非金属阳离子掺杂锐钛矿相TiO_2的第一性原理研究

First-principles study on nonmetallic cation doping anatase TiO_2

采用基于第一性原理的平面波超软赝势方法研究了非金属阳离子掺杂锐钛矿相TiO2的晶体结构、杂质形成能、电子结构及光学性质。计算结果表明掺杂后发生的晶格畸变、原子间的键长及原子的电荷量的变化,导致了晶体中的八面体偶极矩增大,使光生电子-空穴对能有效分离;掺杂离子的p态电子与O2p态、Ti3d态杂化形成杂质能级、价带宽化,从而导致TiO2的禁带宽度变窄、光吸收曲线红移到可见光区。这些计算结果很好地解释了非金属阳离子掺杂锐钛矿相TiO2在可见光下具有优良的光催化性能的内在原因。

The crystal structure, impurity formation energy, electronic structure and optical properties of anatase TiO2 doping with nonmetallic cation were studied by the plane-wave ultrasoft pseudopotential method based on the first-principles in this paper. The calculations shown that the dipole moments of octahedral in crystal were increase due to the changes of lattice parameters, bond length and charges on atoms, which was very effective for the separation of photogenerated electron-hole pairs; the band gap narrowed and the curves of light absorption red-shifted to visible-light region due to the width of valence band broadening from hybridizing dopants＇ electrons in p state with O2p states and Ti3d states. All of these results could explain the higher photocatalytic properties of nonmetallic cation-doped anatase TiO2 in visible-light region.