掺杂铁系元素对TiO_2电子结构和光催化性能的影响

Influence of Doping Iron Group Elements on Electronic Structure and Photocatalytic Activity of TiO_2

采用基于密度泛函理论的第一性原理平面波超软赝势方法研究了纯锐钛矿相TiO2掺杂铁系原子(Fe、Co、N i)的电子结构和光学性质。计算结果表明,掺杂能级的形成主要是掺杂离子3d轨道的贡献,在吸收光谱的红移中起关键作用。随着掺杂原子序数的增加,TiO2的导带、价带及杂质能级向低能量方向移动,且移动的幅度逐渐减小。掺杂后TiO2的带隙宽度减小,吸收光谱移至可见光区域,与实验结果相吻合,合理的解释了Fe、Co、N i金属掺杂对锐钛矿相TiO2光催化性能影响的机理。

The electronic structure and optical properties of titanium dioxide（TiO2） doped with iron group elements（Fe,Co,Ni） were studied by using the plane-wave ultrasoft pesudopotentials method based on density function theory.The calculated results show that the formation of impurity energy levels are contributed by 3d orbitals of the transition metals doped in TiO2,which causing the band gap decreased.These impurity energy levels can reduce the recombination rate of photoexcited carriers and improve the photocatalytic efficiency of doped TiO2.Absorption spectra of doped TiO2 is red-shifted to visible-light region.The experimental results also indicated that doped TiO2 has a high photocatalytic efficiency in both visible-light region and ultraviolet ray region.With the atomic number of the dopant increasing,the conduction band and valence band of TiO2 as well as impurity level will shift to lower energy,and the shift amplitude decreases.