热处理温度对TiO_2/SiO_2复合气凝胶光催化性能的影响

Effects of Heat Treatment Temperature on Photocatalytic Activity of TiO_2/SiO_2 Composite Aerogels

采用溶胶–凝胶法在常压下经不同温度热处理制备了TiO2/SiO2复合气凝胶光催化剂,利用XRD、TGA和BET等手段对其微观结构进行表征,以甲基橙溶液光催化降解实验评价其光催化性能,研究了热处理温度对TiO2/SiO2复合气凝胶的微观结构及光催化性能影响规律.结果表明:随着热处理温度升高,TiO2/SiO2复合气凝胶中锐钛矿结晶度升高,晶粒尺寸增大,比表面积减小,使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.当热处理温度为700℃左右,紫外光照20 min TiO2/SiO2复合气凝胶对甲基橙溶液的降解率达到95.4%.

TiO2/SiO2 composite aerogels were prepared by Sol-Gel method at ambient pressure and heat-treated at different temperatures.The microstructure of TiO2/SiO2 composite aerogels was characterized by X-ray diffraction（XRD）,thermo gravimetric analyzer（TGA） and N2 adsorption-desorption.The photocatalytic activity was evaluated by means of photocatalytic degradation of methyl orange under UV irradiation.The effects of heat treatment temperatures on microstructure and photocatalytic activity were investigated.With the increase of heat treatment temperature,the crystallization of anatase and the anatase grain size increase,however,the specific surface area decreases.As a result,the photocatalytic activity of TiO2/SiO2 composite aerogels is enhanced initially,then decreases with the increase of heat treatment temperature.When the heat treatment temperature is set at about 700℃, the degradation ratio of methyl orange on the TiO2/SiO2 composite aerogels reaches 95.4% after irradiated by ultraviolet light for 20 min.