N/Cu共掺杂锐钛矿型TiO_2第一性原理研究

First-principles study of N/Cu co-doped anatase TiO_2

基于密度泛函理论的第一性原理平面波超软赝势法,采用局域自旋密度近似加Hubbard U值方法研究了纯锐钛矿型Ti O2,N,Cu单掺杂Ti O2及N/Cu共掺杂Ti O2的晶体结构、电子结构和光学性质.研究结果表明,掺杂后晶格发生相应畸变,晶格常数变大.N和Cu的掺杂在Ti O2禁带中引入杂质能级,禁带宽度发生相应改变.对于N掺杂Ti O2禁带宽度减小较弱,而Cu掺杂和N/Cu共掺Ti O2禁带宽度显著降低,导致吸收光谱明显红移,光学催化性增强,有利于实际应用.

Using the first-principles plane-wave ultra-soft pseudo-potential method based on the density functional theory, the structures, electronic-structures and optical properties of pure anatase TiO2, N （Cu） doped TiO2, and N/Cu co-doped TiO2 crystal are studied by the local-spin density approximation plus Hubbard U method. It is shown that the lattice constants become larger because of the lattice distortion caused by doping. Impurity levels in the band gap of TiO2 are introduced by N and Cu doping, and the forbidden band width is correspondingly changed. For N doped TiO2, the reduction of the band gap is weak, while the N/Cu co-doped WiO2 band gap decreases remarkably. It leads to a red shift of visible absorption spectrum and enhances optical catalysis. The effect is useful for the practical application of photo-catalytic.