TiO2/Mo-TiO2 的制备、表征和光催化活性

 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.

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

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.