Highly active SrTiO3 for visible light photocatalysis: A first-principles prediction

•Partially occupied impurity states appear in the mono-doped systems.•Co-doping with anions and cations can inhibit the partially occupied states.•Band gap of co-doped SrTiO3 with Ce and N (C) has been sharply narrowed.•N–Ce–N co-doped SrTiO3 has ideal band edges to straddle water-splitting redox potentials.

The effects of mono-doping (N, C, La, and Ce) and co-doping (N–La, C–Ce, and N–Ce–N) on the electronic structure of SrTiO3 are studied by the first-principles method. The results show that some partially occupied states acting as recombination centers appear in the mono-doped systems and thereby suppress their photocatalytic activity. The co-doping can inhibit the partially occupied states and thus keep the high activity of photocatalysis. Further, the (N–Ce–N) co-doping can significantly narrow the band gap of SrTiO3 to make it fall in the visible light region while keeping the match of the band edges with the redox potential for water splitting. The high activity and narrowed band gap show that the (N–Ce–N) co-doped SrTiO3 is a good candidate for water splitting under visible light irradiation.