摘要
为了研究Si掺杂对锐钛矿TiO_2的电子结构和光催化性能的影响,利用基于第一性原理的密度泛函理论计算了纯TiO_2及Si掺杂TiO_2的杂质形成能、能带结构及态密度.研究结果表明,Si的掺杂位置与制备条件有关,富钛和富氧条件下,Si最容易代替TiO_2中Ti的位置.几何优化后Si掺杂TiO_2超晶胞的晶格参数和晶胞体积都发生一定程度的畸变,有利于电子一空穴分离,促进光催化反应进行.Si代替Ti的位置时,禁带宽度减小,发生红移现象;另外两种掺杂状态下,禁带宽度增大,发生蓝移.掺杂位置不同,Si 3p和3s态分布范围不同,是引起电子结构发生不同变化的主要原因.
In order to investigate the electronic structure and the effect on the photocatalytic activity of Si-doped anatase TiO2, first-principles calculations were carried out based on density-functional theory （DFT）. Defect formation energy, energy band structure and density of states （DOS） of Si-doped anatase TiO2 were calculated and compared with the pure anatase TiO2. The results show that Si doping position is related to the preparation conditions, Si is likely to replace Ti under both Ti-rich and O-rich conditions. The lattice parameters and cell volume change to a certain extent after Si-doped TiO2 supercell takes geometry optimized. The distortion of Si-doped TiO2 supercell is helpful to separate the photo-generated electron-hole pairs, which could promote the photocatalytic activity. In substitutional Si to Tidoped TiO2, the band gap decreases, induce absorption edge shift to long-wave; in substitutional Si to O-doped and interstitial Si-doped TiO2, the band gap increases, induce absorption edge shift to shortwave. In different Si-doped supercell, the distribution of Si 3p and 3s states is different and cause different electronic structure.
出处
《原子与分子物理学报》
CAS
CSCD
北大核心
2011年第2期359-366,共8页
Journal of Atomic and Molecular Physics
基金
煤转化国家重点实验室自主研究项目(2008BWZ011)
