以四氯化钛和钛酸四丁酯为前驱体的TiO_2/C杂化气凝胶光催化性能比较

A comparative study of TiO_2-C hybrid aerogels from TiCl_4 or Ti( OBu)_4 for photocatalytic methylene blue degradation

采用一步溶胶-凝胶法,以四氯化钛、钛酸四丁酯为钛基前驱体,间苯二酚、糠醛为有机相前驱物,制备出TiO2/有机杂化湿凝胶。湿凝胶经溶剂交换、超临界干燥、高温炭化等处理得到TiO2/C杂化气凝胶。利用X射线衍射、透射电子显微镜及N2吸附-脱附等方法对气凝胶的晶型结构、微观形貌及孔结构分布进行表征。通过对亚甲基蓝的光催化降解考察样品的光催化性能。结果表明,钛源前驱体种类及其浓度对亚甲基蓝的光催化降解效率影响较大。相对于以钛酸四丁酯为钛源制备的TiO2/C杂化气凝胶,以四氯化钛为钛源制备的TiO2/C杂化气凝胶对亚甲基蓝的光催化效果更好。以四氯化钛为钛源,以TiO2计的钛源与碳源质量之比为0.38时所制样品具有最佳的性能,其最大平均孔径为7.8nm,最大介孔孔容为0.40 cm3/g,180 min对亚甲基蓝光催化降解率达99.6%。

TiO2-C hybrid aerogels were obtained by a one-pot sol-gel method,followed by supercritical drying and pyrolysis,using resorcinol （R） and furfural（F） as carbon sources,and TiCl4 or Ti（OBu）4 as the TiO2 precursor.The hybrid aerogels were characterized by XRD,HR-TEM and N2 adsorption.The photocatalytic activity of the samples was evaluated based on the conversion of methylene blue （MB） under UV light.Results showed that the type of precursor and the mass ratio of TiO2 to carbon influenced the surface area and MB conversion.The TiO2-C hybrid aerogels using TiCl4 as TiO2 precursor had a higher surface area and a better photocatalytic activity than those using Ti （OBu） 4 as precursor under otherwise identical conditions.The best sample was obtained when TiCl4 was used and the TiO2 content was 40％.This had the largest average pore size of 7.8 nm,the highest mesopore volume of 0.40 cm3/g and the highest MB conversion of 99.6％ under an ultraviolet exposure for 180 min.