Spatial charge separation and transfer in ultrathin CdIn₂S₄/rGO nanosheet arrays decorated by ZnS quantum dots for efficient visible-light-driven hydrogen evolution

In this paper, we report a vertical self-assembly of ultrathin CdIn₂S₄ nanosheet arrays on the conductive substrate of the reduced graphene oxide (rGO) by the facile hydrothermal process, during which ZnS quantum dots (QDs) were in-situ deposited on the gap of CdIn₂S₄ nanosheet arrays to form the intimate interfacial contact between ZnS/CdIn₂S₄ and rGO. The unique structural configuration of this well-ordered three-dimensional (3D) ZnS/CdIn₂S₄/rGO nanosheet arrays were very beneficial for the visible-light absorption, thus strongly improving the light-harvesting. Moreover, the as-prepared 3D nanosheet arrays architecture with the GO content of 13 wt% exhibited the highest photocurrent transient response (107.4 µA cm⁻²), which corresponding to the highest hydrogen generation of 6.82 mmol g⁻¹ h⁻¹ and a relatively high apparent quantum efficiency of 19.34% under visible light irradiation. The enhanced photocatalytic hydrogen production activities can be attribute to the synergistic effects of the favorable light trapping ability, more exposed activity sites and efficient spatial charge separation as well as faster electron transfer between ZnS QDs and CdIn₂S₄ nanosheet arrays through the conductive network of rGO. This work presents a new strategy to reasonably design and fabricate the next generation ultrathin nanosheet arrays architecture for practical applications in efficient photocatalytic water splitting.