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1.
The effect of humidity on the photocatalytic degradation reaction of trichloroethylene (TCE) in gas phase was investigated by using pretreated TiO2 sol-gel films. It was observed that the photocatalytic activity of the TiO2 films depended more greatly on the pretreatment conditions, for example, UV pre-illumination, than on the moisture content. When the relative humidity was over 50%, the reaction rates decreased regardless of treatment conditions of the photocatalyst. The photocatalytic decomposition rate of TCE increased with the increase of light intensity. However, the influence of humidity on the reaction rate was less significant under the increased light intensity. The intermediates and byproducts of the reaction were not changed in different humidity conditions. 相似文献
2.
Photocatalytic activities of TiO2 films were experimentally studied. TiO2 films with different crystal structures (amorphous, anatase, rutile) were prepared by a Low Pressure Metal Organic Chemical
Vapor Deposition (LPMOCVD) at different reaction temperatures and also by a Sol-Gel method using TTIP (Titanium Tetra Iso-Pro-poxyde).
The Effect of CVD preparation method, CVD reaction conditions, crystal structure and wave-length of UV light on the photocatalytic
decomposition rate of methylene blue in aqueous solution were studied. First, the characteristics of CVD preparation of TiO2 films, such as the CVD film growth rate, crystal structure and morphology of the grown TiO2 films, were experimentally studied as a function of CVD reaction temperature. Secondly, photocatalytic activities of TiO2 films were evaluated by using two types of photo-reactors. The results indicated that TiO2 films prepared by CVD exhibit higher photocatalytic activity than a catalyst prepared by the Sol-Gel method. Among the CVD
grown TiO2 films, anatase and rutile showed high photocatalytic activities. However, amorphous TiO2 films showed lower activities. The activity of the photocatalysts of anatase films was excellent under all types of UV-lamps.
The activity of CVD-prepared anatase films was four to seven times higher than that of photocatalyst films prepared by the
Sol-Gel method. 相似文献
3.
Xiufeng Zhou Juan Lu Jingjing Jiang Xiaobin Li Mengna Lu Guotao Yuan Zuoshan Wang Min Zheng Hyo Jin Seo 《Nanoscale research letters》2014,9(1):34
N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol–gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle. 相似文献
4.
Jong Min Jung Mingsong Wang Eui Jung Kim Chinho Park Sung Hong Hahn 《Applied catalysis. B, Environmental》2008,84(3-4):389-392
Au-buffered TiO2 thin films have been prepared by radio frequency magnetron sputtering method. The structural and morphological properties of the thin films were characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The photocatalytic activity of the samples was evaluated by the photodecomposition of methylene blue. The Au-buffer thin layer placed between the TiO2 thin films significantly enhanced photocatalytic activity by 50%. Annealing the Au-buffered TiO2 thin film at 600 °C decreased the film roughness, but it increased the surface area and anatase crystalline size, enhancing the photocatalytic activity. 相似文献
5.
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. 相似文献
6.
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. 相似文献
7.
The solvothermal reaction of titanium tetra-isopropoxide (TTIP) in different alcohol solvents was investigated in the pressure
range 40±2 bar to prepare Titanium (IV) oxide. The results show that the physical properties of the products, such as crystal
size, shape, and structure, are strongly in fluenced by the types of solvents and temperature during the reaction. The effects
of reaction conditions on the physical properties and the crystal structure of powder were investigated by using XRD, SEM,
DLS, DSC and BET. The obtained TiO2 powder prepared at an organic solvent condition exhibited submicron size and huge surface area with a narrow size distribution
but some agglomeration. TiO2 powder prepared at 1,4-butanediol and 623 K shows the highest photoactivity on the photodegradation rate of methyl orange. 相似文献
8.
MeiLing Hu MingHao Fang Chao Tang Tao Yang ZhaoHui Huang YanGai Liu XiaoWen Wu Xin Min 《Nanoscale research letters》2013,8(1):548
TiO2-based nanofibers were synthesized using a sol–gel method and electrospinning technique. The as-spun composite fibers were heat-treated at different temperatures (500°C, 550°C, 600°C, and 650°C) and atmospheres (ammonia and nitrogen) for 4 h. The fibers had diameters of 50 to 200 nm and mainly featured anatase and rutile phases. The anatase phase decreased and the rutile phase increased with increasing temperature. Different nitrogen conditions exerted minimal effects on the TiO2 crystalline phase. Different nitriding atmospheres during preservation heating yielded various effects on fibers. The effect of nitrogen in ammonia atmosphere is better than that in nitrogen atmosphere. The fibers heat-treated at 600°C and subjected to preservation heating in NH3 showed high photocatalytic activity. 相似文献
9.
I. A. Montoya T. Viveros J. M. Domínguez L. A. Canales I. Schifter 《Catalysis Letters》1992,15(1-2):207-217
The effects of alcohol/alkoxide, water/alkoxide molar ratios, acid addition, type of solvent, reaction temperature and calcination temperature on textural, structural and morphological characteristics of TiO2 were studied. The results show that surface area, pore size distribution and crystalline phases were very sensitive to preparation conditions. 相似文献
10.
Anatase TiO2 nano thin films were prepared on glass substrates by sol–gel dip coating method using Tween-80 as a surfactant, TiCl4 as the Ti precursor, and ethanol as a solvent. Atomic force microscopy, X-ray diffraction, and UV–Vis. photospectrometery experiments were performed to analyze the surface, structural and optical characteristics of the films. The effects of chemical aging time on the morphology, photocatalytic and superhydrophilicity behaviors of the films were studied. We show there is an optimum aging time at 2 h which photocatalytic and superhydrophilicity properties are at their maximum values simultaneously. This is useful in the self-cleaning industry. 相似文献
11.
ABSTRACT: Here we present a method to produce TiO2 nanocrystals coated by thin layer of graphitic carbon. The coating process was prepared via chemical vapor deposition (CVD) with acetylene used as a carbon feedstock with TiO2 used as a substrate. Different temperatures (400°C and 500°C) and times (10, 20, and 60 s) of reaction were explored. The prepared nanocomposites were investigated by means of transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy/diffuse reflectance spectroscopy and ultraviolet-vis (UV-vis)/diffuse reflectance spectroscopy. Furthermore, photocatalytic activity of the materials was investigated under visible and UV-vis light irradiation in the process of phenol decomposition. It was found that TiO2 modification with carbon resulted in a significant increase of photoactivity under visible irradiation and decrease under UV-vis light irradiation. Interestingly, a shorter CVD time and higher process temperature resulted in the preparation of the samples exhibiting higher activity in the photocatalytic process under visible light irradiation. 相似文献
12.
A series of S-doped TiO2 with visible-light photocatalytic activity were prepared by a simple hydrolysis method using titanium tetrachloride (TiCl4) and sodium sulfate (Na2SO4) as precursors. The photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectrophotometer (UV–Vis DRS), and X-ray photoelectron spectroscopy (XPS). With the doping of S, photocatalysts with small crystal size, high content of anatase phase were obtained. The result showed that S-doped TiO2 demonstrate considerably high photoactivity under low power visible LED light irradiation, while undoped TiO2 and the Degussa P25 have nearly no activity at all. The possible mechanism of S-doped for the visible-light activity was discussed. 相似文献
13.
Sayaka Yanagida Akira Nakajima Takayoshi Sasaki Toshihiro Isobe Yoshikazu Kameshima Kiyoshi Okada 《Applied Catalysis A: General》2009,366(1):130
Keggin ions (PW12O403− (PW12), SiW12O404− (SiW12), H2W12O406− (H2W12)) and TiO2 hybrid thin films were prepared using the layer-by-layer method. Their photocatalytic activities were investigated using gaseous 2-propanol decomposition. All films were transparent in the visible wavelength range. For 2-propanol decomposition, H2W12 was the most effective for the combination with TiO2 despite having the smallest TiO2 deposition amount. The photocatalytic activity of the PW12–TiO2 hybrid film was increased 2.3 times by visible light with UV illumination. This increase was less remarkable for hybrid films of other Keggin ions, suggesting that the visible light excitation of reduced PW12 plays an important role in the enhancement of 2-propanol decomposition. 相似文献
14.
The article reports on low-temperature high-rate sputtering of hydrophilic transparent TiO2 thin films using dc dual magnetron (DM) sputtering in Ar + O2 mixture on unheated glass substrates. The DM was operated in a bipolar asymmetric mode and was equipped with Ti(99.5) targets
of 50 mm in diameter. The substrate surface temperature Tsurf measured by a thermostrip was less than 180 °C for all experiments. The effect of the repetition frequency fr was investigated in detail. It was found that the increase of fr from 100 to 350 kHz leads to (a) an improvement of the efficiency of the deposition process that results in a significant
increase of the deposition rate aD of sputtered TiO2 films and (b) a decrease of peak pulse voltage and sustaining of the magnetron discharge at higher target power densities.
It was demonstrated that several hundreds nm thick hydrophilic TiO2 films can be sputtered on unheated glass substrates at aD = 80 nm/min, Tsurf < 180 °C when high value of fr = 350 kHz was used. Properties of a thin hydrophilic TiO2 film deposited on a polycarbonate substrate are given. 相似文献
15.
TiO2 thin films have been prepared by physical vapour deposition (PVD) and plasma enhanced chemical vapour deposition (PECVD) to study the UV-induced photo-activity of this material. Wetting angle variations and photo-catalytic activity for the degradation of dyes upon UV illumination have been compared for thin films with different crystalline structure (amorphous, rutile and anatase), microstructure (columnar, compact, etc.) and porosities as estimated from the values of their refraction indices and their direct assessment with a quartz crystal monitor. The surface of the thin films became superhydrophilic upon UV light irradiation and then it recovered its original state by keeping the samples in the dark. Wetting angle decays follow very similar kinetics for amorphous and crystalline films, independently of their actual porosities. By contrast the photo-catalytic activity was very dependent on the crystalline structure of the films (anatase > rutile > amorphous) and on their porosities. The different behaviour depicted by the films with regard to these two properties suggests that they respond to different though related mechanisms and that they cannot be considered as equivalent when trying to prove the photo-activity of TiO2. 相似文献
16.
Yunfang Huang Jihuai Wu Taohai Li Shancun Hao Jianming Lin 《Journal of Porous Materials》2006,13(1):55-59
H2La2Ti3O10/ TiO2 intercalated nanomaterial was fabricated by successive intercalation reactions of H2La2Ti3O10 with n-C6H13NH2/C2H5OH mixed solution and acid TiO2 sol, followed by irradiating with a high-pressure mercury lamp. The intercalated materials possess a gallery height of 0.46
nm and a specific surface area of 31.58 m2·g−1, which indicate the formation of a porous material. H2La2Ti3O10/TiO2 shows photocatalytic activity for the decomposition of organic dye under irradiation with visible light and the activity
of TiO2 intercalated material was superior to the unsupported one. 相似文献
17.
Sang-Chul Jung 《Korean Journal of Chemical Engineering》2008,25(2):364-367
The photocatalytic activity of CVD grown films shows significant, non-linear (sigmoid-like) dependency on the film thickness.
However, the photocatalytic activity of sol-gel grown film is almost independent of the film thickness. The specific surface
area of sol-gel grown films is very small, regardless of the film thickness. Conversely, the specific surface area of CVD
grown films indicates significant thickness dependency. The specific area and photocatalytic activity were found to show very
similar dependencies on the film thickness. 相似文献
18.
Lotus-leaf-structured TiO2 nanocrystals were prepared by a novel simple two-step method. TiO2 nanocrystals obtained by two-step method exhibited better photocatalytic activity than the as-prepared TiO2 nanocrystal obtained by one-step liquid phase deposition method. Even compared with commercial TiO2 photocatalyst with the smaller average size (~ 7 nm), lotus-leaf-structured TiO2 nanocrystals exhibited better photocatalytic activity. The possible reason for the good photocatalytic activity was also investigated. 相似文献
19.
Nb, F-codoped TiO2 hollow spheres (NFTSs) were successfully synthesized via a hydrothermal method with niobium oxide, hydrofluoric acid, and tetrabutyl titanate. The obtained spheres were hollow, with a diameter of about 2 μm, and the sphere wall was made up of nanorods arranged close together. The NFTSs presented anatase phase with more {001} facets exposed, which could be mainly attributed to F ions which were preferentially adsorbed on the {001} facets during the crystal growth process. Ti3+ states in NFTSs were increased due to Nb, F-codoping, resulting in the decrease of the band gap and the red shift of the absorption edge of the NFTSs. The NFTSs exhibited 20.1% higher photocatalytic speed compared to P25 on the degradation of methylene orange. 相似文献
20.
The influence of the direction of ultraviolet irradiation upon the yields of the photocatalytic decomposition of pure water has been investigated in Pt/TiO2 aqueous suspension system. The yields of the photocatalytic decomposition irradiated from the top of the reaction cell are about 103 times higher than those irradiated from the bottom. The difference seems due to the reverse reaction of the formed H2 and O2 in the suspension. 相似文献