Hybrid density functional theory description of non-metal doping in perovskite BaTiO3 for visible-light photocatalysis

Non-metal doping is one of the major strategies to reduce the large band gap of semiconductors into the visible light region. In this work, first-principles calculations based on density functional theory have been performed to investigate the effect of non-metal dopants X (X=C, Si, N, P, S, Se, F, Cl, Br and I) with X@O and X@Ti on the geometric and electronic structures, stability, and photocatalytic property of perovskite BaTiO3 with wide band gap. Our calculations provide reasonable explanations on experimental observations of the narrow band gap for N-doped BaTiO3. It is found that the preferred site of dopant X depends on the ionic size of dopant with respect to that of O2- or Ti4+. The complexity of doping depends on the distortion of local structure and electronegativity of dopants. C- and I-doped BaTiO3 with X@O induce the extension of absorption edge to visible light range with improved abilities of photocatalytic water splitting. The replacement of lattice O/Ti with S or Se not only leads to the band gap narrowing but also enhances the photo-oxidation and photo-reduction capabilities of semiconductor. Further experimental studies are highly demanded to explore the promising application of these four systems for the photocatalytic field.