第一性原理计算Zr/S共掺杂锐钛矿相TiO_2的电子结构

Electronic Structure of Zr/S Codoped Anatase TiO_2 Calculated Using First-Principles

利用基于密度泛函理论的第一性原理平面波赝势方法对Zr/S共掺杂锐钛矿相TiO2的晶格参数、电荷布居、能带结构、电子分态密度和吸收光谱进行了计算.计算结果表明:Zr/S共掺杂导致锐钛矿相TiO2的晶格畸变使其体积变大,共掺杂时Zr和S的电荷布居数与单掺杂前的布居数略有不同;Zr/S共掺杂还导致锐钛矿相TiO2的禁带宽度变大0.1eV,达到2.30eV,但是由于Zr/S共掺杂在TiO2禁带之内引入了杂质能级,这些杂质能级可以作为电子跃迁的"台阶"而降低电子从价带跃迁到导带所需的激发光子能量,这有可能是实验上制备的Zr/S共掺杂TiO2具有较高光催化活性的内在原因.

The lattice parameters, charge populations, band structure, electronic density of states and absorption spectrum of Zr/S codoped anatase TiO2 were calculated using the first-principles plane-wave ultra-soft pseudo-potential method based on the density functional theory. The calculated results indicate that the Zr/S codoping results in the distortion of the lattice, which leads to the volume expansion of the anatase TiO2. The charge populations of Zr and S are different from those of the single Zr and single S doped anatase TiO2. Compared with the pristine TiO2, the band gap of Zr/S codoped anatase TiO2 increases 0.10 eV to 2.30 eV. Because of the introduction of impurity energy levels lying in the forbidden band resulted from the Zr/S codoping, these impurity energy levels can act as a ＂step＂ for the electrons transition, which will decrease the photon＇s energy needed for the electron transiting from the valence band to the conduction band. This is a possible reason for the photocatalytic activity enhancement of Zr/S codoped TiO2 in experimental research.