Band structur e design of semiconduc tors for enhanced photocatalytic activity: The case of TiO2

General strategies are proposed by passivated co-doping in present paper to improve the photocatalytic activity of semiconductors for degradation of environmental pollutants. The ideal band gap of semiconductors for enhancement of photocatalytic activity can be lowered to match with visible light absorption and the location of the Conduction Band (CB) should be raised to meet the reducing capacity. Then we apply the strategy to anatase TiO₂. It is predicted that nonmetal–metal co-doping TiO₂ can modify the catalyst band edges by raising the valence band (VB) edge significantly and making the CB edge increased 0.24 eV. Therefore, the band gap for co-doping system should be narrowed to about 2.72 eV. (N, Ta) is predicted to be the target donor–acceptor combination with the band gap of 2.71 eV, which red-shifts the TiO₂ absorption edge to 457.6 nm in visible range. The band engineering principle will be fit to other wide-band-gap semiconductors for enhanced photocatalytic activity.