Design of S-scheme Sm-ZnO/N-rGO heterosystem for efficient H₂ evolution under visible light illumination

Increasing the separation and transfer of photo-triggered electron-hole pairs is critical for developing a photocatalyst with excellent efficiency for hydrogen evolution reaction. Herein, an efficient and stable S-scheme Sm-ZnO/N-rGO heterosystem is successfully synthesized via a hydrothermal process for increased photocatalytic H₂ activity. The anchoring of Sm-doped ZnO nanoparticles onto N-doped rGO nanosheets effectively enhances the light absorption, surface area, and transport and separation of photo-triggered carriers with strong redox potentials owing to the combined impact of doping and heterosystem formation. Upon light illumination, the photocatalytic hydrogen evolution performance over Sm-ZnO/N-rGO reaches 2361.8 μmolh^-1g^-1, which was significantly higher than that of Sm-ZnO and ZnO/N-rGO catalysts by a factor 5.5 and 2.9, respectively. In addition, the optimized composite shows high stability after five repetitive cycles. This research provides a feasible route to use the synergistic effect of doping and heterojunction for designing outstanding photocatalysts and further verifies the potentiality of ZnO for photocatalysis.