Construction of Dual S‐Scheme Heterojunction Based Co₉S₈ QDs Coupling with NiS/CdS Concave Cubic Derived from Prussian Blue Analog for Enhanced Photocatalytic Hydrogen Evolution

Abstract The design and development of high‐efficiency and low‐energy consumption catalysts for hydrogen evolution are critical to mitigating environmental problems. Herein, amorphous Co₉S₈ quantum dots (QDs) are prepared by hydrothermal method and loaded on concave cubic NiS/CdS derived from Prussian blue analog (PBA) to construct an efficient Co₉S₈ QDs/NiS/CdS dual S‐scheme heterojunction photocatalysts, showing excellent photocatalytic hydrogen performance of 13.45 mmol·g⁻¹·h⁻¹, which is 5.42 times higher than that of pure CdS. The improved photocatalytic performance is ascribed to the creation of a double S‐scheme heterojunction, quantum confinement effect, and a concave cubic structure, accelerating electron transport and offering ample surface active sites. The possible mechanism is demonstrated with valence band XPS (VB‐XPS), ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) calculations. This work provides insight into the exploration of PBA‐based photocatalysts to improve photocatalytic hydrogen evolution and provides an effective strategy for the design of photocatalysts with double the S‐scheme heterojunction.