H₂-Induced Strong MoS₂/CdS Interfacial Coupling with NiS Modification for Efficient Visible-Light-Driven Hydrogen Evolution

The strong interfacial interaction between heterostructured semiconductors plays a vital role in enhancing the separation and transport efficiency of photogenerated charge carriers for photocatalytic applications. In this study, we report a stepwise synthesis strategy to fabricate a high-efficiency ternary heterojunction composed of NiS-decorated MoS₂/CdS with strong interfacial bonding (NS@SI-MCS). Initially, an amorphous MoSₓ layer was deposited onto CdS nanorods via chemical bath deposition, followed by thermal treatment in a reductive H₂/Ar atmosphere to form crystalline MoS₂ with strong interfacial coupling. This treatment not only improved the crystallinity of MoS₂ but also introduced sulfur vacancies, promoting enhanced interfacial contact and thereby strengthening electronic interactions and charge transport across the heterojunction. Subsequently, NiS nanoparticles were deposited as cocatalysts to facilitate efficient electron extraction and proton reduction. Comprehensive structural, optical, and electrochemical characterizations confirmed the formation of a well-integrated heterostructure, characterized by improved light absorption, suppressed charge recombination, and enhanced conductivity. The resulting NS@SI-MCS composite exhibited a remarkable hydrogen evolution rate of 5243 μmol h⁻¹g⁻¹ under visible light, approximately 16.6 times higher than pristine CdS. This enhancement is attributed to the synergistic effects of strong interfacial coupling of MoS₂/CdS and the catalytic contribution of NiS. This work provides valuable insight into designing strongly coupled heterojunctions and offers a scalable, noble-metal-free strategy for efficient solar-to-hydrogen conversion.