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1

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

2

Synthesis of TiO2 photocatalyst and study on their improvement technology of photocatalytic activity  

E-print Network

a Department of Chemistry and Center for Advanced Plasma Surface Technology, SungKyunKwan University, Suwon 440]. This process consists of TiO2 sol coating and the following O2 plasma treatment by RF plasma system%) by sol-gel processing. In order to elevate photocatalytic activity of the as-grown TiO2 films, oxygen

Boo, Jin-Hyo

3

Zn²+La³+ Co-Doped TiO2 Photocatalyst for the Purification of Air  

Microsoft Academic Search

The Zn2+-La3+Co-doped TiO2 photocatalysts prepared by doping lanthanum ion and zinc ion into TiO2 structure in a sol-gel process were shown to be efficient photocatalyst for the purification of Indoor air.The catalyst samples were then characterized by XRD and UV-vis analyses. The analytical results demonstrated that the lanthanum- zinc co-doping could inhibit the phase transformation of TiO2 and enhance the

Liu Baojiang; Cheng Xubang; He Jinxin

2009-01-01

4

Photocatalytic Oxidation of Diethyl Sulfide Vapor over TiO2-Based Composite Photocatalysts.  

PubMed

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

Selishchev, Dmitry; Kozlov, Denis

2014-01-01

5

Mesoporous TiO 2 \\/SBA15, and Cu\\/TiO 2 \\/SBA15 Composite Photocatalysts for Photoreduction of CO 2 to Methanol  

Microsoft Academic Search

A series of mesoporous TiO2\\/SBA-15, Cu\\/TiO2 and Cu\\/TiO2\\/SBA-15 composite photocatalysts were prepared by sol–gel synthesis for photoreduction of CO2 with H2O to methanol. It was found that optimum amount of titanium loading of TiO2\\/SBA-15 was 45 wt% which exhibited higher photoreduction activity than pure TiO2. An addition of copper on TiO2 or TiO2\\/SBA-15 catalyst as cocatalyst was found to enhance the

Hsien-Chang Yang; Hsin-Yu Lin; Yu-Shiang Chien; Jeffrey Chi-Sheng Wu; Hsin-Hsien Wu

2009-01-01

6

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

NASA Astrophysics Data System (ADS)

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

2007-02-01

7

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

8

Plasma surface modification of TiO2 photocatalysts for improvement of catalytic efficiency  

E-print Network

films. This process consists of TiO2 sol coating and the following O2 plasma treatment by RF and MWPlasma surface modification of TiO2 photocatalysts for improvement of catalytic efficiency Chung-Kyung Jung *, I.-S. Bae, Y.-H. Song, J.-H. Boo * Department of Chemistry, Sungkyunkwan University, Suwon 440

Boo, Jin-Hyo

9

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

10

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

11

Optical density and photonic efficiency of silica-supported TiO 2 photocatalysts  

Microsoft Academic Search

Over the last years, many research groups have developed supported TiO2-based materials in order to improve the engineering applications of photocatalytic technologies. However, not many attempts have been made to evaluate the optical behavior of these materials. This work focuses on the study of the photonic efficiencies of silica-supported TiO2 photocatalysts following the photodegradation of dichloroacetic acid (DCA) as model

J. Marugán; D. Hufschmidt; G. Sagawe; V. Selzer; D. Bahnemann

2006-01-01

12

A high-stability silica-clay composite: synthesis, characterization and combination with TiO2 as a novel photocatalyst for Azo dye.  

PubMed

A novel micro-mesopores composite material has successfully been synthesized at basic hydrothermal conditions using natural mineral montmorillonite (MMT) and tetraethoxysilane (TEOS). Two surfactants, cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG), have been employed in order to shape the pores in the composite. The resultant silica-clay has large surface area (472m(2)/g) and high hydrothermal stability, which makes it a potentially host-material for catalyst. The molecular size of different surfactant leads to the multi-peak distribution of pore size, and the surfactant of larger size (PEG) corresponds to the formation of larger pores. Moreover, the photocatalytic results show that, comparing with pure TiO(2) particles, the loaded TiO(2) on such silica-clay shows higher photodegradation rate of methyl orange (MO) in aqueous. And another porous aluminosilicate host, zeolite, was also discussed for comparison. PMID:19036502

Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Sun, Mengmeng; Xue, Bing; Ren, Xuehong

2009-06-15

13

Phenol degradation by TiO2 photocatalysts combined with different pulsed discharge systems.  

PubMed

Films of TiO2 nanotubes distributed over the inner surface of a discharge reactor cylinder (CTD) or adhered to a stainless steel electrode surface (PTD) in a discharge reactor were compared with a single-discharge (SD) system to investigate their efficiencies in phenol degradation. Morphology studies indicated that the TiO2 film was destroyed in the PTD system, but that there was no change in the CTD system after discharge. X-ray diffraction results revealed that the anatase phase of the original sample was preserved in the CTD system, but that an anatase-to-rutile phase transformation occurred in the PTD system after discharge. The highest efficiencies of phenol degradation and total organic carbon (TOC) mineralization were observed in the CTD system, and there was no decrease in phenol degradation efficiency upon reuse of a TiO2 film, indicating high catalysis activity and stability of the TiO2 photocatalysts in the combined treatment. TiO2 photocatalysts favored the formation of hydrogen peroxide and disfavored the formation of ozone. A greater degree of oxidation of intermediates and higher energy efficiency in phenol oxidation were observed with the TiO2-plasma systems, especially in the CTD system, compared to those with the SD system. PMID:23981678

Zhang, Yi; Lu, Jiani; Wang, Xiaoping; Xin, Qing; Cong, Yanqing; Wang, Qi; Li, Chunjuan

2013-11-01

14

Controlled synthesis of hierarchical TiO2 nanoparticles on glass fibres and their photocatalytic performance.  

PubMed

This paper reports the synthesis of novel photocatalysts consisting of TiO2 nanoparticles and glass fibres (GF) using a two-step process. The method involves the hydrolysis of titanium tetrachloride in the presence of GF and a following hydrothermal process under alkaline conditions. Various techniques are employed to characterize the morphology, structure and crystallinity of TiO2 on the fibre surface. The results show that depending on the experiment setups, TiO2 nanoparticles exhibit spherical or flake-like morphology, forming characteristic hierarchical structures along with flexible GF. Flake-like TiO2/GF exhibits much enhanced photocatalytic activity thanks to the large surface area and the hetero-junction of anatase and TiO2-B phases observed in its structure. An interesting observation is that the alkali treatment of GF leads to the formation of porous structures on the fibre surface, facilitating the adsorption-concentration-promoted photocatalytic process. The removal ratio of the organic dye by employing TiO2/GF remains more than 80% after six cyclic runs, showing the reusability of photocatalysts in real application. The novelty of this work lies in the synergy arising from materials with unique morphologies, structures and availabilities as well as capabilities in separating photogenerated electron-hole pairs, which have not been specifically considered previously in photocatalytic semiconductors. PMID:25011616

Chen, Lin; Yang, Sudong; Mäder, Edith; Ma, Peng-Cheng

2014-09-01

15

Silver-modified mesoporous TiO2 photocatalyst for water purification.  

PubMed

Mesoporous anatase (TiO(2)) was modified with silver (Ag) nanoparticles using a photoreduction method. Performance of the resulting TiO(2)-Ag nanocomposites for water purification was evaluated using degradation of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli) under ultraviolet (UV) irradiation. The composites with different Ag loadings were characterized using physical adsorption of nitrogen, X-ray diffraction, X-ray photoelectron spectroscopy and UV-Visible diffuse reflectance spectroscopic techniques. The results showed that metallic Ag nanoparticles were firmly immobilized on the TiO(2) surface, which improved electron-hole separation by forming the Schottky barrier at the TiO(2)-Ag interface. Photocatalytic degradation of RhB and inactivation of E. coli effectively occurred in an analogical trend. The deposited Ag slightly decreased adsorption of target pollutants, but greatly increased adsorption of molecular oxygen with the latter enhancing production of reactive oxygen species (ROSs) with concomitant increase in contaminant photodegradation. The optimal Ag loadings for RhB degradation and E. coli disinfection were 0.25 wt% and 2.0 wt%, respectively. The composite photocatalysts were stable and could be used repeatedly under UV irradiation. PMID:21215983

Xiong, Zhigang; Ma, Jizhen; Ng, Wun Jern; Waite, T David; Zhao, X S

2011-02-01

16

PbO-modified TiO2 thin films: a route to visible light photocatalysts.  

PubMed

PbO clusters were deposited onto polycrystalline titanium dioxide (anatase) films on glass substrates by aerosol-assisted chemical vapor deposition (AACVD). The as-deposited PbO/TiO2 films were then tested for visible light photocatalysis. This was monitored by the photodegradation of stearic acid under visible light conditions. PbO/TiO2 composite films were able to degrade stearic acid at a rate of 2.28 × 10(15) molecules cm(-2) h(-1), which is 2 orders of magnitude greater than what has previously been reported. The PbO/TiO2 composite film demonstrated UVA degradation of resazurin redox dye, with the formal quantum yield (FQY) and formal quantum efficiency (FQE) exceeding that of a TiO2 film grown under the same conditions and Pilkington Activ, a commercially available self-cleaning glass. This work correlates with computational studies that predicted PbO nanoclusters on TiO2 form active visible light photocatalysts through new electronic states through PbO/TiO2 interfacial bonds resulting in new electronic states above the valence band maximum in TiO2, shifting the valence band upward as well as more efficient electron/hole separation with hole localization on PbO particles and electron on the TiO2 surface. PMID:24354409

Bhachu, Davinder S; Sathasivam, Sanjayan; Carmalt, Claire J; Parkin, Ivan P

2014-01-21

17

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

18

Visible light induced photodegradation of organic pollutants on nitrogen and fluorine co-doped TiO2 photocatalyst.  

PubMed

The nitrogen and fluorine co-doped TiO2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetrabutyl titanate with ammonium fluoride. Nitrogen and fluorine co-doping causes the absorption edge of TiO2 to shift to a lower energy region. The photocatalytic activity of co-doped TiO2 with anatase phases was found to be 2.4 times higher than that of the commercial TiO2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co-doped TiO2 powders only contain anatase phases even at 1000 degrees C. Apparently, ammonium fluoride added retarded phase transformation of the TiO2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co-doped TiO2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO2 to shift to a lower energy region. PMID:15900762

Wang, Zheng-peng; Xu, Jun; Cai, Wei-min; Zhou, Bao-xue; He, Zheng-guang; Cai, Chun-guang; Hong, Xiao-ting

2005-01-01

19

Morphologically-tunable TiO2 nanorod film with high energy facets: green synthesis, growth mechanism and photocatalytic activity  

NASA Astrophysics Data System (ADS)

A novel green synthesis strategy was developed to synthesize a film photocatalyst containing anatase TiO2 nanorods wholly dominated with {100} and {101} facets by employing a simple hydrothermal reaction in the presence of NaCl solution and hydrogen titanate nanosheet array film. The formation mechanism of the anatase TiO2 nanorods was deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations, which revealed that the highly reactive {100} facets were derived from the enhanced structural stability of hydrogen titanate induced by Na+ and selective adsorption of Cl- on the {100} facets of anatase TiO2 crystals. Photocatalytic performance has indicated that the TiO2 nanorods with {100} facet exposure exhibit much higher activities than that of rhombic nanoparticles with {101} facet exposure for the degradation of organic contaminants, which may be primarily ascribed to the high surface energy of {100} facets.A novel green synthesis strategy was developed to synthesize a film photocatalyst containing anatase TiO2 nanorods wholly dominated with {100} and {101} facets by employing a simple hydrothermal reaction in the presence of NaCl solution and hydrogen titanate nanosheet array film. The formation mechanism of the anatase TiO2 nanorods was deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations, which revealed that the highly reactive {100} facets were derived from the enhanced structural stability of hydrogen titanate induced by Na+ and selective adsorption of Cl- on the {100} facets of anatase TiO2 crystals. Photocatalytic performance has indicated that the TiO2 nanorods with {100} facet exposure exhibit much higher activities than that of rhombic nanoparticles with {101} facet exposure for the degradation of organic contaminants, which may be primarily ascribed to the high surface energy of {100} facets. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31127e

Wang, Changhua; Zhang, Xintong; Zhang, Yanli; Jia, Yan; Yuan, Bo; Yang, Jikai; Sun, Panpan; Liu, Yichun

2012-07-01

20

A visible-light-driven composite photocatalyst of TiO2 nanotube arrays and graphene quantum dots  

PubMed Central

Summary TiO2 nanotube arrays are well-known efficient UV-driven photocatalysts. The incorporation of graphene quantum dots could extend the photo-response of the nanotubes to the visible-light range. Graphene quantum dot-sensitized TiO2 nanotube arrays were synthesized by covalently coupling these two materials. The product was characterized by Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and UV–vis absorption spectroscopy. The product exhibited high photocatalytic performance in the photodegradation of methylene blue and enhanced photocurrent under visible light irradiation. PMID:24991506

Chan, Donald K L; Cheung, Po Ling

2014-01-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

22

Photocatalytic degradation of mixed gaseous carbonyl compounds at low level on adsorptive TiO 2\\/SiO 2 photocatalyst using a fluidized bed reactor  

Microsoft Academic Search

An adsorptive silica-supported titania photocatalyst TiO2\\/SiO2 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 TiO2\\/SiO2 photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD,

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

2006-01-01

23

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

NASA Astrophysics Data System (ADS)

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

Hong, Hyun-Guk; Kim, Young-Joo

2008-07-01

24

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

25

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

PubMed Central

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

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

2012-01-01

26

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

27

Structuring a TiO2-based photonic crystal photocatalyst with Schottky junction for efficient photocatalysis.  

PubMed

Facile and effective approaches were developed to fabricate the inverse TiO2/Pt opals Schottky structures on the Ti substrate. The as-prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and diffuse reflectance UV-vis spectra (DRS), respectively. The results indicate that these samples were of ordered network, which was built by the Pt skeleton frame and the outer TiO2 layer. The TiO2 layer was identified as anatase with the preferential orientation of (101) plane. The experiments of short-circuit photocurrent (SCPC) and photocatalytic degradation of phenol were also conducted under the UV irradiation in order to evaluate the photoactivity of the samples. By tuning the red edge of photonic stop-band overlapping the absorption maximum of anatase (at 360 nm), both the UV absorption and the carrier separation of the samples were improved. The kinetic constant using the optimal inverse TiO2/Pt opals (0.992 h(-1)) was about 1.5 times as great as that of the disordered inverse TiO2/Pt opals (TiO2/Pt-mix) and was 3.3 times as great as that of pristine TiO2 nanocrystalline film (TiO2-nc) on Ti substrate. PMID:19994850

Chen, Huan; Chen, Shuo; Quan, Xie; Zhang, Yaobin

2010-01-01

28

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...

29

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

30

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

31

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...

32

Factors influencing the photocatalytic decolorization of Bromophenol blue in aqueous solution with different types of TiO 2 as photocatalysts  

Microsoft Academic Search

The photocatalytic decolorization of Bromophenol blue (BPB) in aqueous solution with different types of TiO2 as photocatalysts in slurry form has been carried out using UV-A light at 365nm under a variety of conditions. The efficiency of P25-Degussa and PC500-Millennium photocatalysts were compared. The effects of various parameters such as catalyst loading, light intensity, temperature, pH and initial concentration of

Nour Bouanimba; Razika Zouaghi; Nassima Laid; Tahar Sehili

2011-01-01

33

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

34

Characterization and activity of visible-light driven TiO2 photocatalyst doped with tungsten.  

PubMed

This research aimed to expand the activity of TiO(2) down to the visible light region by modifying the sol-gel conditions and doping with tungsten. The optimum conditions for calcination temperature, acid type, and heating rate were 200°C, HNO(3), and 1°C/min, respectively. The undoped TiO(2) synthesized under these conditions could significantly absorb the visible light whereas the commercial Degussa P-25 could not. The absorptivity decreased sequentially as the wavelength increased from 400 to 700 nm. Within 6 h of 2-W blue-light illumination, 23% of 0.1 mM 2-chlorophenol was removed. The XRD result showed that the crystalline was anatase phase. The visible-light absorption property of the TiO(2) became even better when doped with tungsten. At the optimum W to TiO(2) ratio of 0.5%, the degradation of 0.1 mM 2-chlorophenol increased to 53% indicating a higher photocatalytic activity. Both crystalline and amorphous TiO(2) could exhibit the photocatalytic activity under the visible light region. PMID:21045341

Putta, T; Lu, M C; Anotai, J

2010-01-01

35

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

36

Large-scale synthesis of TiO2 microspheres with hierarchical nanostructure for highly efficient photodriven reduction of CO2 to CH4.  

PubMed

In this study, a simple and reproducible synthesis strategy was employed to fabricate TiO2 microspheres with hierarchical nanostructure. The microspheres are macroscopic in the bulk particle size (several hundreds to more than 1000 ?m), but they are actually composed of P25 nanoparticles as the building units. Although it is simple in the assembly of P25 nanoparticles, the structure of the as-prepared TiO2 microspheres becomes unique because a hierarchical porosity composed of macropores, larger mesopores (ca. 12.4 nm), and smaller mesopores (ca. 2.3 nm) has been developed. The interconnected macropores and larger mesopores can be utilized as fast paths for mass transport. In addition, this hierarchical nanostructure may also contribute to some extent to the enhanced photocatalytic activity due to increased multilight reflection/scattering. Compared with the state-of-the-art photocatalyst, commercial Degussa P25 TiO2, the as-prepared TiO2 microsphere catalyst has demonstrated significant enhancement in photodriven conversion of CO2 into the end product CH4. Further enhancement in photodriven conversion of CO2 into CH4 can be easily achieved by the incorporation of metals such as Pt. The preliminary experiments with Pt loading reveal that there is still much potential for considerable improvement in TiO2 microsphere based photocatalysts. Most interestingly and significantly, the synthesis strategy is simple and large quantity of TiO2 microspheres (i.e., several hundred grams) can be easily prepared at one time in the lab, which makes large-scale industrial synthesis of TiO2 microspheres feasible and less expensive. PMID:25140917

Fang, Baizeng; Bonakdarpour, Arman; Reilly, Kevin; Xing, Yalan; Taghipour, Fariborz; Wilkinson, David P

2014-09-10

37

Highly active mixed-phase tiO2 photocatalysts fabricated at low temperature and the correlation between phase composition and photocatalytic activity.  

PubMed

The idea of varying volume ratio of water to ethanol in solvent was firstly employed to yield phase composition controllable mixed-phase titanium dioxide (TiO2) photocatalysts via a low temperature solvothermal route at 353 K. It was found that anatase contents increase from 0 to 100% with increase of ethanol contents in solvent. The mixed-phase TiO2 with 60% anatase content exhibited the best photocatalytic activity in photodecomposing formaldehyde (FAD) under UV light irradiation, which increases by about 270 or 400% in comparison with single rutile or anatase TiO2, and is slightly better than commercial mixed-phase TiO2 (P25). The synergistic effect in mixed-phase TiO2 including antenna effect by rutile phase and the activation effect by anatase phase was observed. Further, partially quantitive correlation between phase composition and photocatalytic activity was ascribed to maximizing the synergistic effect and an optimal value of anatase content about 60% in mixed-phase TiO2 photocatalyst was therefore suggested. PMID:19143353

Shi, Lei; Weng, Duan

2008-01-01

38

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

39

Sonochemical synthesis and characterization of magnetic separable Fe3O4–TiO2 nanocomposites and their catalytic properties  

Microsoft Academic Search

A novel sonochemical method is described for the preparation of Fe3O4–TiO2 photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core. The Fe3O4 nanoparticles were partially embedded in TiO2 agglomerates. TiO2 nanocrystallites were obtained by hydrolysis and condensation of titanium tetraisopropyl in the presence of ethanol and water under high-intensity ultrasound irradiation. This method is attractive

Wanquan Jiang; Xueping Zhang; Xinglong Gong; Fangfang Yan; Zhong Zhang

2010-01-01

40

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

41

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

PubMed

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

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

2014-05-28

42

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

43

Fabrication of a TiO2-BDD heterojunction and its application as a photocatalyst for the simultaneous oxidation of an azo dye and reduction of Cr(VI).  

PubMed

A TiO2-boron doped diamond (TiO2-BDD) heterojunction was employed as a photocatalyst to simultaneously oxidize an azo dye C.I. reactive yellow 15 (RY15) and reduce hexavalent chromium (Cr(VI)). This heterojunction was fabricated first by depositing a BDD film on a Ti sheet in a hot filament chemical vapor deposition reactor, followed by covering a layer of TiO2 in a metal-organic chemical vapor deposition system. The morphology of this heterojunction was characterized by using a scanning electron microscope (SEM). X-ray diffraction (XRD), Raman spectroscopy, and current-voltage (I-V) measurement were used to characterize its structures. Additionally, the characterization of surface photovoltage showed that the TiO2-BDD heterojunction exhibited a higher photovoltage response and a better ability for charge separation than the photocatalyst of TiO2 directly deposited on a Ti sheet (TiO2-Ti). The photocatalytic experiments revealed that the kinetic constants for the oxidation of RY15 and the reduction of Cr(VI) were, respectively, increased by 85 and 71% when the photocatalyst of TiO2-Ti was replaced by the TiO2-BDD heterojunction. Meanwhile, a significant synergy was confirmed in the simultaneous oxidation of RY15 and reduction of Cr(VI). The enhanced photocatalytic ability of the TiO2-BDD composite could be attributed to the heterojunction. The possible photocatalytic mechanism was also discussed. PMID:18546724

Yu, Hongbin; Chen, Shuo; Quan, Xie; Zhao, Huimin; Zhang, Yaobin

2008-05-15

44

Novel high potential visible-light-active photocatalyst of CNT/Mo, S-codoped TiO2 hetero-nanostructure  

NASA Astrophysics Data System (ADS)

The current study deals with synthesize of novel nanophotocatalysts of CNT/Mo,S-codoped TiO2 by reacting between titanium isopropoxide (Ti(OC3H7)4) and CNT in aqueous ammonia and subsequent calcining of hydrolysis of the products. The prepared catalysts were characterized by N2 adsorption-desorption measurements, XRD, SEM, TEM, EDX, FT-IR, and UV-vis DRS spectroscopy. SEM and TEM images exhibited uniform coverage of CNT with anatase TiO2 nanoclusters. It was also demonstrated that the presence of S and Mo within the TiO2 acts as electrons traps and prevents the charge recombination and also enables the TiO2 photocatalyst to be active in visible-light region. Moreover, the CNT/Mo,S-doped TiO2 nanohybrids has been proven to has a excellent photocatalytic performance in photodecomposition of Congored (CR), at which the rate of decomposition reaches 100% in only 20 and 30 min under UV and visible-light irradiation, respectively. The enhanced photocatalytic activity was ascribed to the synergetic effects of excellent electrical property of CNT and metal-non-metal codoping. Finally, which to best of our knowledge is done for the first time, we have demonstrated that Mo- and S-doped TiO2 decorated over CNT, or CNT/Mo,S-codoped TiO2, may have high potential applications in photocatalysis and environmental protection with superior catalytic activity under visible-light illumination.

Hamadanian, M.; Shamshiri, M.; Jabbari, V.

2014-10-01

45

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

PubMed

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

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

2012-09-26

46

Synthesis and structure of Al clusters supported on TiO2,,110...: A scanning tunneling microscopy study  

E-print Network

Synthesis and structure of Al clusters supported on TiO2,,110...: A scanning tunneling microscopy, Texas 77843-3255 Received 14 October 1997; accepted 6 April 1998 Al clusters supported on TiO2(110) have been investigated using scanning tunneling microscopy. Al interacts strongly with the TiO2(110) surface

Goodman, Wayne

47

Synthesis and characterization of TiO2 and TiO 2/Ag for use in photodegradation of methylviologen, with kinetic study by laser flash photolysis.  

PubMed

This paper reports the synthesis, characterization, and application of TiO2 and TiO2/Ag nanoparticles for use in photocatalysis, employing the herbicide methylviologen (MV) as a substrate for photocatalytic activity testing. At suitable metal to oxide ratios, increases in silver surface coating on TiO2 enhanced the efficiency of heterogeneous photocatalysis by increasing the electron transfer constant. The sol-gel method was used for TiO2 synthesis. P25 TiO2 was the control material. Both oxides were subjected to the same silver incorporation process. The materials were characterized by conventional spectroscopy, SEM micrography, X-ray diffraction, calculation of surface area per mass of catalyst, and thermogravimetry. Also, electron transfers between TiO2 or TiO2/Ag and MV in the absence and presence of sodium formate were investigated using laser flash photolysis. Oxides synthesized with 2.0 % silver exhibited superior photocatalytic activity for MV degradation. PMID:24609723

Ramos, Dayana Doffinger; Bezerra, Paula C S; Quina, Frank H; Dantas, Renato F; Casagrande, Gleison A; Oliveira, Silvio C; Oliveira, Márcio R S; Oliveira, Lincoln C S; Ferreira, Valdir S; Oliveira, Samuel L; Machulek, Amilcar

2015-01-01

48

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

49

Solvothermal synthesis of mesoporous TiO2 microspheres and their excellent photocatalytic performance under simulated sunlight irradiation  

NASA Astrophysics Data System (ADS)

TiO2 nanomaterials have been extensively studied as photocatalysts, in which mesoporous TiO2 microspheres would be good candidates for abatement of organic pollutants in waste water on account of their high photocatalytic activities and easily reclaiming. Here, mesoporous TiO2 microspheres were synthesized by a facile solvothermal method and characterized. The formation mechanism of the TiO2 microspheres was investigated based on series of control experiments. The photocatalytic activities of the as-prepared TiO2 microspheres were evaluated by photodegradations of methyl orange (MO) and phenol aqueous solutions, respectively, under simulated sunlight irradiation, and compared with those of commercial TiO2 (P25). The TiO2 microspheres exhibit excellent photodegradation activities on both MO and phenol, comparing to P25. For the two model pollutants, the photodegradation percentages by the TiO2 microspheres are both more than twice of those by P25 in the same condition. Moreover, it can quickly settle down mostly (>90%) in 20 min from the photocatalytic reaction mixture under gravity after stopping stirring and be reclaimed easily. Thus it could be a promising photocatalyst for waste water treatment.

Zhu, Lianjie; Liu, Kun; Li, Hongbin; Sun, Youguang; Qiu, Mo

2013-06-01

50

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

51

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

52

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

53

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

54

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

PubMed Central

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

Niu, Mang; Cheng, Daojian; Cao, Dapeng

2014-01-01

55

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

56

A new family of sunlight-driven bifunctional photocatalysts based on TiO2 nanoribbon frameworks and bismuth oxohalide nanoplates  

NASA Astrophysics Data System (ADS)

By taking advantage of the structural affinity between bismuth oxohalide and TiO2, we successfully prepare a family of hybrid frameworks via the designated growth of bismuth oxohalide nanoplates on TiO2 nanoribbons, and propose them as sunlight-driven bifunctional photocatalysts for all-weather removal of pollutants. The structural variability of bismuth oxohalide allows the optical absorption of the hybrid framework to be monotonically tuneable across the visible spectrum. Meanwhile, the hybridization greatly increases the surface roughness of the frameworks and enables the frameworks to harvest more photons to participate in photocatalytic reactions. Furthermore, the hybridization establishes two potential gradients to promote the separation of photo-induced electron-hole pairs: the internal electrical field perpendicular to the wide surfaces of bismuth oxohalide nanoplates and across the semiconductor-semiconductor heterojunction. Owing to the synergetic effects of the permeable mesoporous architecture, the intense visible light absorption, and the efficient charge separation, the hybrid frameworks are capable of all-weather removal of pollutants: they utilize the inter-ribbon pores to gather pollutants in the dark (behaving as collectors) and they rapidly degrade the pollutants in the day (behaving as photocatalysts). In particular, the BiOBr@TiO2 framework exhibits very impressive sunlight-driven photocatalytic activity, which is much higher than commercially available P25 TiO2 under the same conditions.By taking advantage of the structural affinity between bismuth oxohalide and TiO2, we successfully prepare a family of hybrid frameworks via the designated growth of bismuth oxohalide nanoplates on TiO2 nanoribbons, and propose them as sunlight-driven bifunctional photocatalysts for all-weather removal of pollutants. The structural variability of bismuth oxohalide allows the optical absorption of the hybrid framework to be monotonically tuneable across the visible spectrum. Meanwhile, the hybridization greatly increases the surface roughness of the frameworks and enables the frameworks to harvest more photons to participate in photocatalytic reactions. Furthermore, the hybridization establishes two potential gradients to promote the separation of photo-induced electron-hole pairs: the internal electrical field perpendicular to the wide surfaces of bismuth oxohalide nanoplates and across the semiconductor-semiconductor heterojunction. Owing to the synergetic effects of the permeable mesoporous architecture, the intense visible light absorption, and the efficient charge separation, the hybrid frameworks are capable of all-weather removal of pollutants: they utilize the inter-ribbon pores to gather pollutants in the dark (behaving as collectors) and they rapidly degrade the pollutants in the day (behaving as photocatalysts). In particular, the BiOBr@TiO2 framework exhibits very impressive sunlight-driven photocatalytic activity, which is much higher than commercially available P25 TiO2 under the same conditions. Electronic supplementary information (ESI) available: XRD patterns of various frameworks, photographs of the nanoribbon frameworks, EDX spectra of the frameworks, nitrogen adsorption-desorption isotherms of various frameworks at 77 K, additional SEM images of the hybrid frameworks, HRTEM image of the BiOBr@TiO2 framework, SEM images of pure bismuth oxohalides, concentration variation of the pollutants without the photocatalysts under the illumination of natural sunlight, and cycling experiments. See DOI: 10.1039/c3nr04785g

Cao, Xuebo; Lu, Zhufeng; Zhu, Lianwen; Yang, Le; Gu, Li; Cai, Liling; Chen, Jie

2014-01-01

57

Selective Biotemplated Synthesis of TiO2 Inside a Protein Cage.  

PubMed

Biological organisms have evolved tremendous control over the synthesis of inorganic materials in aqueous solutions at standard conditions. Such control over material properties is difficult to achieve with current synthesis strategies. Biotemplated synthesis of materials has been demonstrated to be efficient at facilitating the formation of various inorganic species. In this study, we employ a protein cage-based system to synthesize photoactive TiO2 nanoparticles less than 10 nm in diameter. We also demonstrate phase control over the material, with the ability to synthesize both anatase and rutile TiO2 using distinct biomineralization peptides within the protein cage. Finally, using analytical ultracentrifugation, we are able to resolve distinct reaction products and approximate their loading. We find that two distinct species comprise the reaction products, likely representing procapsid-like particles with early, precursor metal oxide clusters, and shells nearly full with crystalline TiO2 nanoparticles, respectively. PMID:25494935

Bedwell, Gregory J; Zhou, Ziyou; Uchida, Masaki; Douglas, Trevor; Gupta, Arunava; Prevelige, Peter E

2015-01-12

58

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

59

Synthesis Of Silver Sulfide Stratified Photocatalyst  

NASA Astrophysics Data System (ADS)

In this report, silver sulfide (Ag2S) was selected as a new H2S splitting photocatalyst material, and considered the synthesis method of Ag2S photocatalyst particles with stratified structure. Previous stratified particles were synthesized by using metal oxide (hydroxide) as the precursor. Ag2O particles as the precursor of Ag2S were synthesized by mixing AgNO3 solution and NaOH, and their particle sizes could be controlled by the solutions' concentration. Then, Ag2S particles were obtained by adding Na2S solution into suspending solution of Ag2O particles with optimum sizes. Particle sizes of Ag2S were changed by Na2S concentration control, and remaining Ag2O precursor could be dissolved by adding NH3 solution. The photocatalytic H2S splitting could be realized by UV-light irradiation on the Ag2S particles without co-catalyst like Pt.

Baba, Y.; Yokoyama, S.; Takahashi, H.; Tohji, K.

2008-02-01

60

Controllable hydrothermal synthesis, optical and photocatalytic properties of TiO2 nanostructures  

NASA Astrophysics Data System (ADS)

Different surface morphologies of TiO2 thin films were prepared by hydrothermal synthesis method on Ti substrates through changing reaction time. The microstructure, composition, optical properties and photocatalytic properties of TiO2 thin films were systematically investigated by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectrometer and ultraviolet-visible spectroscopy. As the reaction time increases, anatase structure and brookite structure of TiO2 films respectively increases and decreases, corresponding to surface morphology changes from irregular structure to regular geometrical shape structure. These structural changes are accompanied by significant variations of optical properties and photocatalytic properties including a widening of the band gap from 2.86 to 3.19 eV, photocatalytic degradation efficiency from 92.5 to 98.1% and photocatalytic degradation rate from 0.032 to 0.048 min-1. Among all samples, TiO2-1 shows the best photocatalytic properties. Compositional analysis indicates that TiO2 surface layer contains Ti and O elements, the ratio of Ti:O is 1:2.28 which is close to the atom ratio of TiO2.

Xu, Yanyan; Zhang, Maocui; Zhang, Miao; Lv, Jianguo; Jiang, Xishun; He, Gang; Song, XuePing; Sun, Zhaoqi

2014-10-01

61

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

62

Characterization, activity and mechanisms of a visible light driven photocatalyst: Manganese and iron co-modified TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

An attempt was made to prepare Mn,Fe-codoped nanostructured TiO2 photocatalyst for visible light assisted degradation of an azo dye (methylene blue) in aqueous solutions by a sol-gel process. The asprepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL) techniques. The photocatalytic activity of Mn,Fe-codoped TiO2 catalyst was evaluated by measuring degradation rates of methylene blue (MB) under visible light. The results showed that doping with the manganese and iron ions significantly enhanced the photocatalytic activity for MB degradation under visible light irradiation. This was ascribed to the fact that a small amount of manganese and iron dopants simultaneously increased MB adsorption capacity and separation efficiency of electron-hole pairs. The results of DRS showed that Mn,Fe-codoped TiO2 had significant absorption between 400 and 500 nm, which increased with the increase of manganese ion content. It is found that the stronger the PL intensity, the higher the photocatalytic activity. This could be explained by the points that PL spectra mainly resulted from surface oxygen vacancies and defects during the process of PL, while surface oxygen vacancies and defects could be favorable in capturing the photoinduced electrons during the process of photocatalytic reactions, so that the recombination of photoinduced electrons and holes could be effectively inhibited.

Zhang, Dongfang; Zeng, Fanbin

2011-10-01

63

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

64

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

65

The hybrid photocatalyst of TiO2-SiO2 thin film prepared from rice husk silica  

NASA Astrophysics Data System (ADS)

The TiO2-SiO2 thin film was prepared by self-assembly method by mixing SiO2 precursor with titanium precursor solution and aged to obtain a co-precipitation of silica and titanium crystals. Dip coating method was applied for thin film preparation on glass slide. The X-ray diffraction (XRD) of the self-assembly thin film had no characteristic property of SiO2 and even anatase TiO2 but indicated new crystal structure which was determined from the Fourier Transform Infrared Spectrophotometer (FTIR) as a hybridized Ti-O-Si bonding. The surface area and surface volume of the self-assembly sample were increased when SiO2 was incorporated into the film. The self-assembly TiO2-SiO2 thin film exhibited the enhanced photocatalytic decolorization of methylene blue (MB) dye. The advantages of SiO2 are; (1) to increase the adsorbability of the film and (2) to provide the hydroxyl radical to promote the photocatalytic reaction. The self-assembly thin film with the optimum molar ratio (SiO2:TiO2) as 20:80 gave the best performance for photocatalytic decolorization of MB dye with the overall efficiency of 81%.

Klankaw, P.; Chawengkijwanich, C.; Grisdanurak, N.; Chiarakorn, Siriluk

2012-03-01

66

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

67

Fabrication characterization and activity of a solar light driven photocatalyst: cerium doped TiO2 magnetic nanofibers.  

PubMed

A novel magnetic separable composite photocatalytic nanofiber consisting of TiO2 as the major phase, CeO(2-y) and CoFe2O4 as the dopant phase was prepared by sol-gel method and electrospinning technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum (UV-vis DRS) and vibrating sample magnetometer (VSM). The photocatalytic activity of the resultant CoFe2O4-TiO2 and CeO(2-y)/CoFe2O4-TiO2 nanofibers was evaluated by photodegradation of methylene blue (MB) in an aqueous solution under xenon lamp (the irradiation spectrum energy distribution is similar to sunlight) irradiation in a photochemical reactor. The results showed that the dopant of Ce could affect the absorbance ability and photo-response range. The sample containing 1.0 wt% CeO(2-y) exhibited the highest degradation with 35% for MB under simulate solar light irradiation. Furthermore, the as-synthesized composite photocatalytic nanofibers could be separated easily by an external magnetic field, thus it might hold potential for application in wastewater treatment. PMID:22755084

Li, Cong-Ju; Wang, Bin; Wang, Jiao-Na

2012-03-01

68

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

PubMed

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

69

Controllable Hydrothermal Synthesis and Morphology Evolution of TiO2 Nanorod Films  

NASA Astrophysics Data System (ADS)

TiO2 nanorod films with diverse and evolutionary morphologies are synthesized by controllable hydrothermal method under mild conditions. The as-prepared nanorod films are well characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy. Results demonstrate that reasonable control of time of secondary growth could easily and conveniently achieve the goal of morphology adjustment during mild condition hydrothermal synthesis process.

Sun, Zhaozong; Lan, Jie; Li, Yitan; Wang, Xiao; Zhao, Minglin; Yu, Xiaohong

2014-07-01

70

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

71

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

72

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

73

Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.  

PubMed

One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed. PMID:25014328

Tian, Jian; Zhao, Zhenhuan; Kumar, Anil; Boughton, Robert I; Liu, Hong

2014-10-21

74

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 50mM (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 12min, 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

75

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

76

Gold-copper nanoalloys supported on TiO2 as photocatalysts for CO2 reduction by water.  

PubMed

Commercial P25 modified by Au-Cu alloy nanoparticles as thin film exhibits, for CO2 reduction by water under sun simulated light, a rate of methane production above 2000 ?mol (g of photocatalyst)(-1) h(-1). Although evolution of hydrogen is observed and O2 and ethane detected, the selectivity of conduction band electrons for methane formation is almost complete, about 97%. This photocatalytic behavior is completely different from that measured for Au/P25 (hydrogen evolution) and Cu/P25 (lower activity, but similar methane selectivity). Characterization by TEM, XPS, and UV-vis spectroscopy shows that Au and Cu are alloyed in the nanoparticles. FT-IR spectroscopy and chemical analysis have allowed one to detect on the photocatalyst surface the presence of CO2(•-), Cu-CO, and elemental C. Accordingly, a mechanism in which the role of Au is to respond under visible light and Cu binds to CO and directs the reduction pathway is proposed. PMID:25329687

Nea?u, ?tefan; Maciá-Agulló, Juan Antonio; Concepción, Patricia; Garcia, Hermenegildo

2014-11-12

77

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

E-print Network

Nanocomposite of a chromium Prussian blue with TiO2. Redox reactions and the synthesis of Prussian is a nanocomposite of CrII [CrIII (CN)6]0.67 � xH2O and TiO2 in the ratio of 1­1.6. These results suggest that Ti; Hexacyanometalate; Magnetic; Hydrolysis; Redox; Nanocomposite 1. Introduction In the 1990s, an entirely new class

Girolami, Gregory S.

78

10BaF2:NaF, Na3AlF6/TiO2 composite as a novel visible-light-driven photocatalyst based on upconversion emission  

NASA Astrophysics Data System (ADS)

A rare-earth free upconversion luminescent material, 10BaF2:NaF, Na3AlF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light (550 nm—610 nm) into ultraviolet light (290 nm—350 nm), and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF2:NaF, Na3AlF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation (? > 515 nm). The results show that 10BaF2:NaF, Na3AlF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 ?mol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF2:NaF, Na3AlF6/TiO2 is proposed.

Liu, En-Zhou; Fan, Jun; Hu, Xiao-Yun; Hou, Wen-Qian; Dai, Hong-Zhe

2012-04-01

79

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

80

Synthesis of BiVO4/TiO2 composites and evaluation of their photocatalytic activity under indoor illumination.  

PubMed

BiVO4/TiO2 composites with different weight ratios have been prepared by coprecipitation-based reactions followed by either thermal or hydrothermal treatment with the aim of evaluating the TiO2 photosensitization by BiVO4. The obtained materials present in all cases the desired monoclinic phase of BiVO4 and anatase phase of TiO2. Visible light absorption increased with increasing amount of bismuth vanadate. XPS results reveal the surface enrichment of Ti with respect to the bulk composition in samples characterised by a higher content of BiVO4. The photocatalytic activity of the prepared materials was tested for the degradation of isopropanol in the gas phase under indoor illumination conditions. Although none of the composites was able to improve the activity of TiO2, the low BiVO4 containing samples appear as more suitable for further synthesis tuning. PMID:24535667

Longo, Giulia; Fresno, Fernando; Gross, Silvia; Štangar, Urška Lavren?i?

2014-10-01

81

Synthesis of TiO 2 nanostructured reservoir with temozolomide: Structural evolution of the occluded drug  

NASA Astrophysics Data System (ADS)

Sol-gel synthesized nanostructured TiO 2 matrix were produced with different channel sizes, where drug are immersed, producing a reservoir with Temozolomide (TMZ). This drug is particularly important for the treatment of cancer tumors, which are fundamentally a consequence of the uncontrolled reproduction of human cell. In this way the chemotherapy plays an important role in the treatment of both recurrent and newly diagnosed patients. In the handling of brain tumors TMZ has been discovered as a recent and efficient second generation drug employed in the control of advanced brain gliomas, and it is a welcome addition. Its active component binds to the cancerous DNA cells, thus preventing their disordered growth, destroying them. In this work, we report the synthesis of TiO 2 nanostructured reservoir with TMZ, focusing the effort to the understanding of structural effects on the TMZ configuration by using nuclear magnetic resonance, Raman and IR spectroscopy methods. Our results establish that TMZ molecules are quite sensible to chemical processes and it produces the activation of the molecule, which is followed and understood with help of quantum molecular simulation methods. The study of the molecules allows determining the conditions that produce the activation and chemical selectivity of the molecules, which determines the conditions of synthesis. This information gives parameters for the reservoir structural and chemical optimization.

López, T.; Sotelo, J.; Navarrete, J.; Ascencio, J. A.

2006-10-01

82

Synthesis and photocatalytic properties of lanthanum doped anatase TiO 2 coated Fe 3 O 4 composites  

Microsoft Academic Search

A composite photocatalyst (La\\/TiO2\\/Fe3O4) with a lanthanum doped TiO2 (La\\/TiO2) shell and a magnetite core was prepared by coating photoactive La\\/TiO2 onto a magnetic Fe3O4 core. The morphological, structural, and optical properties of as-prepared samples were characterized by transmission electron\\u000a microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of lanthanum content on the photocatalytic\\u000a properties was studied,

Zhongliang Shi; Xiaoyan Zhang; Shuhua Yao

2011-01-01

83

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...

84

Nonaqueous synthesis of TiO2 nanocrystals using TiF4 to engineer morphology, oxygen vacancy concentration, and photocatalytic activity.  

PubMed

Control over faceting in nanocrystals (NCs) is pivotal for many applications, but most notably when investigating catalytic reactions which occur on the surfaces of nanostructures. Anatase titanium dioxide (TiO(2)) is one of the most studied photocatalysts, but the shape dependence of its activity has not yet been satisfactorily investigated and many questions still remain unanswered. We report the nonaqueous surfactant-assisted synthesis of highly uniform anatase TiO(2) NCs with tailorable morphology in the 10-100 nm size regime, prepared through a seeded growth technique. Introduction of titanium(IV) fluoride (TiF(4)) preferentially exposes the {001} facet of anatase through in situ release of hydrofluoric acid (HF), allowing for the formation of uniform anatase NCs based on the truncated tetragonal bipyramidal geometry. A method is described to engineer the percentage of {001} and {101} facets through the choice of cosurfactant and titanium precursor. X-ray diffraction studies are performed in conjunction with simulation to determine an average NC dimension which correlates with results obtained using electron microscopy. In addition to altering the particle shape, the introduction of TiF(4) into the synthesis results in TiO(2) NCs that are blue in color and display a broad visible/NIR absorbance which peaks in the infrared (?(max) ? 3400 nm). The blue color results from oxygen vacancies formed in the presence of fluorine, as indicated by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) studies. The surfactants on the surface of the NCs are removed through a simple ligand exchange procedure, allowing the shape dependence of photocatalytic hydrogen evolution to be studied using monodisperse TiO(2) NCs. Preliminary experiments on the photoreforming of methanol, employed as a model sacrificial agent, on platinized samples resulted in high volumes of evolved hydrogen (up to 2.1 mmol h(-1) g(-1)) under simulated solar illumination. Remarkably, the data suggest that, under our experimental conditions, the {101} facets of anatase are more active than the {001}. PMID:22444667

Gordon, Thomas R; Cargnello, Matteo; Paik, Taejong; Mangolini, Filippo; Weber, Ralph T; Fornasiero, Paolo; Murray, Christopher B

2012-04-18

85

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

86

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

EPA Science Inventory

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

87

Silicon carbide coated with TiO2 with enhanced cobalt active phase dispersion for Fischer-Tropsch synthesis.  

PubMed

The introduction of a thin layer of TiO2 on ?-SiC allows a significant improvement of the cobalt dispersion. This catalyst exhibits an excellent and stable catalytic activity for the Fischer-Tropsch synthesis (FTS) with high C5+ selectivity, which contributes to the development of a new active catalyst family in the gas-to-liquid process. PMID:25387082

Liu, Yuefeng; Florea, Ileana; Ersen, Ovidiu; Pham-Huu, Cuong; Meny, Christian

2015-01-01

88

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

89

Characterization of the thin layer photocatalysts TiO2 and V2O5- and Fe2O3- doped TiO2 prepared by the sol–gel method  

NASA Astrophysics Data System (ADS)

The catalysts TiO2 and TiO2 doped with Fe and V were prepared using the sol–gel method. TiO2-modified samples were obtained in the form of a thick film on pyrex glass sticks and tubes and were used as catalysts in the gas phase photo-oxidation of p-xylene. The physico-chemical characteristics of the catalysts were determined using the methods of Brunauer–Emmett–Teller adsorption, x-ray diffraction, and infrared, ultraviolet and visible and Raman spectroscopies. The experimental results show that the introduction of V did not expand the region of light absorption, but slightly reduced the size of the TiO2 particles, and reduced the number of OH-groups, which should decrease the photocatalytic activity and efficiency of the obtained catalysts compared to those of pure TiO2. The Fe-doped TiO2 samples, in contrast, are characterized by an extension of the spectrum of photon absorption to the visible region with wavenumbers ? up to 464 nm and the values of their band gap energy decreased to lower quantities (up to 2.67 eV), therefore they should have higher catalytic activity and conversion efficiency of p-xylene in the visible region than the original sample. For these catalysts, a combined utilization of radiation by ultraviolet (? = 365 nm) and visible (? = 470 nm) light increased the activity and the yield in p-xylene conversion by a factor of around 2–3, as well as making these quantities more stable in comparison with those of TiO2–P25 Degussa.

Loc Luu, Cam; Nguyen, Quoc Tuan; Thoang Ho, Si; Nguyen, Tri

2013-09-01

90

Interaction of ZnII porphyrin with TiO2 nanoparticles: from mechanism to synthesis of hybrid nanomaterials.  

PubMed

The mechanism of interaction of Zn porphyrin (ZnPP) with TiO2 surfaces is investigated with a view to optimizing the synthesis of hybrid nanomaterials. The strategy consists of studying the adsorption of ZnPP on TiO2 flat surfaces by taking advantage of complementary surface characterization techniques. Combining a detailed X-ray photoelectron spectroscopic analysis with AFM imaging allows ZnPP-surface and ZnPP intermolecular interactions to be discriminated. Probing the adsorption of ZnPP on TiO2 nanoparticles (NPs) reveals the dominant role of ZnPP-mediated interactions, which are associated with the formation of ZnPP multilayers and/or with the state of aggregation of NPs. These preliminary investigations provide a guideline to synthesizing a novel ZnPP-TiO2 hybrid nanomaterial in a one-step protocol. In this material, ZnPP molecules are presumably involved in the TiO2 lattice rather than on the NP surface. Furthermore, ZnPP molecules preserve their electronic properties within the TiO2 NPs, and this makes the ZnPP-TiO2 hybrid nanomaterial an excellent candidate for nanomedicine and related applications, such as localization of nanoparticles in cells and tissues or in photodynamic therapy. PMID:23821481

Spadavecchia, Jolanda; Méthivier, Christophe; Landoulsi, Jessem; Pradier, Claire-Marie

2013-08-01

91

Synthesis and optimizable electrochemical performance of reduced graphene oxide wrapped mesoporous TiO2 microspheres  

NASA Astrophysics Data System (ADS)

A facile microwave solvothermal process is developed to prepare an anatase TiO2 anode material that maintains multiple properties including high surface area, high crystallinity, uniform mesoporous, perfect microspheres and uniform particle size. Using this fine anatase TiO2 product, a TiO2/RGO (RGO: reduced graphene oxide) hybrid material is prepared under UV-light irradiation. Incorporation of RGO improves the electrochemical kinetics of the TiO2 microspheres, which results in superior electrochemical performance in terms of specific capacity, rate capability and cycle stability. The material shows a discharge capacity of 155.8 mA h g-1 at the 5 C rate. Even at the 60 C rate, a high discharge capacity of 83.6 mA h g-1 is still obtained which is two times higher than that of pristine mesoporous TiO2.A facile microwave solvothermal process is developed to prepare an anatase TiO2 anode material that maintains multiple properties including high surface area, high crystallinity, uniform mesoporous, perfect microspheres and uniform particle size. Using this fine anatase TiO2 product, a TiO2/RGO (RGO: reduced graphene oxide) hybrid material is prepared under UV-light irradiation. Incorporation of RGO improves the electrochemical kinetics of the TiO2 microspheres, which results in superior electrochemical performance in terms of specific capacity, rate capability and cycle stability. The material shows a discharge capacity of 155.8 mA h g-1 at the 5 C rate. Even at the 60 C rate, a high discharge capacity of 83.6 mA h g-1 is still obtained which is two times higher than that of pristine mesoporous TiO2. Electronic supplementary information (ESI) available: TGA of TiO2/RGO sample, XPS and AFM of the graphene oxide, SEM of TiO2 nanoparticles, SEM of the TiO2 and TiO2/RGO after cycles, rate performance of RGO, rate performance of TiO2/RGO with different contents of RGO. See DOI: 10.1039/c3nr06393c

Yan, Xiao; Li, Yanjuan; Du, Fei; Zhu, Kai; Zhang, Yongquan; Su, Anyu; Chen, Gang; Wei, Yingjin

2014-03-01

92

Conduction-Band Tailing of Ce-Doped TiO2 Visible-Light-Driven Photocatalyst: The Essential Role of Oxygen Vacancy  

NASA Astrophysics Data System (ADS)

The varied electronic structure of Ce-doped TiO2 was probed with x-ray absorption spectra at O K-, Ce L-, Ti L-edge, and Ti K-edges. We expose the essential role of existed oxygen vacancies in band gap narrowing of Ce-doped TiO2 and deduce the mechanism in detail by charge transfer and covalent hybridization. Oxygen vacancies would release electrons behind the Ce 4f state, inducing the mixing valence characteristic of the Ce ions (Ce3+/Ce4+) doped in TiO2. Oxygen defect state thus hybridizes with Ce 4f state (Ce3+/Ce4+) constructing an impurity band below the conduction band, causing a tailing of the conduction band minimum and narrowing of band gap of TiO2. As Ce-doped TiO2 annealed in an oxidized atmosphere, filling up oxygen vacancies, the absorption edge in the O K-edge x-ray absorption spectrum is shifted to higher energy as compared with that for the un-treated sample, indicating the drastic diminution of band-gap-narrowing effect. This study evidences the existed oxygen vacancy is critical to mediate the impurity band formation and band gap narrowing of Ce-doped TiO2. The phenomenon should also be emphasized in TiO2 doped with other elements.

Chen, Shi Wei; Lee, Jenn Min; Chiang, Sunny; Haw, Shu Chih; Liang, Yu Chia; Lu, Kueih Tzu; Pao, Chih Wen; Lee, Jyh Fu; Tang, Mau Tsu; Chen, Jin Ming

2011-11-01

93

Double-doped TiO2 nanoparticles as an efficient visible-light-active photocatalyst and antibacterial agent under solar simulated light  

NASA Astrophysics Data System (ADS)

Silver and nitrogen doped TiO2 nanoparticles (NPs) were synthesized via sol-gel method. The physicochemical properties of the achieved NPs were characterized by various methods including X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultra violet-visible absorption spectroscopy (UV-vis). Both visible-light photocatalytic activity and antimicrobial properties were successfully demonstrated for the degradation of Rhodamine B (Rh. B.), as a model dye, and inactivation of Escherichia coli (E. coli), as a representative of microorganisms. The concentration of the employed dopant was optimized and the results revealed that the silver and nitrogen doped TiO2 NPs extended the light absorption spectrum toward the visible region and significantly enhanced the photodegradation of model dye and inactivation of bacteria under visible-light irradiation while double-doped TiO2 NPs exhibited highest photocatalytic and antibacterial activity compared with single doping. The significant enhancement in the photocatalytic activity and antibacterial properties of the double doped TiO2 NPs, under visible-light irradiation, can be attributed to the generation of two different electronic states acting as electron traps in TiO2 and responsible for narrowing the band gap of TiO2 and shifting its optical response from UV to the visible-light region.

Ashkarran, Ali Akbar; Hamidinezhad, Habib; Haddadi, Hedayat; Mahmoudi, Morteza

2014-05-01

94

One-pot synthesis of peacock-shaped TiO2 light scattering layer with TiO2 nanorods film for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A titanium dioxide (TiO2) film, showing distinctive functions and morphology, was prepared using the hydrothermal method by controlling the ratio of HCl:CH3COOH in acidic medium. A one-dimensional (1-D) TiO2 nanorod (NR) film was synthesized with a length of 2 ?m using a 1:2 ratio of HCl:CH3COOH, whereas a 1-D TiO2 NR film with peacock shaped TiO2 nanobundles as a light scattering layer (LSL) was acquired by employing a 2:1 ratio of HCl:CH3COOH. This LSL exhibited remarkable dual functions with respect to high light harvesting, which was attributable to the large surface area of the micrometer-sized TiO2 nanobundles, consisting of small-sized TiO2 NRs of 30-40 nm in diameter and a light scattering effect in the long wavelength region of 550-700 nm. Accordingly, the dual functions of the LSL resulted in a sharp increase in conversion efficiency (3.93%) that was about twice that (1.49%) of TiO2 NR film synthesized using a 1:2 ratio of HCl:CH3COOH. In particular, a considerably enhanced short-circuit photocurrent (Jsc) was mainly responsible for the resulting increase in overall efficiency with a moderate increase in fill factor and slightly reduced open-circuit voltage.

Kim, Hyun Sik; Kim, Young-Jea; Lee, Wonjoo; Kang, Soon Hyung

2013-05-01

95

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

96

Synthesis of TiO2 nanosheets via an exfoliation route assisted by a surfactant.  

PubMed

Titanium dioxide (TiO2) is an important material for photovoltaics, photocatalysis, sensors and lithium ion batteries. Various morphologies of TiO2 nanomaterials have been synthesized, including zero-dimensional (0D) nanoparticles, one-dimensional (1D) nanowires and nanotubes, as well as three-dimensional (3D) nanostructures. But the two-dimensional (2D) TiO2 nanostructures, which are expected to have more promising properties and applications, are rarely reported. Herein, we report a surfactant-assisted exfoliation method to synthesize TiO2 2D nanosheets. It has been revealed that tetrabutylammonium hydroxide (hereafter TBAOH) as a surfactant plays a crucial role in retaining the 2D nanosheet structures. Compared with TiO2 nanotubes and anatase TiO2 nanoparticles, the as-prepared TiO2 single layered nanosheets delivered much higher capacities as anodes of the coin-type Li ion cells, with a reversible capacity of 82.2 mA h g(-1) at the 630th cycle at a current density of 2000 mA g(-1). PMID:24958361

Leng, Mei; Chen, Yu; Xue, Junmin

2014-08-01

97

Synthesis of anatase TiO 2 nanoparticles with high temperature stability and photocatalytic activity  

NASA Astrophysics Data System (ADS)

A fast and easy method for preparing pure and stable nano-sized TiO 2 anatase phase, using mild hydrothermal conditions, is presented. The precursor is obtained via precipitation route using TiCl 3 as starting material. All samples synthesized are characterized by XRD, TEM and low temperature N 2 adsorption measurements. The photocatalytic behaviour of the prepared pure TiO 2 anatase samples was studied regarding the degradation of diquat aqueous solutions. The prepared materials showed a higher photocatalytic activity when compared with the performance of commercial TiO 2.

Castro, A. L.; Nunes, M. R.; Carvalho, A. P.; Costa, F. M.; Florêncio, M. H.

2008-05-01

98

Photoelectrolysis of water using heterostructural composite of TiO2 nanotubes and nanoparticles  

NASA Astrophysics Data System (ADS)

Efficient photoelectrolysis of water to generate hydrogen (H2) can be carried out by designing photocatalysts with good absorption as well as charge transport properties. One dimensional (1D), self-organized titania (TiO2) nanotubes are known to have excellent charge transport properties and TiO2 nanoparticles (NPs) are good for better photon absorption. This paper describes the synthesis of a composite photocatalyst combining the above two properties of TiO2 nanocomposites with different morphologies. TiO2 NPs (5-9 nm nanocrystals form 500-700 nm clusters) have been synthesized from TiCl4 precursor on TiO2 nanotubular arrays (~80 nm diameter and ~550 nm length) synthesized by the sonoelectrochemical anodization method. This TiO2 nanotube-nanoparticle composite photoanode has enabled obtaining of enhanced photocurrent density (2.2 mA cm-2) as compared with NTs (0.9 mA cm-2) and NPs (0.65 mA cm-2) alone.

Das, Prajna P.; Mohapatra, Susanta K.; Misra, Mano

2008-12-01

99

Comparison of Au and TiO2 based catalysts for the synthesis of chalcogenide nanowires  

NASA Astrophysics Data System (ADS)

We present a comparative study of TiO2-based and Au catalysts for the physical vapor deposition of (Bi1-xSbx)2Se3 topological insulator nanowires. The standard Au nanoparticle catalyst was compared to five TiO2 nanoparticle based catalysts (anatase, rutile, P-25, high surface area anatase, and TiO2 supported Au particles). The use of Au nanoparticles seriously harms the properties of nanowires, thereby limiting their application. In contrast, TiO2 based catalysts lead to the residue-free growth of nanowires with a higher degree of crystallinity. Homogeneous nanowire ensembles are achieved with the mixed phase P-25 catalyst, and a possible growth mechanism is proposed.

Schönherr, P.; Prabhakaran, D.; Jones, W.; Dimitratos, N.; Bowker, M.; Hesjedal, T.

2014-06-01

100

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

101

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

102

Synthesis and photocatalytic activity of graphene based doped TiO2 nanocomposites  

NASA Astrophysics Data System (ADS)

The nanocomposites of reduced graphene oxide based nitrogen doped TiO2 (N-TiO2-RGO) and reduced graphene oxide based nitrogen and vanadium co-doped TiO2 (N, V-TiO2-RGO) were prepared via a facile hydrothermal reaction of graphene oxide and TiO2 in a water solvent. In this hydrothermal treatment, the reduction of graphene oxide and the intimate contact between nitrogen doped TiO2 (N-TiO2) or nitrogen and vanadium co-doped TiO2 (N,V-TiO2) and the RGO sheet is achieved simultaneously. Both N-TiO2-RGO and N,V-TiO2-RGO nanocomposites exhibit much higher visible light photocatalytic activity than N-TiO2 and N,V-TiO2, and the order of visible light photocatalytic activity is N,V-TiO2-RGO > N-TiO2-RGO > N,V-TiO2 > N-TiO2 > TiO2. According to the characterization, the enhanced photocatalytic activity of the nanocomposites is attributed to reasons, such as enhancement of adsorption of pollutants, light absorption intensity, minimizing the recombination of photoinduced electrons and holes and more excited states of these nanocomposites under visible light irradiation. Overall, this work provides a more marked contrast of graphene based semiconductor nanocomposites and a more comprehensive explanation of the mechanism.

Gu, Yongji; Xing, Mingyang; Zhang, Jinlong

2014-11-01

103

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

104

Submerged arc spray synthesis of TiO2 nanoparticles with desired form sphericity using process characterization and optimization.  

PubMed

This article presents a study on process characterization and optimization of the metal nanoparticle fabrication process known as the submerged arc spray nanoparticle synthesis system (SANSS) for obtaining desired geometric sphericity of nanoparticles. The geometric shape characteristics of nanoparticles pose significant impact on innovative product and process design. The sphericity and surface roughness of prepared TiO2 nanoparticles can vary widely and are influenced by the process parameters being employed in the SANSS. To improve this, an in-situ nanofluid sampling and measurement approach was developed to analyze the particle shape characteristics and characterize the nanoparticle synthesis process. The particle shape contours obtained from FE-SEM and TEM were employed to quantify the TiO2 nanoparticle sphericity and analyze the effect of process parameters on particle roundness. The optimized process parameters were identified using the Taguchi method. Our results proved that the average sphericity of TiO2 particles prepared using the optimized process parameters was effectively improved up to three folds. PMID:18464365

Chen, Liang-Chia; Ho, Chie-Chan

2008-02-01

105

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

106

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

PubMed

A novel scaly Sn3O4/TiO2 nanobelt heterostructured photocatalyst was fabricated via a facile hydrothermal route. The scaly Sn3O4 nanoflakes can be synthesized in situ and assembled on surface coarsened TiO2 nanobelts through a hydrothermal process. The morphology and distribution of Sn3O4 nanoflakes can be well-controlled by simply tuning the Sn/Ti molar ratio of the reactants. Compared with single phase nanostructures of Sn3O4 and TiO2, the scaly hybrid nanobelts exhibited markedly enhanced photoelectrochemical (PEC) response, which caused higher photocatalytic hydrogen evolution even without the assistance of Pt as a co-catalyst, and enhanced the degradation ability of organic pollutants under both UV and visible light irradiation. In addition to the increased exposure of active facets and broad light absorption, the outstanding performance is ascribed to the matching energy band structure between Sn3O4 and TiO2 at the two sides of the heterostructure, which efficiently reduces the recombination of photo-excited electron-hole pairs and prolongs the lifetime of charge carriers. Both photocatalytic assessment and PEC tests revealed that Sn3O4/TiO2 heterostructures with a molar ratio of Sn/Ti of 2/1 exhibited the highest photocatalytic activity. This study provides a facile and low-cost method for the large scale production of Sn3O4 based materials in various applications. PMID:25611372

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

2015-02-01

107

Light-Induced Efficient Molecular Oxygen Activation on a Cu(II)-Grafted TiO2/Graphene Photocatalyst for Phenol Degradation.  

PubMed

An efficient photocatalytic process involves two closely related steps: charge separation and the subsequent surface redox reaction. Herein, a ternary hybrid photocatalytic system was designed and fabricated by anchoring Cu(II) clusters onto a TiO2/reduced graphene oxide (RGO) composite. Microscopic and spectroscopic characterization revealed that both TiO2 nanoparticles and Cu(II) clusters were highly dispersed on a graphene sheet with intimate interfacial contact. Compared with pristine TiO2, the TiO2/RGO/Cu(II) composite yielded an almost 3-fold enhancement in the photodegradation rate toward phenol degradation under UV irradiation. Electron spin resonance (ESR) spectra and electrochemical measurements demonstrated that the improved photocatalytic activity of this ternary system benefitted from the synergetic effect between RGO and Cu(II), which facilitates the interfacial charge transfer and simultaneously achieves in situ generation of H2O2 via two-electron reduction of O2. These results highlight the importance to harmonize the charge separation and surface reaction process in achieving high photocatalytic efficiency for practical application. PMID:25556692

Zhang, Hui; Guo, Liang-Hong; Wang, Dabin; Zhao, Lixia; Wan, Bin

2015-01-28

108

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

109

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

110

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

111

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

112

Cytotoxicity of TiO2 nanoparticles to mussel hemocytes and gill cells in vitro: Influence of synthesis method, crystalline structure, size and additive.  

PubMed

Abstract Increasing the production and applications of TiO2 nanoparticles (NPs) has led to grow concerns about the consequences for the environment. In this study, we investigated the effects of a set of TiO2 NPs on the viability of mussel hemocytes and gill cells using neutral red and thiazolyl tetrazolium bromide assays. For this, we compared the cytotoxicity of TiO2 NPs (0.1-100?mg Ti/L) produced by different techniques: rutile NPs (60?nm) produced by milling and containing disodium laureth sulfosuccinate (DSLS), rutile NPs (10, 40 and 60?nm) produced by wet chemistry and anatase/rutile NPs (?100?nm) produced by plasma synthesis. The commercially available P25 anatase/rutile NPs (10-20?nm) were also tested. Exposures were performed in parallel with their respective bulk forms and the cytotoxicity of the additive DSLS was also tested. Z potential values in distilled water indicated different stabilities depending on the NP type and all NPs tested formed agglomerates/aggregates in cell culture media. In general, TiO2 NPs showed a relatively low and dose-dependent toxicity for both cell models with the two assays tested. NPs produced by milling showed the highest effects, probably due to the toxicity of DSLS. Size-dependent toxicity was found for NPs produced by wet chemistry (10?nm?>?40?nm and 60?nm). All TiO2 NPs tested were more toxic than bulk forms excepting for plasma produced ones, which were the least toxic TiO2 tested. The mixture bulk anatase/rutile TiO2 was more toxic than bulk rutile TiO2. In conclusion, the toxicity of TiO2 NPs varied with the mode of synthesis, crystalline structure and size of NPs and can also be influenced by the presence of additives in the suspensions. PMID:25188678

Katsumiti, Alberto; Berhanu, Deborah; Howard, Kieren T; Arostegui, Inmaculada; Oron, Miriam; Reip, Paul; Valsami-Jones, Eugenia; Cajaraville, Miren P

2014-09-01

113

In situ synthesis of TiO2/polyethylene terephthalate hybrid nanocomposites at low temperature  

NASA Astrophysics Data System (ADS)

TiO2 nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl4 in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 °C. Nanocrystal cellulose (NCC) pre-grafted on PET fabric acted as hydrophilic substrate and morphology inducing agent to promote the nucleation and crystal growth of TiO2. Detailed information on the synthetic process was presented. The resulting samples were characterized using FE-SEM, EDS, ATR-IR, Raman microscopy, XRD and TG analysis. The photocatalytic activity of the samples was evaluated by the degradation of orange methyl under solar light. Characteristic results indicate that rutile TiO2 nanoflowers have grown abundantly on PET non-woven fabric, and the established hydrogen bonding strengthens the interfacial interaction between the inorganic particles and the polymeric substrates. The methyl orange decoloration test under natural solar light demonstrates that this TiO2/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

Peng, Xinyan; Ding, Enyong; Xue, Feng

2012-06-01

114

TiO2-Al2O3 binary mixed oxide surfaces for photocatalytic NOx abatement  

NASA Astrophysics Data System (ADS)

TiO2-Al2O3 binary oxide surfaces were utilized in order to develop an alternative photocatalytic NOx abatement approach, where TiO2 sites were used for ambient photocatalytic oxidation of NO with O2 and alumina sites were exploited for NOx storage. Chemical, crystallographic and electronic structure of the TiO2-Al2O3 binary oxide surfaces were characterized (via BET surface area measurements, XRD, Raman spectroscopy and DR-UV-Vis Spectroscopy) as a function of the TiO2 loading in the mixture as well as the calcination temperature used in the synthesis protocol. 0.5 Ti/Al-900 photocatalyst showed remarkable photocatalytic NOx oxidation and storage performance, which was found to be much superior to that of a Degussa P25 industrial benchmark photocatalyst (i.e. 160% higher NOx storage and 55% lower NO2(g) release to the atmosphere). Our results indicate that the onset of the photocatalytic NOx abatement activity is concomitant to the switch between amorphous to a crystalline phase with an electronic band gap within 3.05-3.10 eV; where the most active photocatalyst revealed predominantly rutile phase together and anatase as the minority phase.

Soylu, Asli Melike; Polat, Meryem; Erdogan, Deniz Altunoz; Say, Zafer; Y?ld?r?m, Cansu; Birer, Özgür; Ozensoy, Emrah

2014-11-01

115

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

116

The comparative photodegradation activities of pentachlorophenol (PCP) and polychlorinated biphenyls (PCBs) using UV alone and TiO2-derived photocatalysts in methanol soil washing solution.  

PubMed

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

117

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

118

Synthesis and characterization of La2O3/TiO2-xFx and the visible light photocatalytic oxidation of 4-chlorophenol.  

PubMed

In this work, we investigated the synergetic effect of La and F on the visible light photocatalytic activity of TiO(2) catalysts. La(2)O(3)/TiO(2-x)F(x) photocatalysts were prepared by a simple sol-gel process using tetrabutyl titanate (TBT), La(NO(3))(3) and NH(4)F as precursors. XPS results revealed that La(2)O(3) accumulated on the surface of TiO(2), which enhanced the surface area of TiO(2) and inhibited the recombination of electron-hole pairs. It also showed that two kinds of fluorine species were formed and these increased the acid active sites and enhanced the oxidation potential of the photogenerated holes in the valance band. UV-vis diffuse reflection spectra of La(2)O(3)/TiO(2-x)F(x) showed that intraband gap states were present and these are probably responsible for its absorption of visible light while the intrinsic absorption band was shifted slightly to a longer wavelength. At molar ratios of La and F to Ti of 1.5:100 and 5:100 and after calcination at 500 degrees C, the degradation rate of 4-chlorophenol (4-CP) over the sample was about 1.2-3.0 times higher than that of the other doped samples and undoped TiO(2). The total organic carbon (TOC) removal rates of 4-CP showed that 4-CP was mineralized efficiently in the presence of the sample under visible light illumination. PMID:20149531

Cao, Guangxiu; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2010-06-15

119

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

120

Synthesis of magnetically separable Ag3PO4/TiO2/Fe3O4 heterostructure with enhanced photocatalytic performance under visible light for photoinactivation of bacteria.  

PubMed

Silver orthophosphate (Ag3PO4) is a low-band-gap photocatalyst that has received considerable research interest in recent years. In this work, the magnetic Ag3PO4/TiO2/Fe3O4 heterostructured nanocomposite was synthesized. The nanocomposite was found to exhibit markedly enhanced photocatalytic activity, cycling stability, and long-term durability in the photodegradation of acid orange 7 (AO7) under visible light. Moreover, the antibacterial film prepared from Ag3PO4/TiO2/Fe3O4 nanocomposite presented excellent bactericidal activity and recyclability toward Escherichia coli (E. coli) cells under visible-light irradiation. In addition to the intrinsic cytotoxicity of silver ions, the elevated bactericidal efficiency of Ag3PO4/TiO2/Fe3O4 can be largely attributed to its highly enhanced photocatalytic activity. The photogenerated hydroxyl radicals and superoxide ions on the formed Ag/Ag3PO4/TiO2 interfaces cause considerable morphological changes in the microorganism's cells and lead to the death of the bacteria. PMID:25140916

Xu, Jing-Wen; Gao, Zhi-Da; Han, Kun; Liu, Yongmin; Song, Yan-Yan

2014-09-10

121

Self-organized TiO2 nanotube arrays: synthesis by anodization in an ionic liquid and assessment of photocatalytic properties.  

PubMed

Self-organized TiO(2) nanotube (NT) arrays were produced by anodization in ethylene glycol (EG) electrolytes containing 1-n-butyl-3-methyl-imidazolium tetrafluoroborate (BMI.BF(4)) ionic liquid and water. The morphology of the as-formed NTs was considerably affected by changing the anodization time, voltage, and water and ionic liquid electrolyte concentrations. In general, a nanoporous layer was formed on the top surface of the TiO(2) NTs, except for anodization at 100 V with 1 vol % of BMI.BF(4), where the NT's mouth was revealed. The length and bottom diameter of the NTs as well as the pore diameter of the top layer showed a linear relationship with increased anodization voltage. These TiO(2) NTs were tested as photocatalysts for methyl orange photodegradation and hydrogen evolution from water/methanol solutions by UV light irradiation. The results show that the TiO(2) NTs obtained by anodization in EG/H(2)O/BMI.BF(4) electrolytes are active and efficient for both applications. PMID:21443251

Wender, Heberton; Feil, Adriano F; Diaz, Leonardo B; Ribeiro, Camila S; Machado, Guilherme J; Migowski, Pedro; Weibel, Daniel E; Dupont, Jairton; Teixeira, Sérgio R

2011-04-01

122

Microemulsion-based synthesis of nanoscale TiO 2 hollow spheres  

NASA Astrophysics Data System (ADS)

Nanoscale TiO 2 hollow spheres are prepared based on gelatine-filled reversed microemulsions. The resulting nanomaterial exhibits an outer diameter of 25-35 nm, a thickness of the sphere wall of 4-6 nm and an inner cavity of 15-20 nm in diameter. The as-prepared hollow spheres are characterized based on different electron microscopic techniques, infrared spectroscopy and optical spectroscopy. Thermogravimetry, X-ray powder diffraction and sorption measurements according to the Brunauer-Emmett-Teller analysis are used to elucidate the thermal properties as well as the specific surface of the hollow spheres. Finally, the photocatalytic properties of as-prepared TiO 2 hollow spheres are studied.

Zurmühl, C.; Popescu, R.; Gerthsen, D.; Feldmann, C.

2011-08-01

123

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

124

Plasma-spraying synthesis of high-performance photocatalytic TiO2 coatings  

NASA Astrophysics Data System (ADS)

Anatase (A-) TiO2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO2 without HAp, TiO2 + 10mass%HAp, and TiO2+30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO2 powder by spray granulation in order to facilitate adsorption of acetaldehyde and bacteria. The crystal structure was almost completely maintained during the plasma spray process. HAp enhanced the decomposition of acetaldehyde and bacteria by promoting adsorption. A 10mass% HAp content was the most effective for decomposing acetaldehyde when plasma preheating of the PBS was not carried out before the plasma spraying. The plasma preheating of PBS increased the yield rate of the spray process and facilitated the decomposition of acetaldehyde by A-TiO2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed.

Takahashi, Yasuo; Shibata, Yoshitaka; Maeda, Masakatsu; Miyano, Yasuyuki; Murai, Kensuke; Ohmori, Akira

2014-08-01

125

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

126

Synthesis, characterization and photocatalytic activity of fluorine doped TiO2 nanoflakes synthesized using solid state reaction method.  

PubMed

Fluorine doped TiO2 were synthesized by solid state reaction method. Optical and structural properties of fluorine doped TiO2 were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis diffusion reflectance spectroscopy and scanning electron microscopic techniques. The prepared fluorine doped TiO2 was smaller in size with respect to pure TiO2 and it is tetragonal in crystalline structure. Nanoflakes like structure of pure and fluorine doped TiO2 was confirmed from SEM image. Fluorine doped TiO2 shows smaller band gap, high strain and dislocation density when compared to pure TiO2. It also has higher photocatalytic activity with respect to pure TiO2. PMID:24200650

Umadevi, M; Parimaladevi, R; Sangari, M

2014-01-01

127

Combustion synthesis of TiO2-Al-C/Al2O3 mixture in the presence of oxygen  

NASA Astrophysics Data System (ADS)

Quasi-adiabatic combustion synthesis of optimized 3TiO2+4Al+(3+x)C mixture in the presence of oxygen was carried out to produce TiC-Al2O3 composite. The influence of Al2O3 diluent in combusted (3TiO2+4Al+3.5C+yAl2O3) reactant mixture was investigated. Thermodynamics studies of the system shown that self-sustaining (SS) mode of combustion wave propagation can occur for large amounts of diluents (y = 2.5). Diluent reduced combustion temperature and rate of reaction kinetics. Oxide (Ti2O, Ti3O5) and intermetallic (AlTi2) phases were detected when extra Al2O3 was added to the mixture. Semi-quantitative XRD analysis was employed to study the phase formation of products for various amounts of diluent content in the mixture. The boundary between SS and non-SS modes of wave propagation was determined. Adding Al2O3 diluent slightly increased density that resulted in better thermal conductivity.

Rahbari G, R.; Saw, L. H.; Hamdi, M.; Yahya, R.

2009-03-01

128

In Situ Synthesis of Graphene Molecules on TiO2: Application in Sensitized Solar Cells.  

PubMed

We present a method for preparation of graphene molecules (GMs), whereby a polyphenylene precursor functionalized with surface anchoring groups, preadsorbed on surface of TiO2, is oxidatively dehydrogenated in situ via a Scholl reaction. The reaction, performed at ambient conditions, yields surface adsorbed GMs structurally and electronically equivalent to those synthesized in solution. The new synthetic approach reduces the challenges associated with the tendency of GMs to aggregate and provides a convenient path for integration of GMs into optoelectronic applications. The surface synthesized GMs can be effectively reduced or oxidized via an interfacial charge transfer and can also function as sensitizers for metal oxides in light harvesting applications. Sensitized solar cells (SSCs) prepared from mesoscopic TiO2/GM films and an iodide-based liquid electrolyte show photocurrents of ?2.5 mA/cm(2), an open circuit voltage of ?0.55 V and fill factor of ?0.65 under AM 1.5 illumination. The observed power conversion efficiency of ? = 0.87% is the highest reported efficiency for the GM sensitized solar cell. The performance of the devices was reproducible and stable for a period of at least 3 weeks. We also report first external and internal quantum efficiency measurements for GM SSCs, which point to possible paths for further performance improvements. PMID:25322280

Ji, Zhiqiang; Wu, Ruilian; Adamska, Lyudmyla; Velizhanin, Kirill A; Doorn, Stephen K; Sykora, Milan

2014-11-26

129

Solvent-controlled synthesis of TiO 2 1D nanostructures: Growth mechanism and characterization  

NASA Astrophysics Data System (ADS)

One-dimensional (1D) anatase TiO 2 nanostructures such as nanorods, nanowires and nanotubes with different aspect ratios were synthesized by a simple solvothermal process. The influence of the different organic solvents and the reaction time on the morphology, size and the formation of the nanostructures were investigated. The anatase TiO 2 precursor powder reacted with highly alkaline aqueous solution, yielding layered sodium titanate nanosheets. These nanosheets transformed to different 1D sodium titanates nanostructures like nanorods, nanowires and nanotubes in the different solvents i.e. highly alkaline aqueous solution, highly alkaline water-ethanol and highly alkaline water-ethylene glycol mixed solvent, respectively. Acid treatment of these 1D sodium titanates resulted hydrated titanates and finally dehydration by calcinations at 500 °C in air gave the products retaining the morphology. The synthesized samples were characterized with XRD, SEM and TEM. All the 1D nanostructures showed intense and sharp absorption spectra indicated that the products were almost defect free. Photoluminescence studies of the nanostructures showed photostable UV emission properties that arise from the band-edge free excitation.

Das, Kajari; Panda, Subhendu K.; Chaudhuri, Subhadra

2008-08-01

130

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

131

Synthesis of reduced graphene oxide-anatase TiO2 nanocomposite and its improved photo-induced charge transfer properties  

Microsoft Academic Search

The construction of reduced graphene oxide or graphene oxide with semiconductor has gained more and more attention due to its unexpected optoelectronic and electronic properties. The synthesis of reduced graphene oxide (RGO) or graphene oxide-semiconductor nanocomposite with well-dispersed decorated particles is still a challenge now. Herein, we demonstrate a facile method for the synthesis of graphene oxide-amorphous TiO2 and reduced

Ping Wang; Yueming Zhai; Dejun Wang; Shaojun Dong

2011-01-01

132

Tailored Synthesis of Photoactive TiO2 Nanofibers and Au/TiO2 Nanofiber Composites: Structure and Reactivity Optimization for Water Treatment Applications.  

PubMed

Titanium dioxide (TiO2) nanofibers with tailored structure and composition were synthesized by electrospinning to optimize photocatalytic treatment efficiency. Nanofibers of controlled diameter (30-210 nm), crystal structure (anatase, rutile, mixed phases), and grain size (20-50 nm) were developed along with composite nanofibers with either surface-deposited or bulk-integrated Au nanoparticle cocatalysts. Their reactivity was then examined in batch suspensions toward model (phenol) and emerging (pharmaceuticals, personal care products) pollutants across various water qualities. Optimized TiO2 nanofibers meet or exceed the performance of traditional nanoparticulate photocatalysts (e.g., Aeroxide P25) with the greatest reactivity enhancements arising from (i) decreasing diameter (i.e., increasing surface area), (ii) mixed phase composition [74/26 (±0.5) % anatase/rutile], and (iii) small amounts (1.5 wt %) of surface-deposited, more so than bulk-integrated, Au nanoparticles. Surface Au deposition consistently enhanced photoactivity by 5- to 10-fold across our micropollutant suite independent of their solution concentration, behavior that we attribute to higher photocatalytic efficiency from improved charge separation. However, the practical value of Au/TiO2 nanofibers was limited by their greater degree of inhibition by solution-phase radical scavengers and higher rate of reactivity loss from surface fouling in nonidealized matrixes (e.g., partially treated surface water). Ultimately, unmodified TiO2 nanofibers appear most promising for use as reactive filtration materials because their performance was less influenced by water quality, although future efforts must increase the strength of TiO2 nanofiber mats to realize such applications. PMID:25582552

Nalbandian, Michael J; Greenstein, Katherine E; Shuai, Danmeng; Zhang, Miluo; Choa, Yong-Ho; Parkin, Gene F; Myung, Nosang V; Cwiertny, David M

2015-02-01

133

Effects of water parameters on the degradation of microcystin-LR under visible light-activated TiO2 photocatalyst.  

PubMed

A study was performed to determine the effect of pH, alkalinity, natural organic matter (NOM) and dissolved oxygen in the performance of nitrogen and fluorine doped TiO(2) (NF-TiO(2)) for the degradation of hepatotoxin microcystin-LR (MC-LR) in synthetic and natural water under visible light irradiation. The initial degradation rate of MC-LR was fastest under acidic conditions (3.50 ± 0.02 × 10(-3) ?M min(-1) at pH 3.0) and decreased to 2.29 ± 0.07 × 10(-3) and 0.54 ± 0.02 × 10(-3) ?M min(-1) at pH 5.7 and 7.1, respectively. Attractive forces between the opposite charged MC-LR and NF-TiO(2) are likely responsible for the enhancement in the photocatalytic decomposition of MC-LR resulting from increased interfacial adsorption. For carbonate buffered solutions, the photocatalytic activity of NF-TiO(2) was reduced when increasing the carbonate concentration up to 150 mg CaCO(3) L(-1). The scavenging of radical species by the bicarbonate ion at pH 7.1 is discussed. In the presence of NOM, the degradation rates decreased as pH and initial concentration of the NOM increased. The inhibition was higher with fulvic acid than humic acid under alkaline conditions. Oxygenated solution yields higher NF-TiO(2) photocatalytic degradation of MC-LR compared to nitrogen sparged solution at pH 5.7. The involvement of specific reactive oxygen species implicated in the photodegradation is proposed. Finally, no significant degradation is observed with various natural waters spiked with MC-LR under visible light (? > 420 nm) but high removal was achieved with simulated solar light. This study provides a better understanding of the interactions and photocatalytic processes initiated by NF-TiO(2) under visible and solar light. The results indicate solar photocatalytic oxidation is a promising technology for the treatment of water contaminated with cyanotoxins. PMID:21575981

Pelaez, Miguel; de la Cruz, Armah A; O'Shea, Kevin; Falaras, Polycarpos; Dionysiou, Dionysios D

2011-06-01

134

Recent advances in synthesis and applications of clay-based photocatalysts: a review.  

PubMed

Clay materials including clay minerals and layered double hydroxides (LDHs) have attracted great attention because of their special layer structures, large specific surface areas, and remarkable adsorption capacities. In the past few decades, they have been regarded as important components or precursors for making various functional materials. This paper aims to review and summarize the recent advances in the synthesis and photocatalytic applications of clay-based photocatalysts. Moreover, the effects of surface and structural characteristics of clay-based photocatalysts on photocatalytic properties are also discussed. The clay-based photocatalysts show good application prospects for environmental remediation and energy conversion. Especially, H2 generation and reduction of CO2 into carbon sources can be easily achieved using the LDH-based photocatalysts. Meanwhile, the role of clay materials in the photocatalysis is discussed in detail. PMID:24660221

Liu, Jin; Zhang, Gaoke

2014-05-14

135

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

136

Green synthesis of shape-defined anatase TiO2 nanocrystals wholly exposed with {001} and {100} facets.  

PubMed

Anatase TiO(2) nanocuboids wholly exposed with high-energy {001} and {100} facets were successfully synthesized by a novel, environmentally benign synthetic strategy using acid-delaminated vermiculite (DVMT) and tetramethylammonium hydroxide as synergistic morphology-controlling reagents, where the DVMT layers act as effective hard template selectively stabilizing the {001} facets of TiO(2). PMID:23041712

Wang, Lan; Zang, Ling; Zhao, Jincai; Wang, Chuanyi

2012-12-14

137

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

138

One-step synthesis of TiO2 nanorod arrays on Ti foil for supercapacitor application  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) nanorod arrays grown directly on Ti metal foil were prepared by a facile one-step hydrothermal method, in which the Ti foil serves as both substrate and precursor. The nanorods are tetragonal rutile single crystal with growth orientation along the [001] direction. The electrochemical properties of the TiO2 nanorod arrays were systematically investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy using a three-electrode system. As a result, the TiO2 nanorod arrays exhibit good areal specific capacitance and excellent cyclic stability by retaining more than 98% of the initial specific capacitance after 1000 cycles. In addition, a good flexibility of the Ti foil with TiO2 nanorod arrays was demonstrated by the stable electrochemical performance under different bending angles, which indicates that TiO2 nanorod arrays grown on Ti foil could be a promising electrode material for flexible supercapacitor application.

Zheng, Zhi; Chen, Jiajun; Yoshida, Ryuji; Gao, Xiang; Tarr, Kayla; Ikuhara, Yumi H.; Zhou, Weilie

2014-10-01

139

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

140

Synthesis, crystal structure and optical properties of a naphthylbisimide-Ni complex: a framework on TiO2 for visible light H2 production.  

PubMed

A novel ligand N,N'-di-(3-(pyridin-2-yl)-1H-pyrazole-5-carbohydrazide) naphthalene 1,4,5,8-tetracarboxylic acid bisimide (PPNB) and its nickel (ii) complex (Ni-PPNB) were synthesized and systematically characterized. Both the molecules show higher sensitization activity on the TiO2 semiconducting system. These composites have interesting photophysical properties as they enable photocatalytic hydrogen production from water with a sacrificial electron donor (SED) using visible light, while neither component alone is able to do so. The photocatalysts have shown long term stability and a maximum turnover number (TON) of 7866 based on Ni-PPNB was obtained after 6 h of irradiation at a catalyst concentration of 2.5 × 10(-5) mol g(-1). PMID:25228123

Bala, Sukhen; Mondal, Indranil; Goswami, Arijit; Pal, Ujjwal; Mondal, Raju

2014-11-14

141

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

142

Controlled facile synthesis and photocatalytic activity of ultrafine high crystallinity TiO2 nanocrystals with tunable anatase/rutile ratios  

NASA Astrophysics Data System (ADS)

The superfine high crystallinity TiO2 nanocrystals with tunable anatase/rutile ratios have been synthesized in an ethanol aqueous solution of HCl and sodium dodecylbenzene sulfonate (DBS) by a "low temperature dissolution-reprecipitation process" (LTDRP) and solvethermal treatment composite method. The effect of the synthesis parameters on the crystal structure, crystal size and the photocatalytic properties of the TiO2 nanocrystallines were investigated. The growth and aggregation of TiO2 nanocrystallines can be inhibited, and the high crystallinity spherical nanoparticles with small size are generated in the presence of DBS. The ratios of anatase and rutile can be easily controlled by sample adjusting aging time. The pure phase anatase is obtained by solvethermal treatment without aging process, the contents and the crystallite size of rutile are increased with increase of the aging time and only rutile exists while aging time is 16 h or more. The well-crystallized TiO2 nanocrystals exhibit higher photocatalytic activities. Their high photocatalytic activities could be attributed to high crystallinity, small crystal size (approximately 5 nm for anatase and 8 to 15 nm for rutile), the synergistic effect between anatase and rutile and strong electron-withdrawing characteristic of the sulfoacid radical of DBS.

Gao, Yina; Wang, Hong; Wu, Jie; Zhao, Ruohui; Lu, Yanfang; Xin, Baifu

2014-03-01

143

Reverse micelles directed synthesis of TiO2-CeO2 mixed oxides and investigation of their crystal structure and morphology  

NASA Astrophysics Data System (ADS)

The synthesis of TiO2-CeO2 mixed oxides based on the sol-gel process controlled within reverse micelles of non-ionic surfactant Triton X-114 in cyclohexane is reported. The crystallization, phase composition, trends in nanoparticles growth and porous structure properties are studied as a function of Ti:Ce molar composition and annealing temperature by in-situ X-ray diffraction, Raman spectroscopy and physisorption. The brannerite-type CeTi2O6 crystallizes as a single crystalline phase at Ti:Ce molar composition of 70:30 and in the mixture with cubic CeO2 and anatase TiO2 for composition 50:50. At Ti:Ce molar ratios 90:10 and 30:70 the mixtures of TiO2 anatase, rutile and cubic CeO2 appear. In these mixtures TiO2 rutile is formed at higher temperatures than conventionally. Additionally, the amount of a present amorphous phase in individual mixtures was estimated from diffraction data. The porous structure morphology depends both on molar composition and annealing temperature. This is correlated with the presence of carbon impurities of different character.

Mat?jová, Lenka; Valeš, Václav; Fajgar, Radek; Mat?j, Zden?k; Holý, Václav; Šolcová, Olga

2013-02-01

144

Synthesis of Nanoparticles-Deposited Double-Walled TiO2-B Nanotubes with Enhanced Performance for Lithium-Ion Batteries.  

PubMed

A one-step hydrothermal method, followed by calcination at 300 °C in an argon atmosphere, has been developed to synthesize TiO2-B nanoparticles/double-walled nanotubes (NP/DWNT) and TiO2-B nanoparticles/multiple-walled nanotubes (NP/MWNT). To the best of our knowledge, this is the first synthesis of TiO2-B NP/NT hierarchical structures. Both NP/DWNT and NP/MWNT show high performance as anode materials for lithium-ion batteries, superior to their counterparts of DWNT and MWNT, respectively. Among all the four materials studied herein, NP/DWNT demonstrates the highest discharge-charge capacity, rate capability, and cycling stability. The enhancement due to the NP loading results from the increased surface areas, the improved kinetics, and the decreased transport distance for both electrons and Li ions. The charge capacity at high rates lies in the intercalation pseudocapacitance originating from fast Li-ion transport through the infinite channels in TiO2-B. The superiority of DWNT materials versus MWNT materials is ascribed to the thinner walls, which provide a shorter distance for Li-ion transport through the radial direction. PMID:25419639

Qu, Jie; Cloud, Jacqueline E; Yang, Yongan; Ding, Jianning; Yuan, Ningyi

2014-12-24

145

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

146

Facile and fast synthesis of porous TiO2 spheres for use in lithium ion batteries.  

PubMed

Porous anatase TiO2 spheres have been synthesized by a microwave-assisted hydrothermal reaction of spherical particle precursors followed by annealing in air. The synthesized TiO2 spheres are formed by interconnected nanocrystals with size of 8.7 nm in average and have grain diameters of 250-400 nm. After annealing at 500°C, the TiO2 samples maintain spherical shape and develop highly mesoporous characteristics with a specific surface area of 151 m(2) g(-1). The TiO2 samples annealed at 750°C consist of larger aggregated particles with diameters of 500-900 nm and still retain mesoporous anatase structure, but with a reduced specific surface area of 25.6 m(2) g(-1). Electrochemical studies reveal that the porous TiO2 spheres annealed at 500°C own very high and stable lithium ion (Li(+)) storage capacities of 207, 184, 166, and 119 mA h g(-1) at 0.5, 1, 2, and 5C (850 mA g(-1)) rates, respectively, owing to their highly porous nanostructures and fine spherical morphology. In contrast, the TiO2 spheres annealed at 700°C exhibit modest electrochemical performance due to their reduced pore structures and larger crystallite size. The prepared porous TiO2 spherical particles show great promise for use as high performance anode materials for lithium ion batteries (LIBs). PMID:24407670

Wang, Hong-En; Jin, Jun; Cai, Yi; Xu, Jun-Meng; Chen, Dai-Song; Zheng, Xian-Feng; Deng, Zhao; Li, Yu; Bello, Igor; Su, Bao-Lian

2014-03-01

147

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

148

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

149

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

150

Effect of plasma treatment with various gases on nanocrystalline TiO2 for dye-sensitized solar cell (DSSC)  

Microsoft Academic Search

Titanium dioxide (TiO2) photocatalyst with anatase phase has been extensively investigated for Dye-sensitized solar cell (DSSC). The chemical activation of OH group on TiO2 surface can provide valuable electron transfer from sensitizer dye to TiO2. The plasma treatment is suggested as improving hydrophilic property of nano-structured TiO2 surface, and has different effects on TiO2 surface depending on the gas to

Jumi Kim; Min Jae Sin; Hyung Jin Kim; Byungyou Hong

2010-01-01

151

Influence of TiO2 on prebiotic thermal synthesis of the Gly-Gln polymer.  

PubMed

The role of the titanium dioxide (rutile and anatase) with and without room light on the thermal synthesis of the glycine-L-glutamine (Gly-Gln) polymer is described. The efficiency in percentage of polymerization with room light was increased in 6% in the presence of rutile and in 23% in the presence of anatase. The thermal synthesis in the molten state was carried out in the absence and presence of both oxides. In all cases, the vibrational spectra showed characteristic group frequencies corresponding to a polypeptide structure. No spectral differences were observed by room light effect on the polymer on rutile. However, the polymer obtained in the presence of anatase and room light shows spectral changes associated with the formation of shorter new abundant and conformationally different species compared with the original polymer. The SEM-EDX characterization of the solid phase involved in the thermal synthesis showed that the morphology of the polypeptide is different in the presence of rutile compared to anatase. The SDS-PAGE and GPC results suggest that smaller chains are formed in the presence of both oxides and the distribution of the size and weight of each polymer molecule is completely different when the condensation is performed in the presence of anatase or rutile. Nuclear magnetic resonance analyses confirmed the incorporation of both Gly and Gln residues in the polymers, with a prevalence of Gly. Both possible sequences N-GlyGln-C and N-GlnGly-C were also detected. PMID:21607746

Leyton, P; Saladino, R; Crestini, C; Campos-Vallette, M; Paipa, C; Berríos, A; Fuentes, S; Zárate, R A

2012-06-01

152

TiO2 Nanoparticles Are Phototoxic to Marine Phytoplankton  

PubMed Central

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

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

2012-01-01

153

Hydrothermal synthesis of mesostructured nanocrystalline TiO 2 in an ionic liquid-water mixture and its photocatalytic performance  

NASA Astrophysics Data System (ADS)

Anatase mesostructured TiO 2 nanocrystalline was prepared in a mixture of 1-butyl-3-methyl-imidazolium tetrafluoroborate (BMIM +BF 4-) ionic liquid and water by a low temperature hydrothermal method. The obtained materials were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and N 2 adsorption-desorption. The existence of BMIM +BF 4- enhanced the polycondensation and crystallization rate, which encouraged the formation of anatase crystal. The TiO 2 particles were thermally very stable and thus resistant to anatase-rutile phase transformation during calcination at high temperatures. The anatase TiO 2 showed high photocatalytic activity in the degradation of p-chlorophenol than that of the commercially available TiO 2, Degussa P25. After 2 h reaction under the UV-irradiation of 250 W, the removing rate of p-chlorophenol was up to 96.3%.

Liu, Hong; Liang, Yuguang; Hu, Hongjiu; Wang, Mengyang

2009-09-01

154

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

155

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

156

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

PubMed

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

157

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

158

Synthesis of amorphous TiO2 modified ZnO nanorod film with enhanced photocatalytic properties  

NASA Astrophysics Data System (ADS)

Amorphous TiO2 modified ZnO nanorod films were synthesized via multi-step processes: ZnO nanorod films were prepared by a wet chemical method. Amorphous TiO2 was then anchored on the tops and sides of the nanorods through immersion in tetrabutyltitanate solution for hydrolysis. The as-prepared samples were characterized for the phase structure, chemical state and surface morphology as well as optical absorption using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and ultraviolet-visible (UV-vis) spectrophotometer. The results showed that the nanorod films were covered by amorphous TiO2 layers, and their visible light absorption ability was strengthened. The photocatalytic studies revealed that TiO2 modified films exhibited enhanced photocatalytic efficiency for decomposition of methyl orange under ultraviolet-visible excitation, which might be attributed to the increased UV-vis light absorption and the separation of the charge carrier and prolonged electron lifetime due to the interface between TiO2 and ZnO.

Xiao, Shanshan; Zhao, Lei; Leng, Xuning; Lang, Xingyou; Lian, Jianshe

2014-04-01

159

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

160

Effect of post-synthesis acid activation of TiO2 nanofilms on the photocatalytic efficiency under visible light  

NASA Astrophysics Data System (ADS)

Nanosized TiO2 films were deposited by spray pyrolysis and thermally treated at 400oC. Then the films were dipped in 1M aqueous solution of HCl. The activated samples were divided into two parts - one part was dried (A) and another was annealed (AT) in air. The photocatalytic degradation of Reactive Black (RB5) textile dye under visible light was tested. The following instrumental methods: X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied for the phase and surface characterization of obtained samples. According to Raman and XRD analyses all films are anatase. The XRD showed that activated films are better crystallized than non activated TiO2 film. The presence of chlorine at 200.3 eV was registered for acid activated samples by X-Ray photoelectron spectroscopy. The acidic activated films exhibited higher rate of dye photodegradation than that of the reference TiO2 sample. The photocatalytic efficiency decreases in the order A > AT> non activated TiO2 films. The degradation rate constant for acid activated films is two times higher than those of the reference film. The hydroxyl content in TiO2 acidic activated films is greater than that of the non- activated films, which results in significant increase in the photocatalytic activity. In addition, the presence of chlorine may also lead to enhancement in efficiency.

Stambolova, I.; Blaskov, V.; Shipochka, M.; Eliyas, A.; Vassilev, S.

2014-12-01

161

Large scale synthesis and gas-sensing properties of anatase TiO2 three-dimensional hierarchical nanostructures.  

PubMed

Three-dimensional (3D) crystalline anatase titanium dioxide (TiO(2)) hierarchical nanostructures were synthesized through a facile and controlled hydrothermal and after-annealing process. The formation mechanism for the anatase TiO(2) 3D hierarchical nanostructures was investigated in detail. The 3D hierarchical nanostructures morphologies are formed by self-organization of several tens of radially distributed thin petals with a thickness of several nanometers with a larger surface area. The surface area of TiO(2) hierarchical nanostructures determined by the Brunauer-Emmett-Teller (BET) adsorption isotherms was measured to be 64.8 m(2) g(-1). Gas sensing properties based on the hierarchical nanostructures were investigated. A systematic study on sensitivity as a function of temperatures and gas concentrations was carried out. It reveals an improved ethanol gas sensing response property with a sensitivity of about 6.4 at 350 degrees C upon exposure to 100 ppm ethanol vapor for the TiO(2) hierarchical nanostructures. A gas sensing mechanism based on the adsorption-desorption of oxygen on the surface of TiO(2) is discussed and analyzed. This novel gas sensor can be multifunctional and promising for practical applications. Furthermore, the hierarchical nanostructures with high surface area can find variety of potential applications such as solar cells, biosensors, catalysts, etc. PMID:20597492

Wang, Chengxiang; Yin, Longwei; Zhang, Luyuan; Qi, Yongxin; Lun, Ning; Liu, Ningning

2010-08-01

162

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

163

Biomimetic layer-by-layer deposition assisted synthesis of Cu, N co-doped TiO2 nanosheets with enhanced visible light photocatalytic performance.  

PubMed

In this paper, a Cu, N co-doped TiO2 nanosheet with increased visible light photocatalytic activity was successfully synthesized using a biomimetic layer-by-layer deposition process. The polymer, branched-polyethyleneimine (b-PEI) was used as an induction agent for the hydrolysis of titanium bis(ammonium lactato)-dihydroxide (Ti-BALDH) as well as for a nitrogen resource, and the graphene oxide (GO) was used as a two-dimensional nano-template. The positively charged b-PEI will bind to the negatively charged GO and titania. In a typical layer-by-layer deposition process, GO nanosheets are exposed in an alternating fashion to aqueous b-PEI, CuCl2 and Ti-BALDH solutions, thus, making the layer-by-layer deposition of a conformal b-PEI/Cu-Ti-O coating on the GO. Subsequent b-PEI and GO pyrolysis at 550 °C under air yielded Cu, N co-doped TiO2 nanosheets. The materials obtained were comprehensively investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, Raman spectra, photoluminescence spectra and electron paramagnetic resonance. The Cu, N co-doped TiO2 nanosheets showed obviously enhanced photocatalytic activity which was evaluated by degradation of methylene blue under visible light irradiation. This research might provide some new insights for the "green synthesis" of the simultaneous doping of two kinds of foreign atoms into TiO2 with controlled morphology and photocatalytic properties. PMID:25158222

Wang, Xiaobo; Yan, Yong; Hao, Bo; Chen, Ge

2014-10-01

164

Different methods in TiO 2 photodegradation mechanism studies: Gaseous and TiO 2-adsorbed phases  

Microsoft Academic Search

The development of photocatalysis processes offers a significant number of perspectives especially in gaseous phase depollution. It is proved that the photo-oxidizing properties of photocatalyst (TiO2) activated by UV plays an important role in the degradation of volatile organic compounds (VOC). Heterogeneous photocatalysis is based on the absorption of UV radiations by TiO2. This phenomenon leads to the degradation and

Pierre-Alexandre Deveau; Fabrice Arsac; Pierre-Xavier Thivel; Corinne Ferronato; Françoise Delpech; Jean-Marc Chovelon; Pascal Kaluzny; Christine Monnet

2007-01-01

165

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...

166

Novel Fe doped mesoporous TiO 2 microspheres: Ultrasonic-hydrothermal synthesis, characterization, and photocatalytic properties  

NASA Astrophysics Data System (ADS)

Novel Fe doped mesoporous TiO 2 microspheres were fabricated by an ultrasonic-hydrothermal method when tetrabutyl titanate was used as a precursor and octadecylamine was used as a structure-directing agent. The mesoporous materials were characterized by XRD, SEM, TEM, N 2 adsorption-desorption measurements, XPS, FL, and UV-vis. The results suggest that both ultrasonic treatment and hydrothermal procedure are critical for the fabrication of Fe doped mesoporous TiO 2 microspheres with a combination of regular morphology, large specific surface area, high crystallinity, and high thermal stability. Low-angle XRD and TEM images indicate that the disordered wormhole-like mesostructure of Fe doped TiO 2 microspheres with diameters of about 300-400 nm is actually formed by the agglomerization of nanoparticles with an average size of about 10 nm. The photocatalytic activity of Fe doped mesoporous TiO 2 microspheres was evaluated by the photodegradation of methyl orange. A small amount of Fe 3+ can obviously enhance their photocatalytic activity. The optimal atomic ratio of Fe to Ti for photocatalytic activity is about 0.5 at%.

Li, Haibin; Liu, Guocong; Chen, Shuguang; Liu, Qicheng

2010-04-01

167

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

168

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

169

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

170

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

PubMed

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. PMID:24971593

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

2014-08-01

171

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

172

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

173

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

174

Synthesis of a CNT-grafted TiO(2) nanocatalyst and its activity triggered by a DC voltage.  

PubMed

Carbon nanotube (CNT)-grafted TiO(2) (CNT/TiO(2)) was synthesized as an electrically conductive catalyst that exhibits redox ability under electrical excitation besides ultraviolet (UV) irradiation. The CNT/TiO(2) material was synthesized by a two-step process. Ni nanoparticles were photodeposited onto TiO(2) first. The Ni nanoparticles then served as seeds for the growth of CNTs using the chemical vapor deposition (CVD) of C(2)H(2). The CNT/TiO(2) nanocomposite exhibits strong oxidation activity toward NO gas molecules via both photocatalysis under UV irradiation and electrocatalysis under a DC voltage of 500 V in dark conditions. PMID:21730487

Kuo, Chien-Sheng; Tseng, Yao-Hsuan; Lin, Hong-Ying; Huang, Chia-Hung; Shen, Chih-Yen; Li, Yuan-Yao; Ismat Shah, S; Huang, Chin-Pao

2007-11-21

175

Hydrothermal synthesis of a crystalline rutile TiO2 nanorod based network for efficient dye-sensitized solar cells.  

PubMed

One-dimensional (1D) TiO2 nanostructures are desirable as photoanodes in dye-sensitized solar cells (DSSCs) due to their superior electron-transport capability. However, making use of the DSSC performance of 1D rutile TiO2 photoanodes remains challenging, mainly due to the small surface area and consequently low dye loading. Herein, a new type of photoanode with a three-dimensional (3D) rutile-nanorod-based network structure directly grown on fluorine-doped tin oxide (FTO) substrates was developed by using a facile two-step hydrothermal process. The resultant photoanode possesses oriented rutile nanorod arrays for fast electron transport as the bottom layer and radially packed rutile head-caps with an improved large surface area for efficient dye adsorption. The diffuse reflectance spectra showed that with the radially packed top layer, the light-harvesting efficiency was increased due to an enhanced light-scattering effect. A combination of electrochemical impedance spectroscopy (EIS), dark current, and open-circuit voltage decay (OCVD) analyses confirmed that the electron-recombiantion rate was reduced on formation of the nanorod-based 3D network for fast electron transport. As a resut, a light-to-electricity conversion efficiency of 6.31% was achieved with this photoanode in DSSCs, which is comparable to the best DSSC efficiencies that have been reported to date for 1D rutile TiO2 . PMID:23939704

Yu, Hua; Pan, Jian; Bai, Yang; Zong, Xu; Li, Xinyong; Wang, Lianzhou

2013-09-27

176

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

177

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

178

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

NASA Astrophysics Data System (ADS)

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 ( I sc) of 4.51 mA cm-2, an open-circuit voltage ( V oc) 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.

Zhou, Zhengji; Yuan, Shengjie; Fan, Junqi; Hou, Zeliang; Zhou, Wenhui; Du, Zuliang; Wu, Sixin

2012-11-01

179

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

NASA Astrophysics Data System (ADS)

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.

Hu, Yunxia; Wang, Baoyuan; Zhang, Jieqiong; Wang, Tian; Liu, Rong; Zhang, Jun; Wang, Xina; Wang, Hao

2013-05-01

180

Photocatalytic CO2 reduction using a molecular cobalt complex deposited on TiO2 nanoparticles.  

PubMed

Hybrid photocatalysts were prepared by depositing a macrocyclic cobalt complex on TiO2 surfaces. Upon UV light irradiation, photoexcited electrons in TiO2 nanoparticles were transferred to the surface cobalt catalyst for CO2 reduction. PMID:24781709

Jin, Tong; Liu, Chao; Li, Gonghu

2014-06-14

181

Characterization and mechanistic analysis of the visible light response of cerium and nitrogen co-doped TiO2 nano-photocatalyst synthesized using a one-step technique.  

PubMed

Cerium and nitrogen co-doped anatase TiO(2) nanoparticles were synthesized using a one-step technique via a modified sol-gel process and characterized by XRD, BET, DRS, Raman and XPS. The photocatalytic mechanism of the degradation of methylene blue (MB) under fluorescent light and visible light irradiation was studied. Co-doping cerium and nitrogen in the crystal lattice of TiO(2) narrowed the band gap from 2.40 eV (Ce-doped TiO(2)) to 2.21 eV (Ce/N co-doped TiO(2)). Ce(4+)/Ce(3+) pairs, oxynitride species and Ti-O-N and Ti-O-Ce bonds were determined by XPS. The recombination of photogenerated electron-hole pairs was inhibited due to the synergistic effect of doping with Ce(4+)/Ce(3+) ions and N atoms. The optimal doping ratio was 0.70% Ce and 0.70% N using MB photocatalytic degradation under fluorescent light and visible light irradiation (lambda>420 nm). The enhanced photocatalytic degradation under visible light irradiation was attributed to the increasing number of photogenerated OH radicals. The recombination of photogenerated e(-)-h(+) was attributed to be the key factor for the decrease in the photocatalytic degradation efficiency of MB. PMID:20005630

Yu, Tao; Tan, Xin; Zhao, Lin

2010-04-15

182

TiO2 nanorods: a facile size- and shape-tunable synthesis and effective improvement of charge collection kinetics for dye-sensitized solar cells.  

PubMed

In this paper, we present a novel, high-yield, and cost-effective hydrothermal method for the preparation of single crystal-like anatase TiO2 nanorods (NRs) with specific {101} exposed crystal planes and preferred [001] growth direction, which is governed by the "oriented attachment" mechanism. The successful synthesis of TiO2 NRs and fine tuning on their size and shape could be easily accomplished by adjusting the solvent compositions. The salient feature of these NRs, in lieu of traditional nanoparticles as building blocks of photoanodes in dye-sensitized solar cell (DSSC) system, rests with their significantly reduced grain boundaries. The electron diffusion and recombination kinetics have been critically compared for the first time with respect to the size and shape of the novel building blocks. A high efficiency of 8.87% has finally been achieved for DSSC based on long-thin NRs rather than short-thin or long-thick NRs, which possesses balanced optimizations on charge collection and light-harvesting properties. PMID:24833257

Zhang, Wenjun; Xie, Yan; Xiong, Dehua; Zeng, Xianwei; Li, Zhihong; Wang, Mingkui; Cheng, Yi-Bing; Chen, Wei; Yan, Keyou; Yang, Shihe

2014-06-25

183

Photocatalysis by polyoxometallates and TiO 2: A comparative study  

Microsoft Academic Search

Polyoxometallates (POMs) as a homogeneous photocatalyst and TiO2 as a heterogeneous photocatalyst seem to exhibit overall similar photocatalytic behavior. Both systems cause photodecomposition of a variety of organic pollutants via the formation and decay of several similar intermediates formed by OH addition (hydroxylation), dehalogenation, deamination, decarboxylation, etc. The final degradation products, for most organic substrates for both systems are CO2,

P. Kormali; A. Troupis; T. Triantis; A. Hiskia; E. Papaconstantinou

2007-01-01

184

High-rate and low-temperature synthesis of TiO2, TiN, and TiO2/TiN/TiO2 thin films and study of their optical and interfacial characteristics  

E-print Network

-746, Korea Chung-K. Jung, Jong-S. Moon, and Jin-Hyo Booa Department of Chemistry and Center for Advanced sputtering. The TiO2 101 and TiN 100 thin films were stoichiometric and polycrystalline but highly oriented

Boo, Jin-Hyo

185

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

186

Synthesis of TiO2/WO3 nanoparticles via sonochemical approach for the photocatalytic degradation of methylene blue under visible light illumination.  

PubMed

Through an ultrasound assisted method, TiO2/WO3 nanoparticles were synthesized at room temperature. The XRD pattern of as-prepared TiO2/WO3 nanoparticles matches well with that of pure monoclinic WO3 and rutile TiO2 nanoparticles. TEM images show that the prepared TiO2/WO3 nanoparticles consist of mixed square and hexagonal shape particles about 8-12nm in diameter. The photocatalytic activity of TiO2/WO3 nanoparticles was tested for the degradation of a wastewater containing methylene blue (MB) under visible light illumination. The TiO2/WO3 nanoparticles exhibits a higher degradation rate constant (6.72×10(-4)s(-1)) than bare TiO2 nanoparticles (1.72×10(-4)s(-1)) under similar experimental conditions. PMID:24629580

Anandan, Sambandam; Sivasankar, Thirugnanasambandam; Lana-Villarreal, Teresa

2014-11-01

187

Wavelength-dependent photostimulated adsorption of molecular O 2 and H 2 on second generation titania photocatalysts: The case of the visible-light-active N-doped TiO 2 system  

NASA Astrophysics Data System (ADS)

The wavelength-dependence of photostimulated adsorption of O 2 and H 2 on visible-light-active N-doped TiO 2 has been examined in the intrinsic (? < 387 nm) and in the N-doping induced extrinsic absorption range (? > 387 nm). Rates of photoadsorption scaled linearly with photon flow ? at 4 Pa at four selected wavelengths from 300 to 550 nm, but were independent of gas pressure and correspond to rates of photogeneration of surface-active centers. The spectral dependence of quantum yields ? of surface photoprocesses displayed multi-band-like structural features in both the intrinsic and extrinsic regions ascribed to the existence of three (and perhaps four) different types of defect states, confirming the absorption edge red-shift in N-doped TiO 2 to be due to electronic excitation of intragap localized states that leads to the photogeneration of electrons and/or holes.

Emeline, A. V.; Kuzmin, G. N.; Serpone, N.

2008-03-01

188

Important Role of Surface Fluoride in Nitrogen-Doped TiO2 Nanoparticles with Visible Light Photocatalytic Activity.  

PubMed

Nitrogen-doped TiO2 nanoparticles have been synthesized using sol-gel methods and subsequently fluorinated at room temperature by aging in acidic solutions of NaF. The nanoparticles were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, UV-vis, and IR diffuse reflectance spectroscopy. After aging at room temperature in NaF solutions, the Ti-OH groups on the surface of the TiO2 nanoparticles were replaced by Ti-F bonds, which resulted in a decrease of the point of zero charge from pH 5.4 to 2.8. Most importantly, the nitrogen dopants were retained after the fluorination process, and the amorphous nanoparticles were partially converted into the anatase phase. Annealing the photocatalysts resulted in a decrease of both the nitrogen and fluoride atomic concentration. Diffuse reflectance spectra show an increase in absorbance above 400 nm after annealing the F,N-doped TiO2, which suggests the formation of color centers. The photoactivity of the F,N-doped and N-doped TiO2 catalysts were evaluated by monitoring by the decolorization of methylene blue with visible light. Mass spectrometric analysis revealed that methylene blue undergoes successive demethylation, and more importantly, the rate of decolorization depends on the fluoride concentration. These results show the importance of a two-step synthesis method to independently control the nitrogen and fluoride concentration. PMID:25266909

Brauer, Jonathan I; Szulczewski, Greg

2014-12-11

189

Hyperbranched anatase TiO2 nanocrystals: nonaqueous synthesis, growth mechanism, and exploitation in dye-sensitized solar cells.  

PubMed

A colloidal crystal-splitting growth regime has been accessed, in which TiO(2) nanocrystals, selectively trapped in the metastable anatase phase, can evolve to anisotropic shapes with tunable hyperbranched topologies over a broad size interval. The synthetic strategy relies on a nonaqueous sol-gel route involving programmed activation of aminolysis and pyrolysis of titanium carboxylate complexes in hot surfactant media via a simple multi-injection reactant delivery technique. Detailed investigations indicate that the branched objects initially formed upon the aminolysis reaction possess a strained monocrystalline skeleton, while their corresponding larger derivatives grown in the subsequent pyrolysis stage accommodate additional arms crystallographically decoupled from the lattice underneath. The complex evolution of the nanoarchitectures is rationalized within the frame of complementary mechanistic arguments. Thermodynamic pathways, determined by the shape-directing effect of the anatase structure and free-energy changes accompanying branching and anisotropic development, are considered to interplay with kinetic processes, related to diffusion-limited, spatially inhomogeneous monomer fluxes, lattice symmetry breaking at transient Ti(5)O(5) domains, and surfactant-induced stabilization. Finally, as a proof of functionality, the fabrication of dye-sensitized solar cells based on thin-film photoelectrodes that incorporate networked branched nanocrystals with intact crystal structure and geometric features is demonstrated. An energy conversion efficiency of 6.2% has been achieved with standard device configuration, which significantly overcomes the best performance ever approached with previously documented prototypes of split TiO(2) nanostructures. Analysis of the relevant photovoltaic parameters reveals that the utilized branched building blocks indeed offer light-harvesting and charge-collecting properties that can overwhelm detrimental electron losses due to recombination and trapping events. PMID:22004553

Buonsanti, Raffaella; Carlino, Elvio; Giannini, Cinzia; Altamura, Davide; De Marco, Luisa; Giannuzzi, Roberto; Manca, Michele; Gigli, Giuseppe; Cozzoli, P Davide

2011-11-30

190

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

PubMed

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

Chen, Zhang; Xu, Yi-Jun

2013-12-26

191

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

192

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

PubMed

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

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

2013-05-01

193

Sol-flame synthesis of cobalt-doped TiO2 nanowires with enhanced electrocatalytic activity for oxygen evolution reaction.  

PubMed

Doping nanowires (NWs) is of crucial importance for a range of applications due to the unique properties arising from both impurities' incorporation and nanoscale dimensions. However, existing doping methods face the challenge of simultaneous control over the morphology, crystallinity, dopant distribution and concentration at the nanometer scale. Here, we present a controllable and reliable method, which combines versatile solution phase chemistry and rapid flame annealing process (sol-flame), to dope TiO2 NWs with cobalt (Co). The sol-flame doping method not only preserves the morphology and crystallinity of the TiO2 NWs, but also allows fine control over the Co dopant profile by varying the concentration of Co precursor solution. Characterizations of the TiO2:Co NWs show that Co dopants exhibit 2+ oxidation state and substitutionally occupy Ti sites in the TiO2 lattice. The Co dopant concentration significantly affects the oxygen evolution reaction (OER) activity of TiO2:Co NWs, and the TiO2:Co NWs with 12 at% of Co on the surface show the highest OER activity with a 0.76 V reduction of the overpotential with respect to undoped TiO2 NWs. This enhancement of OER activity for TiO2:Co NWs is attributed to both improved surface charge transfer kinetics and increased bulk conductivity. PMID:24820239

Cai, Lili; Cho, In Sun; Logar, Manca; Mehta, Apurva; He, Jiajun; Lee, Chi Hwan; Rao, Pratap M; Feng, Yunzhe; Wilcox, Jennifer; Prinz, Fritz B; Zheng, Xiaolin

2014-06-28

194

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

195

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

196

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

197

The direct photolysis and photocatalytic degradation of alachlor at different TiO 2 and UV sources  

Microsoft Academic Search

Direct photolysis and photocatalytic degradations of alachlor, a widely used herbicide, were studied using three different monochromatic UV lamps (254, 300 and 350 nm) and two TiO2 sources. Both the direct photolysis and photocatalytic degradations of alachlor follow pseudo-first-order decay kinetics. TiO2-P25 was found to be an effective photocatalyst compared to TiO2-BDH. The direct photolysis of alachlor was dominant at

C. C. Wong; W. Chu

2003-01-01

198

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

199

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.

200

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

201

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

202

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

203

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

204

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...

205

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

206

TiO2 nanofibre assisted photocatalytic degradation of Reactive Blue 19 dye from aqueous solution  

Microsoft Academic Search

The photocatalytic degradation of Reactive Blue 19 (RB19) dye has been studied using TiO2 nanofibre as the photocatalyst in aqueous solution under UV irradiation. Titanium dioxide nanofibre was prepared using a templating method with tetraisopropylorthotitanate as a precursor. The experiments were carried out in the presence of the TiO2 nanofibre, and the effects of pH and electron acceptors on the

A. Rezaee; M. T. Ghaneian; N. Taghavinia; M. K. Aminian; S. J. Hashemian

2009-01-01

207

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

208

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

209

Synthesis of low-cost, rubbery amphiphilic comb-like copolymers and their use in the templated synthesis of mesoporous TiO2 films for solid-state dye-sensitized solar cells.  

PubMed

Low-cost, rubbery amphiphilic comb-like copolymers consisting of hydrophobic poly(lauryl methacrylate) (PLMA) and hydrophilic poly(oxyethylene methacrylate) (POEM) were synthesized via one-step free radical polymerization. The synthesis of PLMA-POEM copolymers was confirmed using Fourier transform infra-red spectroscopy (FT-IR), (1)H-nuclear magnetic resonance ((1)H-NMR) and gel permeation spectroscopy (GPC). The PLMA-POEM copolymers were used as a structure-directing agent for the formation of anatase mesoporous TiO2 films. Careful adjustment of the precursor and polymer molecular weight (MW) was made to systematically vary the TiO2 structure and its effect on the performances of solid-state dye-sensitized solar cells (ssDSSCs). The use of a low MW polymer resulted in a worm-like structure with smaller pores, whereas an aggregated honeycomb-like structure with bimodal pores was obtained for the high MW system, as characterized by scanning electron microscopy (SEM), grazing incidence small-angle X-ray scattering (GI-SAXS) and N2 adsorption-desorption measurement. An efficiency of 4.2% was obtained at 100 mW cm(-2) when using 2 ?m-thick TiO2 film prepared with a high MW copolymer. The higher efficiency was due to better pore filling of the solid electrolyte and improved light scattering properties. By using a layer-by-layer method, the efficiency was further improved to 5.0% at 7 ?m thickness, which was greater than that of commercially available paste (3.9%). PMID:23575937

Kim, Dong Jun; Kim, Sang Jin; Roh, Dong Kyu; Kim, Jong Hak

2013-05-21

210

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

211

Diatom-templated TiO2 with enhanced photocatalytic activity: biomimetics of photonic crystals  

NASA Astrophysics Data System (ADS)

The siliceous frustules with sophisticated optical structure endow diatoms with superior solar light-harvesting abilities for effective photosynthesis. The preserved frustules of diatom ( Cocconeis placentula) cells, as biophotonic crystals, were thus employed as both hard templates and silicon resources to synthesize TiO2 photocatalyst. Characterizations by a combination of physicochemical techniques proved that the bio-inspired sample is TiO2-coated SiO2 with biogenic C self-doped in. It was found that the synthesized composites exhibited similar morphologies to the original diatom templates. In comparison with commercial Degussa P25 TiO2, the C-doped TiO2/SiO2 catalyst exhibited more light absorption in the visible region and higher photocatalytic efficiency for photodegradation of rhodamine B under visible light due to the biomorphic hierarchical structures, TiO2 coating and C-doping.

He, Jiao; Chen, Daomei; Li, Yongli; Shao, Junlong; Xie, Jiao; Sun, Yuejuan; Yan, Zhiying; Wang, Jiaqiang

2013-11-01

212

The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance  

Microsoft Academic Search

Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional

Chia-Liang Cheng; Der-Shan Sun; Wen-Chen Chu; Yao-Hsuan Tseng; Han-Chen Ho; Jia-Bin Wang; Pei-Hua Chung; Jiann-Hwa Chen; Pei-Jane Tsai; Nien-Tsung Lin; Mei-Shiuan Yu; Hsin-Hou Chang

2009-01-01

213

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

214

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

215

Control of the size and shape of TiO2 nanoparticles in restricted media  

NASA Astrophysics Data System (ADS)

Template-capped TiO2 nanostructures have been synthesized. In certain template conditions, TiO2 hexagons are found to form. These hexagonal structures can be effectively sensitized by fluorescein dye without any change in the protonation state of the dye. Bare TiO2 nanoparticles are not so useful for sensitization with dyes like fluorescein as they alter the dye protonation state. The novelty of this work is twofold—the hitherto elusive hexagonal phase of TiO2 nanoparticles has been stabilized and the synthesis of TiO2 in the rutile phase has been achieved under mild conditions.

Biswas, Abhijit; Corani, Alice; Kathiravan, Arunkumar; Infahsaeng, Yingyot; Yartsev, Arkady; Sundstrom, Villy; De, Swati

2013-05-01

216

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.

Hernã¡ndez Rivera, Mayra

2010-08-15

217

Preparation of nanocrystalline TiO 2-coated coal fly ash and effect of iron oxides in coal fly ash on photocatalytic activity  

Microsoft Academic Search

In order to more easily separate TiO2 photocatalyst from the treated wastewater, TiO2 photocatalyst is immobilized on coal fly ash by a precipitation method. The titanium hydroxide precipitated on coal fly ash by neutralization of titanium chloride is transformed into titanium dioxide by heat treatment in the temperature range of 300–700 °C. The crystalline structure of the titanium dioxide shows

Yeon-tae Yu

2004-01-01

218

Microwave-assisted synthesis and characterization of poly(acrylic)\\/SiO 2–TiO 2 core–shell nanoparticle hybrid thin films  

Microsoft Academic Search

In this study, poly(acrylic)\\/SiO2–TiO2 core–shell nanoparticle hybrid thin films were successfully synthesized by microwave-assisted polymerization. The coupling agent 3-(trimethoxysilyl) propyl methacrylate (MSMA) was hydrolyzed with colloidal SiO2–TiO2 core–shell nanoparticles, and then polymerized with two acrylic monomers and initiator to form a precursor solution. The results of this study showed that the spin-coated hybrid films had relatively good surface planarity, high

Wen-Chen Chien; Yang-Yen Yu; Po-Kan Chen; Hui-Huan Yu

2011-01-01

219

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 (2.95eV) compared to undoped sample (3.13eV) and other doped samples (3.05eV) 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

220

The Photocatalytic Degradation of Methylene Blue in Wastewater by Nano-Structured Cr-Doped TiO2 under Low Power Visible-Light Irradiation  

Microsoft Academic Search

The nano-structured TiO2 photocatalysts with the different quantity of Cr-doped (0 wt%, 0.1 wt%, 1 wt%, 1.5 wt%, 5 wt%) were produced at room temperature using the Fritsch Pulverisette 5 planetary ball milling system with tungsten carbide (93 wt% WC and 6 wt% Co) vials and balls. The starting materials for Cr-doped TiO2 were the powders of Titanium(IV) oxide (TiO2,

Ying Hu; Yutao Tang; Xuefeng Tang; Heping Li; Daquan Liu

2011-01-01

221

Synthesis and characterization of Cu2O/TiO2 photocatalysts for H2 evolution from aqueous solution with different scavengers  

NASA Astrophysics Data System (ADS)

A series of Cu2O/TiO2 photocatalysts with different molar fraction of Cu2O were prepared by a facile modified ethanol-induced approach followed by a calcination process. The chemical state of copper compound was proved to be cuprous oxide by the characterization of X-ray photoelectron spectra (XPS). Furthermore, these composite oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption desorption and UV-vis techniques to study the morphologies, structures, and optical properties of the as-prepared samples. The results indicated that the photocatalytic activity of n-type TiO2 was significantly enhanced by combined with p-type Cu2O, due to the efficient p-n heterojunction. The p-n heterojunction between Cu2O and TiO2 can enhance visible-light adsorption, efficiently suppress charge recombination, improve interfacial charge transfer, and especially provide plentiful reaction active sites on the surface of photocatalyst. As a consequence, the prepared 2.5-Cu2O/TiO2 photocatalyst exhibited the highest photocatalytic activity for H2 evolution rate and reached 2048.25 ?mol/(g h), which is 14.48 times larger than that of pure P25. The apparent quantum yield (AQY) of the 2.5-Cu2O/TiO2 sample at 365 nm was estimated to be 4.32%. In addition, the influence of different scavengers, namely methanol, anhydrous ethanol, ethylene glycol and glycerol, on the photocatalytic activity for H2 evolution rate was discussed.

Li, Yanping; Wang, Baowei; Liu, Sihan; Duan, Xiaofei; Hu, Zongyuan

2015-01-01

222

Ultrasound assisted synthesis of TiO2-WO3 heterostructures for the catalytic degradation of Tergitol (NP-9) in water.  

PubMed

TiO2-WO3 heterostructures were synthesized at room temperature, ambient pressure, and short reaction time via a sonochemical approach. TEM and EDX images show that the prepared TiO2-WO3 heterostructures consist of globular agglomerates (?250 nm in diameter) composed of very small (<5 nm) dense particles (WO3) dispersed inside the globules. The observed less intense monoclinic WO3 diffraction peak (around 2?=22° belonging to (001) plane) and the high intense hexagonal WO3 diffraction peak (around 2?=28° belonging to (200) plane) in XRD indicate that there may be phase transition occurring due to the formation of intimate bond between TiO2 and WO3. In addition, the formation of such new phase was also observed from Raman spectra with a new peak at 955 cm(-1), which is due to the symmetric stretching of W=O terminal. The catalytic activity of TiO2-WO3 heterostructures was tested for the degradation of wastewater pollutant containing Tergitol (NP-9) by a process combined with ozonation and it showed two-fold degradation rate compared with ozone process alone. PMID:24491600

Anandan, Sambandam; Wu, Jerry J

2014-07-01

223

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...

224

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

225

Photocatalytic Inhibition of Algae Growth Using TiO2, WO3, and  

E-print Network

to photooxidize organics led naturally to disinfection, the idea that light-activated photocatalysts, principally TiO2, could kill bacteria or other dangerous pathogens in aqueous systems. Most work in this area has bacteria to which this technology may be applied. While not of particular concern from a public health

Ouellette, Anthony J. A.

226

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

227

Solar photocatalytic activity of TiO2 modified with WO3 on the degradation of an organophosphorus pesticide.  

PubMed

In this study, the solar photocatalytic activity (SPA) of WO3/TiO2 photocatalysts synthesized by the sol-gel method with two different percentages of WO3 (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO2 was also prepared by sol-gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV-vis spectroscopy (DRUV-vis), specific surface area by the BET method (SSABET), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO3 was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO3/TiO2 and 1.35 ± 0.3 nm for 5% WO3/TiO2) and uniformly dispersed on the surface of TiO2. The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO3/TiO2, respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO3/TiO2 photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO3/TiO2 and bare TiO2 photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO3/TiO2 catalyst activity on repeated uses; after several successive cycles its photocatalytic activity was retained showing long-term stability. PMID:23993423

Ramos-Delgado, N A; Gracia-Pinilla, M A; Maya-Treviño, L; Hinojosa-Reyes, L; Guzman-Mar, J L; Hernández-Ramírez, A

2013-12-15

228

Preparation and characterization of visible light responsive Fe2O3-TiO2 composites  

NASA Astrophysics Data System (ADS)

In this study we present the effects of iron oxide (Fe2O3) on titanium dioxide (TiO2) in synthesising visible-light reactive photocatalysts. A Fe2O3-TiO2 composite photocatalyst was synthesized from Fe2(SO4)3 and Ti(SO4)2 by a ethanol-assisted hydrothermal method. The preparation conditions were optimized through the investigation of the effects of hydrothermal temperature and time as well as molar ratio of Ti to Fe on the photocatalytic activity. The visual, physical and chemical properties of the Fe2O3-TiO2 composites were investigated. The results showed that ?-Fe2O3 and anatase TiO2 were present in the composites. The Fe2O3-TiO2 synthesized under optimum condition consisted of mesoporous structure with an average pore size of 4 nm and a surface area of 43 m2/g. Under visible and solar light irradiation, the photocatalytic activity of optimized sample was significantly higher than that of pure TiO2. This sample led to a photodegradation efficiency of 90% and 40% of auramine under visible light and solar light, respectively.

Liu, Hong; Shon, H. K.; Sun, Xuan; Vigneswaran, S.; Nan, Hao

2011-04-01

229

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

230

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

231

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

232

Synthesis of dandelion-like TiO2 microspheres as anode materials for lithium ion batteries with enhanced rate capacity and cyclic performances  

NASA Astrophysics Data System (ADS)

Dandelion-like TiO2 microspheres consisting of numerous rutile single-crystalline nanorods were synthesized for the first time by a hydrothermal method. Their crystal structure, morphology and electrochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and galvanostatic charge and discharge tests. The results show that the synthesized TiO2 microspheres exhibit good rate and cycle performances as anode materials of lithium ion batteries. It can be found that the dandelion-like structure provides a larger specific surface area and the single-crystalline nanorod provides a stable structure and fast pathways for electron and lithium ion transport, which contribute to the rate and cycle performances of the battery.

Yi, Jin; Liu, Yan-lin; Wang, Yuan; Li, Xiao-ping; Hu, She-jun; Li, Wei-shan

2012-11-01

233

One-step synthesis of TiO 2–SnO 2 solid solution nanoparticles in a premixed H 2–air CCVD reactor  

Microsoft Academic Search

TiO2–SnO2 solid solution nanoparticles with different Ti:Sn molar ratios were prepared in a premixed H2–air CCVD reactor. These nanoparticles were irregularly shaped aggregates depending on Ti:Sn molar ratios. XRD analyses revealed the formation of single phase solid solutions at low Ti:Sn molar ratios. The FTIR spectra of these nanoparticles exhibited a broad band ~370–450cm?1 due to the formation of solid

Hongyun Yang; Noppadon Sathitsuksanoh; William T. Reynolds; Chunzhong Li

234

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

235

Ceramic foams directly-coated with flame-made V 2O 5\\/TiO 2 for synthesis of phthalic anhydride  

Microsoft Academic Search

Flame-made airborne V2O5\\/TiO2 nanoparticles were deposited directly onto mullite foam supports to create ready-to-use catalysts for the o-xylene conversion to phthalic anhydride. These particles containing 10% (w\\/w) V2O5 were created by combustion of liquid precursor sprays and characterized by transmission electron microscopy, nitrogen adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), and Raman spectroscopy. The specific surface area, anatase content, and

Bjoern Schimmoeller; Heiko Schulz; Sotiris E. Pratsinis; Anika Bareiss; Andreas Reitzmann; Bettina Kraushaar-Czarnetzki

2006-01-01

236

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

237

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

238

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

239

Photocatalytic oxidation of chloroform using immobilized-biogenic TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Although commercial titanium dioxide (TiO2) nanoparticles as a suspension in water are one of the most popular photocatalysts for treatment of chlorinated organic compounds, the reuse and recovery of the nanoscale phtocatalyst is a practical challenge for application in water and groundwater treatment system. As part of efforts to overcome this practical limitation, development of immobilized TiO2 is needed. Diatom Pinnularia sp. were found to be capable of producing nanoscale TiO2 in their microscale silica shells. In order to obtain biogenic TiO2 nanoparticles from Pinnularia sp., soluble Ti was fed to the silicon-starved cells, resulting in deposition of titanium on the microscale features of the silica shells. After thermal treatment at 720 oC for 2 hr, the titanium was eventually converted to nanoscale TiO2. In order to determine the physical and chemical properties of the immobilized TiO2, material characterization such as TEM, STEM-EDS, BET and XRD analysis was carried out. In this study, a novel type of immobilized photocatalytic nanoparticles, biogenic TiO2 on silica shells was used for the mineralization of chloroform in water. Batch tests were conducted to evaluate the chloroform removal efficiency of biogenic and commercial TiO2 nanoparticles. Also, the amount of Cl- ions in water during the mineralization was measured to check mineralization of chloroform by biogenic TiO2 nanoparticles. Kinetic models were used to determine the rate of chloroform mineralization. In addition, the effect of UVA (ultraviolet-A) intensity on chloroform mineralization was investigated. The results obtained from this study could provide useful information for practical application of biogenic TiO2 in the groundwater treatment contaminated with some chlorinated organic compounds.

Kim, Y.; Cho, Y.; Yoo, H.

2011-12-01

240

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

241

Synthesis and characterization of C-doped TiO2 thin films for visible-light-induced photocatalytic degradation of methyl orange  

NASA Astrophysics Data System (ADS)

C-TiO2 thin films were synthesized by a modified sol-gel route based on the self-assembly technique exploiting Tween80 (T80) as a pore directing agent and carbon source. The effect of calcination time on the photocatalytic activity of C-doped TiO2 catalyst was studied. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FTIR), UV-vis diffuse reflectance spectroscopy, and photoluminescence spectra (PL). The XRD results showed that C-TiO2 sample calcined at 400 °C for various times exhibited anatase phase and no other crystal phase was identified. C-TiO2 exhibited a shift in an absorption edge of samples in the visible region than that of conventional or reference TiO2. The XPS results showed an existence of C in the TiO2 catalysts and C might be existed as COTi group. Moreover, the C-TiO2 thin film calcined at 400 °C for 30 min showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under UV light irradiation. Also the photocatalytic activity of synthesized catalyst was evaluated by decomposition of methyl orange (MO) under visible light irradiation. The results showed that the optimum preparations of C-TiO2 thin films were found to be under calcination temperature of 400, calcination time of 30 min, and with preparation 9 layers film.

Hassan, Mohamed Elfatih; Cong, Longchao; Liu, Guanglong; Zhu, Duanwei; Cai, Jianbo

2014-03-01

242

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

243

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

244

Preparation and photocatalytic characteristics of core-shell structure TiO 2\\/BaFe 12O 19 nanoparticles  

Microsoft Academic Search

A core-shell structure TiO2\\/BaFe12O19 composite nanoparticles that can photodegrade organic pollutants in the dispersion system effectively and can be recycled easily by a magnetic field is reported in this paper. The obtained samples were characterized by energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TiO2\\/BaFe12O19 magnetic photocatalyst is composed of two parts: (1) TiO2

Wuyou Fu; Haibin Yang; Minghua Li; Lianxia Chang; Qingjiang Yu; Jing Xu; Guangtian Zou

2006-01-01

245

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

246

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

247

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

PubMed

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

Yu, Jiaguo; Wang, Wenguang; Cheng, Bei

2010-12-01

248

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

249

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

250

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

251

Bactericidal effects and mechanisms of visible light-responsive titanium dioxide photocatalysts on pathogenic bacteria.  

PubMed

This review focuses on the antibacterial activities of visible light-responsive titanium dioxide (TiO(2)) photocatalysts. These photocatalysts have a range of applications including disinfection, air and water cleaning, deodorization, and pollution and environmental control. Titanium dioxide is a chemically stable and inert material, and can continuously exert antimicrobial effects when illuminated. The energy source could be solar light; therefore, TiO(2) photocatalysts are also useful in remote areas where electricity is insufficient. However, because of its large band gap for excitation, only biohazardous ultraviolet (UV) light irradiation can excite TiO(2), which limits its application in the living environment. To extend its application, impurity doping, through metal coating and controlled calcination, has successfully modified the substrates of TiO(2) to expand its absorption wavelengths to the visible light region. Previous studies have investigated the antibacterial abilities of visible light-responsive photocatalysts using the model bacteria Escherichia coli and human pathogens. The modified TiO(2) photocatalysts significantly reduced the numbers of surviving bacterial cells in response to visible light illumination. They also significantly reduced the activity of bacterial endospores; reducing their toxicity while retaining their germinating abilities. It is suggested that the photocatalytic killing mechanism initially damages the surfaces weak points of the bacterial cells, before totally breakage of the cell membranes. The internal bacterial components then leak from the cells through the damaged sites. Finally, the photocatalytic reaction oxidizes the cell debris. In summary, visible light-responsive TiO(2) photocatalysts are more convenient than the traditional UV light-responsive TiO(2) photocatalysts because they do not require harmful UV light irradiation to function. These photocatalysts, thus, provide a promising and feasible approach for disinfection of pathogenic bacteria; facilitating the prevention of infectious diseases. PMID:22678625

Liou, Je-Wen; Chang, Hsin-Hou

2012-08-01

252

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

253

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

254

Hydrogenated TiO2 nanotube arrays for supercapacitors.  

PubMed

We report a new and general strategy for improving the capacitive properties of TiO(2) materials for supercapacitors, involving the synthesis of hydrogenated TiO(2) nanotube arrays (NTAs). The hydrogenated TiO(2) (denoted as H-TiO(2)) were obtained by calcination of anodized TiO(2) NTAs in hydrogen atmosphere in a range of temperatures between 300 to 600 °C. The H-TiO(2) NTAs prepared at 400 °C yields the largest specific capacitance of 3.24 mF cm(-2) at a scan rate of 100 mV s(-1), which is 40 times higher than the capacitance obtained from air-annealed TiO(2) NTAs at the same conditions. Importantly, H-TiO(2) NTAs also show remarkable rate capability with 68% areal capacitance retained when the scan rate increase from 10 to 1000 mV s(-1), as well as outstanding long-term cycling stability with only 3.1% reduction of initial specific capacitance after 10,000 cycles. The prominent electrochemical capacitive properties of H-TiO(2) are attributed to the enhanced carrier density and increased density of hydroxyl group on TiO(2) surface, as a result of hydrogenation. Furthermore, we demonstrate that H-TiO(2) NTAs is a good scaffold to support MnO(2) nanoparticles. The capacitor electrodes made by electrochemical deposition of MnO(2) nanoparticles on H-TiO(2) NTAs achieve a remarkable specific capacitance of 912 F g(-1) at a scan rate of 10 mV s(-1) (based on the mass of MnO(2)). The ability to improve the capacitive properties of TiO(2) electrode materials should open up new opportunities for high-performance supercapacitors. PMID:22364294

Lu, Xihong; Wang, Gongming; Zhai, Teng; Yu, Minghao; Gan, Jiayong; Tong, Yexiang; Li, Yat

2012-03-14

255

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

256

Photoluminescence of anatase and rutile TiO2 particles.  

PubMed

Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) were used for the synthesis of anatase TiO2 particles, while rutile TiO2 particles were synthesized in aqueous media by acidic hydrolysis of titanium(IV) chloride. The X-ray diffraction measurements proved the exclusive presence of either the anatase or the rutile phase in prepared samples. The photoluminescence of both kinds of particles (anatase and rutile) with several well-resolved peaks extending in the visible spectral region was observed, and the quantum yield at room temperature was found to be 0.25%. Photon energy up-conversion from colloidal anatase and rutile TiO2 particles was observed at low excitation intensities. The energy of up-converted photoluminescence spans the range of emission of normal photoluminescence. The explanation of photon energy up-conversion involves mid-gap energy levels originating from oxygen vacancies. PMID:17165983

Abazovi?, Nadica D; Comor, Mirjana I; Drami?anin, Miroslav D; Jovanovi?, Dragana J; Ahrenkiel, S Phillip; Nedeljkovi?, Jovan M

2006-12-21

257

The influence of physico-chemical properties of TiO 2 on photocatalytic generation of C 1–C 3 hydrocarbons and hydrogen from aqueous solution of acetic acid  

Microsoft Academic Search

The present study was focused on the influence of physico-chemical properties of TiO2 on a photocatalytic generation of useful C1–C3 hydrocarbons (mainly methane) and hydrogen from aqueous solution of acetic acid under N2 atmosphere. The photocatalysts applied in the study were prepared from a crude TiO2 obtained by the sulphate technology. The crude TiO2 was calcined at the temperatures of

Sylwia Mozia; Aleksandra Heciak; Antoni W. Morawski

2011-01-01

258

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...

259

Linear correlation between inactivation of E. coli and OH radical concentration in TiO 2 photocatalytic disinfection  

Microsoft Academic Search

The biocidal action of the TiO2 photocatalyst has been now well recognized from massive experimental evidences, which demonstrates that the photocatalytic disinfection process could be technically feasible. However, the understanding on the photochemical mechanism of the biocidal action largely remains unclear. In particular, the identity of main acting photooxidants and their roles in the mechanism of killing microorganisms is under

Min Cho; Hyenmi Chung; Wonyong Choi; Jeyong Yoon

2004-01-01

260

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

261

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

262

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

263

Fabrication of TiO2 binary inverse opals without overlayers via the sandwich-vacuum infiltration of precursor.  

PubMed

A sandwich-vacuum method was demonstrated for the fabrication of titania (TiO(2)) binary inverse opals with an open surface. In this method, a moisture-stable TiO(2) precursor was backfilled into the interstitial spaces of polystyrene binary colloidal crystals (PS bCCs), which served as a template. Removal of the template by calcination yielded TiO(2) binary inverse opals with a 3D-ordered macroporous (3DOM) structure. Optical reflectance spectra revealed the existence of a pseudostop band gap in the 3DOM TiO(2) samples. The position of the pseudostop band gap shifted to the low-wavelength region as the number ratio of small over large PS spheres was increased in the template. The sandwich-vacuum method proved to be simple and rapid for the fabrication of TiO(2) binary inverse opals without overlayers in large domains. The 3DOM TiO(2) materials were used as a photocatalyst for the degradation of benzoic acid. Results showed that in comparison to TiO(2) nanoparticles prepared under the same sintering conditions, the 3DOM TiO(2) materials displayed enhanced photocatalytic activity. PMID:21413750

Cai, Zhongyu; Teng, Jinghua; Xiong, Zhigang; Li, Yanqiang; Li, Qin; Lu, Xianmao; Zhao, X S

2011-04-19

264

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

265

Directly assembled quantum dots on one dimension ordered TiO2 nanostructure in aqueous solution for improving photocatalytic activity  

NASA Astrophysics Data System (ADS)

One dimension (1D) ordered titanium dioxide (TiO2) nanostructured photocatalysts sensitized by quantum dots (QDs) are fabricated. Their morphologies, crystal structures and photocatalytic properties are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectroscopy, respectively. Compared with the original TiO2 nanostructure, the nanostructured TiO2 sensitized by QDs exhibits a good photocatalytic activity for the degradation of methyl orange (MO). The QDs with core-shell structure can reduce the photocatalytic ability due to the higher potential barrier of carrier transport in ZnS shell layer. The results indicate that the proposed photocatalyst shows promising potential for the application in organic dye degradation.

Huang, Jin-zhao; Kuang, Lei; Liu, Song; Zhao, Yong-dan; Jiang, Tao; Liu, Shi-you; Wei, Ming-zhi

2013-07-01

266

TiO2 promoted by two different non-noble metal cocatalysts for enhanced photocatalytic H2 evolution  

NASA Astrophysics Data System (ADS)

TiO2 photocatalysts modified by cobalt and nickel cocatalysts were prepared via polymerized complex method (PCM) and evaluated by photocatalytic hydrogen evolution. Hydrogen generation in 6 h for the TiO2 promoted by cobalt and nickel (0.1%Co + 0.2%Ni/TiO2) is about two times (2456 ?mol H2) compared to that of TiO2 promoted only by cobalt (1180 ?mol H2 for 0.1%Co/TiO2) or nickel (1127 ?mol H2 for 0.2%Ni/TiO2), and mechanically mixed TiO2 promoted by cobalt and TiO2 promoted by nickel (0.1%Co/TiO2:0.2%Ni/TiO2 = 1:1 (m/m), 1282 ?mol H2). The high photocatalytic H2 evolution activity over TiO2 promoted by cobalt and nickel is ascribed to enhanced photo response due to the presence of cobalt and nickel impurity level, and effective separation of photogenerated electrons and holes due to the synergistic effect of cobalt and nickel, which serve as active sites for H2 evolution reaction (HER) and oxidation reaction (OR) respectively. This study demonstrates a viable strategy to design more active photocatalysts for photocatalytic H2 evolution by substituting noble metals with more abundant elements using as HER and OR cocatalysts, respectively.

Lin, Jing-Dong; Yan, Shi; Huang, Qin-Dong; Fan, Mei-Ting; Yuan, You-Zhu; Tan, Timothy Thatt-Yang; Liao, Dai-Wei

2014-08-01

267

Photocatalytic H2 evolution on MoS2-TiO2 catalysts synthesized via mechanochemistry.  

PubMed

At present, composite photocatalysts containing MoS2 as a co-catalyst and a subjective semiconductor material are usually obtained via various complex reduction methods using NH4MoS4 or Na2MoO4 as a precursor. In this work, a simple method was proposed to synthesize MoS2-TiO2 composite photocatalysts via mechanochemistry using MoS2 as a direct precursor. 4.0% MoS2-TiO2 after ball-milling at 300 rpm for 2 h possessed the maximum photocatalytic activity for H2 evolution. The rate of H2 evolution was up to 150.7 ?mol h(-1), which was 48.6 times higher than that of pure TiO2. The MoS2-TiO2 composite possesses stable photocatalytic performance for H2 evolution. Photoelectrochemical measurements confirmed the electronic interaction between TiO2 and MoS2. The photo-generated electrons on the conduction band of TiO2 could easily transfer to the MoS2 co-catalyst, which promoted efficient charge separation and improved the photocatalytic performance. PMID:25406580

Zhu, Yanyan; Ling, Qiang; Liu, Yanfang; Wang, Hua; Zhu, Yongfa

2014-12-10

268

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

269

Photocatalytic reduction of carbon dioxide over ZnFe2O4/TiO2 nanobelts heterostructure in cyclohexanol.  

PubMed

A series of ZnFe2O4/TiO2 heterostructure photocatalysts with different mass percentages of ZnFe2O4 were synthesized through hydrothermal deposition method. The photocatalysts were characterized by SEM, TEM, XRD, XPS, and UV-vis DRS techniques. It is observed that ZnFe2O4 nanoparticles grew on the TiO2 nanobelts, and the obtained nanocomposites have ordered nanobelt structure with a high crystallinity. The photocatalytic activities of the nanocomposites were tested by photocatalytic reduction of CO2 in cyclohexanol under UV light (main wave length at 360nm) irradiation. The experimental results showed that the main products were cyclohexanone (CH) and cyclohexyl formate (CF). Compared with pure TiO2 and ZnFe2O4 samples, the obtained ZnFe2O4/TiO2 nanocomposites showed much higher photocatalytic performance. The loading amount of ZnFe2O4 was an important factor affecting the generation yields of the products. When the loading amount of ZnFe2O4 reached 9.78%, the ZnFe2O4/TiO2 heterostructure sample displayed the highest activity. The Z-scheme system reaction mechanism was proposed to explain the photocatalytic activity of the ZnFe2O4/TiO2 heterostructure sample. PMID:25514648

Song, Guixian; Xin, Feng; Yin, Xiaohong

2015-03-15

270

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

271

[Photocatalytic degradation kinetics of diuron by TiO2 and simulated sunlight].  

PubMed

Photocatalytic degradation kinetics of diuron in aqueous solution was systematically investigated using TiO2 as the photocatalyst. The single-variable-at-a-time (SVAT) method and the central composite design (CCD) based on response surface methodology (RSM) were employed to study the individual and synergistic effects of several classical parameters on photocatalytic efficiencies. Three different parameters, namely TiO2 concentration, pH value and initial temperature of the model pollutant, were found to independently determine the degradation efficiencies. From the SVAT experiments, it could be concluded that neutral solutions were favorable for the degradation of diuron, and the degradation rate increased with the increasing temperature. Moreover, the results from CCD indicated that the optimum degradation conditions were as follows: TiO2 concentration at 2.98 g x L(-1), pH value at 7.78, and temperature at 40 degrees C. PMID:24191560

Yang, Hai; Zeng, Jian; Li, Yuan; Yang, Li-Ping; Yi, Bing

2013-08-01

272

The effect of multiwalled carbon nanotube doping on the CO gas sensitivity of TiO2 xerogel composite film  

NASA Astrophysics Data System (ADS)

A simple sol-gel method was applied for the synthesis of 0.01 wt% multiwalled carbon nanotubes (MWCNTs)-doped TiO2 xerogel composite film. The film's CO gas sensing properties were then evaluated. Doped MWCNTs were coated with TiO2 and distributed on a TiO2 xerogel matrix. The TiO2 xerogel showed an anatase structure after heat treatment at 450 °C under vacuum. The specific surface area of the composite material was larger than the pure TiO2 xerogel material. The CO gas sensitivity of the MWCNTs(0.01 wt%)-doped TiO2 xerogel composite film was found to be seven times higher than that of pure TiO2 xerogel film and to have good stability. This higher gas-sensing property of the composite film was due to both an increase of specific surface area and the n-p junction structure of the TiO2 xerogel coated on MWCNTs. The electrons generated from TiO2 after adsorption of CO gas induces electron transfer from the TiO2 to the MWCNTs. This induces a characteristic change in the MWCNTs from p-type to n-type, and the resistance of MWCNTs-doped TiO2 xerogel composite sensor is therefore decreased.

Lee, Jin-Seok; Ha, Tae-Jung; Hong, Min-Hee; Park, Chang-Sun; Park, Hyung-Ho

2013-03-01

273

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

274

Effect of doping on electronic structure and photocatalytic behavior of amorphous TiO2.  

PubMed

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. PMID:24172752

Ghuman, Kulbir Kaur; Singh, Chandra Veer

2013-11-27

275

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

276

Surface modification of CNTs and enhanced photocatalytic activity of TiO 2 coated on hydrophilically modified CNTs  

NASA Astrophysics Data System (ADS)

A new method to enhance photocatalytic performance of TiO 2 by dispersing it onto hydrophilically surface modified carbon nanotubes is reported. The hydrophilically surface functionalized CNTs and as prepared composite CNTs-TiO 2 photocatalysts were characterized using FT-IR, XPS, XRD, BET adsorption analysis and TEM. The composite samples were evaluated for their photocatalytic activity toward the degradation of methyl orange in aqueous solution under both UV and visible light irradiation. The results indicated that the hydrophilic functional groups were grafted covalently on the surface of CNTs successfully, and the functionalized CNTs exhibit higher BET specific surface area and aquatic solubility. The improved photocatalytic activity of CNTs-TiO 2 was mainly attributed to the high dispersion of TiO 2 on CNTs and the intimate contact between TiO 2 and CNTs resulting in dense heterojunctions at the interface of TiO 2 and CNTs.

Yang, Hanpei; Wu, Sha; Duan, Yunping; Fu, Xiaofei; Wu, Junming

2012-01-01

277

The synthesis of nitrogen/sulfur co-doped TiO2 nanocrystals with a high specific surface area and a high percentage of {001} facets and their enhanced visible-light photocatalytic performance  

PubMed Central

Nitrogen/sulfur co-doped anatase TiO2 nanocrystals with a high specific surface area and a high percentage of {001} facets were synthesized by a solvent-thermal process followed by the calcination with thiourea at an optimum heat treatment temperature. Under current experimental conditions, the optimum heat treatment temperature was found at 300°C, which successfully introduced nitrogen and sulfur dopants into the anatase lattice to replace a small portion of oxygen atoms while preserving the geometry of these anatase TiO2 nanocrystals to maintain a high percentage of {001} facets. These nitrogen/sulfur co-doped anatase TiO2 nanocrystals demonstrated a largely enhanced light absorption in the whole visible-light range and exhibited much higher photocatalytic performance than both P25 TiO2 nanoparticles and anatase TiO2 nanocrystals with a high percentage of {001} facets under visible-light illumination. PMID:23095371

2012-01-01

278

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:25460718

Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

2015-02-15

279

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

280

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

281

Photocatalytic enhancement of hybrid C3N4/TiO2 prepared via ball milling method.  

PubMed

C3N4/TiO2 hybrid photocatalysts with highly enhanced photocatalytic performance were prepared by a facile ball milling method. A layered structure of g-C3N4 was formed on the surface of TiO2. The mechanochemical process can promote the dispersion of C3N4 on the surface of TiO2 particles, to form a single layer hybrid structure and a multi-layer core-shell structure. The photocatalytic activities of C3N4/TiO2 under visible and UV light irradiation were 3.0 and 1.3 times those of pure g-C3N4 and TiO2, respectively. Under visible light and UV irradiation, the photocurrent response was up to 2.5 times and 1.5 times as high as that of the pure TiO2 and C3N4, respectively. The evident performance enhancement of g-C3N4-TiO2 was mainly attributed to high separation and migration efficiency of electron-hole pairs. PMID:25553728

Zhou, Jianwei; Zhang, Mo; Zhu, Yongfa

2015-02-01

282

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

283

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

284

Experimental study of the visible-light photocatalytic activity of oxygen-deficient TiO2 prepared with Ar/H2 plasma surface treatment  

NASA Astrophysics Data System (ADS)

Oxygen-deficient TiO2 (TiO2?x) has been proposed as a visible-light-responsive photocatalyst. TiO2?x thin films were prepared by Ar/H2 plasma surface treatment, applying varying levels of microwave input power and processing times. The highest visible light photocatalytic activity was observed when using an input power of 200 W, a plasma processing time of 10 min, and a 1:1 \\text{Ar}:\\text{H}2 ratio, conditions that generate an electron temperature of 5.7(±1.0) eV and an electron density of 8.5 × 1010 cm?3. The maximum formaldehyde (HCHO) removal rate of the TiO2?x film was 2.6 times higher than that obtained from a TiO2?xNx film under the same test conditions.

Nakano, Takuma; Yazawa, Shota; Araki, Shota; Kogoshi, Sumio; Katayama, Noboru; Kudo, Yusuke; Nakanishi, Tetsuya

2015-01-01

285

Investigation on a novel ZnO/TiO2-B photocatalyst with enhanced visible photocatalytic activity  

NASA Astrophysics Data System (ADS)

A new type of composite photocatalysts (ZnO/TiO2-B) with Zinc oxide nanoparticles dispersed on boron doped titanium dioxide was prepared via a sol-gel method. The as-prepared powders were characterized by HRTEM, XRD, XPS, UV-vis DRS, and PL techniques. The results reveal that B3+ ions are doped into the TiO2 lattice in interstitial mode, while ZnO nanoparticles are dispersed on the surface of TiO2. The absorption of photocatalysts was extended into visible light region and the photogenerated electrons and holes were separated efficiently. Hence, ZnO/TiO2-B composite photocatalyst exhibits much better photocatalytic activity than those of pure TiO2 and TiO2-B on photodegradation of 4-chlorophenol under visible light irradiation.

Li, Wei; Wu, Di; Yu, Yanlong; Zhang, Peng; Yuan, Jing; Cao, Yongqiang; Cao, Yaan; Xu, Jingjun

2014-04-01

286

Preparation and photocatalytic properties of nanometer-sized magnetic TiO2/SiO2/CoFe2O4 composites.  

PubMed

Magnetic TiO2/SiO2/CoFe2O4 nanoparticles (TiO2/SCFs) were prepared by a sol-gel process in a reverse microemulsion combined with solvent-thermal technique. TiO2/SCFs were characterized by Fourier transform infrared spectrometry, thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Raman spectrometry, TEM, BET specific surface area measurement, and magnetic analysis. Structure analyses indicated that TiO2/SCFs presented a core-shell structure with TiO2 uniformly coating on SiO2/CoFe2O4 nanomagnets (SCFs) and typical ferromagnetic hysteresis. TiO2/SCFs showed larger specific surface area and better photocatalytic activities than TiO2 and TiO2/CoFe2O4 photocatalysts prepared by the same method. The doping interaction between TiO2 and CoFe2O4 reduced thanks to the inert SiO2 mesosphere. PMID:22413361

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

2011-11-01

287

Electrorheological property and microstructure of acetamide-modified TiO 2 nanoparticles  

Microsoft Academic Search

A sol–gel method has been proposed to prepare uniform TiO2 nanoparticles whose average size is about 30 nm. The prepared nanometer TiO2 particles are modified by acetamide via different self-assembled processes. X-ray diffraction analyses, scanning electron\\u000a microscopy, and Fourier transform infrared spectrometry are used to determine the structure of the nanoparticles. The results\\u000a indicate that the different synthesis processes do not

Yuchuan Cheng; Jianjun Guo; Gaojie Xu; Ping Cui; Xuehui Liu; Fenghua Liu; Jinghua Wu

2008-01-01

288

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

289

Enhanced degradation of organic pollutant 4-chlorophenol in water by non-thermal plasma process with TiO 2  

Microsoft Academic Search

The combined application of TiO2 photocatalyst and pulsed high-voltage electrical discharge process for the degradation of organic pollutant parachlorophenol (4-CP) in aqueous solution was tentatively investigated. The optimum conditions for 4-CP removal were applied voltage at 14 kV, electrode distance at 2 cm, pH at 6.5 (close to neutral solution), TiO2 concentration at 50 mg\\/L, gas source O2 at 100 L\\/h, and hybrid corona-streamer

Xiao-Long Hao; Ming-Hua Zhou; Yi Zhang; Le-Cheng Lei

2006-01-01

290

Visible light driven photoelectrochemical water oxidation on nitrogen-modified TiO2 nanowires.  

PubMed

We report hydrothermal synthesis of single crystalline TiO(2) nanowire arrays with unprecedented small feature sizes of ~5 nm and lengths up to 4.4 ?m on fluorine-doped tin oxide substrates. A substantial amount of nitrogen (up to 1.08 atomic %) can be incorporated into the TiO(2) lattice via nitridation in NH(3) flow at a relatively low temperature (500 °C) because of the small cross-section of the nanowires. The low-energy threshold of the incident photon to current efficiency (IPCE) spectra of N-modified TiO(2) samples is at ~520 nm, corresponding to 2.4 eV. We also report a simple cobalt treatment for improving the photoelectrochemical (PEC) performance of our N-modified TiO(2) nanowire arrays. With the cobalt treatment, the IPCE of N-modified TiO(2) samples in the ultraviolet region is restored to equal or higher values than those of the unmodified TiO(2) samples, and it remains as high as ~18% at 450 nm. We propose that the cobalt treatment enhances PEC performance via two mechanisms: passivating surface states on the N-modified TiO(2) surface and acting as a water oxidation cocatalyst. PMID:22112010

Hoang, Son; Guo, Siwei; Hahn, Nathan T; Bard, Allen J; Mullins, C Buddie

2012-01-11

291

Preparation of mesoporous nanocrystalline anatase TiO2 for dye sensitized solar cell application  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cell (DSSC) introduced by Prof.M.Gratzel is a low cost alternative to the existing silicon based solar cells. Solar light conversion efficiency of the current DSSC can be further improved by replacing the conventional anatase TiO2 having lesser surface area with mesoporous high surface area anatase TiO2. This paper describes the sol-gel synthesis of mesoporous high surface area nanocrystalline anatase TiO2 by the controlled hydrolysis and condensation of titanium isopropoxide followed by heat treatment. XRD reveals that xerogel heat treated at 500°C is phase pure anatase. Crystallite size of prepared anatase TiO2 calculated using Scherrer equation was found to be 15 nm. BET analysis of prepared anatase TiO2 exhibited relatively high specific surface area of 97 m2/g, which is found to be almost double to that of the anatase TiO2 generally used for DSSC photo anode fabrication. The pore size distribution (BJH plot) also revealed the mesoporous nature of prepared anatase TiO2 having an average pore size of 7.4 nm.

Jacob, K. Stanly; Abraham, P. A.; Panicker, N. Rani; Pramanik, N. C.

2014-01-01

292

Water-dispersible TiO2 nanoparticles via a biphasic solvothermal reaction method  

PubMed Central

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. PMID:24289214

2013-01-01

293

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

294

Water-dispersible TiO2 nanoparticles via a biphasic solvothermal reaction method.  

PubMed

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. PMID:24289214

Mohan, Rajneesh; Drbohlavova, Jana; Hubalek, Jaromir

2013-01-01

295

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

296

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

297

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

298

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)...

299

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

300

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

301

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

302

Visible-light-induced photocatalytic degradation of methylene blue with polyaniline-sensitized TiO composite photocatalysts  

NASA Astrophysics Data System (ADS)

A series of polyaniline (PANI)-sensitized TiO 2 composite photocatalysts (PANI/TiO 2) with different mass ratio of polyaniline to nano- TiO 2 (P25) (1:200-1:700) were facilely prepared by mixing a tetrahydrofuran (THF) solution of camphorsulfonic acid (CSA)-doped polyaniline (PANI-CSA) and TiO 2 nanoparticle suspension in ethanol. Transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (DRS) measurements were used to characterize the resulting composite photocatalysts, and their photocatalytic activities were investigated by degrading methylene blue (MB) under visible-light irradiation ( ?>400 nm). The results showed that the surface polyaniline sensitization had no effect on the crystalline structure but aggravated the agglomeration of TiO 2 nanoparticles by forming multi-particles. After being sensitized by PANI, the light response of TiO 2 was extended to visible-light regions and the photocatalytic activity of the composite photocatalysts was enhanced. MB could be degraded more efficiently on PANI/TiO 2 than on the bare TiO 2 when the mass ratio of polyaniline to TiO 2 was in the range 1:400-1:700, and the optimum sensitized effect was found at a mass ratio of 1:500. The determined rate constant of MB degradation over PANI/TiO 2 (1:500) was 0.01515 min -1, which is 1.57 times higher than that of bare TiO 2 (0.00963 min -1). Furthermore, PANI/TiO 2 composite photocatalysts showed good photocatalytic stability after five runs under visible light. The enhancement of photocatalytic activity of the composite photocatalysts could be attributed to the sensitizing effect of PANI. A possible mechanism for the photocatalytic degradation of methylene blue is also proposed.

Wang, Fang; Min, Shixiong; Han, Yuqi; Feng, Lei

2010-08-01

303

Photoassisted and photocatalytic degradation of sulfur mustard using TiO2 nanoparticles and polyoxometalates.  

PubMed

The decomposition of highly toxic chemical warfare agent, sulfur mustard (bis(2-chloroethyl) sulfide or HD), has been studied by homogeneous photolysis and heterogeneous photocatalytic degradation on titania nanoparticles. Direct photolysis degradation of HD with irradiation system was investigated. The photocatalytic degradation of HD was investigated in the presence of TiO(2) nanoparticles and polyoxometalates embedded in titania nanoparticles in liquid phase at room temperature (33 ± 2 °C). Degradation products during the treatment were identified by gas chromatography-mass spectrometry. Whereas apparent first-order kinetics of ultraviolet (UV) photolysis were slow (0.0091 min(-1)), the highest degradation rate is obtained in the presence of TiO(2) nanoparticles as nanophotocatalyst. Simultaneous photolysis and photocatalysis under the full UV radiation leads to HD complete destruction in 3 h. No degradation products observed in the presence of nanophotocatalyst without irradiation in 3 h. It was found that up to 90 % of agent was decomposed under of UV irradiation without TiO(2), in 6 h. The decontamination mechanisms are often quite complex and multiple mechanisms can be operable such as hydrolysis, oxidation, and elimination. By simultaneously carrying out photolysis and photocatalysis in hexane, we have succeeded in achieving faster HD decontamination after 90 min with low catalyst loading. TiO(2) nanoparticles proved to be a superior photocatalyst under UV irradiation for HD decontamination. PMID:22707206

Naseri, Mohammad Taghi; Sarabadani, Mansour; Ashrafi, Davood; Saeidian, Hamdollah; Babri, Mehran

2013-02-01

304

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

305

TiO2 sol-gel for formaldehyde photodegradation using polymeric support: photocatalysis efficiency versus material stability.  

PubMed

Photocatalysts supported on polymers are not frequently used in heterogeneous photocatalysis because of problems such as wettability and stability that affect photocatalysis conditions. In this work, we used polypropylene as support for TiO2 sol-gel to evaluate its stability and efficiency under UV radiation. We also tested the effect of the thermo-pressing PP/TiO2 system on the photocatalytic efficiency and stability under UV radiation. The films were characterized by scanning electron microscopy (SEM), UV-Vis spectroscopy and X-ray diffraction (XRD). The SEM micrographs showed that the films of TiO2 sol-gel onto PP has approximately 1.0-?m thick and regular surface and the generation of polypropylene nanowires on hot-pressed samples. XRD showed the formation of TiO2 anatase on the surface of the films made by dip-coating. All photocatalysts were tested in decontaminating air-containing gaseous formaldehyde (70 ppmv) presenting degradation of the target compound to the limit of detection. The photocatalysts showed no deactivation during the entire period tested (30 h), and its reuse after washing showed better photocatalytic performance than on first use. The photocatalyst showed the best results were tested for 360 h with no observed deactivation. Aging studies showed that the film of TiO2 causes different effects on the photostability of composites, with stabilizing effect when exposed to most energetic UVC radiation (?max?=?254 nm) and degradative effects when exposed to UVA radiation (?max?=?365 nm). PMID:24604273

Curcio, Monique S; Oliveira, Michel P; Waldman, Walter R; Sánchez, Benigno; Canela, Maria Cristina

2015-01-01

306

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

307

Electrodeposited Ag nanoparticles on TiO2 nanorods for enhanced UV visible light photoreduction CO2 to CH4  

NASA Astrophysics Data System (ADS)

We employed the double-potentiostatic methodology to electrodeposit Ag nanoparticles on oriented single-crystalline rutile TiO2 nanorods synthesized by hydrothermal method. The synthesized composites were used as the photocatalyst to reduce CO2 to CH4 under UV irradiation, and tested by SEM, XRD, TEM, XPS, UV-vis and photoluminescence. Deposition with Ag nanoparticles was observed to enhance the photocatalytic activity (?1.5-2.64 ?mol (gcatal h)-1) up to 5 times with respect to undecorated TiO2 nanorods (?0.5 ?mol (gcatal h)-1). The increase in the CH4 yield was correlated with the surface morphology and structure of TiO2 nanorods.

Kong, Dan; Tan, Jeannie Ziang Yie; Yang, Fei; Zeng, Jieliang; Zhang, Xiwen

2013-07-01

308

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

309

A new dielectric ta-C film coating of Ag-nanoparticle hybrids to enhance TiO2 photocatalysis  

NASA Astrophysics Data System (ADS)

We have demonstrated a novel method to enhance TiO2 photocatalysis by adopting a new ultrathin tetrahedral-amorphous-carbon (ta-C) film coating on Ag nanoparticles to create strong plasmonic near-field enhancement. The result shows that the decomposition rate of methylene blue on the Ag/10 Å ta-C/TiO2 composite photocatalyst is ten times faster than that on a TiO2 photocatalyst and three times faster than that on a Ag/TiO2 photocatalyst. This can be ascribed to the simultaneous realization of two competitive processes: one that excites the surface plasmons (SPs) of the ta-C-film/Ag-nanoparticle hybrid and provides a higher electric field near the ta-C/TiO2 interface compared to Ag nanoparticles alone, while the other takes advantage of the dense diamond-like ta-C layer to help reduce the transfer of photogenerated electrons from the conduction band of TiO2 to the metallic surface, since any electron transfer will suppress the excitation of SP modes in the metal nanoparticles.

Liu, Fanxin; Tang, Chaojun; Wang, Zhenlin; Sui, Chenghua; Ma, Hongtao

2014-03-01

310

Efficient thermal- and photocatalyst of Pd nanoparticles on TiO? achieved by an oxygen vacancies promoted synthesis strategy.  

PubMed

Pd nanoparticles supported on defective TiO2 with oxygen vacancies (TiO2-OV) have been prepared by an oxygen vacancies mediated reduction strategy. The resulting Pd-TiO2-OV catalyst with uniform Pd nanoparticles deposition demonstrates a remarkably thermocatalytic activity toward rapid, efficient reduction of nitroaromatics in water. The reaction proceeds efficiently using HCOONH4 as a hydrogen source under ambient conditions. The controlled experiments show that the (•)CO2(-) radicals produced by dehydrogenation of HCOONH4 are the main active species for the selective nitro reduction. Moreover, defective TiO2 nanostructures deposited with Pd nanoparticles, featuring excellent visible-light absorption via the creation of oxygen vacancies, can take advantage of the solar and thermal energy to drive catalytic reduction reactions more efficiently at room temperature. During this process, the oxygen vacancies and Pd nanoparticles play synergetic roles in the photoreduction of nitro compounds. Our work would be beneficial for implementation of a novel defect-mediated catalytic system in which solar light energy can be coupled with thermal energy to drive an energy efficient catalytic process. PMID:24392776

Pan, Xiaoyang; Xu, Yi-Jun

2014-02-12

311

Nanoporous TiO2 nanoparticle assemblies with mesoscale morphologies: nano-cabbage versus sea-anemone  

NASA Astrophysics Data System (ADS)

We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation.We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation. Electronic supplementary information (ESI) available: Synthesis and characterization procedures, TEM/XRD of samples prepared at different temperature and water content, table of nitrogen adsorption-desorption values of different samples. See DOI: 10.1039/c3nr06154j

Darbandi, Masih; Gebre, Tesfaye; Mitchell, Lucas; Erwin, William; Bardhan, Rizia; Levan, M. Douglas; Mochena, Mogus D.; Dickerson, James H.

2014-05-01

312

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing  

PubMed Central

TiO2-SiO2-Ag composites are fabricated by depositing TiO2 films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO2 originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO2. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell. PMID:23402586

2013-01-01

313

Efficiency enhancements in Ag nanoparticles-SiO2-TiO2 sandwiched structure via plasmonic effect-enhanced light capturing  

NASA Astrophysics Data System (ADS)

TiO2-SiO2-Ag composites are fabricated by depositing TiO2 films on silica substrates embedded with Ag nanoparticles. Enhancement of light absorption of the nanostructural composites is observed. The light absorption enhancement of the synthesized structure in comparison to TiO2 originated from the near-field enhancement caused by the plasmonic effect of Ag nanoparticles, which can be demonstrated by the optical absorption spectra, Raman scattering investigation, and the increase of the photocatalytic activity. The embedded Ag nanoparticles are formed by ion implantation, which effectively prevents Ag to be oxidized through direct contact with TiO2. The suggested incorporation of plasmonic nanostructures shows a great potential application in a highly efficient photocatalyst and ultra-thin solar cell.

Xu, Jinxia; Xiao, Xiangheng; Stepanov, Andrey L.; Ren, Fen; Wu, Wei; Cai, Guangxu; Zhang, Shaofeng; Dai, Zhigao; Mei, Fei; Jiang, Changzhong

2013-02-01

314

Synthesis and characterization of F-N-W-codoped TiO{sub 2} photocatalyst with enhanced visible light response  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Anatase F-N-W-codoped TiO{sub 2} was prepared by a sol–gel-hydrothermal method. ? Under visible illumination, carbon removal rate of RB reached 94% using F-7NW-TiO{sub 2}. ? F, N and W dopants narrowed band gap and lowed charge pairs recombination rate. ? There were W{sub x}Ti{sub 1?x}O{sub 2}, O-Ti-N and valence variation of W ions existing. -- Abstract: Anatase F-N-W-codoped TiO{sub 2} photocatalyst was successfully prepared by a method combining sol–gel with hydrothermal treatment. Effects of F, N and W ion dosage concentration on the crystallinity, morphology, grain size and chemical status of the photocatalyst were investigated. The results showed that the F-7NW-TiO{sub 2} photocatalyst composed of uniform ellipsoidal particles around 20 nm in length and 10 nm in width, and the photocatalyst displayed enhanced visible-light absorption and photocatalytic activities. Using the photocatalyst and under visible irradiation for 1.5 h, the decoloration percent of RB and carbon removal rate were about 98% and 94% respectively, which were much higher than that of commercial P25, TiO{sub 2}, N-W-TiO{sub 2} and F-TiO{sub 2}. The high visible-light photocatalytic activity of F-7NW-TiO{sub 2} might result from narrowing the band gap and lowing charge pairs recombination rate for the W{sub x}Ti{sub 1?x}O{sub 2}, O-Ti-N and valence variation of W ions existing.

Shi, Xiaoliang, E-mail: sxl071932@126.com [School of Mechanical and Electronic Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China) [School of Mechanical and Electronic Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); School of Materials Science and Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Qin, Haibo; Yang, Xingyong [School of Materials Science and Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)] [School of Materials Science and Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Zhang, Qiaoxin [School of Mechanical and Electronic Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China) [School of Mechanical and Electronic Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); School of Materials Science and Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

2012-12-15

315

nanocrystallites condensed in vapor-phase for photocatalyst applications  

NASA Astrophysics Data System (ADS)

We have synthesized titanium dioxide (TiO2) nanocrystallites by pulsed laser ablation (PLA) in oxygen (O2) background gas for photocatalyst applications. Varying O2 background gas pressure or substrate target distance ( D TS), it was possible to change weight fraction of anatase phase in the anatase/rutile mixture from 0.2 to 1.0. Porosity of the deposited TiO2 films increased with increasing and D TS. Relation between the process parameters and the formed crystal phases was explained from the point of cooling process in vapor-phase. Furthermore, rapid thermal annealing (RTA) was performed as post-annealing, suppressing sintering of the nanocrystallites. Photocatalytic activities of the TiO2 nanocrystallites depended on the RTA temperature and following crystallinity restoring as well as the crystal phase: anatase or rutile.

Yoshida, Takehito; Yagi, Nobuyasu; Nakagou, Riki; Sugimura, Akira; Umezu, Ikurou

2014-10-01

316

Investigations of near infrared reflective behaviour of TiO2 nanopowders synthesized by arc discharge  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) nanopowders with different polymorphic phases were successfully synthesized by an arc discharge method. Samples were characterized using synchrotron radiation X-ray diffraction, high resolution scanning electron microscopy, high resolution transmission electron microscope and near infrared diffuse reflectance spectroscopy. Spherical structures were obtained after arc discharge. A mixture of both anatase and rutile phases was discovered in TiO2 samples synthesized at an arc current of 50 A, showing a majority particle size of 34 nm with size distribution between 5 nm and 60 nm. Completed anatase to rutile phase transformation was observed when the arc current increased from 50 A to 74 A. The crystallite size of the TiO2 nanopowders was significant effected by the arc discharge current during synthesis. After the arc current increased from 74 A to 110 A, the majority particle size of the obtained TiO2 increased to 85 nm with a size distribution in the range between 50 nm and 1800 nm. Diffuse reflectance of the TiO2 nanopowders synthesized at different arc discharge currents was measured. Broadband near infrared reflection (800-950 nm) of up to 50% was observed for TiO2 nanopowders synthesized at an arc current of 74 A. It is considered that rutile phase together with an appropriate mean crystallite size of the TiO2 nanopowders synthesized at an arc current of 74 A contributes to the best near infrared reflectivity in this study. The developed TiO2 nanoppowders will be of immense use in NIR reflective pigment.

Fang, Fang; Kennedy, John; Carder, Damian; Futter, John; Rubanov, Sergey

2014-05-01

317

Achieving phase transformation and structure control of crystalline anatase TiO2@C hybrids from titanium glycolate precursor and glucose molecules.  

PubMed

Considerable efforts have focused on functional TiO2@carbonaceous hybrid nanostructured materials (TiO2@C) to satisfy the future requirements of environmental photocatalysis and energy storage using these advanced materials. In this study, we developed a two-step solution-phase reaction to prepare hybrid TiO2@C with tuneable structure and composition from the hydrothermal carbonization (HTC) of glucose. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) were used to determine the crystallite size, composition, and phase purity. The results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution TEM (HRTEM) showed that the morphology of the as-synthesized TiO2@C hybrids could be controlled by varying the amount of glucose, also acting as the carbon source. Based on the observations made with different glucose concentrations, a formation mechanism of nanoparticulate and nanoporous TiO2@C hybrids was proposed. In addition, the as-synthesized TiO2@C hybrids with different compositions and structures showed enhanced adsorption of visible light and improved dye-adsorption capacity, which supported their potential use as photocatalysts with good activity. This new synthetic approach, using a nanoprecursor, provides a simple and versatile way to prepare TiO2@C hybrids with tuneable composition, structures, and properties, and is expected to lead to a family of composites with designed properties. PMID:25454439

Cheng, Gang; Stadler, Florian J

2015-01-15

318

Fabrication of Bi2O3/TiO2 nanocomposites and their applications to the degradation of pollutants in air and water under visible-light.  

PubMed

A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light (lambda > or = 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3. PMID:25076538

Chakraborty, Ashok Kumar; Hossain, Md Emran; Rhaman, Md Masudur; Sobahan, K M A

2014-02-01

319

Effect of transition metal doping under reducing calcination atmosphere on photocatalytic property of TiO2 immobilized on SiO2 beads.  

PubMed

TiO2 immobilized on SiO2 (TiO2/SiO2) have been prepared by sol-gel method and various ions of transition metals (Cr3+, Co2+ Ni2+, CU2+, and Zn2+) were doped on the photocatalyst using wet impregnation method under reducing calcination atmosphere. The photocatalytic activity of metal doped TiO2/SiO2 towards phenol degradation under black light irradiation were investigated and compared with undoped TiO2/SiO2. The results showed that the photoresponse of Cu2+ and Zn2+ doped TiO2/SiO2 were larger than undoped TiO2/SiO2, indicating that the photogenerated carriers were separated more efficiently in Cu2+ and Zn2+ doped TiO2/SiO2. The reactivity was in the order of Cu2+ > Zn2+ > Ni2+ > Cr3+ > Co2+. The different photoreactivity was ascribed to combine effect of the different ionic radii and photocorrison tendency of the dopants. The sample was also characterized by surface analytical methods such as X-ray diffraction, scanning electron micrograph/electron dispersive X-ray analyzer and UV-Vis absorption spectrum. PMID:24218855

Chand, Rumi; Obuchi, Eiko; Katoh, Katsumi; Luitel, Hom Nath; Nakano, Katsuyuki

2013-07-01

320

Surface Plasmons and Optical Properties of TiO2/X(X = Au and Ag) Nanostructure Thin Films  

NASA Astrophysics Data System (ADS)

TiO2/X(X = Au and Ag) nanolayers are fabricated by depositing TiO2 films using rf magnetron sputtering on thin quartz substrates embedded with Au and Ag nanoparticles. Enhancement of light absorption of the nanostructural layers is observed. These plasmonic and non-plasmonic materials are ordered in geometric arrangements with dimensions that are fractions of the wavelength of light. The light absorption enhancement of synthesized structure in comparison to TiO2 is originated from near-field enhancement caused by the plasmonic effect of metallic nanoparticles, which can be demonstrated by the optical absorption spectra. We show that plasmon modes can exist for the infrared region of the optical spectrum. Also, we analyze the optical properties of the metal-insulator films, in order to clarify the role of metal inclusions in the TiO2 dielectric matrix. Optical band gaps of the nanolayer films are calculated by using Tauc's relation, and the n values of optical band gaps with the variation composition are found from 1.80 to 3.69 eV. Band gap narrowing and absorption in the visible spectral region induced by the incorporation of TiO2/X(X=Au and Ag) nanolayers enable the design of nanostructured thin films to be achieved for photocatalysts and solar energy converters.

Zolanvari, A.; Sadeghi, H.; Norouzi, R.; Ranjgar, A.

2013-09-01

321

Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs  

NASA Astrophysics Data System (ADS)

iO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20-100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films.

Kim, Hyun-Bin; Park, Dong-Won; Jeun, Joon-Pyo; Oh, Seung-Hwan; Nho, Young-Chang; Kang, Phil-Hyun

2012-08-01

322

Formation of TiO 2 nano-fiber doped with Gd 3+ and its photocatalytic activity  

Microsoft Academic Search

Titanium dioxide (TiO2) nano-fibers doped with Gd3+ were synthesized by two-step synthesis method. The formed fibers were visualized from transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the average diameter of the TiO2 nano-fibers was 60–80 nm and the length of fibers was in the range of 6–7 ?m. The TiO2 nano-fibers doped with Gd3+ heat

Wuyi Zhou; Yi Zhou; Shaoqiu Tang

2005-01-01

323

Synthesis of dumbbell-like Bi2WO6@CaWO4 composite photocatalyst and application in water treatment  

NASA Astrophysics Data System (ADS)

Dumbbell-like Bi2WO6@CaWO4 composite photocatalyst was successfully synthesized via hydrothermal method in one step, in which the Bi2WO6 nanoplates assembled on the surface of the CaWO4 microspheres. The growth mechanism of such a special micro-nano structure was investigated. This structure holds the advantages of both a microstructure and a nanostructure, which can not only ensure the sufficient contact between the Bi2WO6 photocatalyst and the organic molecules, but also favor the sediment of the catalyst particles. Photocatalytic degradation of rhodamine B (RhB), demonstrated that the Bi2WO6@CaWO4 composite reserved the high photo-activity of Bi2WO6. Besides RhB, the Bi2WO6@CaWO4 composite could also degrade other model pollutants such as methyl orange (MO) and phenol effectively. Moreover, the composite photocatalyst could settle naturally in 15 min, which is beneficial for its separation and recycling.

Zhang, Zhijie; Wang, Wenzhong; Jiang, Dong; Xu, Jiayue

2014-02-01

324

Preparation and characterization of hydrophobic TiO(2) pillared clay: the effect of acid hydrolysis catalyst and doped Pt amount on photocatalytic activity.  

PubMed

Titanium hydrate sols were prepared using different acid hydrolysis catalysts, i.e., acetic acid and hydrochloric acid. The platinum-doped TiO(2) sol-gels were also synthesized by adding K(2)PtCl(6) into the titanium hydrate sols. The hydrophobic montmorillonite clay, treated with organic cationic surfactant, i.e., hexadecyltrimethylammonium bromide, was used as a template to prepare TiO(2) pillared photocatalyst with the above sols. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) were employed to characterize the resulting photocatalysts. The adsorption performance and photoactivity of prepared pillared clays were studied by using methyl orange as a model organic pollutant. The preliminary results indicated that the hydrophobic TiO(2) pillared clay prepared with acetic acid as the acid hydrolysis catalysts possessed higher photocatalytic activity than that with hydrochloric acid. Due to the excellent sedimentation property of the clay, the resulting pillared photocatalyst is easily recovered and reused in the postrun treatment. Also the doping of platinum into the hydrophobic photocatalyst can increase the photocatalytic activity significantly. PMID:18279880

Ding, Xuejun; An, Taicheng; Li, Guiying; Zhang, Shanqing; Chen, Jiaxin; Yuan, Jianmei; Zhao, Huijun; Chen, Hui; Sheng, Guoying; Fu, Jiamo

2008-04-15

325

High-surface-area mesoporous TiO2 microspheres via one-step nanoparticle self-assembly for enhanced lithium-ion storage.  

PubMed

Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m(2) 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. PMID:25363569

Wang, Hsin-Yi; Chen, Jiazang; Hy, Sunny; Yu, Linghui; Xu, Zhichuan; Liu, Bin

2014-12-21

326

The effect of hydrothermal conditions on the mesoporous structure of TiO2 nanotubes  

Microsoft Academic Search

A systematic analysis of the influence of preparation conditions in the alkali hydrothermal synthesis on the morphology of TiO2 nanotubes is performed using HRTEM and low temperature nitrogen adsorption. The possible mechanisms of nanotube formation are reviewed and a mechanism based on the key stage of wrapping of intermediate multilayered titanate nanosheets is suggested. The driving force for wrapping is

Dmitry V. Bavykin; Valentin N. Parmon; Alexei A. Lapkina; Frank C. Walshc

2004-01-01

327

Distinct Structural Behavior and Transport of TiO2 Nano- and Nanostructured Particles in Sand  

EPA Science Inventory

Environmental impact of TiO2 particles along with other widely-used nanomaterials as a new class of contaminants has recently emerged. Due to the lack of detailed information and proper understanding of their properties as a result of synthesis (nanoparticles vs nanost...

328

Synthesis, characterization, and photocatalytic activities of Cobalt(II)-Titanium dioxide nanorods, and electrophoretic deposition of Titanium dioxide nanoparticle/nanorod composite films for self-cleaning applications  

NASA Astrophysics Data System (ADS)

This dissertation consists of two projects. The first project is synthesis, characterization, and photocatalytic activities of Co(II)-TiO2 nanorods. We modified brookite TiO2 nanorods with cobalt(II) ions to design new photocatalysts with visible light absorption. X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) data indicated that the local structure of Co(II)-TiO2 nanorods was shown as tetrahedral and octahedral Co(II) sites at TiO2 nanorod surface. Dimethylglyoxime (DMG) has been used to remove surface Co(II) from Co(II)-TiO2 nanorods to determine single-site Co(II) ions selectively attached to the TiO 2 nanorod surface. We proposed a mechanism that the Co-Co bond of the precursor Co2(CO)8 undergoes heterolysis followed by disproportionation of Co(I) to produce Co(II) and Co(0) precipitate. Finally, the Co(II)-TiO2 nanorods showed greater activity than TiO 2 nanorods in the degradation of 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) dye under visible light irradiation. The second project is electrophoretic deposition (EPD) of TiO2 nanoparticle/nanorod composite films for self-cleaning applications. We developed novel electrolyte system for EPD of TiO2 nanoparticle/nanorod composites for self-cleaning coatings. A mixture of TiO2 powder and TiO2 nanorods was used as EPD suspension in a mixture of THF and acetone. TiO2 nanoparticle/nanorod composite films were fabricated on aluminium substrates via the EPD method, and were characterized by scanning electron microscope (SEM). SEM images showed that TiO2 nanoparticle/nanorod composite films had a uniform pore structure. The hydrophobic properties of surfaces in TiO2 nanoparticle/nanorod composite films were evaluated by water contact angle measurements. It was found that the surfaces of TiO2 nanoparticle/nanorod composite films were hydrophobic with contact angle of 103°. These hydrophobic surfaces are expected to have potential applications for self-cleaning.

Kang, Wonjun

329

TiO2/CdSe core-shell nanofiber film for photoelectrochemical hydrogen generation.  

PubMed

We report on a novel core-shell TiO2/CdSe nanofiber photoanode for photoelectrochemical hydrogen generation. The core-shell nanofiber films, with a hierarchical network structure, are prepared on fluorine-doped tin oxide coated substrates via electrospinning pyrolysis and chemical bath deposition. The hierarchical network structure shows significantly improved photoelectrochemical properties due, we believe, to possessing more active sites for the oxidation reaction and a larger TiO2/CdSe interface area for photogenerated charges' separation. The synthesis details are discussed to provide a generic route for preparing other similar photoanodes with hierarchical network structures. PMID:24876070

Liu, Ya; Zhao, Liang; Li, Mingtao; Guo, Liejin

2014-07-01

330

TiO2/CdSe core-shell nanofiber film for photoelectrochemical hydrogen generation  

NASA Astrophysics Data System (ADS)

We report on a novel core-shell TiO2/CdSe nanofiber photoanode for photoelectrochemical hydrogen generation. The core-shell nanofiber films, with a hierarchical network structure, are prepared on fluorine-doped tin oxide coated substrates via electrospinning pyrolysis and chemical bath deposition. The hierarchical network structure shows significantly improved photoelectrochemical properties due, we believe, to possessing more active sites for the oxidation reaction and a larger TiO2/CdSe interface area for photogenerated charges' separation. The synthesis details are discussed to provide a generic route for preparing other similar photoanodes with hierarchical network structures.

Liu, Ya; Zhao, Liang; Li, Mingtao; Guo, Liejin

2014-06-01

331

TiO2 nanofibrous interface development for Raman detection of environmental pollutants  

NASA Astrophysics Data System (ADS)

Sensor development has been reliant on planar Au and Ag nanoparticle research. The current findings explored a unique 3-D network of crystalline TiO2 nanoparticles linked as nanofibers. In addition to the favorability of using TiO2 for chemical and bio-molecular sensing, the nanofiber network provides molecular diffusion control and an increased confocal volume signal. Controlled femtosecond laser synthesis is also demonstrated that directly impacts surface-enhanced Raman spectroscopy detection of two common environmentally harmful chemicals: bisphenol A and diclofenac sodium salt. These findings assert that 3-D nanofibrous network porosity optimization is crucial for Raman monitoring of drinking water.

Maznichenko, D.; Selvaganapathy, P. R.; Venkatakrishnan, K.; Tan, B.

2012-12-01

332

Textural, structural and electrical properties of TiO2 nanoparticles using Brij 35 and P123 as surfactants  

NASA Astrophysics Data System (ADS)

The effect of the use of the triblock copolymer Pluronic P123[(PEO)20(PPO)70(PEO)20, Aldrich] and the non-ionic polyoxyethylene-lauryl ether Brij 35 as surfactants on the textural, structural and electrical properties of nanosized TiO2 is analyzed in this work. The as-obtained samples were thermally treated at 400 °C to eliminate the surfactant, promote dehydroxylation and crystallize the sample. The TiO2 samples were characterized by thermal analysis, N2 physisorption, x-ray diffraction analysis, micro-Raman spectroscopy and scanning electron microscopy. To evaluate the TiO2 electrical features, I-V data were obtained. The x-ray diffraction results show that in the chemical synthesis using surfactants, the crystallite size is smaller than that of the commercial sample. The Raman spectroscopy results clearly indicate that, when P123 is used, the anatase phase of TiO2 is obtained, whereas when Brij 35 is used a mixture of the anatase and brookite phases is obtained. The specific surface area and crystallite size of the TiO2 prepared as indicated above are higher and smaller, respectively, than the corresponding properties found in commercial TiO2. The I-V plot showed a nonlinear behavior of the nanosized TiO2. The samples obtained with P123 showed the best electrical conductivity.

Solís, Dora; Vigueras-Santiago, Enrique; Hernández-López, Susana; Gómez-Cortés, Antonio; Aguilar-Franco, Manuel; Camacho-López, Marco Antonio

2008-04-01

333

High-performance self-powered UV photodetectors based on TiO2 nano-branched arrays  

NASA Astrophysics Data System (ADS)

Nano-branched TiO2 arrays were fabricated on fluorine-doped tin oxide (FTO) glass by a facile two-step chemical synthesis process. Self-powered UV photodetectors based on photoelectrochemical cells (PECs) were assembled using these TiO2 nano-branched arrays as photoanodes. These visible-blind self-powered UV photodetectors exhibit high sensitivity and high-speed photoresponse. Compared with photodetectors based on bare TiO2 nanorod arrays, TiO2 nano-branched arrays show drastically improved photodetecting performance as photoanodes. The photosensitivity increases from 0.03 to 0.22 A W-1 when optimized nano-branched TiO2 arrays are used, corresponding to an incident photon-to-current conversion efficiency higher than 77%. The UV photodetectors also exhibit excellent spectral selectivity and fast response (0.05 s decay time). The improved performance is attributed to a markedly enlarged TiO2/electrolyte contact area and good electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunk.

Xie, Yanru; Wei, Lin; Li, Qinghao; Chen, Yanxue; Yan, Shishen; Jiao, Jun; Liu, Guolei; Mei, Liangmo

2014-02-01

334

High-performance self-powered UV photodetectors based on TiO2 nano-branched arrays.  

PubMed

Nano-branched TiO2 arrays were fabricated on fluorine-doped tin oxide (FTO) glass by a facile two-step chemical synthesis process. Self-powered UV photodetectors based on photoelectrochemical cells (PECs) were assembled using these TiO2 nano-branched arrays as photoanodes. These visible-blind self-powered UV photodetectors exhibit high sensitivity and high-speed photoresponse. Compared with photodetectors based on bare TiO2 nanorod arrays, TiO2 nano-branched arrays show drastically improved photodetecting performance as photoanodes. The photosensitivity increases from 0.03 to 0.22 A W(-1) when optimized nano-branched TiO2 arrays are used, corresponding to an incident photon-to-current conversion efficiency higher than 77%. The UV photodetectors also exhibit excellent spectral selectivity and fast response (0.05 s decay time). The improved performance is attributed to a markedly enlarged TiO2/electrolyte contact area and good electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunk. PMID:24451997

Xie, Yanru; Wei, Lin; Li, Qinghao; Chen, Yanxue; Yan, Shishen; Jiao, Jun; Liu, Guolei; Mei, Liangmo

2014-02-21

335

Enhanced photocurrent from generated photothermal heat in indium nanoparticles embedded TiO2 film  

NASA Astrophysics Data System (ADS)

We have demonstrated the synthesis of indium (In) nanoparticle (NP) arrays on TiO2 thin film (TF) using glancing angle deposition technique. The deposited In NPs are of the order of 4-10 nm in size. Optical absorption measurements depict 2.5 times enhanced absorption for In-NPs/TiO2-TF compared to TiO2 TF. The plasmonic device shows a turn on voltage at ˜3.0 and ˜1.0 V under dark and 30 min illumination, respectively. The device current increases from 1.6 to 6.5 mA/cm2 (+5 V) with enhanced temperature for 1-30 min continuous light exposures. The plasmonic device shows eight-fold enlarged photoresponsivity (+2.3 V) compared to the TiO2 TF based device.

Choudhuri, B.; Mondal, A.; Dhar, J. C.; Singh, N. K.; Goswami, T.; Chattopadhyay, K. K.

2013-06-01

336

Nanostructure and charge transfer in Bi2S3-TiO2 heterostructures.  

PubMed

Interfacial nanostructures in Bi2S3-TiO2 nanorod-nanoparticle heterostructures with a change of coupling mode have been engineered. The samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet-visual light absorption spectroscopy. By means of in situ growth of TiO2 nanoparticles on the surfaces of Bi2S3 nanorods in one pot, heterostructures with high-quality interfaces were obtained in which the {105} facet of anatase TiO2 selectively coupled with the {010} facet of orthorhombic Bi2S3 nanorods without any crystal defects, showing the epitaxial relationship of Bi2S3 {011} // TiO2 {101}. By means of a two-step method, TiO2 nanoparticles also could be grown on the {310} facet of the pre-prepared Bi2S3 nanorods to form heterostructures but with interfacial defects. Charge transfer in the interface-different heterostructures was evaluated by photodegradation of methyl orange under visible-light irradiation. The defect-free interfaces favored electron-hole separation and transfer, resulting in improved photocatalytic activity. The current structural characterization and interface engineering should be expanded to other heterostructures when studying the relationship between synthesis, interfacial structure, and photocatalytic or photovoltaic applications. PMID:24784772

Yu, Haijing; Huang, Jing; Zhang, Hua; Zhao, Qingfei; Zhong, Xinhua

2014-05-30

337

Nanostructure and charge transfer in Bi2S3-TiO2 heterostructures  

NASA Astrophysics Data System (ADS)

Interfacial nanostructures in Bi2S3-TiO2 nanorod-nanoparticle heterostructures with a change of coupling mode have been engineered. The samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet-visual light absorption spectroscopy. By means of in situ growth of TiO2 nanoparticles on the surfaces of Bi2S3 nanorods in one pot, heterostructures with high-quality interfaces were obtained in which the {105} facet of anatase TiO2 selectively coupled with the {010} facet of orthorhombic Bi2S3 nanorods without any crystal defects, showing the epitaxial relationship of Bi2S3 {011} // TiO2 {101}. By means of a two-step method, TiO2 nanoparticles also could be grown on the {310} facet of the pre-prepared Bi2S3 nanorods to form heterostructures but with interfacial defects. Charge transfer in the interface-different heterostructures was evaluated by photodegradation of methyl orange under visible-light irradiation. The defect-free interfaces favored electron-hole separation and transfer, resulting in improved photocatalytic activity. The current structural characterization and interface engineering should be expanded to other heterostructures when studying the relationship between synthesis, interfacial structure, and photocatalytic or photovoltaic applications.

Yu, Haijing; Huang, Jing; Zhang, Hua; Zhao, Qingfei; Zhong, Xinhua

2014-05-01

338

Highly efficient TiO2-based microreactor for photocatalytic applications.  

PubMed

A photocatalytic, TiO2-based microreactor is designed and fabricated on a metal-titanium foil. The microchannel is mechanically engraved in the substrate foil, and a double-layered TiO2 anatase film is immobilized on its inner walls with a two-step synthesis, which included anodization and a hydrothermal treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm the presence of an approximately 10-?m-thick layer of titania nanotubes and anatase nanoparticles. The SEM and transmission electron microscopy (TEM) of the cross sections show a dense interface between the titanium substrate and the TiO2 nanotubes. An additional layer of TiO2-anatase nanoparticles on the top of the film provides a large, photocatalytic surface area. The metal-titanium substrate with a functionalized serpentine channel is sealed with UV-transparent Plexiglas, and four 0.8-mW UV LEDs combined with a power controller on a small printed-circuit board are fixed over the substrate. The photocatalytic activity and the kinetic properties for the degradation of caffeine are provided, and the longer-term stability of the TiO2 film is evaluated. The results show that after 6 months of use and 3600 working cycles the microreactor still exhibits 60% of its initial efficiency. PMID:23978202

Krivec, Matic; Žagar, Kristina; Suhadolnik, Luka; ?eh, Miran; Draži?, Goran

2013-09-25

339

Preparation of Multilayer TiO2 Thin Films for Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

We adopt TiO2 materials with three different morphologies to fabricate multilayer thin films for dye-sensitized solar cell (DSSC) photoelectrodes. The three different TiO2 morphologies are (1) titania nanotubes (Tnt) hydrothermally fabricated by 550 °C calcinating treatment to form an anatase phase (Tnt-C550), (2) TiO2 nanoparticles (H200) prepared by subjecting Tnt to two cycles of hydrothermal treatment, and (3) a TiO2 nanofluid (SF) fabricated by our developed submerged arc nanofluids synthesis system (SANSS). Experimental results showed that DSSCs fabricated with Tnt photoelectrodes tested with AM 1.5 light to simulate sunlight (100 mW/cm2) had a photoelectric conversion efficiency of 2.84%. The thin-film photoelectrode was prepared using Tnt-C550 calcined at 550 °C. Its photoelectric conversion efficiency increased to 5.77%. The photoelectric conversion efficiency of DSSCs with photoelectrodes fabricated using H200 reached 5.91%. Moreover, the photoelectric conversion efficiency of DSSCs with photoelectrodes prepared using SF reached 4.45%. Finally, the TiO2 materials with three different morphologies were used to prepare a three-layer photoelectrode with the structure of H200/Tnt-C550/SF, which was combined with a counter electrode to assemble DSSCs. These DSSCs had a photoelectric conversion efficiency of as high as 7.07%.

Chang, Ho; Chen, Yu-Ling

2010-06-01

340

Bifunctional-Nanotemplate Assisted Synthesis of Nanoporous SrTiO3 Photocatalysts Toward Efficient Degradation of Organic Pollutant.  

PubMed

Nanoporous SrTiO3 photocatalysts were fabricated via a novel technique, the nanotemplate assisted sol-gel hydrothermal reaction. In the alkaline-environment hydrothermal reaction, the SiO2 nanotemplate not only served as pore generator but also worked on adjusting the local reaction environment around the SrTiO3 nanocrystals. This contributed to a continuous modulation between the surface area and the crystallinity of the photocatalyst. The photocatalytic activities of the nanoporous SrTiO3 samples were evaluated by the degradation of gaseous isopropyl alcohol (IPA). Due to an optimal equilibrium between surface area and crystallinity, a SrTiO3 sample synthesized via adding 40% template (STO-SiO2-40%) showed the highest activity, which achieves 40 and 8 times of enhancement of CO2 evolution in comparison with the sample prepared without template and a commercial nano-SrTiO3, respectively. The photodegradation mechanism of IPA over this sample was also investigated in detail. This synthetic technique is also available to prepare the other nanoporous titanates, such as doped SrTiO3 samples and alkali-metal titanates. PMID:25415827

Ouyang, Shuxin; Li, Peng; Xu, Hua; Tong, Hua; Liu, Lequan; Ye, Jinhua

2014-12-24

341

RESEARCH ARTICLE Nanoimprinted Tio2 solgel passivating diffraction  

E-print Network

RESEARCH ARTICLE Nanoimprinted Tio2 sol­gel passivating diffraction gratings for solar cell, Australia ABSTRACT We report the fabrication and characterization of TiO2 sol­gel diffraction gratings for solar cells. Copyright © 2011 John Wiley & Sons, Ltd. KEYWORDS TiO2 sol­gel; diffraction grating; solar

342

Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.  

PubMed

Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2. PMID:23901525

Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

2013-07-01

343

Two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched and P25-coated TiO2 nanotube arrays and their photocurrent performances  

PubMed Central

We report here for the first time the synthesis of two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched TiO2 nanotube arrays (BTs) and P25-coated TiO2 nanotube arrays (PCTs) using two-step method including electrochemical anodization and hydrothermal modification process. Then the photocurrent densities versus applied potentials of BTs, PCTs, and pure TiO2 nanotube arrays (TNTAs) were investigated as well. Interestingly, at -0.11 V and under the same illumination condition, the photocurrent densities of BTs and PCTs show more than 1.5 and 1 times higher than that of pure TNTAs, respectively, which can be mainly attributed to significant improvement of the light-absorbing and charge-harvesting efficiency resulting from both larger and rougher surface areas of BTs and PCTs. Furthermore, these dramatic improvements suggest that BTs and PCTs will achieve better photoelectric conversion efficiency and become the promising candidates for applications in DSSCs, sensors, and photocatalysis. PMID:21711607

2011-01-01

344

Experimental: Sample Preparation TiO2 compact (TiO2comp) anatase films (0.1  

E-print Network

glass slides. TiO2 and SnO2 nanoparticles (TiO2nps, SnO2nps) were produced by sol gel methods [2 into the conduction band of a metal oxide (MO). The photo-oxidized absorber is regenerated by injection of a hole structures on the metal oxide layer (TiO2 comp or TiO2 nps) are produced by pressing technique Results

345

Photocatalytic activity of S- and F-doped TiO(2) in formic acid mineralization.  

PubMed

Two series of doped titanium dioxide samples (S-TiO(2) and F-TiO(2)) were prepared by the sol-gel method in the presence of different amounts of dopant source (thiourea and NH(4)F, respectively), followed by calcination at 500, 600 or 700 °C, and characterised by BET, UV-vis absorption, XPS, HRTEM, XRD and EPR analyses. Reference undoped materials were prepared by the same synthetic procedure. Their photocatalytic activity under visible light was investigated employing the photocatalytic degradation of formic acid in aqueous suspension as test reaction. S-doped TiO(2) showed a photocatalytic activity quite similar to that of undoped materials. In this regard, the insertion of S, characterised by a relatively large ionic radius, into the TiO(2) crystalline structure appears rather difficult, as confirmed by XPS analysis. On the contrary, moderate F doping was beneficial in increasing the rate of formic acid photocatalytic degradation, especially for photocatalysts calcined at high temperature, consisting of highly crystalline pure anatase, in which the rate of detrimental charge carrier recombination was reduced. For both series of doped materials, high doping levels appear to limit the semiconductor photoactivity, probably due to the formation of a progressively increasing number of charge recombination centres. The EPR characterisation of the investigated doped TiO(2) samples evidenced the presence of nitrogen containing species (nitric oxide radical encapsulated in micro-void, with no photoactivity, and N(b)? species, active in visible light sensitisation) and of titanium reduced centres Ti(3+), due to charge imbalance consequent to dopant introduction in the TiO(2) lattice either in anionic (F(-)) or in cationic form (S(6+)). PMID:20725691

Dozzi, Maria Vittoria; Livraghi, Stefano; Giamello, Elio; Selli, Elena

2011-03-01

346

Synthesis of LLDPE\\/TiO 2 nanocomposites by in situ polymerization with zirconocene\\/dMMAO catalyst: effect of [Al]\\/[Zr] ratios and TiO 2 phases  

Microsoft Academic Search

This article reveals the dependence of crystalline phases in titania on the intrinsic activity during in situ polymerization\\u000a of ethylene\\/1-hexene using the zirconocene\\/dMMAO catalyst to produce LLDPE\\/TiO2 nanocomposites. First, the TiO2 nanoparticles having different crystalline phases were employed as the nanofillers by impregnation with dMMAO to obtain dMMAO\\/TiO2. Then, copolymerization of ethylene\\/1-hexene using zirconocene catalyst was performed in the presence

Wathanyoo Owpradit; Okorn Mekasuwandumrong; Joongjai Panpranot; Artiwan Shotipruk; Bunjerd Jongsomjit

2011-01-01

347

Ruthenium Sensitizers with a Hexylthiophene-Modified Terpyridine Ligand for Dye-Sensitized Solar Cells: Synthesis, Photo- and Electrochemical Properties, and Adsorption Behavior to the TiO2 Surface.  

PubMed

Two novel ruthenium sensitizers with a hexylthiophene-modified terpyridine ligand (TUS-35 and TUS-36) were synthesized to improve the molar absorptivity of the previously reported ruthenium sensitizer (TBA)[Ru{4'-(3,4-dicarboxyphenyl)-4,4?-dicarboxyterpyridine}(NCS)3], TBA = tetrabutylammonium (TUS-21). A relatively strong absorption appeared at ?380 nm, and the molar absorption coefficient at the metal-to-ligand charge transfer (MLCT) band decreased in TUS-35 by introducing a 2-hexylthiophene unit to the 5-position of the terpyridine-derived ligand. For comparison, a relatively strong absorption was observed at ?350 nm without decreasing the molar absorption coefficient at the MLCT band in TUS-36 by introducing a 2-hexylthiophene unit to the 4-position of the terpyridine-derived ligand. On the other hand, the energy levels of the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals of these two sensitizers were found to be almost equal to those of TUS-21. The adsorption behavior of TUS-35 and TUS-36 was similar to that of (TBA)[Ru{4'-(3,4-dicarboxyphenyl)terpyridine}(NCS)3] (TUS-20), which binds to the TiO2 surface by using the 3,4-dicarboxyphenly unit, rather than that of TUS-21, which adsorbs to the TiO2 photoelectrode using one of the carboxyl groups at the terminal pyridines of the terpyridine-derived ligand. Therefore, TUS-35 and TUS-36 are considered to bind to the TiO2 surface by using the 3,4-dicarboxyphenly unit just like TUS-20. The dye-sensitized solar cells (DSCs) with TUS-35 and TUS-36 showed a relatively lower conversion efficiency (6.4% and 5.7%, respectively) compared to the DSC with TUS-21 (10.2%). Open-circuit photovoltage decay and electrochemical impedance spectroscopy measurements revealed that the promoted charge recombination and/or charge transfer of the injected electrons in the TiO2 photoelectrode is a main reason for the inferior performances of TUS-35 and TUS-36. PMID:25587752

Ozawa, Hironobu; Yamamoto, Yasuyuki; Kawaguchi, Hiroki; Shimizu, Ryosuke; Arakawa, Hironori

2015-02-11

348

Visible light photoactivity of TiO2 loaded with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles  

NASA Astrophysics Data System (ADS)

TiO2 modified with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles have been prepared using a water-in-oil microemulsion system (water/AOT/cyclohexane) followed by calcination step. The effect of metal ratio, reducing agent type (NaBH4 or N2H4), TiO2 matrix type (P-25, ST-01, TiO-5, TiO2 nanotubes or TiO2 obtained by TIP hydrolysis) as well as calcination temperature (from 350 to 650 °C) were systematically investigated. Obtained photocatalysts were characterized by UV-vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning transmission microscopy (STEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity under visible light (? > 420 nm) has been estimated in phenol degradation reaction in aqueous phase. The results showed that phenol degradation rate under visible light in the presence of TiO2 loaded with Au/Pt nanoparticles differed from 0.7 to 2.2 ?mol dm-3 min-1 for samples prepared using different reducing agent. Sodium borohydride (NaBH4) favors formation of smaller Au/Pt nanoparticles and higher amount gold in Au/Pt is in the form of electronegative species (Au?-) resulted in higher photoactivity. TiO2 obtained by TIP hydrolysis in microemulsion system seems to be the best support for Au/Pt nanoparticles from all among investigated matrix. It was also observed that enhancement of calcination temperature from 450 to 650 °C resulted in rapid drop of Au/Pt-TiO2 photoactivity under visible light due to surface area shrinkage, crystal structure change and probably change in Au/Pt nanoparticles morphology.

Go??biewska, Anna; Lisowski, Wojciech; Jarek, Marcin; Nowaczyk, Grzegorz; Zieli?ska-Jurek, Anna; Zaleska, Adriana

2014-10-01

349

Photoluminescence: A very sensitive tool to detect the presence of anatase in rutile phase electrospun TiO2 nanofibers  

NASA Astrophysics Data System (ADS)

This paper reports on the synthesis and the characterization of titanium dioxide (TiO2) nanofibers prepared by electrospinning. The samples were annealed at various temperatures in air for 4 h. The as-spun and annealed TiO2/PVP composite nanofibers were characterized by scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence (PL). The results show that the heat treatment has an effect on the crystallization process. Even if the XRD data shows a complete anatase-to-rutile transition in the TiO2 nanofibers at 900 °C, photoluminescence reveals a small portion of anatase in rutile sample. This observation proved that photoluminescence is a very sensitive tool to detect the presence of anatase in rutile phase TiO2 nanostructures.

Nasr, Maryline; Abou Chaaya, Adib; Abboud, Nadine; Bechelany, Mikhael; Viter, Roman; Eid, Cynthia; Khoury, Antonio; Miele, Philippe

2015-01-01

350

Zirconium and silver co-doped TiO2 nanoparticles as visible light catalyst for reduction of 4-nitrophenol, degradation of methyl orange and methylene blue  

NASA Astrophysics Data System (ADS)

Catalytic activity of Zr and Ag co-doped TiO2 nanoparticles on the reduction of 4-nitrophenol, degradation of methylene blue and methyl orange was studied using sodium borohydride as reducing agent. The nanoparticles were characterized using X-ray diffraction, energy dispersive X-ray, high resolution transmission electron microscopy, selected area electron diffraction and UV-Vis spectroscopy. The rate of the reduction/degradation was found to increase with increasing amount of the photocatalyst which could be attributed to higher dispersity and small size of the nanoparticles. The catalytic activity of Zr and Ag co-doped TiO2 nanoparticles showed no significant difference even after recycling the catalyst four times indicating a promising potential for industrial application of the prepared photocatalyst.

Naraginti, Saraschandra; Stephen, Finian Bernard; Radhakrishnan, Adhithya; Sivakumar, A.

2015-01-01

351

[Synthesis of Cu2O-Ag-AgBr/MA visible photocatalyst and its performance in degradation of 2-chlorophenol].  

PubMed

Cu2O-Ag-AgBr/MA plasmon photocatalyst was prepared by the co-deposition of Cu2O and Ag-AgBr nanoparticles on mesoporous alumina (MA). The samples were characterized by means of X-ray diffraction (XRD) ,X-ray photoelectron spectroscopy (XPS) and diffuse reflectance UV-vis spectra (UV-vis DRS). The results showed that both Ag+ and Ag0 existed on the surface. The photocatalytic activity of the samples prepared were evaluated by degradation of 2-chlorophenol (2-CP) under visible light (? >420 nm) irradiation. The results showed that the catalyst had high photocatalytic activity for the degradation of 2-CP. Meanwhile, the doping of Cu2O nanoparticles significantly inhibited the release of silver ions during the photocatalytic reaction, which improved the photostability of the catalyst. Analyses on the effects of various scavengers showed that h+ , O2- and OH radicals were the primary active species. PMID:25518659

Wang, Ran; Zhou, Xue-feng; Hu, Xue-xiang; Hu, Chun

2014-09-01

352

Fe3O 4/SiO 2/TiO 2 nanoparticles for photocatalytic degradation of 2-chlorophenol in simulated wastewater.  

PubMed

Photocatalysis has emerged as an advance and environmental-friendly process for breakdown of organic contaminants in wastewater. This work reports facile synthesis and characterization of stable magnetic core-shell-shell Fe3O4/SiO2/TiO2 nanoparticles and their effectiveness for photocatalysis. The surface morphology, crystal structure, and chemical properties of the photocatalyst were characterized by using scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and nitrogen physisorption. Stability of synthesized nanoparticles in aqueous medium was tested by leaching test. The photocatalytic degradation of 2-chlorophenol was investigated and reaction parameters for best catalyst performance were optimized. Catalyst dose of 0.5 g/L under optimized conditions produced complete degradation of 25 mg/L 2-chlorophenol (2-CP) within 130 min of 100-W ultraviolet (UV) irradiation while 97.2 % degradation of 50 mg/L 2-CP was achieved within 3 h. The rate of photocatalytic degradation was determined by considering pseudo first-order kinetics and Hugul's kinetic equations. The Hugul's kinetics was found to provide a better interpretation of the experimental results than the generally adopted pseudo first-order reaction kinetics. PMID:25239108

Rashid, Jamshaid; Barakat, M A; Ruzmanova, Y; Chianese, A

2014-09-21

353

DRIFTS Evidence for Facet-Dependent Adsorption of Gaseous Toluene on TiO2 with Relative Photocatalytic Properties.  

PubMed

Effective adsorption is of great importance to the photocatalytic degradation of volatile organic compounds. Herein, we succeeded in the preparation of anatase TiO2 with clean dominant {001} and {101} facets. By using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) equipped with a homemade reaction system and a coupling gas-dosing system, we found that TiO2 with dominant {001} facets exhibits higher toluene adsorption capacity than TiO2 with dominant {101} facets, which may be attributed to the different number of unsaturated 5c-Ti capable of forming the main active adsorption sites (terminal Ti-OH species). TiO2 with dominant {001} facets shows a significantly high photocatalytic degradation performance, with its degradation rate being 6 times higher than that of dominant {101} facets. Combined with simulation results, it is suggested that the synergetic effects of the formation of specific active adsorption sites, the low adsorption energy for toluene, and preservation of the free molecularly adsorbed water on the surface promote the degradation of gaseous toluene on the dominant {001} facets. This study exemplifies that the facet-dependent adsorption of volatile organic compounds is one of the most important factors to effectively engineer photocatalysts for air purification. PMID:25602129

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

2015-02-10

354

Mesoporous TiO2 nanocrystals grown in situ on graphene aerogels for high photocatalysis and lithium-ion batteries.  

PubMed

TiO2/graphene composites have been well studied as a solar light photocatalysts and electrode materials for lithium-ion batteries (LIBs). Recent reports have shown that ultralight 3D-graphene aerogels (GAs) can better adsorb organic pollutants and can provide multidimensional electron transport pathways, implying a significant potential application for photocatalysis and LIBs. Here, we report a simple one-step hydrothermal method toward in situ growth of ultradispersed mesoporous TiO2 nanocrystals with (001) facets on GAs. This method uses glucose as the dispersant and linker owing to its hierarchically porous structure and a high surface area. The TiO2/GAs reported here exhibit a highly recyclable photocatalytic activity for methyl orange pollutant and a high specific capacity in LIBs. The strong interaction between TiO2 and GAs, the facet characteristics, the high electrical conductivity, and the three-dimensional hierarchically porous structure of these composites results in highly active photocatalysis, a high rate capability, and stable cycling. PMID:24712676

Qiu, Bocheng; Xing, Mingyang; Zhang, Jinlong

2014-04-23

355

Effects of calcination on the photocatalytic properties of nanosized TiO 2 powders prepared by TiCl 4 hydrolysis  

Microsoft Academic Search

The ultra fine nanosized TiO2 photocatalysts in the anatase, rutile, and both phases were prepared by the hydrolysis of TiCl4 solution. The resulting materials have been characterized by HREM, XRD, BET and UV–VIS absorption spectroscopy. The photoactivity, effective degradation, and the selectivity for complete mineralization of these catalysts were tested in the photocatalytic degradation of phenol. For this reaction, the

Qinghong Zhang; Lian Gao; Jingkun Guo

2000-01-01

356

Properties and photochemistry of valence-induced-Ti(3+) enriched (Nb,N)-codoped anatase TiO2 semiconductors.  

PubMed

Nb and N codoped TiO2s are outstandingly versatile semiconductor oxides. Their high conductivity makes them valid alternatives to commercially available, but very expensive, conductive oxides. They show increased photonic efficiencies compared to the cases of solely Nb or N doped TiO2, when used as visible light sensitised photocatalysts. Furthermore, they are excellent materials for O2 sensors at very low temperature. Despite these remarkable properties, a clear picture of the electronic and optical mechanisms induced by the simultaneous presence of the dopants has just begun to be understood. Using a combination of electron paramagnetic resonance (EPR) spectroscopy, electrochemical impedance spectroscopy (EIS) and optical spectroscopy, we present here novel fundamental insights into the mechanisms responsible for the enhanced conductivity and visible light photochemistry. PMID:25594806

Folli, Andrea; Bloh, Jonathan Z; Lecaplain, Anaïs; Walker, Rebecca; Macphee, Donald E

2015-02-01

357

Photoreduction of CO2 using copper-decorated TiO2 nanorod films with localized surface plasmon behavior  

NASA Astrophysics Data System (ADS)

This Letter shows the activity of a novel metal/semiconductor photocatalyst for reducing CO2 to CH4 in the presence of H2O under UV-light irradiation. This composite is prepared on a transparent conductive substrate by an hydrothermal method for depositing TiO2 nanorod films, and then loaded with Cu nanoparticles (NPs) by an electrochemical method. The plasmonic properties of Cu NPs greatly enhance the resulting photoactivity with respect to that of pure TiO2 nanorod films. The final CH4 production rate observed (?2.91 ppm/gcatal. h) represents an improvement compared to specific values reported by other authors using conventional titania-based catalysts.

Tan, Jeannie Z. Y.; Fernández, Yolanda; Liu, Dong; Maroto-Valer, Mercedes; Bian, Juncao; Zhang, Xiwen

2012-04-01

358

Photocatalytic degradation of carbamazepine in wastewater by using a new class of whey-stabilized nanocrystalline TiO2 and ZnO.  

PubMed

Nanoscale photocatalysts have attracted much attention due to their high surface area to volume ratios. However, due to extremely high reactivity, TiO2 and ZnO nanoparticles prepared using different methods tend to either react with surrounding media or agglomerate, resulting in the formation of much larger flocs and significant loss in reactivity. This work investigates the photocatalytic degradation of carbamazepine (CBZ), a persistent pharmaceutical compound from wastewater (WW) using TiO2 and ZnO nanoparticles prepared in the presence of a water-soluble whey powder as stabilizer. The TiO2 and ZnO nanoparticles prepared in the presence of whey stabilizer displayed much less agglomeration and greater degradation power than those prepared without a stabilizer. Higher photocatalytic degradation of carbamazepine was observed (100%) by using whey stabilized TiO2 nanoparticles with 55 min irradiation time as compared to ZnO nanoparticles (92%). The higher degradation of CBZ in wastewater by using TiO2 nanoparticles as compared to ZnO nanoparticles was due to formation of higher photo-generated holes with high oxidizing power of TiO2. The photocatalytic capacity of ZnO anticipated as similar to that of TiO2 as it has the same band gap energy (3.2 eV) as TiO2. However, in the case of ZnO, photocorrosion frequently occurs with the illumination of UV light and this phenomenon is considered as one of the main reasons for the decrease of ZnO photocatalytic activity in aqueous solutions. Further, the estrogenic activity of photocatalyzed WW sample with CBZ and its by-products was carried out by yeast estrogen screen (YES) assay method. Based upon the YES test results, none of the samples showed estrogenic activity. PMID:24727044

Mohapatra, D P; Brar, S K; Daghrir, R; Tyagi, R D; Picard, P; Surampalli, R Y; Drogui, P

2014-07-01

359

Synthesis, characterization and photocatalytic activity of new photocatalyst ZnBiSbO4 under visible light irradiation.  

PubMed

In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO4(2-) and NO3(-), and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

2014-01-01

360

Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation  

PubMed Central

In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42? and NO3?, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

2014-01-01

361

Well-dispersed Pt nanocrystals on the heterostructured TiO2/SnO2 nanofibers and the enhanced photocatalytic properties  

NASA Astrophysics Data System (ADS)

Heterostructured TiO2/SnO2 nanofibers deposited with ultrafine Pt nanocrystals (Pt-TiO2/SnO2) were prepared by combining electrospinning and polyol reduced method. The samples have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectroscopy (DRS), photoluminescence spectra (PL) and nitrogen adsorption-desorption isotherm analysis. The results indicated that heterojunctions formed between TiO2 fibers and SnO2 fibers in the side-by-side structure with Pt nanocrystals in a crystallite size of 4.5 nm uniformly deposited on them. The Pt-TiO2/SnO2 nanofibers photocatalysts possessed large surface-exposure area, broadened spectral response range, stable recyclability, and efficient charge-separation properties. Furthermore, the photocatalytic activity of Pt-TiO2/SnO2 for the degradation of methylene blue was much higher than that of bare TiO2 and SnO2 nanofibers, which could be ascribed to the formation of heterojunctions in the TiO2/SnO2 nanofibers and the rapid transportation of electrons to the surface assisted by Pt nanocrystals. The results presented herein provide new insights into heterostructured materials as high-performance photocatalysts and their potential use in environmental protection.

Zhang, Li; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2014-11-01

362

Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO4 composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin.  

PubMed

To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO4 composite photocatalysts. The as-produced RGO-BiVO4 composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO4 photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO4 composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO4 particles. The enhancement of photocatalytic activities of RGO-BiVO4 photocatalysts can be attributed to the effective separation of electron-hole pairs rather than the improvement of light absorption. PMID:23434486

Yan, Yan; Sun, Shaofang; Song, Yang; Yan, Xu; Guan, Weisheng; Liu, Xinlin; Shi, Weidong

2013-04-15

363

Solid-state dye-sensitized solar cells fabricated with nanoporous TiO 2 and TPD dyes: Analysis of penetration behavior and I-V characteristics  

NASA Astrophysics Data System (ADS)

We present the synthesis, electrochemical properties and device-based investigation of triphenylene diamine (TPD) sensitizer with an extended ? system consisting of donor, electron conducting and anchoring group for solid-state dye-sensitized solar cells. Solid-state dye-sensitized solar cells were fabricated using blocking TiO2 electrodes, nanoporous TiO2 electrodes and the organic hole-transporting medium, HTM (spiro-OMeTAD) in a fluorine doped tin oxide/blocking TiO2/nanoporous TiO2/TPDs/hole transport material/Au configuration. Solid state dye sensitized solar cell consisting of TPD_2 as sensitizer on mesoporous TiO2 shows the best results with a short-circuit current of 2.8 mA/cm2, an open circuit voltage of 835 mV and an overall conversion efficiency of 0.97%.

Erten-Ela, Sule; Brendel, Johannes; Thelakkat, Mukundan

2011-06-01

364

A facile synthesis of Zn(x)Cd(1-x)S/CNTs nanocomposite photocatalyst for H2 production.  

PubMed

The sulfide solid solution has become a promising and important visible-light-responsive photocatalyst for hydrogen production nowadays. Zn(x)Cd(1-x)S/CNT nanocomposites were synthesized to improve the dispersion, adjust the energy band gap, and enhance the separation of the photogenerated electrons and holes. The as-prepared photocatalysts were characterized by scanning electron-microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectra (UV-visible), respectively. And the effects of CNTs on structure, composition and optical absorption property of the sulfide solid solutions were investigated along with their inherent relationships. For Zn0.83Cd0.17S/CNTs, sulfide solid solution is assembled along the CNTs orderly, with a diameter of 100 nm or so. XPS analysis shows that there is bonding effect between the solid solutions and the CNTs due to the strong adsorption of Zn(2+) and Cd(2+) on the surface of CNTs. There are two obvious absorption edges for Zn0.83Cd0.17S/CNTs, corresponding to two kinds of sulfide solid solutions with different molar ratios of Zn/Cd. The hybridization of solid solutions with CNTs makes the absorption spectrum red shift. The photocatalytic property was evaluated by splitting Na2S + Na2SO3 solution into H2, and the highest rate of H2 evolution of 6.03 mmol h(-1) g(-1) was achieved over Zn0.83Cd0.17S/CNTs. The high activity of photocatalytic H2 production is attributed to the following factors: (1) the optimum band gap and a moderate position of the conduction band (which needs to match the irradiation spectrum of the Xe lamp best), (2) the efficient separation of photogenerated electrons and holes by hybridization, and (3) the improvement of the dispersion of nanocomposites by assembling along the CNTs as well. PMID:23703674

Wang, Lei; Yao, Zhongping; Jia, Fangzhou; Chen, Bin; Jiang, Zhaohua

2013-07-21

365

Room Temperature Synthesis of Highly Compact TiO2 Coatings by Vacuum Kinetic Spraying to Serve as a Blocking Layer in Polymer Electrolyte-Based Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Vacuum kinetic spraying (VKS) was used to form a blocking layer (BL) in order to increase the efficiency of dye-sensitized solar cells. Nano-sized TiO2 powders were deposited on fluorine-doped tin oxide (FTO) glass while varying the coating parameters including the mass flow, substrate transverse speed, and number of coating passes in order to control the thickness of the BL. Compared to the cell without a BL, the open-circuit voltage and short-circuit current density of the solar cell with a VKS-coated BL were noticeably improved. Consequently, the photoconversion efficiency increased up to 5.6%, which is significantly higher than that of a spin-coated BL.

Heo, Jeeae; Sudhagar, P.; Park, Hyungkwon; Cho, Woohyung; Kang, Yong Soo; Lee, Changhee

2015-02-01

366

Hydrogen production by Tuning the Photonic Band Gap with the Electronic Band Gap of TiO2  

NASA Astrophysics Data System (ADS)

Tuning the photonic band gap (PBG) to the electronic band gap (EBG) of Au/TiO2 catalysts resulted in considerable enhancement of the photocatalytic water splitting to hydrogen under direct sunlight. Au/TiO2 (PBG-357 nm) photocatalyst exhibited superior photocatalytic performance under both UV and sunlight compared to the Au/TiO2 (PBG-585 nm) photocatalyst and both are higher than Au/TiO2 without the 3 dimensionally ordered macro-porous structure materials. The very high photocatalytic activity is attributed to suppression of a fraction of electron-hole recombination route due to the co-incidence of the PBG with the EBG of TiO2 These materials that maintain their activity with very small amount of sacrificial agents (down to 0.5 vol.% of ethanol) are poised to find direct applications because of their high activity, low cost of the process, simplicity and stability.

Waterhouse, G. I. N.; Wahab, A. K.; Al-Oufi, M.; Jovic, V.; Anjum, D. H.; Sun-Waterhouse, D.; Llorca, J.; Idriss, H.

2013-10-01

367

CTAB-assisted synthesis of monoclinic BiVO4 photocatalyst and its highly efficient degradation of organic dye under visible-light irradiation.  

PubMed

A highly efficient monoclinic BiVO(4) photocatalyst (C-BVO) was synthesized by an aqueous method with the assistance of cetyltrimethylammonium bromide (CTAB). The structure, morphology and photophysical properties of the C-BVO were characterized by XRD, FE-SEM and diffuse reflectance spectroscopy, respectively. The photocatalytic efficiencies were evaluated by the degradation of rhodamine B (RhB) under visible-light irradiation, revealing that the degradation rate over the C-BVO was much higher than that over the reference BiVO(4) prepared by aqueous method and over the one prepared by solid-state reaction. The efficiency of de-ethylation and that of the cleavage of conjugated chromophore structure were investigated, respectively. The chemical oxygen demand (COD) values of the RhB were measured after the photocatalytic degradation over the C-BVO and demonstrated a 53% decrease in COD. The effects of CTAB on the synthesis of C-BVO were investigated, which revealed that CTAB not only changed the reaction process via the formation of BiOBr as an intermediate, but also facilitated the transition from BiOBr to BiVO(4). Comparison experiments were carried out and showed that the existence of impurity level makes significant contribution to the high photocatalytic efficiency of the C-BVO. PMID:19733435

Yin, Wenzong; Wang, Wenzhong; Zhou, Lin; Sun, Songmei; Zhang, Ling

2010-01-15

368

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays  

PubMed Central

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks. PMID:24597830

2014-01-01

369

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays.  

PubMed

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks. PMID:24597830

Liu, Chang; Li, Yitan; Wei, Lin; Wu, Cuncun; Chen, Yanxue; Mei, Liangmo; Jiao, Jun

2014-01-01

370

Enhanced ethanol sensing properties of TiO2/ZnO core-shell nanorod sensors  

NASA Astrophysics Data System (ADS)

TiO2-core/ZnO-shell nanorods were synthesized using a two-step process: the synthesis of TiO2 nanorods using a hydrothermal method followed by atomic layer deposition of ZnO. The mean diameter and length of the nanorods were ˜300 nm and ˜2.3 ?m, respectively. The cores and shells of the nanorods were monoclinic-structured single-crystal TiO2 and wurtzite-structured single-crystal ZnO, respectively. The multiple networked TiO2-core/ZnO-shell nanorod sensors showed responses of 132-1054 % at ethanol (C2H5OH) concentrations ranging from 5 to 25 ppm at 150 ?C. These responses were 1-5 times higher than those of the pristine TiO2 nanorod sensors at the same C2H5OH concentration range. The substantial improvement in the response of the pristine TiO2 nanorods to C2H5OH gas by their encapsulation with ZnO may be attributed to the enhanced absorption and dehydrogenation of ethanol. In addition, the enhanced sensor response of the core-shell nanorods can be attributed partly to changes in resistance due to both the surface depletion layer of each core-shell nanorod and the potential barriers built in the junctions caused by a combination of homointerfaces and heterointerfaces.

Park, Sunghoon; An, Soyeon; Ko, Hyunsung; Lee, Sangmin; Kim, Hyoun Woo; Lee, Chongmu

2014-06-01

371

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays  

NASA Astrophysics Data System (ADS)

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks.

Liu, Chang; Li, Yitan; Wei, Lin; Wu, Cuncun; Chen, Yanxue; Mei, Liangmo; Jiao, Jun

2014-03-01

372

A facile approach to TiO2 colloidal spheres decorated with Au nanoparticles displaying well-defined sizes and uniform dispersion.  

PubMed

This paper describes a straightforward approach for the synthesis of hybrid materials composed of titanium dioxide (TiO(2)) colloidal spheres decorated with gold nanoparticles (Au NPs). In the reported method, monodisperse TiO(2) colloidal spheres (?220 nm in diameter) could be directly employed as templates for the nucleation and growth of Au NPs over their surface using AuCl(4)(-)(aq) as the Au precursor, ascorbic acid as the reducing agent, PVP as the stabilizer, and water as the solvent. The Au NPs presented a uniform distribution over the TiO(2) surface. Interestingly, the size of the Au NPs could be controlled by performing sequential reduction steps with AuCl(4)(-)(aq). This method could also be adapted for the production of TiO(2) colloidal spheres decorated with other metal NPs including silver (Ag), palladium (Pd), and platinum (Pt). The catalytic activities of the TiO(2)-Au materials as a function of composition and NPs size were investigated toward the reduction of 4-nitrophenol to 4-aminophenol under ambient conditions. An increase of up to 10.3-fold was observed for TiO(2)-Au relative to TiO(2). A surface-enhanced Raman scattering application for TiO(2)-Au was also demonstrated employing 4-mercaptopyridine as the probe molecule. The results presented herein indicate that our approach may serve as a platform for the synthesis of hybrid materials containing TiO(2) and metal NPs displaying well-defined morphologies, compositions, and sizes. This can have important implications for the design of TiO(2)-based materials with improved performances for photocatalysis and photovoltaic applications. PMID:23311597

Damato, Tatiana C; de Oliveira, Caio C S; Ando, Rômulo A; Camargo, Pedro H C

2013-02-01

373

Microfluidic chip-based analytical system for rapid screening of photocatalysts.  

PubMed

A simple and efficient microfluidic chip-based analytical system for rapid screening of photocatalysts was developed. The catalyst screening system consisted of a microchip with multiple channels for parallel reactions, a UV light source, and a CCD camera-based photometric detection system for monitoring the photocatalytic reaction. A novel microfluidic introduction method for loading particle samples into chip microchannels was established using dry sample powders and wedge-structure channel design. With this method, multiple different photocatalyst samples could be quickly introduced into the microchip with good reproducibility without the need of additional pumps or valves. We applied the present system in the rapid screening of doping TiO2 photocatalysts in terms of their activity for methylene blue (MB) degradation under UV light irradiation. Ten parallel photocatalyst screening reactions were achieved within 15 min in the multi-channel chip. We also examined nine element doped TiO2 materials to investigate the doping effects of different elements on TiO2. Compared with conventional systems, the photocatalyst consumption (0.1mg) in the present system was significantly reduced at least 100 times. High reaction rate in chip microreactors was obtained with an increase of two orders of magnitude over bulk reactors. The miniaturization of the photocatalytic reaction on the microchip significantly improves the reaction rates, reduces the sample and reagent consumptions, and increases the throughput of screening for multiple catalyst samples in parallel. The present work provides a novel application for microfluidic chip-based analytical systems, as well as a rapid, highly-efficient and low-consumption method for screening of photocatalysts. PMID:24148499

Zhang, Hao; Wang, Jing-Jing; Fan, Jie; Fang, Qun

2013-11-15

374

Photoelectrochemical behavior of Nb-doped TiO2 electrodes.  

PubMed

The photoelectrochemical behavior of degenerate Nb-doped TiO2 (Ti(1-x)Nb(x)O2: x = 0, 0.01, 0.03, 0.06, 0.1) electrodes prepared by pulsed laser deposition on LaAlO3 (LAO) and SrTiO3 (STO) was examined, revealing that an increase in Nb concentration causes a significant decay of titania photoactivity. One reason for such behavior may be a Burstein-Moss effect, which leads to a blue shift of the spectral limit of photoactivity. Another reason typical for metal-doped photocatalysts is the increase of the efficiency of charge carrier recombination. PMID:16375445

Emeline, Alexei V; Furubayashi, Yutaka; Zhang, Xintong; Jin, Ming; Murakami, Taketoshi; Fujishima, Akira

2005-12-29

375

Surfactant free most probable TiO2 nanostructures via hydrothermal and its dye sensitized solar cell properties  

NASA Astrophysics Data System (ADS)

Tailoring the nano-morphology and nano-architecture of titanium dioxide (TiO2) is the most important task in the third generation solar cells (Dye sensitized solar cells/Quantum dot sensitized solar cells) (DSSCs/QDSSCs). In this article we present complete study of surfactant free synthesis of TiO2 nanostructures by a simple and promising hydrothermal route. The plethora of nanostructures like nanoparticles clusters, 1D tetragonal nanorods, 3D dendrites containing nanorods having <30 nm diameter and 3D hollow urchin like have been synthesized. These nanostructures possess effective large surface area and thus useful in DSSCs. In the present work, 7.16% power conversion efficiency has been demonstrated for 3D dendritic hollow urchin like morphology. Our synthetic strategy provides an effective solution for surfactant free synthesis of efficient TiO2 nanoarchitectures.

Mali, Sawanta S.; Kim, Hyungjin; Shim, Chang Su; Patil, Pramod S.; Kim, Jin Hyeok; Hong, Chang Kook

2013-10-01

376

Surfactant free most probable TiO2 nanostructures via hydrothermal and its dye sensitized solar cell properties  

PubMed Central

Tailoring the nano-morphology and nano-architecture of titanium dioxide (TiO2) is the most important task in the third generation solar cells (Dye sensitized solar cells/Quantum dot sensitized solar cells) (DSSCs/QDSSCs). In this article we present complete study of surfactant free synthesis of TiO2 nanostructures by a simple and promising hydrothermal route. The plethora of nanostructures like nanoparticles clusters, 1D tetragonal nanorods, 3D dendrites containing nanorods having <30?nm diameter and 3D hollow urchin like have been synthesized. These nanostructures possess effective large surface area and thus useful in DSSCs. In the present work, 7.16% power conversion efficiency has been demonstrated for 3D dendritic hollow urchin like morphology. Our synthetic strategy provides an effective solution for surfactant free synthesis of efficient TiO2 nanoarchitectures. PMID:24141599

Mali, Sawanta S.; Kim, Hyungjin; Shim, Chang Su; Patil, Pramod S.; Kim, Jin Hyeok; Hong, Chang Kook

2013-01-01

377

Synthesis and Microstructure Evolution of Nano-Titania Doped Silicon Coatings  

NASA Astrophysics Data System (ADS)

The Anatase phase of Titania (TiO2) in nanocrystalline form is a well known photocatalyst. Photocatalysts are commercially used to accelerate photoreactions and increase photovoltaic efficiency such as in solar cells. This study investigates the in-flight synthesis of Titania and its doping into a Silicon matrix resulting in a catalyst-dispersed coating. A liquid precursor of Titanium Isopropoxide and ethanol was coaxially fed into the plasma gun to form Titania nanoparticles, while Silicon powder was externally injected downstream. Coatings of 75-150 ?m thick were deposited onto flat coupons. Further, Silicon powder was alloyed with aluminum to promote crystallization and reduce the amorphous phase in the Silicon matrix. Dense coatings containing nano-Titania particles were observed under electron microscope. X-ray diffraction showed that both the Rutile and Anatase phases of the Titania exist. The influence of process parameters and aluminum alloying on the microstructure evolution of the doped coatings is analyzed and presented.

Moroz, N. A.; Umapathy, H.; Mohanty, P.

2010-01-01

378

[Preparation and spectral characterisation of TiO2/polyaniline nanocomposites with 2D lamellar morphology].  

PubMed

Nanostructured polyanilines (PANIs) are selected quite often as the matrix for the synthesis of inorganic/conductive polymer composites due to their excellent optical, electrical and magnetic properties. Herein both 2D lamellar PANI and the cor responding composite loading TiO2 species were successfully prepared from a microemulsion system, as composed by dodecyl benzenesulfonic acid (DBSA) and water. The composite was achieved through a simultaneous polymerization of aniline in the presence of ammonium persulfate and hydrolysis of tetrabutyl titanate. Scanning electron microscopy (SEM) images indicate clearly that 2D PANI lamella are formed through organization of small PANI sheets. The inter-lamellar distance of PANI and that of TiO2/polyaniline composite, as derived from X-ray diffraction (XRD), is about 3.4 nm (nearly twice the length of one DBS molecule), suggesting that PANI and double-layered DBSA species are arranged in an alternated way. FTIR spectrum displays that PANI chains exhibit quinonoid and benzenoid strutures while both Raman and X-ray photoelectron spectroscopy (XPS) indicate that rutile TiO2 is produced upon hydrolyzation of tetrabutyl titanate in the microemulsion system. Moreover, UV-Vis spectrum suggests that the electronic absorption behaviour of PANI species is influenced upon loading TiO2. PMID:21510404

Shi, Li; Luo, Zhi-Yuan; Wu, Xiao-Dong; Yang, Xu-Jie; Lu, Lu-De; Wang, Xin

2011-02-01

379

Antimicrobial photodisinfection with Zn(II) phthalocyanine adsorbed on TiO2 upon UVA and red irradiation  

NASA Astrophysics Data System (ADS)

The light exposure on a daily basis has been well accepted as a competitive method for decontamination of wastewater. The catalytic properties of TiO2 offer a great potential to reduce the transmission of pathogens in the environment. Although the titanium dioxide shows high activity against pathogens, its general usage in water cleaning is limited due to the insufficient excitation natural light (about 3% of the solar spectrum). A hydrophobic dodecylpyridyloxy Zn(II)-phthalocyanine with four peripheral hydrocarbon chains of C12 (ZnPcDo) was immobilized on a photocatalyst TiO2 anatase (P25). The resulted greenish colored nanoparticles of phthalocyanine were characterized by the means of absorption, fluorescence and infrared spectroscopy. The laser scanning confocal fluorescence microscopy was used to visualize the phthalocyanine dye by the red fluorescence emission (650 - 740 nm). The intensive Q-band in the far red visible spectral region (~ 690 nm) suggested a monomeric state of phthalocyanine on TiO2 nanoparticles. Two pathogenic bacterial strains (methicillin-resistant Staphylococcus aureus - MRSA and Salmonella enteritidis) associated with wastewater were photoinactivated with the suspension of the particles. The effective photoinactivation was observed with 1 g.L-1 TiO2 anatase at irradiation with UVA 364 nm as with UVA 364 nm and LED 643 nm. The gram-negative Salmonella enteritidis was fully photoinactivated with ZnPcDo-TiO2 and TiO2 alone at UVA 346 nm and at irradiation with two light sources (364 nm + 643 nm). The proposed conjugate appears as an useful composite material for antibacterial disinfection.

Mantareva, Vanya; Eneva, Ivelina; Kussovski, Vesselin; Borisova, Ekaterina; Angelov, Ivan

2015-01-01

380

Synthesis and photocatalytic activity of mesoporous cerium doped TiO{sub 2} as visible light sensitive photocatalyst  

SciTech Connect

Graphical abstract: Cerium doped titania having optimum 5 wt% of cerium can decompose methylene blue and reduce selenium (IV) efficiently under visible light. Highlights: Black-Right-Pointing-Pointer Effect of cerium doping on the surface properties and visible light mediated photocatalytic reaction is studied. Black-Right-Pointing-Pointer Cerium doping increases the anatase phase stability, surface area (up to 137 m{sup 2}/g) and visible light absorption. Black-Right-Pointing-Pointer Importance of Ce{sup 3+}/Ce{sup 4+}, oxygen vacancy, surface area and crystallinity is correlated with improved catalytic activity. Black-Right-Pointing-Pointer Material with 5 wt% Ce is found to be most active photocatalyst for methylene blue decomposition and Se (IV) reduction. -- Abstract: Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N{sub 2} adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 Degree-Sign C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 Degree-Sign C shows better activity than that calcined at 400 Degree-Sign C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce{sup 4+}/Ce{sup 3+} rather than only visible light absorption.

Aman, Noor [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Satapathy, P.K. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India); Mishra, T., E-mail: drtmishra@yahoo.com [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mahato, M. [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Das, N.N. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)

2012-02-15

381

Core-shell VO2@TiO2 nanorods that combine thermochromic and photocatalytic properties for application as energy-saving smart coatings  

PubMed Central

Vanadium dioxide (VO2) is a Mott phase transition compound that can be applied as a thermochromic smart material for energy saving and comfort, and titanium dioxide (TiO2) is a well-known photocatalyst for self-cleaning coatings. In this paper, we report a VO2@TiO2 core-shell structure, in which the VO2 nanorod core exhibits a remarkable modulation ability for solar infrared light, and the TiO2 anatase shell exhibits significant photocatalytic degradation of organic dye. In addition, the TiO2 overcoating not only increased the luminous transmittance of VO2 based on an antireflection effect, but also modified the intrinsic colour of VO2 films from yellow to light blue. The TiO2 also enhanced the chemical stability of VO2 against oxidation. This is the first report of such a single nanoparticle structure with both thermochromic and photocatalytic properties that offer significant potential for creating a multifunctional smart coating. PMID:23546301

Li, Yamei; Ji, Shidong; Gao, Yanfeng; Luo, Hongjie; Kanehira, Minoru

2013-01-01

382

Cobalt(II) phthalocyanine-sensitized hollow Fe3O4@SiO2@TiO2 hierarchical nanostructures: Fabrication and enhanced photocatalytic properties  

NASA Astrophysics Data System (ADS)

Cobalt(II) phthalocyanine-sensitized hollow Fe3O4@SiO2@TiO2 hierarchical nanostructures had been successfully obtained by combination of solvothermal processing and dipping processing. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), UV-vis diffuse reflectance (DR) and vibrating sample magnetometer (VSM). The results revealed that the cobalt(II) phthalocyanine was successfully grown on the primary Fe3O4@SiO2@TiO2 nanostructures (Fe3O4@SiO2@TiO2@CoPcS). The hollow Fe3O4@SiO2@TiO2@CoPcS hierarchical nanostructure showed excellent photocatalytic efficiency for the degradation of methylene blue (MB) under UV-vis and visible light irradiation. More importantly, the photocatalyst could be effectively separated for reuse by simply applying an external magnetic field. A possible mechanism for the visible photocatalysis with the Fe3O4@SiO2@TiO2@CoPcS heterostructures was suggested.

Wu, Song-Hai; Wu, Jing-Long; Jia, Shao-Yi; Chang, Qiao-Wan; Ren, Hai-Tao; Liu, Yong

2013-12-01

383

Photocatalytic degradation of p-chlorophenol by hybrid H2O2 and TiO2 in aqueous suspensions under UV irradiation.  

PubMed

In this study, TiO2 particles were used as photocatalysts for the degradation of aqueous p-chlorophenol (p-CP) under UV irradiation. The effect of TiO2 dose (0-3 g/L), initial p-CP concentration, H2O2 concentration (2-45 mM), solution pH (4.6-9.5), and UV light intensity on the degradation of p-CP were examined. Four oxidative degradation processes, which utilized UV alone (direct photolysis), H2O2/UV, TiO2/UV, and H2O2/TiO2/UV, were compared in a batch photoreactor with a 100-W high-pressure mercury lamp. The photodegradation of p-CP could be described by the pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Moreover, the apparent degradation rate constants increased considerably from 3.5 × 10(-)(3) min(-)(1) (direct photolysis) to 19.9 × 10(-)(3) min(-)(1) (H2O2/TiO2/UV system). PMID:25234272

Nguyen, Anh Thu; Juang, Ruey-Shin

2015-01-01

384

Core-shell VO2@TiO2 nanorods that combine thermochromic and photocatalytic properties for application as energy-saving smart coatings  

NASA Astrophysics Data System (ADS)

Vanadium dioxide (VO2) is a Mott phase transition compound that can be applied as a thermochromic smart material for energy saving and comfort, and titanium dioxide (TiO2) is a well-known photocatalyst for self-cleaning coatings. In this paper, we report a VO2@TiO2 core-shell structure, in which the VO2 nanorod core exhibits a remarkable modulation ability for solar infrared light, and the TiO2 anatase shell exhibits significant photocatalytic degradation of organic dye. In addition, the TiO2 overcoating not only increased the luminous transmittance of VO2 based on an antireflection effect, but also modified the intrinsic colour of VO2 films from yellow to light blue. The TiO2 also enhanced the chemical stability of VO2 against oxidation. This is the first report of such a single nanoparticle structure with both thermochromic and photocatalytic properties that offer significant potential for creating a multifunctional smart coating.

Li, Yamei; Ji, Shidong; Gao, Yanfeng; Luo, Hongjie; Kanehira, Minoru

2013-04-01

385

Thin wetted film cylindrical flow photo reactor for the degradation of Procion blue H-B dye over TiO2 and ZnO.  

PubMed

A thin wetted film cylindrical flow reactor was fabricated for photocatalytic oxidation of Procion blue H-B dye in textile washwater with the suspensions of TiO2 and ZnO. The disappearance of colour and organic reduction were studied in terms of the removal of colour and chemical oxygen demand (COD). Operating parameters such as effect of pH, UV irradiation with and without catalyst, initial concentration of dye and effect of flow rate were studied and kinetics of Procion blue H-B dye has been studied over TiO2 and ZnO surfaces. Since adsorption is the prerequisite condition for decolorization/degradation of dye molecules in the presence of heterogeneous catalysis, the Langmuir and Freundlich isotherms were examined to verify the adsorption intensity. The results clearly demonstrated that, the optimum loading of the photocatalyst was found to be 300 and 400 mg/L of TiO2 and ZnO, respectively. The maximum COD reduction efficiency was 68% for TiO2 and 58% for ZnO. On the other hand, the colour removal efficiency was found to be 74% and 69%, respectively for TiO2- and ZnO-assisted systems under optimum conditions. Conclusively, these two semiconductors could degrade Procion blue H-B dye at different time intervals and both isotherms fit well. PMID:21879557

Neelavannan, M G; Basha, C Ahmed

2011-01-01

386

Preparation of a porous nanocrystalline TiO 2 layer by deposition of hydrothermally synthesized nanoparticles  

Microsoft Academic Search

In this work, a porous nanocrystalline anatase TiO2 layer is prepared by tape casting a viscous dispersion of nanoparticles. Phase pure anatase titanium dioxide nanoparticles with a particle size of 10–20nm are prepared by a very simple low temperature (100°C) hydrothermal synthesis route in a pressure vessel, using only water as the medium and Ti(IV)-isopropoxide as starting material without additives.

J. Beusen; M. K. Van Bael; H. Van den Rul; J. D’Haen; J. Mullens

2007-01-01

387

Graphene oxide as a promising photocatalyst for CO2 to methanol conversion.  

PubMed

Photocatalytic conversion of carbon dioxide (CO(2)) to hydrocarbons such as methanol makes possible simultaneous solar energy harvesting and CO(2) reduction, two birds with one stone for the energy and environmental issues. This work describes a high photocatalytic conversion of CO(2) to methanol using graphene oxides (GOs) as a promising photocatalyst. The modified Hummer's method has been applied to synthesize the GO based photocatalyst for the enhanced catalytic activity. The photocatalytic CO(2) to methanol conversion rate on modified graphene oxide (GO-3) is 0.172 ?mol g cat(-1) h(-1) under visible light, which is six-fold higher than the pure TiO(2). PMID:23160369

Hsu, Hsin-Cheng; Shown, Indrajit; Wei, Hsieh-Yu; Chang, Yu-Chung; Du, He-Yun; Lin, Yan-Gu; Tseng, Chi-Ang; Wang, Chen-Hao; Chen, Li-Chyong; Lin, Yu-Chuan; Chen, Kuei-Hsien

2013-01-01

388

Photocatalytic degradation of phenolic syntan using TiO2 impregnated activated carbon.  

PubMed

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 TiO(2) was used as the precursor for the preparation of TiO(2) impregnated activated carbon (Ti-AC) photocatalyst. Experiments were conducted by varying the concentrations of PS solution (50-1000 mg/l), pH (2.5-10) and time intervals to optimize the working parameters. A 254 nm UV light was used throughout the study. The effect of PS degradation using Ti-AC was also compared with direct UV photolysis. The Ti-AC was characterized using X-ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscopy (SEM) and energy dispersive X-ray analysis (EDX) to determine the structural, optical, surface morphology and elemental analysis respectively. X-ray studies revealed the formation of catalytically active anatase phase in Ti-AC. Photodegradation of PS was examined by chemical oxygen demand (COD) method. PS degradation occurred at both the extreme end of acidic and alkaline pH conditions. However, the percentage degradation was comparatively higher at pH 2.5. The photodegradation followed pseudo first order kinetics. UV-Visible studies substantiated the occurrence of bathochromic and hyperchromic effects as a result of ring opening in the PS molecule. PMID:21194708

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

2011-03-01

389

Graphene TiO2 nanocomposites with high photocatalytic activity for the degradation of sodium pentachlorophenol.  

PubMed

A series of graphene-TiO2 photocatalysts was synthesized by doping TiO2 with graphene oxide via hydrothermal treatment. The photocatalytic capability of the catalysts under ultraviolet irradiation was evaluated in terms of sodium pentachlorophenol (PCP-Na) decomposition and mineralization. The structural and physicochemical properties of these nanocomposites were characterized by X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, scanning electron microscopy, Ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectra, and Fourier-transform infrared spectroscopy. The graphene-TiO2 nanocomposites exhibited higher photocatalytic efficiency than commercial P25 for the degradation of PCP-Na, and 63.4% to 82.9% of the total organic carbon was fully mineralized. The improved photocatalytic activity may be attributed to the accelerated interfacial electron-transfer process and the significantly prolonged lifetime of electron-hole pairs imparted by graphene sheets in the nanocomposites. However, excessive graphene and the inhomogeneous aggregation of TiO2 nanoparticles may decrease photodegradation efficiency. PMID:25288556

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

2014-10-01

390

Photocatalytic decomposition of gaseous water over TiO 2 and TiO 2—RuO 2 surfaces  

NASA Astrophysics Data System (ADS)

Hg-lamp irradiation of TiO 2 powders mixed with RuO 2 leads to the continuous production of hydrogen and oxygen from gaseous water at room temperature. The rate of hydrogen evolution per 100 mg TiO 2—RuO 2 and 20 h was 11 ?mole at a steady state. A mechanism of water decomposition over TiO 2 is proposed from the dependence of the reactivity on the surface treatments.

Kawai, Tomoji; Sakata, Tadayoshi

1980-05-01

391

Effect of Coadsorbed Water on the Photodecomposition of Acetone on TiO2(110)  

SciTech Connect

The influence of coadsorbed water on the photodecomposition of acetone on TiO2 was examined using temperature programmed desorption (TPD) and the rutile TiO2(110) surface as a model photocatalyst. Of the two major influences ascribed to water in the heterogeneous photocatalysis literature (promotion via OH radical supply and inhibition due to site blocking), only the negative influence of water was observed. As long as the total water and acetone coverage was maintained well below the first layer saturation coverage (‘1 ML’), little inhibition of acetone photodecomposition was observed. However, as the total water+acetone coverage exceeded 1 ML, acetone was preferentially displaced from the first layer to physisorbed states by water and the extent of acetone photodecomposition attenuated. The displacement originated from water compressing acetone into high coverage regions where increased acetone-acetone repulsions caused displacement from the first layer. The immediate product of acetone photodecomposition was adsorbed acetate, which occupies twice as many surface sites per molecule as compared to acetone. Since the acetate intermediate was more stable on the TiO2(110) surface than either water or acetone (as gauged by TPD) and since its photodecomposition rate was less than that of acetone, additional surface sites were not opened up during acetone photodecomposition for previously displaced acetone molecules to re-enter the first layer. Results in this study suggest that increased molecular-level repulsions between organic molecules brought about by increased water coverage are as influential in the inhibiting effect of water on photooxidation rates as are water-organic repulsions.

Henderson, Michael A.

2008-06-10

392

Photochemically deposited nano-Ag/sol-gel TiO2-In2O3 mixed oxide mesoporous-assembled nanocrystals for photocatalytic dye degradation.  

PubMed

This work focused on the improvement of the photocatalytic activity for Congo Red (CR) azo dye degradation of mesoporous-assembled 0.95 TiO2-0.05 In2O3 mixed oxide photocatalyst (with a TiO2-to-In2O3 molar ratio of 0.95:0.05) by loading with Ag nanoparticles. The mesoporous-assembled 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was synthesized by a hydrolytic sol-gel method with the aid of a structure-directing surfactant, prior to loading with various Ag contents (0.5-2 wt.%) by a photochemical deposition method. The optimum Ag loading content was found to be 1.5 wt.%, exhibiting a great increase in photocatalytic CR dye degradation activity. The 1.5 wt.% Ag-loaded 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was further applied for the CR dye degradation in the presence of water hardness. Different types (Ca2+ and Ca2+ -Mg2+ mixture) and concentrations (200 and 500 mg/l) of water hardness were investigated. The results showed that the water hardness reduced the photocatalytic CR dye degradation activity, particularly for the extremely hard water with 500 mg/l of Ca2+ -Mg2+ mixture. The adjustment of initial solution pH of the CR dye-containing hard water to an appropriate value was found to improve the photocatalytic CR dye degradation activity under the identical reaction conditions. PMID:24594050

Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

2014-05-01

393

Enhanced Photocatalytic Activity for H2 Evolution under Irradiation of UV–Vis Light by Au-Modified Nitrogen-Doped TiO2  

PubMed Central

Background Purpose Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Methods Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV–vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. Results DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV–vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Conclusion Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV–vis light. PMID:25090093

Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

2014-01-01

394

TiO2-based nanopowders and thin films for photocatalytical applications.  

PubMed

TiO2-based nanopowders are elaborated by flame spray synthesis, FSS from organic precursors of titanium and chromium with the Cr content changing from 0 to 15 at.%. Well-crystallized nanopowders with high specific surface area SSA reaching 107 m2/g for undoped TiO2 and 177 m2/g for TiO2 + 15 at.% Cr are obtained. Thin films are deposited by rf reactive sputtering from metallic Ti and Ti-Cr targets in Ar + O2 flow controlled atmosphere. The adjustable area of Cr/Ti allows to obtain up to 16 at.% Cr in TiO2 thin films. X-ray diffraction, transmission electron spectroscopy, TEM, atomic force microscopy, AFM and optical spectrophotometry over the ultraviolet UV and visible VIS range of the light spectrum have been performed in order to characterize the nanomaterials. The particle size of nanopowders is within the range of 5-42 nm. Anatase is the predominating polymorphic form while the amount of rutile increases with Cr content to reach of about 25 wt.% at 15 at.% Cr. The post-deposition annealing of thin films in air at temperatures from 770 K to 1280 K modifies the phase composition, leads to irreversible transformation from anatase to rutile and affects the surface roughness. Structural and optical properties of TiO2-based nanopowders and thin films are compared. The effect of grain size and the level of chromium doping on the band gap E(g) is discussed. Photocatalytic activity of the nanopowders is tested for degradation of methylene blue, MB. PMID:20352753

Radecka, M; Rekas, M; Kusior, E; Zakrzewska, K; Heel, A; Michalow, K A; Graule, T

2010-02-01

395

Degradation of Sucrose and Nitrate Over Titania Coated Nano-hematite Photocatalysts  

Microsoft Academic Search

Photodegradation of sucrose and\\/or nitrate in aqueous solutions was studied over the titania coated nano-hematite photocatalysts under near-UV irradiation. The efficiency of the photocatalytic oxidation and reduction of these coated particles was compared to the prepared single phase TiO2. It was found that in different environments (O2 or N2) the particles showed differences in the photocatalytic efficiency due to the

Metta Penpolcharoen; Rose Amal; Michael Brungs

2001-01-01

396

The design and development of highly reactive titanium oxide photocatalysts operating under visible light irradiation  

Microsoft Academic Search

This review deals with the preparation of highly reactive titanium oxide photocatalysts and the clarification of the active sites as well as the detection of the reaction intermediates at the molecular level. Furthermore, we discuss the advancement of photofunctional systems and processes that can utilize visible and\\/or solar light. The photocatalytic reactivity of semiconducting TiO2 powder was found to be

Masakazu Anpo; Masato Takeuchi

2003-01-01

397

Oxidation of S(IV) in Seawater by Pulsed High Voltage Discharge Plasma with TiO2/Ti Electrode as Catalyst  

NASA Astrophysics Data System (ADS)

Oxidation of S(IV) to S(VI) in the effluent of a flue gas desulfurization(FGD) system is very critical for industrial applications of seawater FGD. This paper reports a pulsed corona discharge oxidation process combined with a TiO2 photocatalyst to convert S(IV) to S(VI) in artificial seawater. Experimental results show that the oxidation of S(IV) in artificial seawater is enhanced in the pulsed discharge plasma process through the application of TiO2 coating electrodes. The oxidation rate of S(IV) using Ti metal as a ground electrode is about 2.0×10-4 mol · L-1 · min-1, the oxidation rate using TiO2/Ti electrode prepared by annealing at 500°C in air is 4.5×10-4 mol · L-1 · min-1, an increase with a factor 2.25. The annealing temperature for preparing TiO2/Ti electrode has a strong effect on the oxidation of S(IV) in artificial seawater. The results of in-situ emission spectroscopic analysis show that chemically active species (i.e. hydroxyl radicals and oxygen radicals) are produced in the pulsed discharge plasma process. Compared with the traditional air oxidation process and the sole plasma-induced oxidation process, the combined application of TiO2 photocatalysts and a pulsed high-voltage electrical discharge process is useful in enhancing the energy and conversion efficiency of S(IV) for the seawater FGD system.

Gong, Jianying; Zhang, Xingwang; Wang, Xiaoping; Lei, Lecheng

2013-12-01

398

Graphene strongly wrapped TiO? for high-reactive photocatalyst: a new sight for significant application of graphene.  

PubMed

A new idea was employed to simultaneously reduce graphene oxide (GO) and wrap it on the surface of high-reactive anatase TiO2 for fabricating novel TiO2-graphene (GP) hybrid materials. The process was based on the surface negatively charged property of GO. With the introduction of strong chemical interaction between TiO2 and GP, the GP wrapped TiO2 gives a strong red-shift of the light absorption edge and a further narrowed bandgap compared to that of GP randomly supported TiO2. This structure can also significantly enhance the separation efficiency of photogenerated electrons and holes. Furthermore, in contrast to the normal anatase TiO2, as-prepared TiO2 is dominated with the high-reactive {001} facet. The superiority of the formed "core-shell" structure is confirmed by photocatalytic degradation of methylene blue (MB) under the xenon lamp and visible light irradiation. New photocatalytic mechanisms are also proposed based on the obtained results. This work may open a new doorway for new significant application of GP to prepare more GP-based high-reactive photocatalysts for environmental protection. PMID:24910049

Ni, Yaru; Wang, Wei; Huang, Wenjuan; Lu, Chunhua; Xu, Zhongzi

2014-08-15

399

Synthesis of ordered multivalent Mn-TiO 2 nanospheres with tunable size: A high performance visible-light photocatalyst  

Microsoft Academic Search

A facile and reproducible method has been developed for the synthesis of ordered anatase Mn-TiO2 nanospheres with controllable sizes in the range 200–300 nm by simply varying the amount of manganese(II) chloride added.\\u000a The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope\\u000a (SEM), and transmission electron microscope (TEM) measurements, and it was found that

Haiyan Li; Dejun Wang; Haimei Fan; Tengfei Jiang; Xinglin Li; Tengfeng Xie

2011-01-01

400

Catalytic, Self-Cleaning Surface with Stable Superhydrophobic Properties: Printed Polydimethylsiloxane (PDMS) Arrays Embedded with TiO2 Nanoparticles.  

PubMed

Maintaining the long-term stability of superhydrophobic surfaces is challenging because of contamination from organic molecules and proteins that render the surface hydrophilic. Reactive oxygen species generated on a photocatalyst, such as TiO2, could mitigate this effect by oxidizing these contaminants. However, incorporation of such catalyst particles into a superhydrophobic surface is challenging because the particles become hydrophilic under UV exposure, causing the surface to transition to the Wenzel state. Here we show that a high concentration of hydrophilic TiO2 catalytic nanoparticles can be incorporated into a superhydrophobic surface by partially embedding the particles into a printed array of high aspect ratio polydimethylsiloxane posts. A stable Cassie state was maintained on these surfaces, even under UV irradiation, because of the significant degree of hierarchical roughness. By printing the surface on a porous support, oxygen could be flowed through the plastron, resulting in higher photooxidation rates relative to a static ambient. Rhodamine B and bovine serum albumin were photooxidized both in solution and after drying onto these TiO2-containing surfaces, and the effects of particle location and plastron gas composition were studied in static and flowing gas environments. This approach may prove useful for water purification, medical devices, and other applications where Cassie stability is required in the presence of organic compounds. PMID:25525836

Zhao, Yuanyuan; Liu, Yang; Xu, Qianfeng; Barahman, Mark; Lyons, Alan M

2015-02-01

401

Amorphous TiO2 doped with carbon for visible light photodegradation of rhodamine B and 4-chlorophenol  

NASA Astrophysics Data System (ADS)

Visible light photocatalytic activity of amorphous TiO2 doped with carbon is prepared by a facile sol-gel route for the first time. The most active sample with mesostructure of amorphous phase, high surface area (273 m2 g-1) and large pore volume (0.33 cm3 g-1) is identified by X-ray diffractometer, Raman spectrometer, transmission electron microscope and N2 adsorption-desorption isotherms. In addition, the most active sample is characterized by Fourier transform-infrared spectrometer, X-ray photoelectron spectrometer, UV-vis diffuse reflectance spectrometer and luminescence spectrometer. The results show that the most active sample with oxygenic groups has a narrower bandgap and lower recombination of electron-hole, due to the carbon doping and phase of amorphous. Effective photodegradation capability and stability of rhodamine B and colorless 4-chlorophenol are verified by photocatalytic tests under visible light irradiation. A possible mechanism of amorphous TiO2 doped with carbon for visible light photocatalysis is proposed. The findings of this paper will provide new insights to design visible light-induced photocatalyst based on amorphous TiO2 for organic removal.

Shao, Penghui; Tian, Jiayu; Zhao, Zhiwei; Shi, Wenxin; Gao, Shanshan; Cui, Fuyi

2015-01-01

402

Photocatalytic degradation of 17?-ethinylestradiol (EE2) in the presence of TiO2-doped zeolite.  

PubMed

Current design limitations and ineffective remediation techniques in wastewater treatment plants have led to concerns about the prevalence of pharmaceutical and personal care products (PPCPs) in receiving waters. A novel photocatalyst, TiO2-doped low-silica X zeolite (TiO2-LSX), was used to study the degradation of the pharmaceutical compound, 17?-ethinylestradiol (EE2). The catalyst was synthesized and characterized using XRD, BET surface analysis, SEM-EDAX, and ICP-OES. The effects of different UV light intensities, initial EE2 concentrations, and catalyst dosages on the EE2 removal efficiency were studied. A higher EE2 removal efficiency was attained with UV-TiO2-LSX when compared with UV-TiO2 or UV alone. The EE2 degradation process followed pseudo-first-order kinetics. A comprehensive empirical model was developed to describe the EE2 degradation kinetics under different conditions using multiple linear regression analysis. The EE2 degradation mechanism was proposed based on molecular calculations, identification of photoproducts using HPLC-MS/MS, and reactive species quenching experiments; the results showed that oxidative degradation pathways initiated by hydroxyl radicals were predominant. This novel TiO2-doped zeolite system provides a promising application for the UV disinfection process in wastewater treatment plants. PMID:25036996

Pan, Zhong; Stemmler, Elizabeth A; Cho, Hong Je; Fan, Wei; LeBlanc, Lawrence A; Patterson, Howard H; Amirbahman, Aria

2014-08-30

403

Synergistic effects of nonmetal co-doping with sulfur in anatase TiO2: a DFT + U study.  

PubMed

Using DFT + U calculations, the crystal structure and electronic properties of nonmetal co-doping with sulfur in anatase TiO2 are systematically investigated. The initial purpose of this work is to improve the photocatalytic performance of S mono-doped TiO2, in which S occupies the lattice Ti site and acts as a recombination center. Among eight nonmetal impurities that occupy the interstitial site of a TiO6 octahedron, the synergistic effects of B, C, and O with S could achieve this purpose: suppressing the recombination of photogenerated electron-hole pairs by inducing a local inner built-in electric field and eliminating the deep impurity energy bands of S mono-doped TiO2. Furthermore, the photon absorption could be extended to the visible-light region, owing to the overlap of impurity energy bands with the top of the valence band or the bottom of the conduction band. Thus, Ti1-xO2SxBy, Ti1-xO2SxCy and Ti1-xO2SxOy could be considered as promising efficient photocatalysts. Furthermore, the underlying mechanism and tendency of these synergistic effects have been discussed, according to the relationship between the photocatalytic performance and the crystal or electronic structure. PMID:25529485

Liu, Qing-Lu; Zhao, Zong-Yan; Liu, Qing-Ju

2015-01-21

404

Acetaldehyde photochemistry on TiO2(110)  

SciTech Connect

The ultraviolet (UV) photon induced decomposition of acetaldehyde absorbed on the oxidized retile TIO2(110) surface was studied with photon stimulated desorption (PSD) and theral programmed desorption (TPD). Acetaldehyde desorbs molecularly from TiO2(110) with minor decomposition channels yielding butene on the reduced TiO2 surface and acetate on the oxidized TiO2 surface. Acetaldehyde absorbed on oxidized TiO2(110) undergoes a facile thermal reaction to form a photoactive acetaldehyde-oxygen complex. UV irradiation of the acetaldehyde-oxygen complex resulting in the ejection of methyl radical into gas phase and conversion of the surface bound fragment to formate.

Zehr, Robert T.; Henderson, Michael A.

2008-07-01

405

Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells  

SciTech Connect

One-dimensional (1D) semiconducting oxides have attracted great attention for dye sensitized solar cells (DSCs), but the overall performance is still quite limited as compared to TiO2 nanocrystalline DSCs. Here, we report the synthesis of aggregated TiO2 based nanotubes with controlled morphologies and crystalline structures to obtain an overall power conversion efficiency of 9.9% using conventional dye without any additional chemical treatment steps. The high efficiency is attributed to the unique aggregate structure for light harvesting, optimized high surface area, and good crystallinity of the nanotube aggregates obtained through proper thermal annealing. This study demonstrates that high efficiency DSCs can be obtained with 1D nanomaterials, and provides lessons on the importance of optimizing both the nanocrystalline structure and the overall microscale morphology.

Nie, Zimin; Zhou, Xiaoyuan; Zhang, Qifeng; Cao, Guozhong; Liu, Jun

2013-11-01

406

Growth of nanograins in TiO2 nanofibers synthesized by electrospinning.  

PubMed

Present study focuses the effect of calcination temperature and its duration on the morphology and growth of nanograins in individual TiO2 nanofibers synthesized by electrospinning method. Polyvinyl acetate and titanium tetraisopropoxide were used as chemical precursors along with other standard solvents in the synthesis process. This study shows that synthesized TiO2 nanofibers are randomly arranged and spreads uniformly over the Si substrate and possess polycrystalline nature consisting of nanograins. Similar to the sintering behavior generally observed in bulk ceramics, the nanograins coalesce and grow under higher calcination temperature and longer calcination time. The activation energy for the growth of nanograins is found to be 47.2 kJ/mol. The dominant growth mechanism changes depending on the stages of calcination. PMID:20359009

Park, Jae Young; Choi, Sun-Woo; Asokan, Kandasami; Kim, Sang Sub

2010-05-01

407

P-doped TiO2 with superior visible-light activity prepared by rapid microwave hydrothermal method  

NASA Astrophysics Data System (ADS)

Phosphorous-doped anatase TiO2 powders (P-TiO2) were prepared by rapid microwave hydrothermal method. The resulting materials were characterized by XRD, SEM, XPS, DRS and N2 adsorption. P-doping decreased the band gap and enlarged the surface area of P-doped samples than that of undoped TiO2 samples. Therefore, the photocatalytic degradation of methyl blue (MB) and tetracycline hydrochloride (Tc) experiments showed that the P-TiO2 catalysts, especially the two-steps-controlling products P-TiO2-2, exhibited higher degradation efficiency than the undoped TiO2 and commercial P25 under visible-light irradiation. Hydroxyl radicals (rad OH) have been confirmed to be the active species during the photocatalytic oxidation reaction. The microwave hydrothermal method confirms to be very suitable for the synthesis of superior visible-light activity P-doped samples.

Niu, Jinfen; Lu, Pan; Kang, Mei; Deng, Kunfa; Yao, Binghua; Yu, Xiaojiao; Zhang, Qian

2014-11-01

408

Fabrication and investigation of gas sensing properties of Nb-doped TiO(2) nanotubular arrays.  

PubMed

Synthesis of Nb-containing titania nanotubular arrays at room temperature by electrochemical anodization is reported. Crystallization of pure and Nb-doped TiO(2) nanotubes was carried out by post-growth annealing at 400°C. The morphology of the tubes obtained was characterized by scanning electron microscopy (SEM). Crystal structure and composition of tubes were investigated by glancing incidence x-ray diffraction (GIXRD) and total reflection x-ray fluorescence (TXRF). For the first time gas sensing characteristics of Nb-doped TiO(2) nanotubes were investigated and compared to those of undoped nanotubes. The functional properties of nanotubular arrays towards CO, H(2), NO(2), ethanol and acetone were tested in a wide range of operating temperature. The introduction of Nb largely improves conductivity and enhances gas sensing performances of TiO(2) nanotubes. PMID:22595952

Galstyan, Vardan; Comini, Elisabetta; Faglia, Guido; Vomiero, Alberto; Borgese, Laura; Bontempi, Elza; Sberveglieri, Giorgio

2012-06-15

409

Preparation of a titania/x-zeolite/porous glass composite photocatalyst using hydrothermal and drop coating processes.  

PubMed

Combinations of TiO2 photocatalysts and various adsorbents have been widely studied for the adsorption and photocatalytic decomposition of gaseous pollutants such as volatile organic compounds (VOCs). Herein, a TiO2-zeolite-porous glass composite was prepared using melt-quenching and partial sintering, hydrothermal treatment, and drop coating for preparation of the porous glass support and X-zeolite and their combination with TiO2, respectively. The obtained composite comprised anatase phase TiO2, X-zeolite, and the porous glass support, which were combined at the micro to nanometer scales. The composite had a relatively high specific surface area of approximately 25 m2/g and exhibited a good adsorption capacity for 2-propanol. These data indicated that utilization of this particular phase-separated glass as the support was appropriate for the formation of the bulk photocatalyst-adsorbent composite. Importantly, the photocatalytic decomposition of adsorbed 2-propanol proceeded under UV light irradiation. The 2-propanol was oxidized to acetone and then trapped by the X-zeolite rather than being released to the atmosphere. Consequently, it was demonstrated that the micrometer-scaled combination of TiO2 and zeolite in the bulk form is very useful for achieving both the removal of gaseous organic pollutants and decreasing the emission of harmful intermediates. PMID:25647574

Yasumori, Atsuo; Yanagida, Sayaka; Sawada, Jun

2015-01-01

410

The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance  

PubMed Central

Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2. PMID:19272171

Cheng, Chia-Liang; Sun, Der-Shan; Chu, Wen-Chen; Tseng, Yao-Hsuan; Ho, Han-Chen; Wang, Jia-Bin; Chung, Pei-Hua; Chen, Jiann-Hwa; Tsai, Pei-Jane; Lin, Nien-Tsung; Yu, Mei-Shiuan; Chang, Hsin-Hou

2009-01-01

411

DEVELOPMENT OF SUPPORTED TiO 2 PHOTOCATALYST BASED ADSORBENT FOR PHOTOCATALYTIC DEGRADATION OF PHENOL  

Microsoft Academic Search

The presence of harmful organic compounds such as phenols and their derivatives in water supplies and from industrial effluents is a topic of global concern. In recent years, it has received considerable attention as an alternative for treating industrial waste water. Photocatalysis is an emerging promising technology as it will completely oxidize harmful organic compounds present in the waste stream

NOR FAUZIAH ZAINUDIN; AHMAD ZUHAIRI ABDULLAH; ABDUL RAHMAN

412

Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating  

NASA Astrophysics Data System (ADS)

Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 ?m of the Cu-polymer coating to 206 ?m of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei

2014-01-01

413

Highly active nanocrystalline TiO(2) photoelectrodes.  

PubMed

A simple method for the fabrication of highly photoactive nanocrystalline two-layer TiO(2) electrodes for solar cell applications is presented. Diluted titanium acetylacetonate has been used as a precursor for covering SnO(2):F (FTO) films with dense packed TiO(2) nanocrystallites. The nanoporous thick TiO(2) film follows the dense packed thin TiO(2) film as a second layer. For the latter, amorphous TiO(2) nanoparticles have been successfully synthesized by a sol-gel technique in an acidic environment with pH<1 and hydrothermal growth at a temperature of 200?°C. The acidic nanoparticle gel was neutralized by basic ammonia and a TiO(2) gel of pH 5 was obtained; this pH value is higher than the recently reported value of 3.1 (Park et al 2005 Adv. Mater. 17 2349-53). Highly interconnected, nanoporous, transparent and active TiO(2) films have been fabricated from the pH 5 gel. SEM, AFM and XRD analyses have been carried out for investigation of the crystal structure and the size of nanoparticles as well as the surface morphology of the films. Investigation of the photocurrent-voltage characteristics has shown improvement in cell performance along with the modification of the surface morphology, depending on pH of the TiO(2) gel. Increasing the pH of the gel from 2.1 to 5 enhanced the overall conversion efficiency of the dye-sensitized solar cells by approximately 30%. An energy conversion efficiency of 8.83% has been achieved for the cell (AM1.5, 100  mWcm(-2) simulated sunlight) compared to 6.61% efficiency in the absence of ammonia in the TiO(2) gel. PMID:21730548

Paronyan, Tereza M; Kechiantz, A M; Lin, M C

2008-03-19

414

Graphene oxide as a promising photocatalyst for CO2 to methanol conversion  

NASA Astrophysics Data System (ADS)

Photocatalytic conversion of carbon dioxide (CO2) to hydrocarbons such as methanol makes possible simultaneous solar energy harvesting and CO2 reduction, two birds with one stone for the energy and environmental issues. This work describes a high photocatalytic conversion of CO2 to methanol using graphene oxides (GOs) as a promising photocatalyst. The modified Hummer's method has been applied to synthesize the GO based photocatalyst for the enhanced catalytic activity. The photocatalytic CO2 to methanol conversion rate on modified graphene oxide (GO-3) is 0.172 ?mol g cat-1 h-1 under visible light, which is six-fold higher than the pure TiO2.Photocatalytic conversion of carbon dioxide (CO2) to hydrocarbons such as methanol makes possible simultaneous solar energy harvesting and CO2 reduction, two birds with one stone for the energy and environmental issues. This work describes a high photocatalytic conversion of CO2 to methanol using graphene oxides (GOs) as a promising photocatalyst. The modified Hummer's method has been applied to synthesize the GO based photocatalyst for the enhanced catalytic activity. The photocatalytic CO2 to methanol conversion rate on modified graphene oxide (GO-3) is 0.172 ?mol g cat-1 h-1 under visible light, which is six-fold higher than the pure TiO2. Electronic supplementary information (ESI) available: Additional figures are provided including electrochemical determination of the conduction band potential, photocatalytic experimental setup. See DOI: 10.1039/c2nr31718d

Hsu, Hsin-Cheng; Shown, Indrajit; Wei, Hsieh-Yu; Chang, Yu-Chung; Du, He-Yun; Lin, Yan-Gu; Tseng, Chi-Ang; Wang, Chen-Hao; Chen, Li-Chyong; Lin, Yu-Chuan; Chen, Kuei-Hsien

2012-12-01

415

Photoinactivation of Escherichia coli by sulfur-doped and nitrogen-fluorine-codoped TiO2 nanoparticles under solar simulated light and visible light irradiation.  

PubMed

Titanium dioxide (TiO2) is one of the most widely used photocatalysts for the degradation of organic contaminants in water and air. Visible light (VL) activated sulfur-doped TiO2 (S-TiO2) and nitrogen-fluorine-codoped TiO2 (N-F-TiO2) were synthesized by sol-gel methods and characterized. Their photoinactivation performance was tested against Escherichia coli under solar simulated light (SSL) and VL irradiation with comparison to commercially available TiO2. Undoped Degussa-Evonik P-25 (P-25) and Sigma-TiO2 showed the highest photocatalytic activity toward E. coli inactivation under SSL irradiation, while S-TiO2 showed a moderate toxicity. After VL irradiation, Sigma-TiO2 showed higher photoinactivation, whereas S-TiO2 and P-25 showed moderate toxicity. Oxidative stress to E. coli occurred via formation of hydroxyl radicals leading to lipid peroxidation as the primary mechanism of bacterial inactivation. Various other biological models, including human keratinocytes (HaCaT), zebrafish liver cells (ZFL), and zebrafish embryos were also used to study the toxicity of TiO2 NPs. In conclusion, N-F-TiO2 did not show any toxicity based on the assay results from all the biological models used in this study, whereas S-TiO2 was toxic to zebrafish embryos under all the test conditions. These findings also demonstrate that the tested TiO2 nanoparticles do not show any adverse effects in HaCaT and ZFL cells. PMID:23906338

Pathakoti, Kavitha; Morrow, Shavonda; Han, Changseok; Pelaez, Miguel; He, Xiaojia; Dionysiou, Dionysios D; Hwang, Huey-Min

2013-09-01

416

Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO(2) nanostructures for photoelectrochemical solar hydrogen generation.  

PubMed

We report the synthesis and photoelectrochemical (PEC) studies of TiO(2) nanoparticles and nanowires simultaneously doped with nitrogen and sensitized with CdSe quantum dots (QDs). These novel nanocomposite structures have been applied successfully as photoanodes for PEC hydrogen generation using Na(2)S and Na(2)SO(3) as sacrificial reagents. We observe significant enhanced photoresponse in these nanocomposites compared to N-doped TiO(2) or CdSe QD sensitized TiO(2). The enhancement is attributed to the synergistic effect of CdSe sensitization and N-doping that facilitate hole transfer/transport from CdSe to TiO(2) through oxygen vacancy states (V(o)) mediated by N-doping. The results demonstrate the importance of designing and manipulating the energy band alignment in composite nanomaterials for fundamentally improving charge separation and transport and thereby PEC properties. PMID:20102190

Hensel, Jennifer; Wang, Gongming; Li, Yat; Zhang, Jin Z

2010-02-10

417

TiO2 thin film deposition by chemical methods  

NASA Astrophysics Data System (ADS)

Mesoporous nanocrystalline TiO2 dye sensitized solar cells was obtained by the sol-gel process in an aqueous solution using the titanium diethanolamine complex as the precursor and the spin coating technique to obtain TiO2 films on ITO (Indium tin oxide) glass substrates. TG - DTA, BET, FT-IR, UV - VIS, SEM, Raman spectroscopy, X-ray diffraction techniques, have been used to investigate the chemical and physical changes during the sol - gel process and the characteristics of the TiO2 powder precursor.

Suciu, R.-C.; Ro?u, M. C.-; Marian, I.; Silipa?, T. D.; Varodi, C.; Popa, A.; Mihe?, M.; Indrea, E.

2012-02-01

418

Preparation of SiO2/TiO2 and TiO2/TiO2 micropattern and their effects on platelet adhesion and endothelial cell regulation  

NASA Astrophysics Data System (ADS)

TiO2 films were applied on blood contact biomaterials for its excellent biocompatibility. The topological structure of the biomaterial surfaces have a significant impact on cell adhesion, spreading and proliferation. Thus, it is anticipated that the combination of TiO2 film deposition and surface micro-patterning will provide a potential application for cardiovascular implants materials. In this work, TiO2/TiO2 and SiO2/TiO2 micro-groove/ridge stripes on Si (100) were prepared by photolithography, wet etching and unbalanced magnetron sputtering (UBMS). Their surface morphology, chemical composition and wettability were investigated. The crystal structure of TiO2 films was characterised by X-ray diffraction (XRD). Platelet adhesion on the SiO2/TiO2 and TiO2/TiO2 surfaces was tested, and the morphology and behaviour of endothelial cells cultured on the micropatterned surfaces were observed. It was proved that the SiO2/TiO2 pattern could reduce platelet adhesion and aggregation compared with TiO2/TiO2 pattern, endothelial cells grew along the micro-stripes and their behaviour could be effectively regulated by micropatterned surface. So, it is suggested that the micropatterned SiO2/TiO2 surface can contribute more bio-compatible function of regulating and coordinating the behaviour of endothelial cells and platelets.

Li, Jing-an; Yang, Ping; Zhang, Kun; Ren, Hui-lan; Huang, Nan

2013-07-01

419

Effective charge separation in the rutile TiO2 nanorod-coupled ?-Fe2O3 with exceptionally high visible activities.  

PubMed

Herein, we have fabricated rutile TiO2 nanorod-coupled ?-Fe2O3 by a wet-chemical process. It is demonstrated that the visible activities for photoelectrochemical water oxidation and for degrading pollutant of ?-Fe2O3 are greatly enhanced after coupling a proper amount of rutile nanorods. The enhanced activity is attributed to the prolonged lifetime and improved separation of photogenerated charges mainly by the transient surface photovoltage responses. Interestingly, the observed EPR signals (with g? = 1.963 and g|| = 1.948) of Ti(3+) in the fabricated TiO2-Fe2O3 nanocomposite at ultra low temperature (1.8?k) after visible laser excitation, along with the electrochemical impedance spectra and the normalized photocurrent action spectra, testify evidently that the spacial transfers of visible-excited high-energy electrons of ?-Fe2O3 to TiO2 could happen. Moreover, it is confirmed that it is more favorable for the uncommon electron transfers of ?-Fe2O3 to rutile than to anatase. This is responsible for the much obvious enhancement of visible activity of Fe2O3 after coupling with rutile TiO2, compared with anatase and phase-mixed P25 ones. This work would help us to deeply understand the uncommon photophysical processes, and also provide a feasible route to improve the photocatalytic performance of visible-response semiconductor photocatalyst for water splitting and pollutant degradation. PMID:25154460

Luan, Peng; Xie, Mingzheng; Liu, Dening; Fu, Xuedong; Jing, Liqiang

2014-01-01

420

Effective charge separation in the rutile TiO2 nanorod-coupled ?-Fe2O3 with exceptionally high visible activities  

NASA Astrophysics Data System (ADS)

Herein, we have fabricated rutile TiO2 nanorod-coupled ?-Fe2O3 by a wet-chemical process. It is demonstrated that the visible activities for photoelectrochemical water oxidation and for degrading pollutant of ?-Fe2O3 are greatly enhanced after coupling a proper amount of rutile nanorods. The enhanced activity is attributed to the prolonged lifetime and improved separation of photogenerated charges mainly by the transient surface photovoltage responses. Interestingly, the observed EPR signals (with g? = 1.963 and g|| = 1.948) of Ti3+ in the fabricated TiO2-Fe2O3 nanocomposite at ultra low temperature (1.8 k) after visible laser excitation, along with the electrochemical impedance spectra and the normalized photocurrent action spectra, testify evidently that the spacial transfers of visible-excited high-energy electrons of ?-Fe2O3 to TiO2 could happen. Moreover, it is confirmed that it is more favorable for the uncommon electron transfers of ?-Fe2O3 to rutile than to anatase. This is responsible for the much obvious enhancement of visible activity of Fe2O3 after coupling with rutile TiO2, compared with anatase and phase-mixed P25 ones. This work would help us to deeply understand the uncommon photophysical processes, and also provide a feasible route to improve the photocatalytic performance of visible-response semiconductor photocatalyst for water splitting and pollutant degradation.

Luan, Peng; Xie, Mingzheng; Liu, Dening; Fu, Xuedong; Jing, Liqiang

2014-08-01

421

Floating growth of large-scale freestanding TiO2 nanorod films at the gas-liquid interface for additive-free Li-ion battery applications.  

PubMed

The floating growth process of large-scale freestanding TiO2 nanorod films at the gas-liquid interface was investigated. On the basis of the experiments, a self-templated growth scenario was developed to account for the self-assembly process. In the scenario, titanium complexes function not only as the Ti source for the growth of TiO2 but also as a soft template provider for the floating growth. According to the scenario, several new recipes of preparing freestanding TiO2 nanorod films at the gas-liquid interface were developed. The freestanding film was applied to a lithium ion battery as a binder-free and conducting agent-free anode, and good cyclability was obtained. This work may pave a new way to floating and freestanding TiO2 and other semiconductor materials, which has great potential not only in basic science but also in the applications such as materials engineering, Li-ion battery, photocatalyst, dye-sensitized solar cell, and flexible electronics. PMID:25280381

Xia, Hua-Rong; Li, Jia; Peng, Chen; Sun, Wen-Tao; Li, Long-Wei; Peng, Lian-Mao

2014-10-22

422

TiO2 nanobelts with a uniform coating of g-C3N4 as a highly effective heterostructure for enhanced photocatalytic activities  

NASA Astrophysics Data System (ADS)

A novel g-C3N4/TiO2 nanobelt (NB) heterostructure was successfully designed and prepared. The as-prepared g-C3N4/TiO2 NB heterostructure exhibited high photocatalytic activity not only in the photodegradation of Rhodamine B (RhB) but also in photocatalytic H2 production. The g-C3N4/TiO2 NB heterostructure with a mass ratio of 1:1 demonstrated the best performance in the photodegradation of RhB, whereas a mass ratio of 3:1 demonstrated the highest H2 production rate of 46.6 ?mol h-1 in photocatalytic H2 production. We conclude that the synergistic effect between g-C3N4 and TiO2 NBs promotes the photogenerated carrier separation in space. This valuable insight into the rational architectural design of nanostructure-based photocatalysts is expected to shed light on other photocatalytic reaction systems in the future.

Zhong, Xing; Jin, Meimei; Dong, Huaqing; Liu, Lin; Wang, Lei; Yu, Huiyou; Leng, Shuai; Zhuang, Guilin; Li, Xiaonian; Wang, Jian-guo

2014-12-01

423

Effective charge separation in the rutile TiO2 nanorod-coupled ?-Fe2O3 with exceptionally high visible activities  

PubMed Central

Herein, we have fabricated rutile TiO2 nanorod-coupled ?-Fe2O3 by a wet-chemical process. It is demonstrated that the visible activities for photoelectrochemical water oxidation and for degrading pollutant of ?-Fe2O3 are greatly enhanced after coupling a proper amount of rutile nanorods. The enhanced activity is attributed to the prolonged lifetime and improved separation of photogenerated charges mainly by the transient surface photovoltage responses. Interestingly, the observed EPR signals (with g? = 1.963 and g|| = 1.948) of Ti3+ in the fabricated TiO2-Fe2O3 nanocomposite at ultra low temperature (1.8?k) after visible laser excitation, along with the electrochemical impedance spectra and the normalized photocurrent action spectra, testify evidently that the spacial transfers of visible-excited high-energy electrons of ?-Fe2O3 to TiO2 could happen. Moreover, it is confirmed that it is more favorable for the uncommon electron transfers of ?-Fe2O3 to rutile than to anatase. This is responsible for the much obvious enhancement of visible activity of Fe2O3 after coupling with rutile TiO2, compared with anatase and phase-mixed P25 ones. This work would help us to deeply understand the uncommon photophysical processes, and also provide a feasible route to improve the photocatalytic performance of visible-response semiconductor photocatalyst for water splitting and pollutant degradation. PMID:25154460

Luan, Peng; Xie, Mingzheng; Liu, Dening; Fu, Xuedong; Jing, Liqiang

2014-01-01

424

Preparation, characterization and activity evaluation of p-n junction photocatalyst p-ZnO/n-TiO 2  

NASA Astrophysics Data System (ADS)

In this paper, p-type ZnO powder was prepared by decomposition of zinc nitrate at 350 °C for 1 h. p-n junction photocatalyst p-ZnO/TiO 2 was prepared by ball milling of TiO 2 in H 2O solution doped with p-ZnO. The p-n junction photocatalyst p-ZnO/TiO 2 was characterized by UV-vis diffuse reflection spectrum, scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and the fluorescence emission spectra. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr 2O 72- and photocatalytic oxidation of methyl orange (MO). The results showed that the photocatalytic activity of the p-n junction p-ZnO/TiO 2 is much higher than that of TiO 2 on the photocatalytic reduction of Cr 2O 72-. However, the photocatalytic activity of the photocatalyst is much lower than that of TiO 2 on the photocatalytic oxidation of methyl orange. Namely, the p-n junction photocatalyst p-ZnO/TiO 2 has higher photocatalytic reduction activity, but lower photocatalytic oxidation activity. When the amounts of doped p-ZnO are 0.0 and 2.0 wt.%, illumination for 20 min, the photoreduction efficiencies are 15.7 and 42.8%, and the photooxidation efficiencies are 68.1 and 26.1%, respectively. Effect of ball milling time on the photocatalytic activity of the photocatalyst was also investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p-n junction principle.

Chen, Shifu; Zhao, Wei; Liu, Wei; Zhang, Sujuan

2008-12-01

425

Growth of Aligned Single-Crystalline TiO2 Nanorod Arrays on Transparent Conducting Oxide Coated Glass  

NASA Astrophysics Data System (ADS)

In this work, we report a simple hydrothermal method for growth of aligned TiO2 nanorod arrays directly on SnO2:F (FTO) coated glass substrates without any seed layer. The rectangular nanorod is single crystalline with a tetragonal rutile structure. The diameter, length and density of the nanorods are determined by the synthesis temperature. When synthesis temperature increases from 110 to 190 °C, the diameter increases from 53 to 249 nm, and the length increases from to 324 to 1904 nm. However, the highest density is obtained at 150 °C due to nuclei coalescence at the high synthesis temperature. The activation energy for formation of TiO2 nanorod arrays is 102 kJ/mol obtained by using an Arrhenius equation.

Tsai, Jung-Che; Hon, Min-Hsiung; Leu, Ing-Chi

2013-06-01

426

Photocatalytic Reduction of Carbon Dioxide by Hydrous Hydrazine over Au-Cu Alloy Nanoparticles Supported on SrTiO3 /TiO2 Coaxial Nanotube Arrays.  

PubMed

Efficient photocatalytic conversion of CO2 into CO and hydrocarbons by hydrous hydrazine (N2 H4 ?H2 O) is achieved on SrTiO3 /TiO2 coaxial nanotube arrays loaded with Au-Cu bimetallic alloy nanoparticles. The synergetic catalytic effect by the Au-Cu alloy nanoparticles and the fast electron-transfer in SrTiO3 /TiO2 coaxial nanoarchitecture are the main reasons for the efficiency, while N2 H4 ?H2 O as the H source and electron donor provides a reducing atmosphere to protect the surface Cu atoms from oxidation, therefore maintaining the alloying effect which is the basis for the high photocatalytic activity and stability. This approach opens a feasible route to enhance the photocatalytic efficiency, which also benefits the development of photocatalysts and co-catalysts. PMID:25422137

Kang, Qing; Wang, Tao; Li, Peng; Liu, Lequan; Chang, Kun; Li, Mu; Ye, Jinhua

2015-01-12

427

SYNTHESIZING ORGANIC COMPOUNDS USING LIGHT-ACTIVATED TIO2  

EPA Science Inventory

High-value organic compounds have been synthesized successfully from linear and cyclic hydrocarbons, by photocatalytic oxidation using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxgenated in both liquid and gaseous phase reactors usi...

428

Fabrication of mesoporous TiO2 membranes by a nanoparticle-modified polymeric sol process.  

PubMed

A straightforward synthesis of crack-free mesoporous titania membrane on a macroporous support without intermediate layers by a nanoparticle-modified polymeric sol-gel process is reported. TiO2 nanoparticle (Degussa P25) was dispersed into the prepared sol to toughen the formed gel. This helped to avoid the cracking of membrane during the drying and early stage of sintering, particularly when the sol-gel transformation occurred on a substrate with an uneven surface. The results of X-ray diffraction and Brunauer-Emmett-Teller analyses show that the nanoparticle doping did not significantly affect the particle size of TiO2 nanocrystals; however, it slightly broadened the pore size distribution because it has a larger particle size compared to the prepared materials. The sols with and without P25 nanoparticle were subsequently dip-coated on a support with average pore size of 150nm, thus formed a mesoporous membrane layer after drying and sintering processes. An integrated, crack-free mesoporous TiO2 membrane layer was obtained by this method, while the membrane prepared with the original sol developed a few cracks. Further, the filtration experiment showed that the prepared membrane had a high flux, and the membrane with nanoparticle modification delivered better separation performance by rejection of dextran. PMID:25112911

Li, Dan; Wang, Hui; Jing, Wenheng; Fan, Yiqun; Xing, Weihong

2014-11-01

429

TiO 2 anatase thin films as gas sensors  

Microsoft Academic Search

The anatase modification of TiO2 shows properties quite different from those of the extensively studied and used rutile phase. We have investigated the chemi-resistive behavior of anatase TiO2 thin films exposed to oxidizing and reducing gases (O2, H2 and ethanol) in the temperature range between 300 and 400 °C. The undoped anatase films demonstrate significant and rapid response to ethanol

H. Tang; K. Prasad; R. Sanjinés; F. Lévy

1995-01-01

430

TiO2 Nanoparticles Induced Hippocampal Neuroinflammation in Mice  

PubMed Central

Titanium dioxide nanoparticles (TiO2 NPs) have been used in various medical and industrial areas. However, the impacts of these nanoparticles on neuroinflammation in the brain are poorly understood. In this study, mice were exposed to 2.5, 5, or 10 mg/kg body weight TiO2 NPs for 90 consecutive days, and the TLRs/TNF-?/NF-?B signaling pathway associated with the hippocampal neuroinflammation was investigated. Our findings showed titanium accumulation in the hippocampus, neuroinflammation and impairment of spatial memory in mice following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly activated the expression of Toll-like receptors (TLR2, TLR4), tumor necrosis factor-?, nucleic I?B kinase, NF-?B-inducible kinase, nucleic factor–?B, NF-?B2(p52), RelA(p65), and significantly suppressed the expression of I?B and interleukin-2. These findings suggest that neuroinflammation may be involved in TiO2 NP-induced alterations of cytokine expression in mouse hippocampus. Therefore, more attention should be focused on the application of TiO2 NPs in the food industry and their long-term exposure effects, especially in the human central nervous system. PMID:24658543

Ze, Xiao; Yu, Xiaohong; Pan, Xiaoyu; Lin, Anan; Zhao, Yue; Zhang, Chi; Zhou, Qiuping; Wang, Ling; Hong, Fashui

2014-01-01

431

Single-Step Preparation of TiO2/MWCNT Nanohybrid Materials by Laser Pyrolysis and Application to Efficient Photovoltaic Energy Conversion.  

PubMed

This paper presents the continuous-flowand single-step synthesis of a TiO2/MWCNT (multiwall carbon nanotubes) nanohybrid material. The synthesis method allows achieving high coverage and intimate interface between the TiO2particles and MWCNTs, together with a highly homogeneous distribution of nanotubes within the oxide. Such materials used as active layer in theporous photoelectrode of solid-state dye-sensitized solar cells leads to a substantial performance improvement (20%) as compared to reference devices. PMID:25545402

Wang, Jin; Lin, Yaochen; Pinault, Mathieu; Filoramo, Arianna; Fabert, Marc; Ratier, Bernard; Bouclé, Johann; Herlin-Boime, Nathalie

2015-01-14

432

Arsenite oxidation-enhanced photocatalytic degradation of phenolic pollutants on platinized TiO2.  

PubMed

The effect of As(III) on the photocatalytic degradation of phenolic pollutants such as 4-chlorophenol (4-CP) and bisphenol A (BPA) in a suspension of platinized TiO2 (Pt/TiO2) was investigated. In the presence of As(III), the photocatalytic degradation of 4-CP and BPA was significantly enhanced, and the simultaneous ox