TiO_2/Mo-TiO_2的制备、表征和光催化活性

Preparation,Charaterization,and Photocatalytic Activity of TiO_2/Mo-TiO_2

采用溶胶-凝胶法制备了掺Mo的TiO2粉末,再由其制得TiO2/Mo-TiO2复合物光催化剂.使用X射线光电子能谱、X射线衍射、透射电镜、N2吸附-脱附、紫外-可见漫反射光谱和荧光光谱等手段对催化剂进行了表征.在紫外光照射下,以甲基橙溶液降解为探针反应,研究了Mo掺杂量对样品光催化活性的影响.结果表明,Mo-TiO2催化剂的活性不如纯TiO2,这是因为Mo离子促进了光生载流子的复合;而带有n-n异质结半导体结构的TiO2/Mo-TiO2复合催化剂具有比纯TiO2和Mo-TiO2催化剂更高的光催化活性.当Mo掺杂摩尔分数为2%,TiO2:Mo-TiO2质量比为10:1时,活性是纯TiO2的1.57倍.

Mo-doped TiO2 photocatalysts（Mo-TiO2） were prepared by the traditional sol-gel method using（NH4）6Mo7O24·4H2O and tetrabutyl titanate（Ti（OC4H9）4） as the raw materials.TiO2/Mo-TiO2 composite photocatalysts were prepared by mixing TiO2 sol with sol-gel derived Mo-TiO2 powder followed by drying and calcination.The samples were used as catalysts for methyl orange photodegradation in aqueous suspension under UV irradiation,which was used as a probe reaction.X-ray diffraction patterns showed that particles were in the form of anatase and there was no change in crystal structure except a slight variation in crystallite size.The photocatalytic activity of the Mo-TiO2 photocatalysts was lower than that of undoped TiO2,and the photodegradation rate decreased with an increase in the level of molybdenum doped（on TiO2）.The reduced activity can be explained by the fact that dopants act more as recombination centers than as trap sites for charge transfer at the interface,especially for the samples with higher molybdenum ion dopant concentration.The TiO2/Mo-TiO2 composite photocatalysts have the n-n heterojunction and have a higher photocatalytic destruction rate than the Mo-TiO2 photocatalysts and undoped TiO2,which is mainly ascribed to the electrostatic-field-driven electron-hole separation in the TiO2/Mo-TiO2 composite photocatalysts.The best TiO2/Mo-TiO2 composite with TiO2：2mol% Mo-TiO2 mass ratio of 10：1 shows 1.57 times the photocatalytic activity of undoped TiO2.