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 photo- catalyst 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.