晶相组成可调的高活性可见光应答型二氧化钛纳米复合光催化材料的制备

采用新的化学溶液法,通过不同体积的钛酸四异丙酯的2-乙二醇单乙醚溶液与一定浓度的H₂O₂水溶液直接反应并对生成的钛过氧化配合物进行焙烧,制备了一系列TiO₂光催化剂. 表征发现,所得TiO₂样品为金红石和锐钛矿的纳米复合晶体,改变2-乙二醇单乙醚的体积可实现金红石相比例在0~96%广范围的调变.与商业二氧化钛P-25相比,所得的TiO₂紫外-可见光吸收谱出现明显红移,间隙能降低, 在可见光照射下,该样品对亚甲基蓝有良好的降解活性. 当2-乙二醇单乙醚的添加量为5 ml时,所得样品体相中金红石相比例接近50%,其光催化活性和吸附性能最好,可分别是P-25的3倍和5倍. 拉曼光谱结合X射线衍射等表征结果表明,该样品的表面仅含少量的金红石相. TiO₂纳米复合晶表面晶相的组成和分布对其光催化降解亚甲基蓝的活性及其吸附能力有直接的影响. 另外,TiO₂纳米复合晶的缺陷浓度也是增强其光吸收能力,提高其可见光光催化活性的原因之一.     

TiO2制备方法对光催化分解十二烷基苯磺酸钠的影响

本文以TiCl4为前体，采用沉淀法、气相沉积法和溶胶-凝胶法分别制备了TiO2光催化剂，比较了它们在十二烷基苯磺酸钠（SDBS）光解反应中的催化活性。结果表明，以日光灯作光源时，气相沉积法获得的催化剂效果最好；以500W紫外线高压汞灯作光源时，沉淀法获得的催化剂活性最高，100ml初始化学需氧量（COD）为381mg/L的SDBS溶液，在0.1g催化剂作用下，室温光照8h,COD去除率可达98.8%。在沉淀法制备的催化剂上，SDBS溶液的催化光解为一级反应。     

PHASE STRUCTURE OF W-DOPED NANO-TiO2 PRODUCED BY SOL-GEL METHOD

With Ti（OBu）4 as precursor, and HAc as complexing agent, pure and W-doped TiO2 gelatins were prepared by a sol-gel method. During the process of gel formation, metal ions were dispersed in the porous TiO2 matrix. Then, powders of nano-TiO2 and W-doped nano-TiO2 were prepared by drying, grinding and heat treatment at different temperatures. The grain size and structure of the samples, pure TiO2 and W-doped, and treated at different temperatures were studied by X-ray diffraction （XRD）, Beckman Coulter Sorption Analysis and TEM. Results showed that, with increasing temperature, the TiO2 transformed from anatase to rutile and the grain size increased. This transformation and grain growth of TiO2 could be retarded by doping with W.     

表面修饰的二氧化钛纳米材料的结构相变和光吸收性质

采用胶体化学法制备表面修饰的二氧化钛纳米材料，并使用XRD，TEM，UV-vis光谱等手段研究表面修饰的二氧化钛纳米微粒的结构相变和光吸收性质.结果表明，表面修饰可以改变二氧化钛的晶化行为、加快锐钛矿→金红石的相变进程、引起二氧化钛纳米粒子的光吸收带边大幅度红移.光吸收系数与光子能量之间关系的计算分析显示，在吸收带边附近，二氧化钛纳米微粒溶胶及二氧化钛纳米薄膜的(αhν)^1/2vs hν(间接)和(αhν)² vs hν(直接)均呈线性关系，其间接和直接光学带隙能可以分别通过外推这种线性关系来测量. 关键词： 二氧化钛纳米材料 结构相变 表面改性 光吸收     

Time—resolved Microwave Conductivity Studies on the Chemical Treatment of the Nanocrystalline Porous TiO2 Films

Effect of Ti(iso-C3H7O)4 treatment on the photoinduced charge carrier kinetics of nanocrystalline porous TiO2 films is studied by time-resolved microwave conductivity measurements. Analysis of the transient photoconductivity decays indicates that Ti(iso-C3H7O)4 treatment leads to an increased concentration of photogenerated charge carriers and a fast interfacial transfer rate of holes via the surface modification of the fleshly growing TiO2 nanocrystallites.     

水合二氧化钛晶种粒径的控制研究

硫酸氧钛溶液(简称钛液)在适当温度和水合TiO_2晶种的作用下,水解生成水合TiO_2(俗称偏钛酸)和硫酸。这是硫酸法制备钛白粉的最重要工艺过程。钛白粉的质量与用途与钛白粉的粒度和粒度分布有直接关系,因此水合TiO_2晶种粒径大小等就直接影响到最终产物     

纳米晶TiO2敏化多孔膜电极的光电化学研究

合成了RuL2(SCN)2(L=2,2‘-bipyridine-4,4‘-dicarboxylic acid)及电化学聚合了聚吡咯，将其作为敏化剂修饰在TiO2纳米晶多孔膜电极上，用光电化学方法研究了纳米晶TiO2／敏化剂多孔膜电极的光电转换机理，系统研究了两类敏化剂对光致电荷转移的影响，并比较了两类敏化复合电极的光电转换效能。用染料或聚吡咯修饰纳米晶多孔膜电极后，可使该复合电极在可见光区吸收增加、光电流增强、光电响应波长红移，有利提高了TiO2电极的光电转换效率。     

Is Water Physisorption Reversible for TiO_2 Nanocrystals？ A Combinational Spectral Study

In this work,the nature of physisorbed water and its impacts on the structure,surface chemistry,and proton conduction properties of TiO2 nanocrystals were investigated by a combinational spectral technique.All TiO2 nanocrystals were directly prepared by a hydrothermal method,which showed highly hydrated and sulfated surfaces.The surface water molecules were indicated to exist in a wide set of energetically nonequivalent surface hydration groups,leading to the removal of physisorbed and chemisorbed water in sequence with increasing temperature.After heating treatment at 100 ℃ in air,physisorbed water layers were recovered with no significant impacts on the TiO2 nanostructure.On the other hand,when treated at the same temperature in vacuum,the recovery of physisorbed water layers was partially reversible,while a new hydration state appeared due to the filling of the high-energy adsorption sites by water molecules,which led to a significant increase in the amount of water molecules for surface hydration and an accelerated dehydration process toward lower temperature.As a result,an abnormal increase was observed in proton conductivity.These observations were explained in terms of thermally induced changes of surface chemistry and the amount of hydrated water.The results reported in this work are important,which may help understand the roles that the physisorbed water plays in stabilizing the nanostructures and therefore could have a broad class of implications.