Exploiting Weak Interlayer-Coupling ReS2 as Electron Sinks in In2S3 Heterojunctions for Photocatalytic Hydrogen Production.

Indium sulfide (In2S3) 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 In2S3. Herein, we introduce weak-interlayer-coupling Rhenium disulfide (ReS2) as a robust electron sink to overcome this limitation. The weak interlayer interactions of ReS2 enable ultrafast electron extraction and spatial separation, thereby suppressing recombination and extending carrier lifetimes. Consequently, the In2S3/ReS2 heterojunction achieves a hydrogen evolution rate nearly 300% higher than that of pristine In2S3 under visible light irradiation. This study highlights the potential of weak-coupling 2D materials for overcoming charge-separation bottlenecks in photocatalytic heterostructures.