N-Co共掺锐钛矿相TiO_2光学性质的第一性原理研究

First-Principles Study on Optical Properties of N-Co Co-Doped Anatase TiO_2

采用基于密度泛函理论的第一性原理和广义梯度近似方法,对N、Co单掺以及两者共掺锐钛矿相TiO_2的电子结构和光学性质进行了研究,并探究了两种不同的N替换O位置对掺杂结果的影响。研究结果表明,N、Co单掺杂锐钛矿相TiO_2带隙内均出现了杂质能级,N-Co共掺杂锐钛矿相TiO_2带隙内出现了更复杂的杂质能级;经掺杂后锐钛矿相TiO_2的带隙均减小,N-Co共掺杂比单掺杂N、Co的锐钛矿相TiO_2稳定性更好,在可见光区域的光吸收效率得到明显提高,吸收光谱红移更加明显;type 2较type 1位形的N-Co共掺锐钛矿相TiO_2有着更大的可见光区域吸收率以及更广的红移范围。

By using the first principles based on the density functional theory and the general gradient approximation method, the electronic structures and optical properties of N, Co single-doped and N-Co co-doped anatase TiO2 are studied, and the effects of two kinds of different substitutions where the O site replaced by N are explored. The study results show that the impurity energy levels of both N and Co single-doped anatase TiO2 appear within the band gaps, and as for N-Co co-doped anatase TiO2, the more complicated impurity energy levels appear within the band gaps. The band gaps of the doped anatase TiO2 become narrower. Compared with that of the N, Co single- doped anatase TiO2, the stability of the co-doped anatase TiO2 is better, the optical absorption efficiency in the visible light region improves obviously and the absorption spectral redshift is more obvious. Compared with the type 1, the type 2 of co-doped anatase TiO2 has a higher absorptivity in the visible light region and a wider absorption spectral redshift range.