采用基于密度泛函理论的第一性原理赝势平面波方法,计算了 Bi-N 共掺杂前后锐钛矿相 TiO2的晶格参数、电子结构、电荷布居、光吸收系数及其带边位置。结果表明,Bi-N 共掺杂导致 TiO2晶格发生畸变,八面体内的偶极矩较 Bi/N 单掺杂均略有增加,因而可更有效地分离光生电子-空穴对；同时共掺杂引起价带宽化,带边位置发生明显变化,提高了载流子的迁移率和 TiO2的氧化还原能力；Bi-N 共掺杂后价带顶和导带底附近形成了浅的杂质能级,增强了 TiO2对可见光的响应范围。因此,Bi-N 共掺杂 TiO2有效提高了TiO2的光催化能力和太阳光的利用率。%Using the first-principles pseudopotential plane-wave method based on density functional theory,the lattice parameters,electronic structures,charge populations,absorption spectra,and the band edge position of anatase TiO2 before and after Bi-N co-doping were calculated.The results indicate that the lattice distortion gives rise to the octahedral dipole moments when the crystal was doped.The dipole moment of Bi-N co-doping was more slightly than that of Bi/N single doping,which was very effective for the separation of photo-excited electron-hole pairs.With the valence band and the conduction band toward the lower energy direction in Bi-N co-doping model,the valence band broadens.It was beneficial to the mobility of photo-generated carriers;on the other hand,the band edge position of co-doping anatase TiO2 changes significantly and manifests more excellent redox capacity than that Bi/N single doping.Moreover the shallow impurity energy levels of acceptor level and donor level have formed between the valence band maximum and the conduct band minimum,which can in-crease the responsive range of the visible light.Therefore,the co-doping of TiO2 with Bi and N can effectively improve the photo-catalytic performance of TiO2 and enhance the utilization of the solar light.
展开▼
