Band structure controls of SrTiO3 towards two-step overall water splitting

We prepared two types of SrTiO3-based photocatalyst powders, Bi,Ga-doped SrTiO3 and In,V-doped SrTiO3. UV–visible reflectance spectra of these powders indicated that their band-gaps remained constant in comparison with that of SrTiO3. In conjunction with the reported band structure control of oxides, our results indicated that Bi,Ga-doped SrTiO3 and In,V-doped SrTiO3 formed isolated mini-bands composed of Bi 6s orbitals in the forbidden band above the valence band, composed of O 2p, and V 3d orbitals below the conduction band, composed of Ti 3d, resulting in the observed visible-light absorption. Utilizing the prepared SrTiO3-based photocatalysts, we established a two-step overall water-splitting system, in which simultaneous liberation of hydrogen and oxygen with a molar ratio of ∼2:1 was observed in the presence of I− (NaI) under irradiation with UV-containing light. Moreover, visible light contributed the cycling of I−/IO3− redox mediators, resulting in enhanced hydrogen and oxygen liberation when compared to irradiation with UV light alone.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We establish a novel two-step overall water-splitting system. ► The system is composed of two types of SrTiO3-based photocatalysts. ► The band structure of SrTiO3 was controlled, producing two types of SrTiO3. ► The system simultaneously evolves H2 and O2 with the aid of I− irradiated with light.