A cascaded SrTiO3/TiO2/SrTiS3 heterojunction with enhanced charge separation for highly efficient photocatalytic hydrogen production

Designing efficient catalysts for photocatalytic hydrogen production is a significant challenge due to the intrinsic limitations of wide-band-gap semiconductors, such as severe charge recombination and poor visible-light absorption. Herein, a novel SrTiO₃/TiO₂/SrTiS₃ ternary heterojunction is rationally designed and fabricated via a controllable, one-step thermal vulcanization strategy to overcome these limitations. Structural and morphological characterization confirms the successful formation of an intimate three-component heterostructure. The resulting composite exhibits a significantly broadened light absorption range extending into the visible region. More importantly, photoelectrochemical measurements reveal that the ternary heterojunction possesses vastly superior charge separation and transfer efficiency compared to its individual counterparts. Consequently, the optimized photocatalyst demonstrates a remarkable, over 11-fold enhancement in H₂ evolution activity compared to pristine SrTiO₃, and maintains excellent stability in cycling tests. The outstanding performance is attributed to a multi-step charge separation mechanism across the dual type-II interfaces. This unique architecture synergistically combines the enhanced light harvesting of the SrTiS₃ sensitizer with the efficient spatial separation of photogenerated electrons and holes. This work provides a robust strategy for designing advanced multi-component sulfide/oxide heterojunctions for efficient solar energy conversion.