NiSx Quantum Dots Accelerate Electron Transfer in Cd_0.8Zn_0.2S Photocatalytic System via an rGO Nanosheet "bridge" toward Visible-Light-Driven Hydrogen Evolution

Minimizing the charge transfer barrier to realize fast spatial separation of photoexcited electron-hole pairs is of crucial importance for strongly enhancing the photocatalytic H₂ generation activity of photocatalysts. Herein, we propose an electron transfer strategy by reasonable design and fabrication of high-density NiSx quantum dots (QDs) as a highly efficient cocatalyst on the surface of Cd_0.8Zn_0.2S/rGO nanosheet composites. Under visible-light irradiation, the formation of a two-dimensional (2D) Cd_0.8Zn_0.2S/rGO nanohybrid system with 2 wt % NiSx loading gave a prominent apparent quantum efficiency (QE) of 20.88% (435 nm) and H₂ evolution rate of 7.84 mmol g^-1 h^-1, which is 1.4 times higher than that of Pt/Cd_0.8Zn_0.2S/rGO. It is believe that the introduced rGO nanosheets and NiSx QDs obviously improved the interfacial conductivity and altered the spatial distribution of electrons in this nanoarchitecture. Thus, the synergistic effects of interfacial junctions result in a regulated electron transportation pathway along the basal planes and ultrafast transfer and spatial separation of photoexcited carriers, which are responsible for the enhanced photocatalytic performance. This work gives a facile and effective strategy to understand and realize rationally designed advanced photocatalysts for high-efficiency, stable, and cost-efficient solar hydrogen evolution applications.