中文摘要：

采用溶胶-凝胶法制备出纯TiO2和不同浓度Sn4＋离子掺杂的TiO2光催化剂（TiOz—Snx％，x％代表Sn4＋离子掺杂的TiO2样品中Sn4＋离子摩尔分数）．利用X射线衍射（XRD）、X射线光电子能谱（XPS）和表面光电压谱（SPS）确定了TiO2-Snx％催化剂的晶相结构和能带结构，结果表明：当Sn4＋离子浓度较低时，Sn4＋离子进入TiOz晶格，取代并占据Ti4＋离子的位置，形成取代式掺杂结构（Ti1—SnxO2），其掺杂能级在导带下0．38eV处：当Sn4＋离子浓度较高时，掺入的Sn4＋离子在TiO2表面生成金红石SnO2，形成TiO2和SnO2复合结构（TiO2/SnO2），SnO2的导带位于TiO2导带下0．33eV处．利用瞬态光电压谱和荧光光谱研究了TiO2-Snx％催化剂光生载流子的分离和复合的动力学过程，结果表明，Sn4＋离子掺杂能级和表面SnO2能带存在促进光生载流子的分离，有效地抑制了光生电子与空穴的复合；然而，Sn4＋离子掺杂能级能更有效地增加光生电子的分离寿命，提高了光生载流子的分离效率，从而揭示了TiO2-Snx％催化剂的光催化机理．

英文摘要：

Pure TiO2 and Sn4＋ doped TiO2 （TiO2-Snx%） photocatalysts were prepared by a sol-gel method, where x% represents the nominal molar fraction of Sn4＋ ions in the TiO2 structure. The crystal structure and energy band structure of the resultant catalysts were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, and surface photovoltage spectroscopy （SPS）. The results show that for a low content of Sn4＋ ions, the Sn4＋ ions are doped into the TiO2 lattice and replace lattice Ti4＋ ions in a substitute mode （Ti1-xSnxO2）. The energy levels of these Sn4＋ ions are located 0.38 eV below the conduction band. Moreover, the rutile SnO2 crystal structure evolves with increasing content of Sn4＋ ions, i.e., a TiO2 /SnO2 structure is formed. The conduction band of SnO2 is located 0.33 eV lower than that of TiO2. The separation and recombination mechanism of the photo-generated carriers was characterized by photoluminescence and transient photovoltage techniques. The results showed that the formation of the energy levels of Sn4＋ ions and the conduction band of rutile SnO~ can enhance the separation of the photo- generated carriers, and suppress the recombination of photo-generated carriers. However, the energy levels of Sn4＋ can lead to a much longer life time and higher separation efficiency of the photo-generated carriers. For different content of Sn4＋ in Sn4＋ ion doped TiO2 （TiO2-Snx%）, the abovementioned aspects improve the photocatalytic activity.