Graphdiyne-Based Nickel–Cobalt Bimetallic Sulfide Cocatalyst for Efficient Photocatalytic Hydrogen Evolution

Abstract

Initially, CoNiS_x is synthesized on the graphdiyne (GDY) surface through a precipitation method, followed by the straightforward physical stirring approach to attach CoNiS_x/GDY to the maple leaf CdS. This synthesis method significantly mitigates the accumulation of CoNiS_x/GDY and concurrently augments the count of sites that are active for generating hydrogen. This three-phase composite demonstrates exceptional performance in the area of photocatalytic hydrogen production, achieving a hydrogen evolution rate of 15.37 mmol·h⁻¹ g⁻¹. The employment of various characterization methodologies and density functional theory calculations have demonstrated the formation of a Z-scheme heterojunction forms between GDY and CdS. This discovery indicates that the combination of GDY and CdS markedly improves the photogenerated carrier separation capability of the composite catalyst. The cocatalyst CoNiS_x loaded on GDY effectively accelerates the electron transfer from the conduction band of GDY, thereby reducing the photogenerated carrier complexation of GDY. This phenomenon results in an increased quantity of photogenerated electron holes engaged in the redox reaction, ultimately achieving exceptional photocatalytic performance.