV\\/TiO2 system used in the study. Complete (100%) decomposition of dimethoate and glyphosate was attained within 60min of irradiation, while total degradation

Glory Rose Mangat Echavia; Fumiko Matzusawa; Nobuaki Negishi

2009-01-01

364

Degradation of Cochlodinium polykrikoides using photocatalytic reactor with TiO 2 -coated alumina  

Microsoft Academic Search

Cochlodinium polykrikoides (C. polykrikoides) is one of the most harmful red tide dinoflagellates due to its great economic damage and compromising recreational opportunity\\u000a and public health. Titanium dioxide (TiO2) is known to be used as a photocatalyst for the control of the aquatic invasive algae under natural and artificial light.\\u000a The purpose of this study was to design a highly

Hyun-Jae Shin; Byung-Hoon Kim; Hyun Suk Seo; Chun Sung Kim; Joong-Ki Kook; Gyeong-Taek Lim; Dong-Lyun Cho; Doman Kim; Seung Ho Ohk; Yeong-Mu Ko

2009-01-01

365

Comparative activity of TiO2 microspheres and P25 powder for organic degradation: Implicative importance of structural defects and organic adsorption  

NASA Astrophysics Data System (ADS)

TiO2 microspheres have been employed as a promisingly new photocatalyst for water and wastewater treatment. P25 TiO2 is commonly employed and its properties are well established as photocatalyst. In this study, photocatalytic activities of the two TiO2 samples are compared by degrading sulfosalicylic acid (SSA), phenol, and 2,4-Dichlorophenoxyacetic acid (2,4-D) under 365 nm UV illumination in a suspension system at neutral pH and associated optimized TiO2 dosages. The results showed that the three organic compounds unexceptionally degraded more rapidly on P25 than on TiO2 microspheres in terms of the concentration-time curves and total organic carbon removals at 120 min. This might me attributed the presence of oxygen vacancies and Ti(III) defects already present on P25 as determined by electron paramagnetic resonance, implying that the defects played an important role for the enhancement of the charge transfer step as rate-determining step. The degradations of three organic compounds on P25 and TiO2 microspheres could be well described by the first-order rate equation, while the degradation kinetics of SSA on TiO2 microspheres was quite different. The difference was ascribed to the medium adsorption ability of SSA on the TiO2 surface.

Wang, Chuan; Liu, Hong; Liu, Yuan; He, Guang'an; Jiang, Chengchun

2014-11-01

366

Photocatalytic degradation of an azo dye Sunset Yellow under UV-A light using TiO2/CAC composite catalysts  

NASA Astrophysics Data System (ADS)

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.

Rajamanickam, D.; Shanthi, M.

2014-07-01

367

C ion-implanted TiO2 thin film for photocatalytic applications  

NASA Astrophysics Data System (ADS)

Third-generation TiO2 photocatalysts were prepared by implantation of C+ ions into 110 nm thick TiO2 films. An accurate structural investigation was performed by Rutherford backscattering spectrometry, secondary ion mass spectrometry, X-ray diffraction, Raman-luminescence spectroscopy, and UV/VIS optical characterization. The C doping locally modified the TiO2 pure films, lowering the band-gap energy from 3.3 eV to a value of 1.8 eV, making the material sensitive to visible light. The synthesized materials are photocatalytically active in the degradation of organic compounds in water under both UV and visible light irradiation, without the help of any additional thermal treatment. These results increase the understanding of the C-doped titanium dioxide, helpful for future environmental applications.

Impellizzeri, G.; Scuderi, V.; Romano, L.; Napolitani, E.; Sanz, R.; Carles, R.; Privitera, V.

2015-03-01

368

TiO2 nanosized powders controlling by ultrasound sol-gel reaction.  

PubMed

We studied that anatase-TiO2 powders prepared from sol-gel process of titanium tetra-isopropoxide (TTIP) were developed under ultrasonic irradiation with different frequency of 28, 45 and 100 kHz. The irradiated ultrasound (US) was controlled by using semi-cylindrical reflection plate that was placed onto the vicinity of reaction vessel. The focused US influenced the reduction of particles size and increased the surface area of resultant nanosized TiO2 powders. We also examined photodegradation of rhodamine 640 dye (Rh-640) solution by the resultant TiO2 under UV light exposure. It was observed that low frequency for TiO2 photocatalyst preparation and low calcination temperature were more affected onto the photodegradation of the dye. PMID:17904404

Latt, Kyaing Kyaing; Kobayashi, Takaomi

2008-04-01

369

Photocatalytic NOx abatement: the role of the material supporting the TiO2 active layer.  

PubMed

The importance of the choice of a suitable substrate as supporting material for photoactive TiO(2), either in the form of powders or thin films or in photoactive paints, is frequently disregarded. In this paper four different supports (stainless steel, sand-blasted stainless steel, Teflon and glass) are object of investigation. The final aim is to verify the presence of interactions between the photocatalyst (AEROXIDE(®) TiO(2) P25 by Evonik Degussa Corporation) and the support, directly involved in the photocatalytic activity in the NO(x) abatement. The characterization results have been correlated with the photoactivity of the different samples. In particular, a coating of about 6-9 ?m seems to allow a photocatalytic result free from any positive or negative interference with the supporting material, therefore giving reliable results about the photoactivity of the TiO(2) under investigation. PMID:22119301

Bianchi, Claudia L; Pirola, Carlo; Selli, Elena; Biella, Serena

2012-04-15

370

Enhanced photoactivity with nanocluster-grafted titanium dioxide photocatalysts.  

PubMed

Titanium dioxide (TiO2), as an excellent photocatalyst, has been intensively investigated and widely used in environmental purification. However, the wide band gap of TiO2 and rapid recombination of photogenerated charge carriers significantly limit its overall photocatalytic efficiency. Here, efficient visible-light-active photocatalysts were developed on the basis of TiO2 modified with two ubiquitous nanoclusters. In this photocatalytic system, amorphous Ti(IV) oxide nanoclusters were demonstrated to act as hole-trapping centers on the surface of TiO2 to efficiently oxidize organic contaminants, while amorphous Fe(III) or Cu(II) oxide nanoclusters mediate the reduction of oxygen molecules. Ti(IV) and Fe(III) nanoclusters-modified TiO2 exhibited the highest quantum efficiency (QE = 92.2%) and reaction rate (0.69 ?mol/h) for 2-propanol decomposition among previously reported photocatalysts, even under visible-light irradiation (420-530 nm). The desirable properties of efficient photocatalytic performance with high stability under visible light with safe and ubiquitous elements composition enable these catalysts feasible for large-scale practical applications. PMID:24883952

Liu, Min; Inde, Ryota; Nishikawa, Masami; Qiu, Xiaoqing; Atarashi, Daiki; Sakai, Etsuo; Nosaka, Yoshio; Hashimoto, Kazuhito; Miyauchi, Masahiro

2014-07-22

371

DESIGN OF NANOSTRUCTURED PHOTOCATALYSTS FOR HYDROGEN PRODUCTION AND ENVIRONMENTAL  

E-print Network

DESIGN OF NANOSTRUCTURED PHOTOCATALYSTS FOR HYDROGEN PRODUCTION AND ENVIRONMENTAL APPLICATION Thèse decades for a wide variety of applications including hydrogen production from water splitting under sunlight. The goal of the research presented in this thesis is to design efficient TiO2 based

372

Low temperature synthesis of anatase rare earth doped titania-silica photocatalyst and its photocatalytic activity under solar-light  

Microsoft Academic Search

A series of rare earth (Sm3+, Nd3+, Ce3+ and Pr3+) doped titania-silica photocatalysts, as a reclaimed solar-light responsive photocatalyst, was prepared by sol–gel method with TEOS and TBT as precursors, by keeping the molar of TEOS:TBT constant at 1:1 and with different rare earth dopant content. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning

Jianjun Zhu; Jimin Xie; Min Chen; Deli Jiang; Dan Wu

2010-01-01

373

Effect of doping on electronic structure and photocatalytic behavior of amorphous TiO2  

NASA Astrophysics Data System (ADS)

Visible light photocatalysts based on doped crystalline forms of titanium dioxide (TiO2) have attracted significant scientific attention in recent decades. Amorphous TiO2, despite many merits over crystalline phases, has not been studied as thoroughly. In this paper, an in-depth analysis of the electronic properties of doped amorphous TiO2 is performed using density functional theory with Hubbard’s energy correction (DFT + U). Monodoping with p-type (N) and n-type (Nb) dopants shows appreciable bandgap reduction, but leads to recombination centers due to the presence of uncompensated charges. To resolve this issue, charge compensation via codoping is attempted. The charge compensated codoping not only reduces the bandgap by 0.4 eV but also eliminates the bandgap states present in monodoped systems responsible for charge carrier recombination. Furthermore, the localized tail states present in the aTiO2 system are eliminated to a large extent which leads to a decrease in the charge recombination and an increase in the charge migration. Thus, appropriate doping of amorphous TiO2 may lead to an alternative route for the development of visible light photocatalysts.

Ghuman, Kulbir Kaur; Veer Singh, Chandra

2013-11-01

374

Photocatalytic activity for hydrogen evolution of electrospun TiO2 nanofibers.  

PubMed

We report herein a simple procedure for the fabrication of TiO2 nanofibers by the combination of electrospinning and sol-gel techniques by using poly(vinylpyrrolidone) (PVP), titanium(IV) butoxide, and acetylacetone in methanol as a spinning solution. TiO2 nanofibers (260-355 nm in diameter), with a bundle of nanofibrils (20-25 nm in diameters) aligned in the fiber direction, or particle-linked structures were obtained from the calcination of as-spun TiO2/PVP composite fibers at temperatures ranging from 300 to 700 degrees C. These nanofibers were utilized as photocatalysts for hydrogen evolution. The nanofiber photocatalyst calcined at 450 degrees C showed the highest activity among the TiO2 nanofibers tested such as ones prepared by the hydrothermal method and anatase nanoparticles (Ishihara ST-01). These results indicate that one-dimensional electrospun nanofibers with highly aligned bundled nanofibrils are beneficial for enhancement of the crystallinity, large surface area, and higher photocatalytic activity. PMID:20355902

Chuangchote, Surawut; Jitputti, Jaturong; Sagawa, Takashi; Yoshikawa, Susumu

2009-05-01

375

Preparation and Characterization of Rutile-Type TiO2 Doped with Cu  

NASA Astrophysics Data System (ADS)

Visible-light active photocatalysts were prepared by doping Cu-TiO2 through the sol-gel method. The influence of the preparation conditions such as pH of sol-gel solution and calcination temperature on the properties of TiO2-Cu was investigated. The presence of Cu caused reduction of band-gap energy, which was more visible in the rutile-type TiO2. Low pH of sol-gel solution such as pH 1.5 favorized formation of rutile during calcination and caused slower growth of the crystallites with increasing temperature of calcination in comparison with sol-gel prepared at pH 3. XPS measurements showed that Cu was placed mostly on the surface of TiO2. For sample calcined at 600 °C, the surface concentration of copper was 1.1 wt.%. The presence of both, rutile phase and Cu, increased adsorption of phenol and facilitated its photocatalytic decomposition. Moreover, reduced band-gap energy in rutile-type TiO2-Cu photocatalyst enabled phenol decomposition under visible light.

Tryba, B.; Orlikowski, J.; Wróbel, R. J.; Przepiórski, J.; Morawski, A. W.

2015-03-01

376

Electrochemical degradation of refractory pollutants using TiO2 single crystals exposed by high-energy {001} facets.  

PubMed

Anodic material plays a vital role in electrochemical water treatment. Titanium dioxide (TiO2) has been widely recognized as an excellent semiconductor photocatalyst, rather than an efficient electrocatalyst, due to its relatively low electric conductivity and poor electrochemical activity. In this work, it is found that TiO2 can actually become a superior electrocatalyst when its crystal shape and exposed facet are finely tuned. The shape-engineered TiO2 single crystals with {001} facets exhibit an excellent electro-catalytic activity and stability for degrading typical organic pollutants such as rhodamine B and bisphenol A, and treating complex landfill leachate. Its electro-catalytic superiority is mainly attributed to the single-crystalline structure and exposed polar {001} facet. Our findings could provide new possibility of utilizing TiO2 for efficient electrochemical water treatment because of its high activity, great stability, low cost and no toxicity. PMID:25222331

Zhang, Ai-Yong; Long, Lu-Lu; Liu, Chang; Li, Wen-Wei; Yu, Han-Qing

2014-12-01

377

Fabrication of TiO2 Colloidal Crystal Films and Characterization of Their Photocatalytic Properties  

SciTech Connect

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.

Huang, Wei [Zaozhuang University, People's Republic of China; Wang, Feng [Zaozhuang University, People's Republic of China; Wang, Wei [ORNL

2011-01-01

378

Ultraslow recombination in AOT-capped TiO2 nanoparticles sensitized by protoporphyrin IX.  

PubMed

Aerosol OT (AOT) capped TiO2 nanoparticles have been prepared by a phase transfer mechanism. The TiO2 nanoparticles have a diameter of 5-10 nm, are highly crystalline (anatase) and show high photoluminescence. They are effectively sensitized by protoporphyrin IX (PPIX) and show high electron injection rates while the rate of back recombination is much slower than those reported previously. Thus the AOT capped TiO2 nanoparticles synthesized in this work are highly effective not only in promoting ultrafast electron injection from PPIX to TiO2 but more importantly they lead to extremely slow back recombination rates. The significance of this work is in the synthesis of highly photoluminescent TiO2 nanoparticles which can be easily sensitized by a porphyrin dye, whereby ultraslow recombination is observed. PMID:25142514

Biswas, Sudipta; De, Swati; Kathiravan, Arunkumar

2014-10-28

379

TiO2 nanocomposites: Preparation, characterization, mechanical and biological properties  

NASA Astrophysics Data System (ADS)

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.

Ko?arsoy, Gözde; ?en, Elif Hilal; Aksöz, Nilüfer; ?de, Semra; Aksoy, Hüsnü

2014-11-01

380

Reprint of: Photostability of wool fabrics coated with pure and modified TiO2 colloids.  

PubMed

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

Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

2015-06-01

381

Transformation of rutile to TiO2-II in a high pressure hydrothermal environment  

NASA Astrophysics Data System (ADS)

The high pressure transformation of rutile to TiO2-II with the ?-PbO2 structure is known to be kinetically hindered. In this study we show that a hydrothermal environment at 6 GPa and 650 °C provides appreciable rates for producing single phase bulk samples of TiO2-II. So obtained TiO2-II was characterized by scanning electron microscopy, powder X-ray diffraction, Raman and Far-IR spectroscopy. The structural properties are identical to TiO2-II from dry transitions. Transmission electron microscopy studies strongly indicate that Ostwald ripening processes play an important role in the hydrothermally assisted transformation and subsequent growth of TiO2-II crystals. TiO2-II is thermally stable to about 550 °C. At 600 °C the onset of the transformation to rutile is observed. The thermal expansion in the temperature range from room temperature to 500 °C is highly anisotropic, virtually affecting only the c unit cell parameter (?c=7.1(2)×10-6 °C-1). The pressure-temperature conditions for the hydrothermally assisted transformation of rutile are viable for industrial production settings, and in light of the large technological significance of TiO2, TiO2-II may present an interesting target for large-scale synthesis.

Spektor, Kristina; Tran, Dung Trung; Leinenweber, Kurt; Häussermann, Ulrich

2013-10-01

382

Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials.  

PubMed

Hollow mesoporous one dimensional (1D) TiO(2) nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO(2) nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO(2) nanofibers possess a high surface area of 118 m(2) g(-1) with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO(2) nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (J(sc)) are measured as 5.6% and 10.38 mA cm(-2) respectively, which are higher than those of DSSC made using regular TiO(2) nanofibers under identical conditions (? = 4.2%, J(sc) = 8.99 mA cm(-2)). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO(2) nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO(2) nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO(2) nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO(2) nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO(2) nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO(2) nanocatalysts. PMID:22315140

Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S G; Ramakrishna, Seeram

2012-03-01

383

Synthesis of multifunctional nanostructured zinc-iron mixed oxide photocatalyst by a simple solution-combustion technique.  

PubMed

A series of nanostructure zinc-iron mixed oxide photocatalysts have been fabricated by solution-combustion method using urea as the fuel, and nitrate salts of both iron and zinc as the metal source. Different characterization tools, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-visible spectra (DRUV-vis), electron microscopy, and photoelectrochemical measurement were employed to establish the structural, electronic, and optical properties of the material. Electron microscopy confirmed the nanostructure of the photocatalyst. The synthesized photocatalysts were examined towards photodegradation of 4-chloro-2-nitro phenol (CNP), rhodamine 6G (R6G), and photocatalytic hydrogen production under visible light (? ? 400 nm). The photocatalyst having zinc to iron ratio of 50:50 showed best photocatalytic activity among all the synthesized photocatalysts. PMID:22201304

Pradhan, Gajendra Kumar; Martha, Satyabadi; Parida, K M

2012-02-01

384

Nano-design of quantum dot-based photocatalysts for hydrogen generation using advanced surface molecular chemistry.  

PubMed

Efficient photocatalytic hydrogen generation in a suspension system requires a sophisticated nano-device that combines a photon absorber with effective redox catalysts. This study demonstrates an innovative molecular linking strategy for fabricating photocatalytic materials that allow effective charge separation of excited carriers, followed by efficient hydrogen evolution. The method for the sequential replacement of ligands with appropriate molecules developed in this study tethers both quantum dots (QDs), as photosensitizers, and metal nanoparticles, as hydrogen evolution catalysts, to TiO2 surfaces in a controlled manner at the nano-level. Combining hydrophobic and hydrophilic interactions on the surface, CdSe-ZnS core-shell QDs and an Au-Pt alloy were attached to TiO2 without overlapping during the synthesis. The resultant nano-photocatalysts achieved substantially high-performance visible-light-driven photocatalysis for hydrogen evolution. All syntheses were conducted at room temperature and in ambient air, providing a promising route for fabricating visible-light-responsive photocatalysts. PMID:25410936

Yu, Weili; Noureldine, Dalal; Isimjan, Tayirjan; Lin, Bin; Del Gobbo, Silvano; Abulikemu, Mutalifu; Hedhili, Mohamed Nejib; Anjum, Dalaver H; Takanabe, Kazuhiro

2015-01-14

385

InVO4/TiO2 composite for visible-light photocatalytic degradation of 2-chlorophenol in wastewater.  

PubMed

InVO4/TiO2 composite was synthesized via amalgamation of InVO4 with TiO2 (Degussa P-25) powders. Application of the produced composite was evaluated as a catalyst for visible-light photocatalytic degradation of 2-chlorophenol (2-CP) in synthetic wastewater solutions. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy energy dispersive X-ray microanalyses and nitrogen physisorption. The degradation of 2-CP was affected by solution pH, light intensity, photocatalyst dosage and 2-CP initial concentration. InVO4/TiO2 showed higher photocatalytic degradation of 2-CP as compared with Degussa P-25 TiO2. Complete degradation of 2-CP was achieved with the InVO4/TiO2 catalyst under optimized conditions (1 g/L catalyst with a pollutant concentration of 50 mg/L at solution pH 5 and irradiation time of 180 min). Comparatively, 2-CP degradation efficiency of 50.5% was achieved with the TiO2 (Degussa P-25) at the same experimental conditions. The study confirmed that InVO4/TiO2 has high potential for degradation of 2-CP from wastewater under visible-light irradiation. PMID:25145167

Rashid, J; Barakat, M A; Pettit, S L; Kuhn, J N

2014-01-01

386

Self-cleaning cotton functionalized with TiO2/SiO2: focus on the role of silica.  

PubMed

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

Pakdel, Esfandiar; Daoud, Walid A

2013-07-01

387

Construction of amorphous TiO2/BiOBr heterojunctions via facets coupling for enhanced photocatalytic activity.  

PubMed

Facets coupled BiOBr with amorphous TiO2 composite photocatalysts are synthesized via an in situ direct growth approach under microwave irradiation. XRD, SEM and HRTEM characterizations indicate that the heterointerface between BiOBr and amorphous TiO2 occurs mainly on the {001} facets of BiOBr. BET and TEM verify that the heterojunctions possess higher specific surface areas and smaller amorphous TiO2 particle size than bare BiOBr and amorphous TiO2, exhibiting the inhibition function of BiOBr on the growth of TiO2 particles. XPS verifies the interaction between the two components. The degradation of methyl orange (MO) and phenol are used as the objective reaction to evaluate the photocatalytic activity of the as-prepared samples. The reaction rate constant of 15% TiO2/BiOBr composite is 3.4 times greater than that of pure BiOBr, which is attributed to its higher surface area, and efficient separation of photo-generated electron-hole pairs between BiOBr and amorphous TiO2. PMID:25814184

Wang, Xiao-Jing; Yang, Wen-Yan; Li, Fa-Tang; Zhao, Jun; Liu, Rui-Hong; Liu, Shuang-Jun; Li, Bo

2015-07-15

388

Photogreying of TiO 2 nanoparticles  

Microsoft Academic Search

Photogreying, the change in brightness on UV irradiation in the absence of oxygen, of TiO2 nanoparticulate dispersions is shown to depend on the nature of the liquid, consistent with a surface reaction. Measurements\\u000a on a series of TiO2 particles (mainly 7510 nm) dispersed in, e.g., alkyl benzoate correlate well with those on the same TiO2’s dispersed in a second liquid (e.g.

Terry A. Egerton; Lorna M. Kessell; Ian R. Tooley; Liwei Wang

2007-01-01

389

Biomolecule-assisted synthesis of carbon nitride and sulfur-doped carbon nitride heterojunction nanosheets: An efficient heterojunction photocatalyst for photoelectrochemical applications  

PubMed Central

Summary A biomolecule-assisted pyrolysis method has been developed to synthesize sulfur-doped graphitic carbon nitride (CNS) nanosheets. During the synthesis, sulfur could be introduced as a dopant into the lattice of carbon nitride (CN). Sulfur doping changed the texture as well as relative band positions of CN. By growing CN on preformed sulfur-doped CN nanosheets, composite CN/CNS heterojunction nanosheets were constructed, which significantly enhanced the photoelectrochemical performance as compared with various control counterparts including CN, CNS and physically mixed CN and CNS (CN+CNS). The enhanced photoelectrochemical performance of CN/CNS heterojunction nanosheets could be ascribed to the efficient separation of photoexcited charge carriers across the heterojunction interface. The strategy of designing and preparing CN/CNS heterojunction photocatalysts in this work can open up new directions for the construction of all CN-based heterojunction photocatalysts. PMID:24991514

Tao, Hua Bing; Chen, Jiazang; Miao, Jianwei

2014-01-01

390

Photo-catalytic degradation of Rhodamine B on C-, S-, N-, and Fe-doped TiO 2 under visible-light irradiation  

Microsoft Academic Search

C-, S-, N-, and Fe-doped TiO2 photocatalysts were synthesized by a facile sol–gel method. The structure and properties of catalysts were characterized by N2 desorption–adsorption, X-ray diffraction (XRD), UV–vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). Results revealed that the surface area of the multi-doped TiO2 was significantly increased and the crystallite size was smaller than the pure TiO2 obtained by

Xiangxin Yang; Chundi Cao; Larry Erickson; Keith Hohn; Ronaldo Maghirang; Kenneth Klabunde

2009-01-01

391

Control of TiO2 grain size and positioning in three-dimensionally ordered macroporous TiO2/C composite anodes for lithium ion batteries.  

PubMed

After several high-profile incidents that raised concerns about the hazards posed by lithium ion batteries, research has accelerated in the development of safer electrodes and electrolytes. One anode material, titanium dioxide (TiO2), offers a distinct safety advantage in comparison to commercialized graphite anodes, since TiO2 has a higher potential for lithium intercalation. In this article, we present two routes for the facile, robust synthesis of nanostructured TiO2/carbon composites for use as lithium ion battery anodes. These materials are made using a combination of colloidal crystal templating and surfactant templating, leading to the first report of a three-dimensionally ordered macroporous TiO2/C composite with mesoporous walls. Control over the size and location of the TiO2 crystallites in the composite (an often difficult task) has been achieved by changing the chelating agent in the precursor. Adjustment of the pyrolysis temperature has also allowed us to strike a balance between the size of the TiO2 crystallites and the degree of carbonization. Using these pathways to optimize electrochemical performance, the primarily macroporous TiO2/C composites can attain a capacity of 171 mAh/g at a rate of 1 C. Additionally, the carbon in these composites can function as a secondary template for high-surface-area, macroporous TiO2 with disordered mesoporous voids. Combining the advantages of a nanocrystalline framework and significant open porosity, the macroporous TiO2 delivers a stable capacity (>170 mAh/g at a rate of C/2) over 100 cycles. PMID:24392955

Petkovich, Nicholas D; Rudisill, Stephen G; Wilson, Benjamin E; Mukherjee, Anwesha; Stein, Andreas

2014-01-21

392

Photocatalytically active titanium dioxide nanopowders: Synthesis, photoactivity and magnetic separation  

NASA Astrophysics Data System (ADS)

Two approaches were used to obtain nanocrystalline titanium dioxide (TiO2) photocatalyst powders. Firstly, low-temperature synthesis method and secondly liquid flame spraying. The structural properties of the produced powders were determined with X-ray diffraction, transmission electron microscopy and nitrogen adsorption tests. The photocatalytic properties of the powders were studied with methylene blue (MB) discoloration tests. After discolorations tests, TiO2 was coagulated with magnetite particles using FeCl3·6 H2O at a fixed pH value. Magnetic separation of coagulated TiO2 and magnetite was carried out by a permanent magnet. The obtained results showed that the particle size of the powders synthesized at low-temperature was very small and the specific surface area high. The phase content of the powder was also shown to depend greatly on the acidity of the synthesis solution. Powder synthesized by liquid flame spraying was mixture of anatase and rutile phases with essentially larger particle size and lower specific surface area than those of low-temperature synthesized powders. The MB discoloration test showed that photocatalytic activity depends on the phase structure as well as the specific surface area of the synthesized TiO2 powder. The magnetic separation of TiO2-magnetite coagulate from solution proved to be efficient around pH:8.

Nikkanen, J.-P.; Heinonen, S.; Huttunen Saarivirta, E.; Honkanen, M.; Levänen, E.

2013-12-01

393

Easy synthesis of bismuth iron oxide nanoparticles as photocatalyst for solar hydrogen generation from water  

NASA Astrophysics Data System (ADS)

In this study, high purity bismuth iron oxide (BiFeO3/BFO) nanoparticles of size 50-80 nm have been successfully synthesized by a simple sol-gel method using urea and polyvinyl alcohol at low temperature. X-ray diffraction (XRD) measurement is used to optimize the synthetic process to get highly crystalline and pure phase material. Diffuse reflectance ultraviolet-visible (DRUV-Vis) spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about 620 nm, corresponding to an energy band gap of 2.1 eV. Compared to BaTiO3, BFO has a better degradation of methyl orange under light radiation. Also, photocatalytic tests prove this material to be efficient towards water splitting under simulated solar light to generate hydrogen. The simple synthetic methodology adopted in this paper will be useful in developing low-cost semiconductor materials as effective photocatalysts for hydrogen generation. Photocatalytic tests followed by gas chromatography (GC) analyses show that BiFeO3 generates three times more hydrogen than commercial titania P25 catalyst under the same experimental conditions.

Deng, Jinyi

394

TiO 2 -basednanopowders obtained from different Ti-alkoxides  

Microsoft Academic Search

Pure TiO2\\u000a and S-doped TiO2 sol–gel nanopowders were prepared\\u000a by controlled hydrolysis-condensation of titanium alkoxides. The influence\\u000a of different Ti-alkoxides (tetraethyl-, tetraisopropyl- and tetrabutyl-orthotitanate)\\u000a used in obtaining TiO2 porous materials in similar\\u000a conditions (water\\/alkoxide ratio, solvent\\/alkoxide ratio, pH and temperature\\u000a of reaction) has been investigated. The relationship between the synthesis\\u000a conditions and the properties of titania nanosized powders, such as

M. Cri?an; Ana Br?ileanu; M. R?ileanu; D. Cri?an; V. S. Teodorescu; R. Bîrjega; V. E. Marinescu; J. Madarász; G. Pokol

2007-01-01

395

Composite TiO2/clays materials for photocatalytic NOx oxidation  

NASA Astrophysics Data System (ADS)

TiO2 photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO2 in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO2). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al3+ and Ca2+ intercalation was applied in order to improve the dispersion of TiO2 and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania under both types of irradiation. Significant visible light activity was recorded for the composites containing urea-modified titania that was accredited to the N-doping of the semiconductor. Among the different substrates, the hydrotalcite caused highest increase in the NOx removal, while among the intercalation ions the Ca2+ was more efficient. The results were related to the improved dispersion of the TiO2 and the synergetic activity of the substrates as NOx adsorbers.

Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D.; Vaimakis, T.; Trapalis, C.

2014-11-01

396

Template-free synthesis of a CdSnO3?3H2O hollow-nanocuboid photocatalyst via a facile microwave hydrothermal method  

NASA Astrophysics Data System (ADS)

A CdSnO3?3H2O hollow-nanocuboid photocatalyst was successfully synthesized via a facile template-free microwave hydrothermal method for the first time. The as-prepared samples were characterized by x-ray diffraction, UV-vis diffuse reflectance spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and x-ray photoelectron spectroscopy. Moreover, samples prepared under different reaction times were analyzed by transmission electron microscopy to investigate the formation process of the CdSnO3?3H2O hollow-nanocuboids. Based on this result, a possible mechanism for the formation process was proposed. The sample prepared at 160?° C for 2 h at pH 11 exhibited the best photocatalytic activity and stability for the degradation of gaseous benzene under UV irradiation (? = 254 nm) as compared with the other samples. The conversion and mineralization rates of benzene were about 12.5% and 67%, respectively. The mineralization rate was twice as high as that of commercial TiO2 (Degussa Co.). Furthermore, the excellent stability for the benzene decomposition was attributed to the positive charge on the catalyst surface, which was analyzed both by electron spin resonance and Zeta-potentials.

Liu, Guodong; Liang, Shijing; Wu, Weiming; Lin, Rui; Qing, Na; Liang, Ruowen; Wu, Ling

2013-06-01

397

Nanoporous TiO2 nanoparticle assemblies with mesoscale morphologies: nano-cabbage versus sea-anemone.  

PubMed

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. PMID:24760418

Darbandi, Masih; Gebre, Tesfaye; Mitchell, Lucas; Erwin, William; Bardhan, Rizia; Levan, M Douglas; Mochena, Mogus D; Dickerson, James H

2014-06-01

398

Photocatalytic degradation of an azo-dye on TiO2/activated carbon composite material.  

PubMed

A sequential adsorption/photocatalytic regeneration process to remove tartrazine, an azo-dye in aqueous solution, has been investigated. The aim ofthis work was to compare the effectiveness of an adsorbent/photocatalyst composite-TiO2 deposited onto activated carbon (AC) - and a simple mixture of powders of TiO2 and AC in same proportion. The composite was an innovative material as the photocatalyst, TiO2, was deposited on the porous surface ofa microporous-AC using metal-organic chemical vapour deposition in fluidized bed. The sequential process was composed of two-batch step cycles: every cycle alternated a step of adsorption and a step of photocatalytic oxidation under ultra-violet (365 nm), at 25 degreeC and atmospheric pressure. Both steps, adsorption and photocatalytic oxidation, have been investigated during four cycles. For both materials, the cumulated amounts adsorbed during four cycles corresponded to nearly twice the maximum adsorption capacities qmax proving the photocatalytic oxidation to regenerate the adsorbent. Concerning photocatalytic oxidation, the degree of mineralization was higher with the TiO2/AC composite: for each cycle, the value of the total organic carbon removal was 25% higher than that obtained with the mixture powder. These better photocatalytic performances involved better regeneration than higher adsorbed amounts for cycles 2, 3 and 4. Better performances with this promising material - TiO2 deposited onto AC - compared with TiO2 powder could be explained by the vicinity of photocatalytic and AC adsorption sites. PMID:24600875

Andriantsiferana, C; Mohamed, E F; Delmas, H

2014-01-01

399

Enhanced TiO2 Photocatalytic Processing of Organic Wastes for Green Space Exploration  

NASA Technical Reports Server (NTRS)

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.

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

400

Effect of Aging Time on Crystalline Structure Evolution of TiO2 Nanoparticles  

Microsoft Academic Search

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.

Sitthisuntorn Supothina; Kannikar Juengsuwattananon; Thammarat Panyathanmaporn; Angkhana Jaroenworaluck; Supatra Jinawath; Tawan Sooknoi; Sittinun Tawkaew

2007-01-01

401

Self-assembly and photocatalysis of mesoporous TiO 2 nanocrystal clusters  

Microsoft Academic Search

Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the\\u000a self-assembly of hydrophobic TiO2 nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic\\u000a ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts.

Qiao Zhang; Ji-Bong Joo; Zhenda Lu; Michael Dahl; Diana Q. L. Oliveira; Miaomiao Ye; Yadong Yin

2011-01-01

402

Fabrication of bidirectionally doped ?-Bi2O3/TiO2-NTs with enhanced photocatalysis under visible light irradiation.  

PubMed

Stable ?-Bi2O3/TiO2-NTs photocatalyst with excellent visible-light-activity is successfully prepared by bidirectional doping. Stake structure of the TiO2-NTs provides a larger specific surface area and makes the contact area between the TiO2-NTs and ?-Bi2O3 much larger; The stake structure of TiO2-NTs not only leads to a firmer combination of TiO2-NTs and ?-Bi2O3, but also makes them dope one another deeply. The modification of Bi species into TiO2-NTs can form Bi-O-Ti chemical absorption bonds, then a localized impurity level is generated within the band gap. Electrons can be excited and transferred from the Bi(3+) impurity level to the conduction band (CB) of TiO2, similar to narrowing the band-gap of TiO2-NTs, resulting in a red shift of the absorption edge and an enhancement in visible-light activity. During annealing, Bi atoms are partially replaced by Ti atoms. The lattice of ?-Bi2O3 is compressed around the Ti impurity, making the lattice dislocate and distort. This dislocation and distortion leads to an increase in the ?-Bi2O3 valance band (VB), from 2.02 to 2.28 eV. Accordingly, the weak oxidability of ?-Bi2O3 is improved, and its photocatalytic ability is further enhanced. Moreover, this lattice dislocation and distortion changes the Bi-O distances, thus remarkably improving the stability of the ?-Bi2O3/TiO2-NTs. PMID:23692682

Li, Deyi; Zhang, Yonggang; Zhang, Yalei; Zhou, Xuefei; Guo, Sujin

2013-08-15

403

5.1% Apparent quantum efficiency for stable hydrogen generation over eosin-sensitized CuO\\/TiO 2 photocatalyst under visible light irradiation  

Microsoft Academic Search

A dye-sensitized CuO incorporated TiO2 catalyst was found to be an active photocatalyst for the photocatalytic hydrogen production from water under visible light (>420nm) irradiation in the presence of electron donors such as triethanolamine, acetonitrile and triethylamine. The stronger adsorption of eosin Y on the CuO incorporated TiO2 catalyst by multidentate complexation than on pure TiO2 was proved by the

Zhiliang Jin; Xiaojie Zhang; Yuexiang Li; Shuben Li; Gongxuan Lu

2007-01-01

404

Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials  

NASA Astrophysics Data System (ADS)

Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (? = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts.Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (?) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (? = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11251e

Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S. G.; Ramakrishna, Seeram

2012-02-01

405

Water-dispersible TiO2 nanoparticles via a biphasic solvothermal reaction method  

NASA Astrophysics Data System (ADS)

A biphasic solvothermal reaction method has been used for the synthesis of TiO2 nanoparticles (NPs). In this method, hydrolysis and nucleation occur at the interface of organic phase (titanium (IV) n-propoxide and stearic acid dissolved in toluene) and water phase ( tert-butylamine dissolved in water) resulting in the nucleation of the stearic acid-capped TiO2 NPs. These NPs are hydrophilic due to hydrophobic stearic acid ligands and could be dispersed in toluene, but not in water. These stearic acid-capped TiO2 NPs were surface-modified with 2,3-dimercaptosuccinic acid (DMSA) in order to make them water soluble. The resultant TiO2 NPs were easily redispersed in water without any noticeable aggregation. The Rietveld profile fitting of X-ray diffraction (XRD) pattern of the TiO2 NPs revealed highly crystalline anatase structure. The average crystallite size of TiO2 NPs was calculated to be 6.89 nm, which agrees with TEM results. These results have important implications for the use of TiO2 in biomedical, environmental, and industrial applications.

Mohan, Rajneesh; Drbohlavova, Jana; Hubalek, Jaromir

2013-12-01

406

Enhanced photocatalytic activity of TiO2-C hybrid aerogels for methylene blue degradation  

NASA Astrophysics Data System (ADS)

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.

Shao, Xia; Lu, Wencong; Zhang, Rui; Pan, Feng

2013-10-01

407

Enhanced photocatalytic activity of TiO2-C hybrid aerogels for methylene blue degradation  

PubMed Central

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. PMID:24145581

Shao, Xia; Lu, Wencong; Zhang, Rui; Pan, Feng

2013-01-01

408

TiO2-graphene oxide nanocomposite as advanced photocatalytic materials  

PubMed Central

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

2013-01-01

409

Preparation of nano-sized mixed crystal TiO2-coated Er3+:YAlO3 by sol-gel method for photocatalytic degradation of organic dyes under visible light irradiation.  

PubMed

In this work, an upconversion luminescence agent, crystallized Er(3 + ):YAlO(3), was synthesized and then coated by the nano-sized TiO(2) film through sol-gel technique. A novel TiO(2) photocatalyst, Er(3 + ):YAlO(3)/TiO(2), with high activity in visible light was subsequently prepared. The Er(3 + ):YAlO(3) and Er(3 + ):YAlO(3)/TiO(2) were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The photocatalytic activity of Er(3 + ):YAlO(3)/TiO(2) photocatalyst was tested by the degradation of acid red B in aqueous solution as the primary model compound under visible light irradiation. The experimental results proved that the prepared TiO(2)-coated crystallized Er(3 + ):YAlO(3) was able to decompose the acid red B efficiently, and it is promising to use the idea to develop new TiO(2) photocatalyst with high activity for photocatalytic degradation under visible light. PMID:19700830

Wang, Jun; Li, Jia; Liu, Bin; Xie, Yingpeng; Han, Guangxi; Li, Ying; Zhang, Liqun; Zhang, Xiangdong

2009-01-01

410

Effect of gas flow rates on the anatase-rutile transformation temperature of nanocrystalline TiO2 synthesised by chemical vapour synthesis.  

PubMed

Of the three crystallographic allotropes of nanocrystalline titania (rutile, anatase and brookite), anatase exhibits the greatest potential for a variety of applications, especially in the area of catalysis and sensors. However, with rutile being thermodynamically the most stable phase, anatase tends to transform into rutile on heating to temperatures in the range of 500 degrees C to 700 degrees C. Efforts made to stabilize the anatase phase at higher temperatures by doping with metal oxides suffer from the problems of having a large amorphous content on synthesis as well as the formation of secondary impurity phases on doping. Recent studies have suggested that the as-synthesised phase composition, crystallite size, initial surface area and processing conditions greatly influence the anatase to rutile transformation temperature. In this study nanocrystalline titania was synthesised in the anatase form bya chemical vapour synthesis (CVS) method using titanium tetra iso-propoxide (TTIP) as a precursor under varying flow rates of oxygen and helium. The anatase to rutile transformation was studied using high temperature X-ray diffraction (HTXRD) and simultaneous thermogravimetric analysis (STA), followed by transmission electron microscopy (TEM). It was demonstrated that the anatase-rutile transformation temperatures were dependent on the oxygen to helium flow rate ratio during CVS and the results are presented and discussed. PMID:19928267

Ahmad, Md Imteyaz; Bhattacharya, S S; Fasel, Claudia; Hahn, Horst

2009-09-01

411

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88  

NASA Astrophysics Data System (ADS)

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.

Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

2014-07-01

412

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: a comparative study of photo catalysis on acid red 88.  

PubMed

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 6h 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 m(2)/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 4h 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. PMID:24682063

Balachandran, K; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P

2014-07-15

413

Eosin Y-sensitized nitrogen-doped TiO 2 for efficient visible light photocatalytic hydrogen evolution  

Microsoft Academic Search

A nitrogen-doped TiO2 (N-TiO2) photocatalyst was prepared by the calcination of the hydrolysis product of Ti(SO4)2 with aqueous ammonia. Pt was loaded on N-TiO2 by photodeposition method. A dye-sensitization photocatalyst was prepared by impregnation method with Eosin Y and the platinized N-TiO2. The prepared samples were characterized by XRD, UV–vis diffuse reflectance spectra (DRS), BET and FT-IR. The visible light

Yuexiang Li; Chengfu Xie; Shaoqin Peng; Gongxuan Lu; Shuben Li

2008-01-01

414

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)...

415

Noble-metal-free plasmonic photocatalyst: hydrogen doped semiconductors  

PubMed Central

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

Ma, Xiangchao; Dai, Ying; Yu, Lin; Huang, Baibiao

2014-01-01

416

The doping mechanism of Cr into TiO2 and its influence on the photocatalytic performance.  

PubMed

The chromium doped titanium dioxide (Cr-TiO2) has been synthesized using a hydrothermal method. The as-prepared samples have been characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HR-TEM), XPS valence band spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DR), photoluminescence (PL) spectroscopy and time resolved PL (TR-PL) spectroscopy. The doping mechanism and related influence on the photocatalytic performance of TiO2 are thus proposed. The doped Cr(3+) ions can replace the Ti atoms in the lattice with oxygen vacancy compensation, distribute homogeneously in the framework of TiO2 crystals, and may make the n-type TiO2 less n-type or more p-type due to the resultant formation of oxygen vacancies, resulting in absorption of visible light, decrease of the intensity of PL emission and prolonged lifetime of photogenerated charge carriers. Compared with TiO2, the doped samples exhibit an improved visible-light photocatalytic activity. The influence of nitrogen modification has also been studied. We envision that these results would afford a better understanding of the doping mechanism of TiO2 using metal ions and, therefore, may provide a feasible way to prepare the TiO2-based photocatalysts for real applications. PMID:24154550

Li, Xuemin; Guo, Zhengkai; He, Tao

2013-12-14

417

3D silk fibroin scaffold incorporating titanium dioxide (TiO2) nanoparticle (NPs) for tissue engineering.  

PubMed

The present study deals with fabrication of scaffolds composing of silk fibroin and TiO2 NPs fabricated using a salt-leaching process. At first instance, the TiO2 NPs were prepared by using sol-gel synthesis, affording to have average diameter of 77±21?m. Furthermore, the aqueous solutions of silk fibroin were mixed with 0.2%, 2.0% and 4.0% of TiO2 NPs and salt-leaching process was introduced which resulted in creation of porous scaffolds modified with TiO2 NPs. The presence of TiO2 NPs in scaffolds was confirmed by VP-FE-SEM-EDS, TGA and XRD. The presence of TiO2 NPs influenced in decrease in pore size and swelling behavior of composite scaffolds. The resultant mechanical property of scaffolds was improved upon the introduction of TiO2 NPs. Moreover, cell cytotoxicity results for 1, 3 and 7 days; revealed no toxic behavior to osteoblasts. However, a mild toxicity to NIH 3T3 fibroblasts was observed with the scaffolds containing 4.0% TiO2 NPs. The cell fixation results from 1 and 7 days of incubation indicated the attachment, spreading and subsequent proliferation of fibroblasts. However, these findings were independent to the amount of TiO2 NPs in scaffolds. PMID:24794196

Kim, Jung-Ho; Sheikh, Faheem A; Ju, Hyung Woo; Park, Hyun Jung; Moon, Bo Mi; Lee, Ok Joo; Park, Chan Hum

2014-07-01

418

Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method.  

PubMed

TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles. PMID:22409037

Jin, Young Sam; Kim, Kyung Hwan; Park, Sang Joon; Yoon, Hyon Hee; Choi, Hyung Wook

2011-12-01

419

Study of the efficiency of UV and visible-light photocatalytic oxidation of methanol on mesoporous RuO2-TiO2 nanocomposites.  

PubMed

Mesoporous RuO(2)-TiO(2) nanocomposites at different RuO(2) concentrations (0-10 wt%) are prepared through a simple one-step sol-gel reaction of tetrabutyl orthotitanate with ruthenium(III) acetylacetonate in the presence of an F127 triblock copolymer as structure-directing agent. The thus-formed RuO(2)-TiO(2) network gels are calcined at 450 °C for 4 h leading to mesoporous RuO(2)-TiO(2) nanocomposites. The photocatalytic CH(3)OH oxidation to HCHO is chosen as the test reaction to examine the photocatalytic activity of the mesoporous RuO(2)-TiO(2) nanocomposites under UV and visible light. The photooxidation of CH(3)OH is substantially affected by the loading amount and the degree of dispersion of RuO(2) particles onto the TiO(2), which indicates the exclusive effect of the RuO(2) nanoparticles on this photocatalytic reaction under visible light. The measured photonic efficiency ?=0.53% of 0.5 wt% RuO(2)-TiO(2) nanocomposite for CH(3)OH oxidation is maximal and the further increase of RuO(2) loading up to 10 wt% gradually decreases this value. The cause of the visible-light photocatalytic behavior is the incorporation of small amounts of Ru(4+) into the anatase lattice. On the other hand, under UV light, undoped TiO(2) shows a very good photonic efficiency, which is more than three times that for commercial photocatalyst, P-25 (Evonik-Degussa); however, addition of RuO(2) suppresses the photonic efficiency of TiO(2). The proposed reaction mechanism based on the observed behavior of RuO(2)-TiO(2) photocatalysts under UV and visible light is explored. PMID:21381175

Ismail, Adel A; Robben, Lars; Bahnemann, Detlef W

2011-04-01

420

Origin of the visible-light photoactivity of NH3-treated TiO2: Effect of nitrogen doping and oxygen vacancies  

NASA Astrophysics Data System (ADS)

N-doped and oxygen-deficient TiO2 photocatalysts were obtained by heating commercial TiO2 in NH3 atmosphere, followed by a postcalcination process. Catalysts were characterized by X-ray diffraction (XRD), N2-sorption BET surface area, X-ray photoelectron spectroscopy (XPS), Elemental analysis (EA), UV/vis diffuse reflectance spectroscopy (DRS), Electron spin resonance (ESR) and Photoluminescence (PL). It shows that the NH3-heat-treatment of TiO2 resulted in not only nitrogen doping but also creation of oxygen vacancies with optical absorption in visible-light region. The postcalcination achieved several beneficial effects including dramatic removal of surface amino species, a rapid decrease in surface Ti3+ species, and a low recombination rate of photogenerated carriers on the co-doped TiO2. The photocatalytic measurement was carried out by the degradation of gas-phase benzene under visible light irradiation. At steady state, the photocatalytic conversion rate of benzene over the postannealed catalyst was 35.8%, accompanied by the yield of 115 ppmv CO2, which was much higher than that on the NH3-treated TiO2 before postcalcination or the H2-treated TiO2 catalysts. Results show that the visible-light activity of the NH3-treated TiO2 is attributed to a synergistic effect of substitutional nitrogen species and oxygen vacancies in TiO2.

Chen, Yilin; Cao, Xiaoxin; Lin, Bizhou; Gao, Bifen

2013-01-01

421

Capacitive and Oxidant Generating Properties of Black-Colored TiO2 Nanotube Array Fabricated by Electrochemical Self-Doping.  

PubMed

Recently, black-colored TiO2 NTA (denoted as black TiO2 NTA) fabricated by self-doping of TiO2 NTA with the amorphous phase led to significant success as a visible-light-active photocatalyst. This enhanced photocatalytic activity is largely attributed to a higher charge carrier density as an effect of electrochemical self-doping resulting in a higher optical absorbance and lower transport resistance. Nevertheless, the potential of black TiO2 NTA for other electrochemical applications, such as a supercapacitor and an oxidant-generating anode, has not been fully investigated. Here, we report the capacitive and oxidant generating properties of black TiO2 NTA. The black TiO2 NTA exhibited significantly a high value for areal capacitance with a good rate capability and novel electrocatalytic activity in generating (•)OHs and Cl2 compared to pristine TiO2 NTA with the anatase phase. This study suggests that the black TiO2 NTA be applied as a supercapacitor and an oxidant generating anode. PMID:25793300

Kim, Choonsoo; Kim, Seonghwan; Lee, Jaehan; Kim, Jiye; Yoon, Jeyong

2015-04-15

422

Photocatalytic degradation of DIPA using bimetallic Cu-Ni/TiO2 photocatalyst under visible light irradiation.  

PubMed

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

Riaz, Nadia; Bustam, Mohamad Azmi; Chong, Fai Kait; Man, Zakaria B; Khan, Muhammad Saqib; Shariff, Azmi M

2014-01-01

423

Photocatalytic Degradation of DIPA Using Bimetallic Cu-Ni/TiO2 Photocatalyst under Visible Light Irradiation  

PubMed Central

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

Bustam, Mohamad Azmi; Chong, Fai Kait; Man, Zakaria B.; Khan, Muhammad Saqib; Shariff, Azmi M.

2014-01-01

424

SILAR deposited TiO2 thin film for supercapacitor application  

NASA Astrophysics Data System (ADS)

The paper presents the synthesis and characterization of Titanium dioxide (TiO2) thin films prepared by the simple and low cost successive ionic layer adsorption and reaction (SILAR) method. The TiO2 thin films are characterized by scanning electron microscopy (SEM), FT-IR, FT-Raman and UV-VIS spectroscopy techniques. The SEM study of TiO2 shows the cracked morphology on the substrate surface. The characteristic peaks of TiO2 are observed in the FT-IR and FT-Raman studies. The optical study shows band gap of 3.3 eV. The cyclic voltammetry study shows the specific capacitance of 16 F.g-1.

Deshmukh, P. R.; Lokhande, C. D.

2013-06-01

425

Improved TiO2 photocatalytic reduction by the intrinsic electrostatic potential of BN nanotubes.  

PubMed

We describe the synthesis of novel nanocrystalline TiO(2) closely attached to BN nanotubes (BNNTs). The method involves the reaction of Ti(3+) with the oxidized radicals BN-H(+) to form BN-Ti(4+) bonds first, and then in situ hydrolytic conversion of the attached Ti(4+) into TiO(2). The designed reaction was carried out in a strongly acidic ethanol solution to ensure that the TiO(2) forms on the BNNT surface rather than in solution. We also report the improved photocatalytic reduction properties of TiO(2) when functionalized on BNNT surfaces and take advantage of the strong underlying electrostatic potential of the high-purity nanotubes. PMID:20391468

Tang, Chengchun; Li, Jiguang; Bando, Yoshio; Zhi, Chunyi; Golberg, Dmitri

2010-05-01

426

Cu doped TiO2/GF for photocatalytic disinfection of Escherichia coli in bioaerosols under visible light irradiation: Application and mechanism  

NASA Astrophysics Data System (ADS)

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.

Pham, Thanh-Dong; Lee, Byeong-Kyu

2014-03-01

427

Photocatalytic removal of C.I. Basic Red 46 on immobilized TiO2 nanoparticles: Artificial neural network modelling  

Microsoft Academic Search

C.I. Basic Red 46, commonly used as a textile dye, was photocatalytically removed using supported TiO2 nanoparticles irradiated by a 30 W UV?C lamp in a batch reactor. The investigated photocatalyst was industrial Degussa P25 (crystallite mean size 21 nm) immobilized on glass beads by a heat attachment method. The catalyst was characterized by XRD, SEM, TEM and BET techniques.

A. R. Khataee

2009-01-01

428

Factors influencing the photocatalytic degradation of Rhodamine B by TiO 2-coated non-woven paper  

Microsoft Academic Search

The photocatalytic degradation of Rhodamine B (RhB) has been investigated in aqueous solutions using TiO2-coated non-woven paper as photocatalyst. The experiments were carried out to investigate the factors that influence the RhB photocatalytic degradation, such as adsorption, initial concentration of dye solution, temperature, and some inorganic species commonly present in real wastewaters such as Cl?, NO3?, SO42?, CH3COO? and HPO42?.

Noureddine Barka; Samir Qourzal; Ali Assabbane; Abederrahman Nounah; Yhya Ait-Ichou

2008-01-01

429

Photocatalysis with chromium-doped TiO2: bulk and surface doping.  

PubMed

The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56?wt?% have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts. PMID:24737636

Ould-Chikh, Samy; Proux, Olivier; Afanasiev, Pavel; Khrouz, Lhoussain; Hedhili, Mohamed N; Anjum, Dalaver H; Harb, Moussab; Geantet, Christophe; Basset, Jean-Marie; Puzenat, Eric

2014-05-01

430

Fe ion-implanted TiO2 thin film for efficient visible-light photocatalysis  

NASA Astrophysics Data System (ADS)

This work shows the application of metal ion-implantation to realize an efficient second-generation TiO2 photocatalyst. High fluence Fe+ ions were implanted into thin TiO2 films and subsequently annealed up to 550 °C. The ion-implantation process modified the TiO2 pure film, locally lowering its band-gap energy from 3.2 eV to 1.6-1.9 eV, making the material sensitive to visible light. The measured optical band-gap of 1.6-1.9 eV was associated with the presence of effective energy levels in the energy band structure of the titanium dioxide, due to implantation-induced defects. An accurate structural characterization was performed by Rutherford backscattering spectrometry, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and UV/VIS spectroscopy. The synthesized materials revealed a remarkable photocatalytic efficiency in the degradation of organic compounds in water under visible light irradiation, without the help of any thermal treatments. The photocatalytic activity has been correlated with the amount of defects induced by the ion-implantation process, clarifying the operative physical mechanism. These results can be fruitfully applied for environmental applications of TiO2.

Impellizzeri, G.; Scuderi, V.; Romano, L.; Sberna, P. M.; Arcadipane, E.; Sanz, R.; Scuderi, M.; Nicotra, G.; Bayle, M.; Carles, R.; Simone, F.; Privitera, V.

2014-11-01

431

Photocatalysis of Thin Films of TiO2 on Al2O3 Substrates  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) has grown to be one of the most promising photocatalysts in recent years because of extensive applications in renewable and clean energy. The rise in demand for these new energies has driven an increase in research on metal oxides and their properties. Our interest in growing the rutile structure of TiO2 stems from its lower excitation energy (3.0 eV) when compared to anatase (3.2 eV), which indicates it has better activity in the visible portion of the spectrum. It has been shown that sapphire (Al2O3) substrates are conducive to epitaxial rutile growth. In this study, we measured the photocatalytic activity of thin films of TiO2 on r-Al2O3 (1 -1 0 2) substrates. We used PLD and MBE to grow the films, which were characterized using XPS and AFM. Photoactivity was measured via the decomposition of methyl orange on the film's surface using a UV/VIS spectrophotometer. The decomposition of this organic compound is driven by oxidation-reduction reactions on the surface of the TiO2 film. From this, we calculated the charge carrier diffusion length and compared it to that of anatase.

Turbay, David; Luttrell, Timothy; Batzill, Matthias

2013-03-01

432

Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst.  

PubMed

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

Zavahir, Sifani; Zhu, Huaiyong

2015-01-01

433

High-surface-area mesoporous TiO2 microspheres via one-step nanoparticle self-assembly for enhanced lithium-ion storage  

NASA Astrophysics Data System (ADS)

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

Wang, Hsin-Yi; Chen, Jiazang; Hy, Sunny; Yu, Linghui; Xu, Zhichuan; Liu, Bin

2014-11-01

434

Fabrication of TiO2 film with different morphologies on Ni anode and application in photoassisted water electrolysis  

NASA Astrophysics Data System (ADS)

The anode of an alkaline electrolytic cell for water electrolysis was modified by TiO2 photocatalysts with different morphologies. The water electrolysis was coupled with photocatalytic decomposition of water by irradiation of UV light on the modified anode. And a feasible process for the hydrogen production of water electrolysis assisted by photocatalysis (WEAP) was proposed and experimentally confirmed. The results show that the highly ordered, vertically oriented tubular arrays structure on Ni anode surface has better hydrogen production performance than random TiO2. In WEAP process, the maximum rate of hydrogen production is 2.77 ml/(h*cm2) when the anode modified by ordered TiO2 nanotube arrays, compared to traditional alkaline electrolytic cell for water electrolysis with Ni anode, H2-production rate increased by 139%.

He, Hongbo; Chen, Aiping; Lv, Hui; Dong, Haijun; Chang, Ming; Li, Chunzhong

2013-02-01

435

Synergistic effect of the combination of immobilized TiO2, UVA and ozone on the decomposition of dichloroacetic acid.  

PubMed

The performance of a heterogeneous photocatalytic ozonation system (TiO(2)/UVA/O(3)) was evaluated on the degradation and mineralization of dichloroacetic acid as a contaminant in aqueous solutions by means of a planar reactor. The commercial product "Pilkington Active™ glass" was used as the immobilized TiO(2) photocatalyst and it was irradiated by near UV light in this study. The synergistic interaction between ozone and the photoactivated TiO(2) surface was discussed and highlighted. Furthermore, the influences of initial concentration and temperature on the degradation rate of dichloroacetic acid and the ozone consumption level during the oxidation process were investigated. The concentrations of dichloroacetic acid and chloride anions produced during degradation were measured using ion chromatography. The mineralization of dichloroacetic acid was evaluated by Total Organic Carbon (TOC) measurements. The degradation of dichloroacetic acid by photocatalytic ozonation showed good agreement with the kinetics of first-order reactions with respect to dichloroacetic acid. PMID:22506699

Mehrjouei, Mohammad; Müller, Siegfried; Möller, Detlev

2012-01-01

436

Investigation of Hydrogen Centers in TiO2 Anatase Phase  

NASA Astrophysics Data System (ADS)

TiO2 in Anatase Phase is a material with valuable applications in photovoltaic cells and photocatalysts. As part of our program of studying its electronic structure and associated spectroscopic and other properties we are working on hydrogen (muonium) centers in this system. The presence of hydrogen in this system is expected to be responsible for the observed blue color in as grown anatase TiO2 single crystals(T. Sekiya et al., Jour. Phys. Chem. Solids, 61, 1237 (2000)). This suggestion is tested theoretically in the present work by studying hydrogen sites in the system and particularly if this leads to partial reduction of Ti^+4 to Ti^+3 which would be responsible for the observed low frequency absorption. Additionally, muonium, which resembles hydrogen, except for greater vibrational effects, is also being studied to predict its hyperfine interaction which could be tested by Muon Spin Rotation measurements.

Byahut, S. P.; Kurita, S.; Chow, L.; Gaire, C.; Jeong, Junho; Scheicher, R. H.; Das, T. P.

2003-03-01

437

Light-storing photocatalyst  

SciTech Connect

Light-storing photocatalyst was prepared by coating light-storing phosphor and TiO{sub 2} photocatalyst in sequence on ceramic. The light-storing photocatalyst can store light irradiation and emit slowly. Consequently, the photocatalyst remains active when the irradiation source is cut off. Rhodamine B (RhB) can be decomposed efficiently by this photocatalyst in the dark after it absorbs light irradiation. This photocatalyst is photoreactive in an outdoor environment or can save energy by supplying irradiation intermittently for the photocatalyst.

Zhang Junying; Pan Feng; Hao Weichang; Ge Qi; Wang Tianmian [Center of Ma