Electronic and optical properties of mono and co-doped anatase TiO2: First principles calculations

Abstract

Density functional theory-based calculations are adopted for clarifying the validity of mono-dopant (Co, Cr, B), co-dopant (Co/B, Cr/B), and oxygen deficiency on the photocatalytic activity of anatase TiO2. The crystal structure, formation energies, electronic, and optical properties are calculated in the framework of HSE06 hybrid functional. The impurity states appear in the band gap region, thus changing the electronic structures and resulting in red shift of the absorption edge in the defected systems. Furthermore, the main band gap is narrowed for all defected systems except for Co mono-doping and oxygen vacancy. The deep impurity states on mono-doping, could affect the recombination of photo-excited electron-hole pairs, while the charge separation efficiency could be enhanced on Cr/B co-doping by shallow receptor state. The calculated optical properties emphasize the enhanced absorption efficiency and the extended absorption edge to the visible light on Cr/B co-doping. The findings in this paper could suggest the Cr/B co-doped anatase TiO2 as a good photocatalyst with longer life of the photogenerated charge carriers.