非金属杂质C,N,S共掺金红石相TiO_2引起的光谱红移效应

Effect of Red Shift in Rutile TiO_2 Caused by Nonmetallic Impurity C,N,S Co-Doping

非金属掺杂金红石相TiO2使它的光学性质发生改变，拓展其在光催化和光电转换领域的应用是近年来的一个热点。基于密度泛函理论的平面超软赝势方法对C单掺杂、N单掺杂、S单掺杂以及C-N共掺、C-S共掺、N-S共掺TiO2的超晶胞进行电子性质和光学性质的计算，包括能带结构、电子态密度、介电常数、吸收光谱和反射光谱等。非金属元素的掺杂都使得TiO2禁带宽度减小，吸收光谱和反射光谱发生红移，在一定程度上改善了TiO2对可见光的利用，但非金属双掺杂比单掺杂对可见光的利用率更高。研究表明：在可见光高能区400-575 nm范围内，有C元素的掺杂比其他几种掺杂的吸收系数和反射率更高，而在可见光低能区575-760 nm范围内，有N元素的掺杂比其他几种掺杂的吸收系数和反射率更佳。因此C-N共掺对可见光的利用比其他非金属掺杂体系更好。

Recently, through nonmetallic impurity doping rutile TiO2 to change its optical properties and expand the application in the fields of photocatalysis and photoelectric conversion is a hot research topic. The electronic properties and optical properties of rutile TiO2 super cell with nonmetallic impurity doped （including C,N,S,C-N,C-S,N-S） are calculated by plane wave pseudopotential method based on the density functional theory, such as the band structure, density of states, dielectric constant, absorption spectroscopy and reflection spectroscopy, etc. Nonmetallic elements doping makes TiO2 band gap decrease, and the absorption spectrum and reflection spectra exhibit red shift. To a certain extent, nonmetallic impurity doping improves the TiO2 utilization of visible light, but visible light utilization rate of co-doped TiO2 is higher than that of single-doped TiO2. The research results show that in the visible light high energy area from 400 nm to 575 nm, C-doped rutile TiO2 performs much better than others in absorptivity and reflectivity. In the visible light low energy area from 575 nm to 760 nm, absorptivity and reflectivity of N-doped rutile TiO2 are much better than others. Therefore, the visible light utilization in C-N co-doped TiO2 is better than those of other nonmetallic doped systems.