NiCoP Nanoparticles Supported on ZnIn2S4 Nanosheets as Photocatalyst for Hydrogen Evolution

ZnIn2S4 has been extensively investigated for photocatalytic hydrogen (H2) evolution owing to its suitable electronic structure, visible-light response, and relatively low toxicity. However, rapid recombination of photogenerated charge carriers and photocorrosion severely limit its photocatalytic efficiency and stability. Cocatalyst integration provides an effective strategy for promoting charge separation and introducing additional catalytic sites. Herein, bimetallic nickel-cobalt phosphide (NiCoP) nanoparticles were supported on ZnIn2S4 nanosheets through a low-temperature solvothermal method, yielding a NiCoP−ZnIn2S4 composite with intimate interfacial contact. Spectroscopic characterization and density functional theory (DFT) calculations collectively indicate ground-state charge redistribution from NiCoP toward ZnIn2S4 at the interface. The combined photoresponse and electrochemical results support a cocatalyst mechanism in which photogenerated electrons are proposed to transfer from ZnIn2S4 to conductive NiCoP for proton reduction under illumination. Consequently, the optimized NiCoP−ZnIn2S4 composite achieves an H2 evolution rate of 14.73 mmol g−1 h−1 under visible-light irradiation using triethanolamine (TEOA) as the hole scavenger, representing a 20.18-fold enhancement over pristine ZnIn2S4. These results underscore the importance of interfacial electronic coupling in regulating ground-state charge redistribution and photogenerated-electron transfer and offer a basis for designing efficient noble-metal-free phosphide/semiconductor photocatalysts for solar H2 production.