Si含量对TiO_2/SiO_2复合气凝胶结构及光催化性能的影响

Effects of Silicon Content on Microstructure and Photocatalytic Activity of TiO_2/SiO_2 Composite Aerogels

采用溶胶-凝胶法制备了不同Si含量的TiO2/SiO2复合气凝胶.利用XRD、FTIR、XPS和BET等手段表征了复合气凝胶组织结构,以甲基橙溶液光催化降解实验评价其光催化活性,研究了Si含量对TiO2/SiO2复合气凝胶的结构及光催化性能影响规律.结果表明:TiO2/SiO2复合气凝胶中Ti-O-Ti、Si-O-Si和Ti-O-Si键相互交织,使复合气凝胶具有小晶粒尺寸、高比表面积和高热稳定性.随着Si含量增大,TiO2/SiO2复合气凝胶中TiO2晶粒尺寸减小,TiO2结晶度降低,比表面积增大,平均孔径减小,且TiO2/SiO2复合气凝胶对甲基橙溶液的光催化降解活性呈现先升后降的变化趋势.适当Si含量能显著改善TiO2/SiO2复合气凝胶的结构和光催化性能,Si含量最佳值在9wt%附近.

TiO2/SiO2 composite aerogels with different silicon contents were prepared by Sol-Gel method.The microstructure of TiO2/SiO2 composite aerogels was characterized by X-ray diffraction（XRD）,Fourier transform infrared spectroscope（FTIR）,X-ray photoelectron spectroscope（XPS）and N2 adsorption-desorption,the photocatalytic activity was evaluated by means of photocatalytic degradation of methyl orange under UV irradiation.The effects of silicon content on microstructure and photocatalytic activity were investigated.The results show that Ti-O-Ti bonds,Si-O-Si bonds and Ti-O-Si bonds all form in TiO2/SiO2 composite aerogels,which make com-posite aerogels have smaller crystal size,higher specific surface area and better thermal stability.As the silicon content increases,the specific surface area increases,however the anatase grain size,the anatase content and the average pore diameter reduce.At higher silicon content level,the photocatalytic activity of composite aerogels for methyl orange is improved initially,then decreases with the increase of silicon content.Proper silicon content can refine the structure and improve photocatalytic activity of TiO2/SiO2 composite aerogels dramatically,and the optimal silicon content is about 9wt%.