摘要
基于第一性原理的平面波超软赝势方法,本文研究了C分别代替Ti和O原子位置掺杂的锐钛矿TiO_2的晶体结构,电子结构以及光学性质。结果表明,C在掺杂体系中的存在状态与掺杂位置密切相关;掺杂后引起晶格参数,键长等变化,导致晶体中结构单元偶极矩增大,从而可以改善光催化性能。C掺入后由于C 2p态与O 2p和Ti 3d态发生杂化,引起态密度分布发生变化,禁带宽度减小,且代替TiO_2中O位置掺杂时,出现杂质能级。光学性质的计算结果与电子结构一致,2种掺杂模型的光吸收带边均发生红移。这些结果较好地解释了C掺杂TiO_2具有优良光催化活性的原因。此外,研究比较了C原子在不同掺杂位置对锐钛矿TiO_2电子结构和光催化活性影响的差别。
The crystal structure, electronic structure and optical properties of C-doped anatase TiO2 with different impurity locations were studied by using the plane-wave pseudopotential method based on the first-principles. The existence form of C element was dependent on the impurity locations, both the lattice parameters and bond lengths of TiO2 changed after C-doping, which led to the increase of dipole moment, and thus improving the photocatalytic activity. By analyzing the results of the band structure and density of states, it was found that C 2p state hybridized with O 2p and Ti 3d states in C-doped TiO2. The band gap was narrowed due to the valence band upward shifting. When C was substituted for O, some impurity states appeared. The optical properties were in good agreement with the electronic structure and the light absorption of C-doped TiO2 showed red-shift. All the results can well explain the better photocatalytic properties of C-doped anatase TiO2 in visible-light region. Furthermore, the electronic structure and photocatalytic properties of doped anatase TiO2 with different C locations were compared.
出处
《计算机与应用化学》
CAS
CSCD
北大核心
2011年第3期270-274,共5页
Computers and Applied Chemistry
基金
煤转化国家自然科学基金重点项目(10835008)
国家重点实验室自主研究项目(2008BWZ011)
