论文部分内容阅读
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 structures and optical absorption properties of N-doped rutile TiO_2 were investigated by the first-principles LDA + U (U-Ti-3d = 7eV, U_ (O-2p) = 4eV) The results show that the doping of N element can reduce the band gap of TiO_2 and introduce impurity level in the bandgap. The impurity level is mainly formed by the coupling between the O-2p orbit and the N-2p orbit. The introduction of impurity level and the reduction of band gap can increase the response of TiO2 to visible light and increase the photocatalytic activity of Ti O2. The density of states in the vicinity of the Fermi level consists of π-bonds formed by the coupling between the O-2p orbitals and the N-2p orbitals. The electrons occupy the π-bond state and the vacant σ bond state energy difference is about 0.4 eV, The optical absorption edge of Ti O2 falls in the red region, that is, the so-called red-shift phenomenon of optical absorption occurs.