Visible-light-driven photocatalytic H2 evolution from water splitting with band structure tunable solid solution (AgNbO3)1−x(SrTiO3)x

Abstract

(AgNbO3)1−x(SrTiO3)x samples were successfully employed as photocatalysts for photocatalytic hydrogen evolution under visible light. The samples were characterized by a series of techniques, including X-ray diffractometry, scanning electron microscopy, UV–Vis spectrophotometry, and electrochemistry technology. The band gaps of (AgNbO3)1−x(SrTiO3)x solid solutions can be tuned continuously from 3.21 to 2.65 eV and the flat-band potentials (Vfb) can be shifted positively from −0.79 to −0.31 V vs. SHE when x decreased from 1 to 0. Band positions of (AgNbO3)1−x(SrTiO3)x samples were further testified by density functional theory, suggesting that the band gap narrowing of the solid solutions derived from the hybridization of (Ti 3d and Nb 4d) and (O 2p and Ag 4d) orbital. The photocatalytic activities of samples for H2 evolution with Pt cocatalyst were evaluated in aqueous methanol solution under visible light irradiation. The highest photocatalytic activity was obtained at (AgNbO3)0.25(SrTiO3)0.75. Photocatalytic activity in hydrogen evolution of these solid solutions proved to be closely dependent on band structures.