(Cu+N)共掺杂锐钛矿相TiO_2(001)面和(101)面电子结构的第一性原理计算  

Electronic structure of(Cu+N) co-doped anatase TiO_2 at the surfaces of(001) and(101): A first-principle study

作　　者：张琳[1] 蔡琳琳[1] 任俊峰[1] 原晓波[1] 胡贵超[1] 

机构地区：[1]山东师范大学物理与电子科学学院,济南250014

出　　处：《中国科学：物理学、力学、天文学》2016年第3期74-82,共9页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：山东省高等学校科技计划项目(编号:J13LA05);山东省自然科学基金(编号:ZR2014AM017)资助

摘　　要：采用基于密度泛函理论的第一性原理方法研究了3d过渡元素Cu掺杂及(Cu+N)共掺杂于锐钛矿相TiO_2(001)面和(101)面的电子性质,给出了不同掺杂形式形成能、能带结构、态密度及电荷分布的变化,得出了(Cu+N)共掺杂时最稳定的结构.通过计算Cu表层吸附、表层和次表层替位掺杂以及晶体间隙掺杂的形成能,发现Cu掺杂更易发生在TiO_2(001)面的空穴位,此时N偏向于在水平方向上的O位发生替位掺杂.计算结果表明(Cu+N)共掺杂后Cu-3d与O-2p,N-2p及Ti-3d轨道上的电子发生p-d杂化效应,引发O-2p,N-2p态发生劈裂使得价带范围扩大,Ti-3d态下移且发生劈裂形成新的导带底,并且禁带中产生了新的电子态,禁带宽度减小,同时(Cu+N)施主受主杂质对的出现可以有效防止电子空穴对的复合,提高了TiO_2的光催化活性.Electronic structures of 3d transition element Cu-doped anatase TiO2 and（Cu＋N） co-doped anatase TiO2 are studied by using the first-principle method based on density functional theory. The calculations are performed by using the projector augmented wave method within the generalized gradient approximation as implemented in the VASP package. Different doping possibilities, for example, Cu doped in anatase TiO2 supercell, Cu adsorbed on the surfaces of（001） and（101）, Cu replacement on Ti sites at the surfaces and subsurfaces, Cu doped in the vacancy of horizontal and longitudinal directions, as well as six kinds of（Cu＋N） co-doping methods, are studied in detail. The formation energies, band structures and electronic density of states are investigated and the most stable structure is obtained theoretically. The results suggest that Cu prefers to be doped at the vacancy of the TiO2（001） surface, while N atom prefers to substitute O sites at the horizontal direction. The calculated results also show that 3d orbital of Cu interacts with O-2p and N-2p orbitals, which leads to the fission of the O-2p and N-2p orbitals and produces new electronic states in the band gap, and also the band gap of TiO2 becomes narrow. By analyzing the band structure and the densities of states, it is found that the band edges of system have been modified by（Cu＋N） codopants. The valence band edge moves up and close to the Fermi level, while the conduction band edge moves down slightly, which make the band gap narrow. Charge transfer properties are also discussed to show the bond effects after doping. The appearance of the compensated donor（Cu） and acceptor（N） pairs after（Cu＋N） co-doping could prevent the recombination of photo-generated electron-hole pairs, which can improve the photoelectrochemical performance of TiO2.

关 键 词：锐钛矿相TIO2 密度泛函理论 (Cu+N)共掺杂 电子结构 

分 类 号：O483[理学—固体物理]