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1.
The high performance photocatalytic TiO2 films were successfully obtained by a galvanostatic anodization of metallic titanium using the optimum anodization condition, subsequent to pre-nitridation treatment. The optimized anodization parameters on the formation of high photocatalytic TiO2 film were investigated. The pre-nitridation treatment was performed by annealing metallic Ti under a nitrogen atmosphere of 0.1 MPa. The anodized TiO2 film showed the high photocatalytic activities to decompose not only gaseous acetaldehyde but also tetrachloroethylene, which revealed that the anodized TiO2 film is a possible candidate of the photocatalyst for environmental purifications comparable to the best photocatalyst of fine crystalline powder.  相似文献   

2.
A novel synthesis method of a highly active photocatalyst was proposed. Titanium dioxide (TiO2) nano-particles were prepared by three-step procedure, precipitation of hydroxyapatite (HAp) on TiO2 particles, heat treatment of the TiO2/HAp composites, and acid treatment in hydrochloric acid. The unique point of this procedure is the selective dissolution of HAp to obtain exposed TiO2 surfaces. The HAp precipitation was achieved by stirring TiO2 powders in the mixtures of Ca(NO3)2 and NH4H2PO4 aqueous solutions at pH 8.5. Then, the heat-treated TiO2/HAp composites were treated with hydrochloric acid. The precipitated HAp avoided the direct contact of TiO2 particles and suppressed the phase transformation from anatase-to-rutile >200 °C. The HAp also suppressed a decrease of specific surface area of TiO2 during the heat treatment. The photocatalytic activities were evaluated from an absorbance decrease of methylene blue (MB) under ultraviolet (UV) irradiation. The MB photodecomposition was approximated to the first-order reaction and the reaction rate constants of the obtained TiO2 powders heated at various temperatures were higher than those of conventional TiO2 powders heated at same temperatures. The enhanced photocatalytic activity is attributed to the suppression effects for the phase transformation to rutile phase and the decreasing of specific surface area in the heat treatment.  相似文献   

3.
A method for the preparation of efficient TiO2/multi-wall carbon nanotubes nanocomposite photocatalysts by precipitation of anatase TiO2 nanoparticles onto differently oxidized carbon nanotubes is presented. The precursor compound titanium(IV) bromide was hydrolyzed producing pure anatase phase TiO2 nanoparticles decorated on the surface of the oxidized carbon nanotubes. The oxidative treatment of the carbon nanotubes influenced the type, quantity and distribution of oxygen-containing functional groups, which had a significant influence on the electron transfer properties, i.e., the photocatalytic activity of the synthesized nanocomposites. The results of C.I. Reactive Orange 16 photodegradation in the presence of all the synthesized nanocomposites showed their better photocatalytic activity in comparison to the commercial photocatalyst Degussa P-25.  相似文献   

4.
Anatase titanium dioxide (TiO2) photocatalytic thin films were directly formed on glass slide and commercial dental mirror substrate surfaces by a hydrolysis of titanium alkoxide, and the hydrophilicity, the degree of oxidizing power and the transparency of the anatase TiO2-coated substrate surfaces. The contact angles of water and the decomposition rates of methylene blue on the anatase TiO2 photocatalytic thin films improved with the increasing duration of a tetraethyl orthotitanate (TEOT) hydrolysis, but they hardly changed for the longer duration. The reflectance of anatase TiO2 photocatalytic thin films coated on glass slide substrate surfaces was higher as the duration of a TEOT hydrolysis increased. Similar tendencies concerning hydrophilicity and transparency were recognized in cases of commercial dental mirror substrate surfaces. A hydrolysis of titanium alkoxide obtained superhydrophilic and antibacterial treatments with excellent transparency on commercial dental mirror substrate surfaces.  相似文献   

5.
In the present work, nanostructured TiO2 films were prepared by electrochemical anodization process of titanium in fluoride-containing electrolytes using an innovative approach. After anodization, the TiO2 films were annealed at 480?°C for 2 h in air in order to acquire anatase phase transformation and increase its crystallinity. The effects of anodization voltage, electrolyte concentration and anodization time on the formation of TiO2 films and the photocatalytic degradation of methylene blue (MB) were discussed in details. The phase structure and surface morphology of the samples characterized by means of X-ray diffraction and scanning electron microscope. The as-prepared nanostructured TiO2 film anodized in 0.5% HF electrolyte at 15 V for 240 min showed excellent photocatalytic degradation of MB and is promising for environmental purification.  相似文献   

6.
The effects of annealing temperature on the photocatalytic activity of nitrogen-doped (N-doped) titanium oxide (TiO2) thin films deposited on soda-lime-silica slide glass by radio frequency (RF) magnetron sputtering have been studied. Glancing incident X-ray diffraction (GIAXRD), Raman spectrum, scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-vis spectra were utilized to characterize the N-doped TiO2 thin films with and without annealing treatment. GIAXRD and Raman results show as-deposited N-doped TiO2 thin films to be nearly amorphous and that the rutile and anatase phases coexisted when the N-doped TiO2 thin films were annealed at 623 and 823 K for 1 h, respectively. SEM microstructure shows uniformly close packed and nearly round particles with a size of about 10 nm which are on the slide glass surface for TiO2 thin films annealed at 623 K for 1 h. AFM image shows the lowest surface roughness for the N-doped TiO2 thin films annealed at 623 K for 1 h. The N-doped TiO2 thin films annealed at 623 K for 1 h exhibit the best photocatalytic activity, with a rate constant (ka) of about 0.0034 h−1.  相似文献   

7.
Synthesis and Photocatalytic Activity of Titania Pillared Clays   总被引:13,自引:0,他引:13  
TiO2-pillared clays such as montmorillonite, saponite and mica were prepared with an intercalation of polynuclear titanium complex formed by the reaction of Ti(i-C3H7O)4 and acetic acid. Characterization of the products was performed by XRD, XPS, IR, UV-V spectra, the measurement of surface area and pore size distribution. The photocatalytic decomposition of carboxylic acids has been studied on TiO2-pillared montmorillonite, saponite and mica. TiO2-pillared mica showed higher catalytic activity than TiO2 for the photocatalytic decomposition of acetic acid and adipic acid. On the contrarily, TiO2 was the most active catalyst and TiO2-pillared mica showed low activity for the photocatalytic decomposition of capric acid. The results show that the molecular size of carboxylic acid contributes to the catalytic activity of TiO2-pillared clays.  相似文献   

8.
Titanium dioxide nanoparticles were synthesized by the hydrolysis and condensation of TiCl4, an economic titanium precursor, in a mixed solvent of iso-propyl alcohol and water. As-prepared powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy filtering transmission electron microscopy (EF-TEM). To examine the photocatalytic activity of the as-prepared TiO2, the photodegradation of MB which is a typical dye resistant to biodegradation has been investigated on TiO2 powders in aqueous heterogeneous suspensions. The photocatalytic activity of TiO2 powders prepared by the hydrolysis of TiCl4 in the mixed solutions of iso-PrOH/H2O exceeded that of commercial TiO2 powders. The apparent first order rate constants (k app) for the photodegradation of methylene blue (MB) showed a good correlation with the absorbance area obtained by UV-VIS DRS on wavelength in the limits of used lamp emission 300∼420 nm.  相似文献   

9.
Polymer/semiconductor oxide nanocomposite films have been intensively investigated for various applications. In this work, we reported a simple hydrothermal method to fabricate highly transparent poly(vinyl alcohol)/titanium dioxide (PVA/TiO2) nanocomposite films with enhanced visible-light photocatalytic activity. The as-prepared PVA/TiO2 nanocomposite films showed high optical transparency in the visible region even at a high TiO2 content (up to 40 wt.%). The determination of photocatalytic activity by photodegradation of methyl orange (MO) and colorless phenol showed that PVA/TiO2 nanocomposite films exhibited enhanced visible-light photocatalytic activity and excellent recycle stability. This work provided new insights into fabrication of polymer/TiO2 nanocomposites as high performance photocatalysts in waste water treatment.  相似文献   

10.
TiO2, TiO2/Ag and TiO2/Au photocatalysts exhibiting a hollow spherical morphology were prepared by spray pyrolysis of aqueous solutions of titanium citrate complex and titanium oxalate precursors in one-step. Effects of precursor concentration and spray pyrolysis temperature were investigated. By subsequent heat treatment, photocatalysts with phase compositions from 10 to 100% rutile and crystallite sizes from 12 to 120 nm were obtained. A correlation between precursor concentration and size of the hollow spherical agglomerates obtained during spray pyrolysis was established. The anatase to rutile transformation was enhanced with metal incorporations and increased precursor concentration. The photocatalytic activity was evaluated by oxidation of methylene blue under UV-irradiation. As-prepared TiO2 particles with large amounts of amorphous phase and organic residuals showed similar photocatalytic activity as the commercial Degussa P25. The metal incorporated samples showed comparable photocatalytic activity to the pure TiO2 photocatalysts.  相似文献   

11.
TiO2 nanocomposite films with different concentrations of TiO2 MT-150A nanoparticles were immobilized on glass substrates using a dip coating process. The crystalline structure and surface chemical state of nanocomposite film properties were examined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The specific surface area and morphology of TiO2 MT-150A nanoparticles were evaluated by the BET method and Field Emission Scanning Electron Microscopy (FE-SEM). The photocatalytic activities of films were evaluated by the methyl orange decoloring rate. XPS measurements showed that the oxygen amount (%) was related to the film composition. The composite film with 10 g/L MT-150A loading yielded the highest amount of surface oxygen (26.82%) and TiO2 rutile showed the lowest amount of surface oxygen (13.67%) in the form of surface hydroxyl groups. The remaining oxygen was identified as lattice oxygen. In addition, the nanocomposite film with 10 g/L MT-150A loading yielded the highest photocatalytic activity.  相似文献   

12.
TiO2 nanoparticles modified with 5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin (HTPP), 5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin zinc (ZnHTPP) and trans-dichloro-5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin tin (SnHTPP) were prepared in order to improve the visible photocatalytic activity of TiO2 nanoparticles. The photocatalytic activity of the modified TiO2 nanoparticles was investigated by carrying out the photodegradation of methyl orange in aqueous solution under visible light irradiation. The TiO2 nanoparticles modified with SnHTPP show the highest visible photocatalytic activity with a degradation ratio of 86% of methyl orange after 180 min irradiation among three catalysts. This result indicates that the central metal ions in porphyrins can significantly influence the sensitization efficiency of porphyrins. In addition, the photoelectrochemical behavior of the modified TiO2 nanoparticles was examined and related to their photocatalytic activity. Finally, the photocatalytic mechanism was discussed preliminarily.  相似文献   

13.
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   

14.
Self-organized V-N co-doped TiO2 nanotube arrays (TNAs) with various doping amount were synthesized by anodizing in association with hydrothermal treatment. Impacts of V-N co-doping on the morphologies, phase structures, and photoelectrochemical properties of the TNAs films were thoroughly investigated. The co-doped TiO2 photocatalysts show remarkably enhanced photocatalytic activity for the CO2 photoreduction to methane under ultraviolet illumination. The mechanism of the enhanced photocatalytic activity is discussed in detail.  相似文献   

15.
Nanostructural TiO2/modified multi-wall carbon nanotubes photocatalysts were prepared by hydrolysis of Ti(iso-OC3H7)4 providing chemical bonding of anatase TiO2 nanoparticles onto oxidized- or amino-functionalized multi-wall carbon nanotubes (MWCNT). The processes of functionalization of the MWCNT and the deposition of TiO2 influence the photocatalytic activity of the synthesized nanocomposites. The phase composition, crystallite size, and the structural and surface properties of the obtained TiO2/modified-MWCNT nanocomposite were analyzed from XRD, FEG-SEM, TEM/HRTEM and FTIR data, as well low temperature N2 adsorption. In the photocatalytic study, the TiO2/oxidized-MWCNT catalyst showed the highest and the TiO2/amino functionalized-MWCNT catalysts somewhat lower degradation rates, indicating that the enhancement of photocatalysis was supported by the more effective electron transfer properties of the oxygen- than amino-containing functional groups, which support the efficient charge transportation and separation of the photogenerated electron-hole pairs.  相似文献   

16.
Y2O3-doped TiO2 films were prepared on glass substrates by means of pulsed DC reactive magnetron sputtering method using titanium and yttrium mixed target. XPS results showed that the films were composed of fully oxidation states of the two elements, Y2O3–TiO2 composite oxides. The existence of yttrium inhibited the crystal growth of TiO2 in the films and Y2O3 mainly presented in its amorphous state in the films. UV–vis transmittance of the films decreased whereas their reflectance increased slightly. Yttrium doping had detrimental effect on photocatalytic activity of the TiO2 films. Photocatalytic degradation efficiency of methyl orange solution declined along with increasing yttrium concentration.  相似文献   

17.
TiO2 films in various thicknesses were prepared by sol-gel method, and their photocatalytic activities in the decomposition of gaseous 2-propanol were evaluated. It was found that the photocatalytic activities of transparent TiO2 films increase with the increase of film thickness: The photocatalytic activity of TiO2 films in 670 nm-thickness was 3.7 times that of films in 70 nm-thickness. We proposed that the higher photocatalytic activities for the thicker TiO2 films originate from the greater amount of photogenerated electron and hole pairs, which are transferred from the inside to the surface of TiO2 films. We also provided some experimental evidences supporting this mechanism.  相似文献   

18.
Titanium oxide films were formed on metallic titanium substrates by employing a thermal treatment at 800 °C under air atmosphere. Component and microstructure of the oxide films were characterized by XRD and SEM method. Water contact angles on titanium oxide film surface were measured in both dark and sunlight illumination condition. Corrosion tests were carried in seawater solution under different illuminate conditions. Electrochemical impedance spectroscopy (EIS) techniques were used to study the changes on TiO2 film. Results indicated that: hydrophilic TiO2 film suffered a severe photo-corrosion effect in seawater due to their semiconductor properties under sunlight condition, but the hydrophobic TiO2 film under dark condition exhibited a good corrosion resistance.  相似文献   

19.
Unique visible-light-responsive TiO2 photocatalysts (λ>450 nm) were successfully developed by implantation of V ions into the TiO2 thin films prepared on a quartz substrate by an ionized cluster beam (ICB) deposition method. After V ions implantation into TiO2 thin film, the photocatalytic activity of the thin films for the decomposition of formic acid into CO2 and H2O was found to proceed efficiently under visible light irradiation longer than 450 nm. The TiO2 thin film photocatalysts were characterized by XRD, UV-vis, XPS, FE-SEM and AFM.  相似文献   

20.
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   

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