First-principles study of configurations, electronic and photocatalytic properties of carbon-doped anatase TiO2

Abstract C-Doping TiO2 could significantly enhance the photocatalytic activity, as found in experiments, but the mechanism behind is elusive. We systematically investigated the configurations, electronic and photocatalytic properties of C-doped anatase TiO2 by first-principles calculation. The results show that the structures for the C-anion (Ca) and C-cation (Cc) doped TiO2 could exist in different form, and the Ca and substitutional Cc doping are favored under O-poor and O-poor conditions, respectively. The calculated electric and optical properties demonstrate that the substitutional Cc doping play the vital role in narrowing the bandgap, responsible for enhanced visible-light absorption of the TiO2. Finally, the calculated band edges using the hybrid functional of Heyd, Scuseria and Ernzerhof (HSE) suggested that substitutional Cc doped TiO2 could exhibit the small band gap and appropriate band edges for visible-light photocatalytic water splitting. The findings could not only give new insights into atomistic origin of visible-light response and photocatalysis of the C-doped TiO2.