Role of Defects in Photocatalytic Water Splitting: Monodoped vs Codoped SrTiO3

Using the hybrid density functional theory and ab initio atomistic thermodynamics, we report that monodoping of nonmetal (N) or metal (Mn) in SrTiO3 can induce visible-light absorption, but none of them are suitable to ameliorate the photocatalytic activity. Therefore, in order to achieve enhanced photocatalytic activity of SrTiO3, we have employed codoped Mn and N simultaneously in SrTiO3 to modulate its electronic properties effectively. In the codoped SrTiO3, the recombination of photogenerated charge carriers is suppressed, and the diffusion and mobility are increased owing to the passivation of discrete localized states. Our results reveal that MnSrNO (codoping of Mn at the Sr site and N at the O site) is the most promising candidate for enhancing the photocatalytic activity of SrTiO3 under visible light.