La/S共掺杂对锐钛矿相TiO_2电子结构的影响

Effects of La/S co-doping on the electronic structures of anatase TiO_2

采用基于密度泛函理论的第一性原理对La/S共掺杂前后锐钛矿相TiO2的晶格参数、电荷布居以及电子结构进行了计算.结果表明:La/S共掺杂导致TiO2晶格膨胀并减小了锐钛矿相TiO2的禁带宽度,同时在TiO2禁带之内引入了局域态的杂质能级,这些杂质能级可以充当电子从价带到导带跃迁的"桥梁"以减小激发光子的能量从而提高太阳光的利用率.为实验上合成的La/S共掺杂TiO2可见光催化剂提供了一定的理论基础.

The lattice parameters, charge populations and electronic structures of anatase TiO2 before and after La/S co-doping were calculated using first-principles based on the density functional theory. The results show that the La/S co-doping results in the expansion of the TiO2 lattice and decreases the width of the forbidden band of anatase TiO2 as well as introduces local impurity energy levels into the TiO2 forbidden band. These impurity energy levels can act as the ＂transitional bridge＂ for the electrons from the valence band to the conduction band, thereby decreases the exciting photons＇ energy and enhances the utilization of the solar light. This article will provide theoretical basis for the experimental synthesis of La/S co-doped TiO2 catalyst with visible light sensitiveness.