Construction of SrTiO₃–LaCrO₃ Solid Solutions with Consecutive Band Structures for Photocatalytic H₂ Evolution under Visible Light Irradiation

SrTiO₃–LaCrO₃ continuous solid solutions with LaCrO₃ content ranging from 0.00 to 1.00 were prepared via a polymerized complex method. The light absorption ability of SrTiO₃ was improved by the consecutive tuning of the bandgap upon the introduction of LaCrO₃ (up to 570 nm). The solid solutions exhibited significantly enhanced photocatalytic activities for H₂ evolution under visible light irradiation, with an optimized H₂ evolution rate of 1368 μmol h⁻¹ g⁻¹ obtained when LaCrO₃ content was 0.10 (with 1 wt% Pt as cocatalyst), corresponding to an apparent quantum yield of 3.68% at 400 nm. Supported by comprehensive characterization, the improved photocatalytic performance was attributed to the simultaneously adjusted conduction band and valance band originating from the hybridization of Cr 3d, Ti 3d and O 2p orbitals, as well as the accelerated separation and migration of photogenerated charge carriers derived from the distortion of TiO₆ octahedra.