La-Ce共掺杂锐钛矿TiO2的缺陷形成能和电子结构分析

采用基于密度泛函的第一性原理研究了稀土元素La、Ce共掺杂锐钛矿相TiO₂的缺陷形成能,缺陷电荷转变能级以及电子结构.研究发现,富氧状态下La、Ce掺杂以及La-Ce共掺的缺陷形成能均为负值,而贫氧状态下La、Ce掺杂形成能为正,表明La、Ce的掺杂TiO₂只能在氧气氛制备条件下进行;替代Ti掺杂缺陷电荷转变能级计算结果表明:0/1-的缺陷电荷转变能级分别位于VBM上面0.522 eV及2.440 eV处;与纯锐钛矿相TiO₂相比,La、Ce单掺杂以及La-Ce共掺杂均能减小TiO₂的禁带宽度,但共掺杂体系的禁带宽度更窄,因此共掺杂体系将更有利于提高TiO₂对可见光的响应能力和光催化性能.

Analysis on Defect Formation Energy and Electronic Structure of La-Ce Co-doped Anatase TiO2

Analysis on Defect Formation Energy and Electronic Structure of La-Ce Co-doped Anatase TiO2 Abstract: The defect formation energy, defect charge transition energy level and electronic structure of La-Ce co-doped anatase TiO2 were calculated by the first principle method based on density functional theory. The results show that, the defect formation energy of La, Ce doped TiO2 and La-Ce co-doped TiO2, are all negative in oxygen-rich state, but the formation energies of each defect state are all positive in oxygen-poor state, which indicate that La, Ce doped TiO2 can only be prepared in oxygen atmosphere. The results of replacing Ti doped defect charge transition levels show that, the defect charge transition levels of 0/1- are located at 0.522eV and 2.440eV above VBM respectively. Compared with pure anatase TiO2, La-doped, Ce-doped and La-Ce co-doped can all reduce the band gap width of TiO2, but the band gap width of co-doped pattern is narrower. Therefore, co-doped pattern will be more conducive to increase the visible light response ability and photocatalytic performance of TiO2.