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1.
Ag2S quantum dots (QDs) were deposited on ordered TiO2 nanotube arrays (TNTAs) using a sequential chemical bath deposition (S-CBD) approach. AgNO3 and thiourea were used as the precursor materials of Ag+ and S2− ions, respectively. The decoration of Ag2S QDs significantly shifted the absorption spectrum of the TNTAs to visible light region. As a result, Ag2S QDs-sensitized TNTAs exhibited much higher photocurrent density than pure TNTAs under visible light irradiation. 相似文献
2.
A novel preparation method to synthesize TiO2/SnO2 nanocrystalline sol under mild conditions was presented. Ti(OC4H9)4 used as a precursor was hydrolyzed in the rutile SnO2 nanocrystalline sol, and in-situ formed TiO2/SnO2 nanocrystalline sol. The crystal structure, morphology and photocatalysis performance of samples were investigated. The results show that the additional rutile SnO2 nano grains serve as heterogeneous crystal nucleus and exhibite the inducing effect on TiO2 grains growth, thus leading to the changes in crystalline phase and particle morphology. In addition, the photoluminescence (PL) spectra analysis indicates that TiO2/SnO2 composite structure induces a better charge separation, and thus the photocatalytic activity of TiO2/SnO2 sol is increased significantly compared with TiO2 sol. 相似文献
3.
Tae Ho Jun 《Materials Letters》2010,64(21):2287-2289
Cr-doped TiO2 thin films with different band gaps were prepared. Higher Cr doping was beneficial to the formation of the rutile-TiO2 phase over the anatase-TiO2 phase. A 4.8% Cr-doped thin film indicated a band gap of 2.95 eV, which was lower than the band gap of the rutile-TiO2. Cr doping was accompanied by the formation of not only the rutile-TiO2 phase but also the Cr2O3 phase, lead to the degradation of the hydrophilicity. The TiO2 thin films with the mixed phase were not desirable to improve the hydrophilicity. 相似文献
4.
Ti thin films were anodized in aqueous HF (0.5 wt.%) and in polar organic (0.5 wt.% NH4F + ethylene glycol) electrolytes to form TiO2 nanotube arrays. Ti thin films were deposited on microscope glass substrates and then anodized. Anodization was performed at potentials ranging from 5 V to 20 V for the aqueous HF and from 20 V to 60 V for the polar organic electrolytes over the temperatures range from 0 to 20 °C. The TiO2 nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). It has been observed that anodization of the deposited Ti thin films with aqueous HF solution at 0 °C resulted in nanotube-type structures with diameters in the range of 30-80 nm for an applied voltage of 10 V. In addition, the nanotube-type structure is observed for polar organic electrolyte at room temperature at the anodization voltage higher than 40 V. The volatile organic compound (VOC) sensing properties of TiO2 nanotubes fabricated using different electrolytes were investigated at 200 °C. The maximum sensor response is obtained for carbon tetrachloride. The sensor response is dependent on porosity of TiO2. The highest sensor response is observed for TiO2 nanotubes which are synthesized using aqueous HF electrolyte and have very high porosity. 相似文献
5.
Zongwen ZhangDengyu Pan Juanjuan FengLei Guo Liwei PengChen Xi Jinghui LiZhen Li Minghong WuZhaoyu Ren 《Materials Letters》2012,66(1):54-56
The use of TiO2 nanotube arrays fabricated by anode oxidation of titanium sheets as a photoelectrocatalyst is limited by low surface activity owing to passive crystallization post-treatment. We report here on a vacuum assisted filling route for modifying TiO2 nanotube arrays using high-activity anatase TiO2 nanoparticles as a filling. Photoelectrocatalytic degradation experiments show that a nearly 4-fold activity enhancement in photoelectrocatalysis is achieved and good photoelectrocatalytic stability is kept after the nanotube arrays are filled with the high-activity TiO2 nanoparticles. The remarkable enhancement in photoelectrocatalysis is ascribed to the key modification of the TiO2 nanotube arrays using the high-activity TiO2 nanoparticles. Our findings provide an insight into designing excellent photoelectrocatalysts by filling TNAs with available high-activity TiO2 nanoparticles. 相似文献
6.
This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV–vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79–100% under visible light (λ > 400 nm), compared with TiO2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range. 相似文献
7.
DNA-like dye-sensitized solar cells based on TiO2 nanowire-covered nanotube bilayer film electrodes 总被引:1,自引:0,他引:1
This paper reports a two-step formation of a TiO2 nanowire-covered nanotube bilayer film technique and its application in DNA-like dye-sensitized solar cells. The bilayer film was prepared by the electrochemical anodization first and then the hydrothermal method. From the reflectivity spectrum and scanning electron microscopy it is observed that the nanowire layer on the top cannot only decrease the reflectivity of the film, but also play a role to modify the film cracks. Compared with the dye-sensitized solar cells based on a single layer electrode, the cell with the bilayer film showed higher photovoltaic parameters and a lower dark current, which is due to its higher light harvesting efficiency and lower charge recombination between the electrolyte and the substrates. 相似文献
8.
Arrays of TiO2 nanotubes were fabricated by the anodization of Ti foils and then used in assembling dye-sensitized solar cells (DSSCs). The role of the morphologies of the TiO2 nanotubes in the photovoltaic performances of the DSSCs was studied in terms of the surface topography and the tube length. The necessity of removing the nanoporous films from the surface of the nanotube arrays for good DSSC performance has been demonstrated. Also, it has been shown that appropriately increasing the tube length was an effective measure for enhancing both the short-circuit current density and the conversion efficiency of the DSSCs. 相似文献
9.
A sol-gel dip coating technique was used to fabricate TiO2/SnO2 nano composite thin films on soda-lime glass. The solutions of SnO2 and TiO2 were mixed with different molar ratios of SnO2:TiO2 as 0, 3, 4, 6, 8, 9, 10.5, 13, 15, 19.5, 25 and 28 mol.% then the films were prepared by dip coating of the glasses. The effects of SnO2 concentration, number of coating cycles and annealing temperature on the hydrophilicity of films were studied using contact angle measurement. The films were characterized by means of scanning electron microscopy, X-ray diffraction and atomic force microscopy measurements. The nano composite thin films fabricated with 8 mol.% of SnO2, four dip coating cycles and annealing temperature of 500 °C showed super-hydrophilicity. 相似文献
10.
Electrochromic TiO2 anatase thin films on ITO were prepared by the sol-gel dipping method using a solution of titanium tetraisopropoxide, diethanolamine and ethanol. The films were transparent in the visible range and can be colored in a solution of LiClO4 in propylene carbonate. The transmittances of the colored films were found to be strongly dependent on the Li+ inserted charge. Combining the experimental data obtained from in situ Raman and in situ transmittance spectra with the data from chronoamperometic measurements, it was demonstrated that the fully colorated state of the TiO2 anatase films is Li0.5TiO2 with a crystalline structure of Imma space group symmetry. In the Raman spectra this coloration state exhibits five characteristic bands at 176, 224, 316, 531 and 629 cm−1. 相似文献
11.
Anatase nano-TiO2 thin films were fabricated by reactive magnetron sputtering metal Ti target followed by thermal annealing in air at 450 °C for 2 hrs. The crystalline structure of the sample films were characterized by X-ray diffraction (XRD) and the hydrophilicity was characterized with the diameters of 1 μl water drop. The films were irradiated by oxygen plasmas and the effects of the radio frequency (rf) power, the gas pressure and the irradiation time of the oxygen plasmas on the hydrophilicity of the TiO2 thin films were investigated. Hydrophilicity can be induced by oxygen plasmas and further more the hydrophilicity shows high stability whenever under the natural light or in dark. 相似文献
12.
We have studied the structural and optical properties of thin films of TiO2, doped with 5% ZrO2 and deposited on glass substrate (by the sol-gel method). The dip-coated thin films have been examined at different annealing temperatures (350 to 450 °C) and for various layer thicknesses (63-286 nm). Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range of 1.62-2.29 and the porosity is in the range of 0.21-0.70. The coefficient of transmission varies from 50 to 90%. In the case of the powder of TiO2, doped with 5% ZrO2, and aged for 3 months in ambient temperature, we have noticed the formation of the anatase phase (tetragonal structure with 14.8 nm grains). However, the undoped TiO2 exhibits an amorphous phase. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 350 °C. The obtained structures are anatase and brookite. The calculated grain size, depending on the annealing temperature and the layer thickness, is in the range (8.58-20.56 nm). 相似文献
13.
采用超声辅助溶胶凝胶法制备了LaFeO3颗粒,进一步以碳纳米管(CNTs)为基底和钛酸丁酯为前体,通过一步水热法煅烧合成CNTs/TiO2/LaFeO3(CTF)三元异质结光催化复合材料。通过扫描电子显微镜(SEM)、X射线衍射分析(XRD)、氮气吸附-解吸等温线(BET)、紫外-可见分光光度计(UV-Vis)、光致发光光谱(PL)等表征手段对材料的形貌与特征结构、比表面积和孔径结构以及光学特征进行了分析,并在紫外光下通过降解活性黑五(RB5)测试样品的光催化性能。结果表明,以CNTs作为载体,能够有效提升LaFeO3/TiO2复合材料的光催化性能。当CNTs在复合材料中的质量占比为5%时,150 W汞灯照射下RB5的50 min去除率可达99.5%。CNTs一方面通过增加复合材料的比较面积为催化反应的进行提供了更多的活性位点,更为重要的是,CNTs作为光生载流子传输的通道加快了电荷分离效率,提升了复合材料的降解能力和催化反应动力学进程。 相似文献
14.
Nanoporous titanium dioxide (TiO2) based conductometric sensors have been fabricated and their sensitivity to hydrogen (H2) gas has been investigated. A filtered cathodic vacuum arc (FCVA) system was used to deposit ultra-smooth Ti thin films on a transducer having patterned inter-digital gold electrodes (IDTs). Nanoporous TiO2 films were obtained by anodization of the titanium (Ti) thin films using a neutral 0.5% (wt) NH4F in ethylene glycol solution at 5 V for 1 h. After anodization, the films were annealed at 600 °C for 8 h to convert the remaining Ti into TiO2. The scanning electron microscopy (SEM) images revealed that the average diameters of the nanopores are in the range of 20 to 25 nm. The sensor was exposed to different concentrations of H2 in synthetic air at operating temperatures between 100 °C and 300 °C. The sensor responded with a highest sensitivity of 1.24 to 1% of H2 gas at 225 °C. 相似文献
15.
Photocatalytic properties of porous TiO2/Ag thin films 总被引:1,自引:0,他引:1
In this study, nanocrystalline TiO2/Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO2/Ag thin films were prepared after calcination at a temperature of 500 °C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO2 films. The as-prepared TiO2 and TiO2/Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation.When PS spheres of different sizes were introduced after calcination, the as-prepared TiO2 films exhibited different porous structures. XRD results showed that all TiO2/Ag films exhibited a major anatase phase. The photodegradation of porous TiO2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure. 相似文献
16.
Metal plasma ion implantation has being successfully developed for improving the electronic and optical properties of semiconductor materials. Prior to deposition, a TiO2 colloidal suspension was synthesized by microwave-induced thermal hydrolysis of the titanium tetrachloride aqueous solution. The TiO2 thin film was optimized to obtain a high-purity crystalline anatase phase by calcinations at 550 °C. The TiO2 coating was uniform without aggregation, which provided good photo conversion efficiency. Ag ion implantation into the as-calcined TiO2 thin films was conducted with 1 × 1015 ~ 1 × 1016 ions/cm2 at 40 keV. The peak position and intensity of the photoluminescence and UV-Vis absorption spectra are quite sensitive to Ag doping. The optical characterization showed a shift in optical absorption wavelength towards infrared ray side, which was correlated with the structure variation of the Ag+ implanted TiO2. Due to the strong capability of forming compounds between the energetic silver ions and TiO2, the photoluminescence emission and UV-Vis absorption efficiencies were improved. 相似文献
17.
K. Zakrzewska 《Vacuum》2004,74(2):335-338
Two classes of thin film gas sensors have been studied: TiO2 doped with Cr or Nb and TiO2-SnO2 mixed systems. Thin films have been prepared by the reactive sputtering from mosaic targets. It is demonstrated that titanium dioxide doped with Nb and Cr should be considered as a bulk sensor. Its performance is governed by the diffusion of point defects, i.e. very slow diffusion of Ti vacancies for TiO2: 9.5 at% of Nb and fast diffusion of oxygen vacancies in the case of TiO2: 2.5 at% Cr sensor. The corresponding response times are 55 min for TiO2: 9.5 at% of Nb and 20 s for TiO2: 2.5 at% Cr. In turn, sensors based on TiO2-SnO2, particularly those of the SnO2-rich composition, belong to the group of surface sensors. 相似文献
18.
TiO2 nanotube (TN) arrays were fabricated by an anodic oxidation process. Through a heat treatment of the as-fabricated TN arrays under a continuous Ar and acetylene flux, carbon-modified TN (C-TN) arrays were obtained. The as-fabricated catalysts were characterized by FE-SEM, HRTEM, XPS, Raman and UV-Vis spectra. Moreover, photocatalytic activity of the C-TN arrays was evaluated through the photodegradation of aqueous methyl blue. The experiments demonstrated that the C-TN arrays display an excellent photocatalytic activity. Under sunlight irradiation, the C-TN arrays are able to almost completely decompose the methylene blue pollutant of 1 × 10− 5 M within 300 min. 相似文献
19.
TiO2/SnO2 stacked-layers are synthesized by reactive sputter deposition on the glass substrate. Very thin TiO2/SnO2 bilayer-photocatalysts exhibited a very high photocatalytic activity for a degradation of gaseous acetaldehyde. Both the control of an electronic structure of TiO2 overlayer in the near-surface region and the interfacial separation of photogenerated electrons/holes in the TiO2/SnO2 stacked-layer are keys to improve the photocatalytic performance. 相似文献
20.
The effect of silicon dioxide (SiO2) on the hydrophilicity of the TiO2 thin film is investigated. SiO2 and TiO2 films were deposited on the glass by RF-magnetron sputtering. Heat-treatment for 15 h at 573 K on TiO2/glass and TiO2/SiO2/glass is carried out to make Na+-ion diffused from the glass to the TiO2 thin film, which results in no band-gap change but instead the enhanced crystallinity of the anatase phase-TiO2. This in turn leads to the improvement in hydrophilicity. Irrespective of the SiO2 interlayer, the anatase phase-TiO2 thin film with enhanced crystallinity shows outstanding super-hydrophilicity. Consequently, under the heat-treatment condition, the SiO2 interlayer played an important role in improving the crystallinity of the anatase phase-TiO2 rather than preventing Na+-ion diffusion. 相似文献