Surface chemical structure of titania-silica nanocomposite powder  

作　　者：WANG LuYan SUN YanPingi XU BingShe 

机构地区：[1]Chemical Engineering Department, Taiyuan University of Technology, Taiyuan 030024, China [2]Key Laboratory of Interface and Engineering in Advanced Materials of Ministry of Education of China, Taiyuan University of Technology, Taiyuan 030024, China

出　　处：《Chinese Science Bulletin》2008年第19期2964-2972,共9页

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 20776091 and 90306014)

摘　　要：Titania-silica (TS) nanocomposite powder with three different composite structures, containing 10―30 mol% SiO2 in each structure, have been prepared by sol-gel processes. The surface characteristics of these titania-silica samples have been investigated by X-ray photo-emission spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The study for all TS oxides annealed at 773 and 1173 K showed: an abnormal surface enrichment in Si increased with increasing annealing temperature; the Ti3+, Ti2+, Si3+ and Si2+ oxides coexisted with Ti4+ and Si4+ oxides, and the contents of these Ti/Si suboxides increased with increasing SiO2 content and annealing temperature; there was a layer rich in O on the topmost surface and the excess O could be attributed to the chemadsorption of H2O; different composite structures could lead to different contents of Ti/Si suboxides. These results indi- cated that the surface of TS oxide powder derived by sol-gel process was a double layer with enriched O first and then SiOx/TiOy (x, y<2). Ti/Si suboxides could result from the thermal diffusion of Ti4+ and Si4+, which might be induced by the strong interaction between Ti4+ and Si4+.Titania-silica （TS） nanocomposite powder with three different composite structures, containing 10-30 mol% SiO2 in each structure, have been prepared by sol-gel processes. The surface characteristics of these titania-silica samples have been investigated by X-ray photo-emission spectroscopy （XPS） and high resolution transmission electron microscopy （HRTEM）. The study for all TS oxides annealed at 773 and 1173 K showed： an abnormal surface enrichment in Si increased with increasing annealing temperature; the Ti^3＋, Ti^2＋, Si^3＋ and Si^2＋ oxides coexisted with Ti^4＋ and Si^4＋ oxides, and the contents of these Ti/Si suboxides increased with increasing SiO2 content and annealing temperature; there was a layer rich in O on the topmost surface and the excess O could be attributed to the chem-adsorption of H2O; different composite structures could lead to different contents of Ti/Si suboxides. These results indicated that the surface of TS oxide powder derived by sol-gel process was a double layer with enriched O first and then SiOx/TiOy（x, y〈2）. Ti/Si suboxides could result from the thermal diffusion of Ti^4＋ and Si^4＋, which might be induced by the strong interaction between Ti^4＋ and Si^4＋.

关 键 词：表面结构 三氧化钛 硅石 低值氧化物 

分 类 号：O61[理学—无机化学]