Aluminum Cation Doping in Ruddlesden-Popper Sr₂TiO₄ Enables High-Performance Photocatalytic Hydrogen Evolution

Hydrogen (H₂) is regarded as a promising and renewable energy carrier to achieve a sustainable future. Among the various H₂ production routes, photocatalytic water splitting has received particular interest; it strongly relies on the optical and structural properties of photocatalysts such as their sunlight absorption capabilities, carrier transport properties, and amount of oxygen vacancy. Perovskite oxides have been widely investigated as photocatalysts for photocatalytic water splitting to produce H₂ because of their distinct optical properties, tunable band gaps and excellent compositional/structural flexibility. Herein, an aluminum cation (Al³⁺) doping strategy is developed to enhance the photocatalytic performance of Ruddlesden-Popper (RP) Sr₂TiO₄ perovskite oxides for photocatalytic H₂ production. After optimizing the Al³⁺ substitution concentration, Sr₂Ti_0.9Al_0.1O₄ exhibits a superior H₂ evolution rate of 331 μmol h⁻¹ g⁻¹, which is ~3 times better than that of Sr₂TiO₄ under full-range light illumination, due to its enhanced light harvesting capabilities, facilitated charge transfer, and tailored band structure. This work presents a simple and useful Al³⁺ cation doping strategy to boost the photocatalytic performance of RP-phase perovskites for solar water splitting.