Gd-N共掺杂锐钛矿相TiO2的电子结构及光学性质研究

Study on the electronic structures and optical properties of Dd-N co-doped anatase TiO2

采用基于密度泛函理论的第一性原理计算了Gd与N单掺杂及Gd与N共掺杂锐钛矿相TiO2的电子结构、差分电荷密度、能带结构、态密度及光学性质。结果显示：Gd与N共掺杂TiO2的Gd—N键键长比Gd单掺杂TiO2的Gd—O键键长短,共价性更强,因此,Gd与N共掺杂TiO2比Gd单掺杂TiO2时结构更稳定;Gd单掺杂TiO2时,Gd 4f电子态贡献了有利于电子分步跃迁的杂质能级,吸收光谱发生红移,N单掺杂TiO2时,N2p电子态与Ti 3d电子态的强相互作用,使得带隙减小,吸收光谱发生红移,Gd-N共掺杂TiO2时,由于Gd 4f电子态与N 2p电子态的协同作用,在TiO2能带中产生了有利于电子跃迁的杂质能级且禁带宽度最小,吸收光谱红移最明显。证明,Gd-N共掺杂TiO2比Gd、N单掺杂TiO2时光谱响应范围更宽,光催化性能最优异。

The electron structure,electron density difference,density of state,optical properties of Gd doped TiO2,N doped TiO2 and Gd-N co-doped TiO2 have been calculated by the first principle based on density functional theory. The results show that： the Gd—N bond length of Gd and N co-doped TiO2 is smaller than Gd—O bond of Gd doped TiO2. Therefore,Gd and N co-doped TiO2 is more stable than Gd doped TiO2. Gd 4 f electronic state contributed to the electronic transition of impurity level and the absorption spectrum red shift with the Gd doped TiO2. The strong interaction of N2p electronic state and Ti3d electronic state results the band gap decreases and the absorption spectrum red shift with the N doped TiO2. After Gd and N co-doped TiO2,due to the synergy of Gd4f electronic state and N2p electronic state,the impurity level is produced in the TiO2 bandgap which is advantageous to the electron transition,has minimum forbidden band width and the absorption spectrum red shift is the most obvious. It is proved that compared with Gd,N single doped TiO2,Gd and N co-doped TiO2 have a broader spectrum response range with the photocatalytic performance is the best.