S掺杂对锐钛矿相TiO2电子结构与光催化性能的影响

采用基于第一性原理的平面波超软赝势方法研究了掺杂不同价态S的锐钛矿相TiO₂的晶体结构、杂质形成能、电子结构及光学性质.计算结果表明硫在掺杂体系中的存在形态与实验中的制备条件有关；掺杂后晶格发生畸变、原子间的键长及原子的电荷量也发生了变化，导致晶体中的八面体偶极矩增大； S 3p态与O 2p态、Ti 3d态杂化而使导带位置下移、价带位置上移及价带宽化，从而导致TiO₂的禁带宽度变窄、光吸收曲线红移到可见光区.这些结果很好地解释了S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.根据计算结果分析比较了硫以不同离子价态掺杂对锐钛矿相TiO₂电子结构和光催化性能影响的差别. 关键词： 2')" href="#">锐钛矿相TiO₂ S掺杂 第一性原理 光催化性能

Effects of S doping on electronic structures and photocatalytic properties of anatase TiO2

The crystal structure, impurity formation energy, electronic structure and optical properties of anatase TiO₂ doped with sulfur in different valence states were studied by using the plane-wave ultrasoft pseudopotential method based on first_principles. The calculations shown that the existence form of sulfur element in anatase TiO₂ was related to the experimental conditions; the octahedral dipole moments were increased due to the changes of lattice parameters, bond length and charges on atoms; the band gap narrowed and the curves of light absorption red-shifted to visible-light region due to the position of conduction band downward shifting, the position of valence band upper shifting and the width of valence band broadening result from hybridizing S 3p states with O 2p states and Ti 3d states. All of these results can explain the better photocatalytic properties of S-doped anatase TiO₂ in visible-light region. According to these results, the effects on electronic structures and photocatalytic properties of anatase TiO₂ doping with different valence states of sulfur were compared and analyzed.