摘要
运用第一性原理的LDA+U(U_(Ti-3d)=7eV,U_(O-2p)=4eV)方法研究了N掺杂金红石TiO_2的电子结构和光学吸收性质。研究表明N元素的掺杂可以降低TiO_2的禁带宽度并在带隙中引入杂质能级。杂质能级主要由O-2p轨道和N-2p轨道之间的耦合形成。杂质能级的引入以及带隙宽度的降低可以增加TiO_2对可见光的响应,并提高Ti O2的光催化活性。费米能级附近的态密度由O-2p轨道和N-2p轨道之间的耦合形成π键构成,电子占据π键态和空的σ键态能级差大约为0.4 eV,可使N掺杂Ti O2的光学吸收边落在在红外区域,即发生了所谓的光学吸收边的红移现象。
The electronic structure and optical properties of N doped rutile TiO_2 systems were investigated by the firstprinciples calculations of LDA ＋ U method with U for Ti-3d and O-2p（ UTi-3d= 7 e V,U_（O-2p）= 4 eV）. The calculations results showthat the impurity energy level is introduced due to the coupling between O-2p and N-2p,and the band-gap is reduced because of the N dopant,which both can increase the TiO_2 absorption edge to the visible region,and therefore facilitate the enhancement of the photocatalytic efficiency. The coupling of O-2p and N-2p states near the Fermi level forms the π bonds. The energy difference between the occupied π bonds and unoccupied σ bonds is 0. 4 e V,which implies that the optical absorption-edge is in the infrared region. In other words,the N dopant makes the absorption-edge red shift.
出处
《山东大学学报（理学版）》
CAS
CSCD
北大核心
2016年第1期20-26,共7页
Journal of Shandong University(Natural Science)
基金
宁夏高等学校科学研究项目(NGY2014048)
