Exploiting Weak Interlayer-Coupling ReS 2 as Electron Sinks in In 2 S 3 Heterojunctions for Photocatalytic Hydrogen Production

Indium sulfide (In 2 S 3 ) is a promising photocatalyst but is hampered by rapid electron–hole recombination and limited charge carrier mobility, restricting its hydrogen evolution performance. Constructing heterojunctions with 2D sulfides is an effective strategy to improve carrier separation as their inherent in-plane carrier transport facilitates fast electron migration. However, conventional 2D sulfides often exhibit relatively strong interlayer coupling, which still leads to undesired interlayer charge hopping and consequently limits the efficiency of interfacial electron extraction from In 2 S 3 . Herein, we introduce weak-interlayer-coupling Rhenium disulfide (ReS 2 ) as a robust electron sink to overcome this limitation. The weak interlayer interactions of ReS 2 enable ultrafast electron extraction and spatial separation, thereby suppressing recombination and extending carrier lifetimes. Consequently, the In 2 S 3 /ReS 2 heterojunction achieves a hydrogen evolution rate nearly 300% higher than that of pristine In 2 S 3 under visible light irradiation. This study highlights the potential of weak-coupling 2D materials for overcoming charge-separation bottlenecks in photocatalytic heterostructures.