Construction of 0D/2D ZnxCd1−xS/protonated g-C3N4 S-scheme heterojunction for boosting photocatalytic hydrogen evolution

To tackle the pressing dual challenges of the energy crisis and environmental pollution , it is urgent to develop low-cost, high-activity photocatalysts for solar-driven hydrogen production. In this work, a Zn x Cd 1-x S/protonated g-C 3 N 4 S-scheme heterojunction photocatalyst is successfully constructed using an electrostatic interaction-driven assembly strategy. The optimized composite photocatalyst exhibits a hydrogen evolution rate of 17.64 mmol g −1   h −1 , which is approximately 4.14 times and 28.45 times higher than that of pure Zn x Cd 1-x S and protonated g-C 3 N 4 . The apparent quantum efficiency (AQE) of ZCSCN-20 reaches 12.3 % at 420 nm. The electrostatic interaction drives the assembly of the heterojunction, leading to an intimate interfacial contact. This close connection, in turn, significantly shortens the migration distance and transfer time of photogenerated charges. The established S-scheme charge transfer pathway enables the efficient separation of photogenerated charge carriers while preserving the strong redox capability inherent in the constituent semiconductors. Furthermore, the use of sacrificial agents to deplete photogenerated holes further suppresses charge carrier recombination, synergistically enhancing the overall catalytic activity. This work provides an efficient strategy for preparing and optimizing sulfide-based S-scheme heterojunction photocatalysts, laying a foundation for developing stable, high-performance solar-driven hydrogen production systems.