First-principle calculations of the electronic and optical properties of Tm-doped anatase titanium dioxide

Abstract

Doping titanium dioxide (TiO2) with impurities has been extensively investigated for the optimal use of solar energy in order to improve photocatalyst performance. Density functional theory calculations are performed to investigate the effects of Tm doping on the energy band structures and optical properties of anatase TiO2 with various doping concentrations. The results show that Tm doping can effectively reduce the band gap of pure anatase TiO2 by introducing Tm 4f states above the top of the valence band, and thus results in a red shift in the optical absorption edges. Furthermore, the calculations of optical properties indicate that Tm doping TiO2 at low levels presents the prominent optical absorbance in the low energy region. Our results have important implications for the understanding and further development of photocatalytic functionalities of anatase TiO2 by introducing a dopant for effective band gap engineering.