Enhanced H ₂ O ₂ Photosynthesis and Selective Oxidation over Na‐Doped SrTiO ₃

Sodium‐doped strontium titanate (Na–SrTiO ₃ ) photocatalysts were synthesized via a flux‐assisted method and investigated for the coupled production of H ₂ O ₂ and selective oxidation of benzyl alcohol under aerobic conditions. Among the prepared samples, SrTiO ₃ doped with 3 mol% Na exhibited the highest activity, achieving H ₂ O ₂ and benzaldehyde production rates of 0.42 and 0.31 mmol g ⁻¹  h ⁻¹ , respectively, with 93% selectivity toward benzaldehyde. Aliovalent substitution of Na ⁺ for Sr ²⁺ induces lattice contraction and surface reconstruction, accompanied by the formation of oxygen vacancy–related defects. These defect states predominantly generate shallow electronic traps that promote charge separation and suppress electron–hole recombination. Consequently, photogenerated electrons efficiently drive the two‐electron oxygen reduction reaction toward H ₂ O ₂ formation, while photogenerated holes selectively oxidize benzyl alcohol to benzaldehyde. The optimized Na‐doped SrTiO ₃ thus enables efficient coupling of solar H ₂ O ₂ photosynthesis with value‐added selective organic transformation. This work demonstrates that defect‐mediated alkali‐metal doping is an effective strategy for engineering perovskite photocatalysts for integrated redox photochemistry.