同主族Si/C共掺杂TiO2可见光区光催化性能的第一性原理计算

The first-principles calculation in region on photocatalytic properties of main group Si/C-codoped TiO_2

本文利用密度泛函理论(DFT)第一性原理平面波超软赝方法对Si/C共掺杂锐钛矿TiO_2电子结构、差分电荷密度和光学特性进行了研究.计算结果表明,共掺杂能明显降低体系的带隙(约为1.7eV),能有效增加其光催化活性.从总态密度图可以得到,费米能级附近的杂质态降低了跃迁能.Si/C共掺杂锐钛矿TiO_2能有效提高其在可见光区域的吸收系数,特别是在三种不同的构型中,第三种构型在可见光区域具有最大吸收系数.

In this work, the electronic structures, charge density differenceand optical properties of Si and C codoped anatase TiO2 are studied by using the plane-wave ultrasoft pseudopotential method of density functional theory （DFT）. The calculated results reveal that C-Si-codoped anatase TiO2 results in band gap narrowing that increases the probability of electronic transition from the impurity energy levels to the conduction band （about 1.7eV）, then improves the solar energy utilization, the existence of impurity energy levels in the forbidden gap reduces the carrier transition energy. The C-Si-codoped TiO2 has been helpful for enhancing the absorption coefficient under visible-light region, especially, among the three models, the third model exhibits the largest value of absorption coefficient under visible-light region.