载体对负载型TiO2催化剂光催化性能的影响

 以活性碳（AC）和镁铝尖晶石（MA）为载体，采用真空吸附水解法制备了负载型光催化剂TiO2／AC和TiO2／MA，并采用TiO2溶胶负载法制备了活性碳负载催化剂TiO2（C）／AC．以氯仿为探针分子研究了其在催化剂上的吸附及光催化降解反应性能．结果表明，催化剂的制备方法、TiO2负载量与载体的吸附性能对光催化活性有明显的影响．通过优化制备条件，TiO2／AC催化剂的催化活性可提高到纳米TiO2的2．5倍．氯仿在AC上的饱和吸附量较高，但吸附强度较弱；在纳米TiO2上的吸附情况则正好相反．氯仿在AC和TiO2上吸附性质的差异有利于吸附在TiO2／AC上的氯仿分子从活性碳载体向TiO2光催化活性中心迁移．镁铝尖晶石载体对光催化反应没有明显的促进作用，与其基本上不吸附氯仿分子有关．与TiO2胶体负载法相比，真空吸附水解法是一种较好的负载型TiO2光催化剂制备方法．     

Photocatalytic Oxidation of Aniline in the Gas Phase Using Porous TiO2 Thin Films

The gas-phase photocatalytic oxidation of aniline on a new kind of porous nano-TiO₂ composite films is investigated. The composite film was prepared on glass fiber with the water glass as binders and dilute H₂SO₄ solution as solidifying reagent. The surface characters were observed by scanning electron microscope. The photocatalytic degradation of aniline on the composite films was carried out in a TiO₂/UV system. Some important factors affecting the photodegradation, such as the concentration of TiO₂, the initial concentration of aniline, and the existing water vapor, are also studied. The product of photocatalytic oxidation was detected by Fourier transform-Infrared. The partial intermediate products were absorbed on TiO₂ surface, which resulted in catalyst deactivation. But when it was irradiated under UV illumination or solar irradiation for some time, the catalyst could be reused without loss of catalytic activity. Translated from the Journal of Wuhan University (Natural Science Edition), 2005, 51(2) (in Chinese)     

纳米TiO2膜用于光催化氧化测定化学需氧量的研究

A photocatalytic oxidation method for determination of chemical oxygen demand （COD） using nano-TiO2 film, based on the use of a nano-TiO2-Ce（SO4）2 system and electrochemical detection, was proposed. The technique was originated from the direct determination of the Ce（Ⅲ） concentration change resulting from photocatalytic oxidation of organic compounds. Ce（Ⅲ）, which was produced by photocatalytic reduction of Ce（SO4）2, could be measured at a multi-walled carbon nanotubes （MWNT） chemically modified electrode （CME）. The COD values by this method were calculated from the differential pulse voltammetry （DPV） current of Ce（Ⅲ） at the CME. Under the optimal operation conditions, the detection limit of 0.5 mg·L^-1 COD with the linear range of 1-600 mg·L^-1 was achieved. This method was also applied to determination of various COD of ground water and wastewater samples. The resuits were in good agreement with those from the conventional COD methods, i.e., permanganate and dichromate ones.     

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Fe³⁺-doped TiO₂ composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe³⁺/TiO₂ nanoparticles under visible light irradiation. The influence of doping amount of Fe³⁺ (ω: 0.00%–3.00%) on photocatalytic activities of TiO₂ was investigated. Results show that the size of Fe³⁺/TiO₂ particles decreases with the increase of the amount of Fe³⁺ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe³⁺ can control the conversion of TiO₂ from anatase to rutile. The doping amount of Fe³⁺ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe³⁺ can markedly increase the catalytic activity of TiO₂ under visible light irradiation. __________ Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)]     

Carbon dioxide reduction under visible light: a comparison of cadmium sulfide and titania photocatalysts

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负载型光催化材料CeO2-TiO2/SiO2的表面结构与光响应性能

采用表面改性法制备了负载型光催化材料CeO2-TiO2/SiO2,并用X射线衍射,比表面积测定,红外光谱,程序升温还原和紫外可见漫反射光谱技术对固体材料的结构和光响应性能进行了表征.结果表明,CeO2与TiO2在材料表面存在相互修饰作用,CeO2能拓展TiO2的光响应范围,使TiO2吸光区域由紫外拓宽至可见光区,从而提高材料的光能利用率;Ti4 可以进入CeO2晶格,形成Ce-O-Ti键合,使得Ti4 平均配位数增加,同时提高了CeO2体相晶格氧的活性;TiO2有助于提高CeO2在载体表面的分散程度,减小CeO2的微晶尺寸,提高固体材料的能隙值和氧化还原能力.     

H2O2络合凝胶法制备纳米TiO2/SiO2复合催化剂及其光催化性能

采用H2O2络合凝胶法获得钛的络合物[TiO(H2O2)]2 水溶胶,并与SiO2水溶胶包覆复合,制备了纳米TiO2/SiO2复合半导体催化剂,其结构经XRD和BET表征。以含阳离子艳红染料模拟废水降解为模型反应,考察了复合催化剂的光催化性能。实验结果表明:经650℃焙烧后的复合催化剂中TiO2粒径为9.8 nm,光催化活性最好,SiO2的最佳掺杂量为25%。     

以钛氧有机物为前驱物制备具有高光催化活性的纳米二氧化钛晶体

 纳米二氧化钛的制备方法及前驱物的差别影响其光催化活性．将20ml钛酸丁酯及30ml乙酐在密闭容器中与50ml环己烷混合，在70～85℃反应30min，生成微细的非晶钛氧有机物；经FT－IR和TGA分析，该物质被确认为计量式是TiOOOCCH3）2和TiO（OC4H9）（OOCCH3）的混合体．该钛氧有机物前驱物经焙烧后得到具有高光催化活性的纳米二氧化钛晶体．表征结果表明，钛氧有机物在焙烧过程中，其表面的吸附物及键合有机基团在400℃以前发生脱附和氧化分解；在389～405℃间形成锐钛矿型晶体，在600℃出现金红石晶型；600℃焙烧3h所得样品的比表面积为86m2／g，其二次粒子呈200～300nm条形体，孔隙大于20nm；单分散粒子为球形单晶，粒径为22nm；表面物理吸附水量为1．21％，加热至800℃时失重1．48％，粉体稳定纯净．光催化实验结果表明，以钛氧有机物为前驱物制备的纳米二氧化钛晶体具有高的光催化活性，光降解丁基罗丹明溶液的反应速率常数约为溶胶－凝胶法制备的催化剂样品的4倍．表面氧空缺和一定量的表面羟基可能是粉体具有高光催化活性的重要因素．     

制备具有光催化活性的金红石相纳米氧化钛粉体

以TiCl4为原料，通过控制盐浓度和水解温度可以在温和条件下制备出晶粒尺 寸为6nm的金红石相氧化钛粉体，比表面积为175m^2/g。测定了粉体的X衍射、红外 和拉曼光谱。TEM照片显示粉体呈放射状颗粒，其粒径尺寸在200－400nm。苯酚的 光催化降解实验表明它比具有相同比表面积的锐钛矿粉体有更高的光催化活性。其 较大的团聚颗粒尺寸有利于光催化反应后的分离。     

纳米TiO_2-SnO_2介孔材料的制备及其对含氰废水的光催化降解性能

以TiCl4和SnCl4为原料,采用直接水解常压液相反应合成出了纳米TiO2-SnO2复合介孔材料.利用XRD和TEM及漫反射谱等对样品进行了表征,并研究了纳米TiO2-SnO2复合介孔材料对含氰废水的光催化降解性能.结果表明,纳米TiO2与SnO2复合后,导致材料的光谱响应拓宽;此种催化剂在日光灯下比在紫外灯下对废水中CN-的降解效果要好.