To get an effective doping model of rutile TiO₂, we systematically study geometrical parameters, density of states, electron densities, dielectric functions, optical absorption spectra for the pure, C mono-doping, Cr mono-doping and (Cr,C) co-doping rutile TiO₂, using density functional calculations. We find that a C doped system presents higher stability under Ti-rich condition, while Cr doped and (Cr,C) co-doped systems are more stable under O-rich condition. For (Cr,C) co-doping situation, the imaginary part of the dielectric function reflects the higher energy absorption efficiency for incident photons. Moreover, co-doping system exhibits much bigger red-shift of optical absorption edge compared with Cr/C single doping systems, because of the great reduction of the direct band gap. The calculated optical absorption spectra show that the (Cr,C) co-doping rutile TiO₂ has higher photocatalytic activity in the visible light region.

为了获得有效的金红石型TiO ₂掺杂模型，我们系统地研究了纯，C单掺杂，Cr单掺杂和（Cr，C）co的几何参数，态密度，电子密度，介电函数，光吸收光谱掺杂金红石型TiO ₂，使用密度泛函计算。我们发现碳掺杂系统在富钛条件下表现出更高的稳定性，而铬掺杂和（Cr，C）共掺杂系统在富氧条件下更稳定。对于（Cr，C）共掺杂情况，介电函数的虚部反映了入射光子的更高能量吸收效率。而且，由于直接带隙的大大减小，与Cr / C单掺杂系统相比，共掺杂系统表现出更大的光吸收边缘红移。计算的光吸收光谱表明，（Cr，C）共掺杂金红石型TiO ₂在可见光区具有较高的光催化活性。