A theoretical study on tetragonal BaTiO3 modified by surface co-doping for photocatalytic overall water splitting

Density functional theory calculations are applied to study the influence of co-doping on the stability, electronic structure, and photocatalytic activity of tetragonal BaTiO3 (001) surface. The results show that the formations of all the metal-nonmetal co-doped BaTiO3 (metal = V, Nb, Ta, Mo, W and nonmetal = N, C) are energetically favorable. Most of co-doped surfaces have remarkable narrower bandgaps than the pristine surface, which favors the movement of absorption edge to the visible light region. Co-doped systems have better affinity toward H2O than the pure surface. For most of the studied systems, the active sites of HER and OER are the O site and the Ti site adjacent to the metal dopant, respectively. Surface co-doping results in remarkable decreases in | ΔGH | of HER and the OER overpotential of BaTiO3 (001) surface. This work proposes the potential application of BaTiO3 modified by surface co-doping as efficient photocatalysts for overall water splitting.