Synergistic Sn/Cr Co‐Doping in SrTiO ₃ for Enhanced Visible‐Light‐Driven Overall Photocatalytic Water Splitting

ABSTRACT Developing efficient visible‐light‐driven photocatalysts for overall water splitting remains a significant challenge. Herein, Sn/Cr co‐doped SrTiO 3 (SCSTO) was synthesized via a flux‐assisted solid‐state reaction, with Sn substituting Sr sites and Cr replacing Ti sites in the perovskite lattice. Sn/Cr synergistic co‐doping extends optical absorption into the visible region, narrows the bandgap to 3.04 eV, suppresses Ti3+ defects and oxygen vacancies, and promotes charge separation and migration. Benefiting from the rational band structure and defect engineering, under visible‐light irradiation (λ > 380 nm), the optimal SCSTO exhibits a hydrogen evolution rate of 15.4 µmol·h − 1 and oxygen evolution rate of 7.34 µmol·h −1 , with outstanding cycling stability. DFT calculations confirm that Cr 3d mid‐gap states below the Ti 3d conduction band enhance visible‐light response and charge transfer. This work provides a universal and feasible co‐doping strategy for designing high‐performance perovskite oxide photocatalysts toward efficient solar fuel production, which is instructive for the development of advanced visible‐light‐driven photocatalytic systems.