Theoretical studies on the electronic structure and optical absorption property of (Ni, C) co-doped anatase TiO2

Abstract

Reducing the band gap of TiO2 has a great potential in solar energy application. Among them, doping is a very effective method. We systematically study C/Ni mono-doped and (Ni, C) co-doped anatase TiO2, using density functional calculations. We first optimize the geometric structures with pseudopotential plane wave approach. Then on the optimized structure, we perform band-structure calculations with HSE06 hybrid functional calculation on the frame of Gaussian type of orbital. Therefore, we can obtain accurate band gaps close to experimental values if they exist at lower computation cost. Among three doped models, the Ni single doped model has the lowest impurity formation energy under reduction condition. Compared with the single doped models, (Ni, C) co-doped titanium dioxide has the smallest direct band gap, and the absorption band edge shows an apparent bigger red-shift. Through calculating the optical absorption spectra of several doped models in the visible light region (400–760 nm), (Ni, C) co-doped model can absorb much more visible light. Thus it has a much higher photocatalytic activity.