Boosting the photocatalytic hydrogen generation: The multifunctional role of NiWO4 in NiS2/NiWO4/ZnIn2S4 hollow microsphere

As a promising metal sulfide co-catalyst, nickel disulfide (NiS2) has become extremely attractive for cost-effectiveness and efficiency during the photocatalytic activity of hydrogen evolution reaction (HER). However, the strong bonding strength of S-Hads poses a challenge in desorbing H atoms from the active S-site, hindering the photocatalytic hydrogen evolution performance of NiS2. Intrinsically, accelerating the photoproduction electron transfer and promoting the release of more hydrogen protons from active adsorption water is essential for enhancing photocatalytic hydrogen evolution. Herein, we propose an interface modulation strategy for promoting photocatalytic performance: fabricating amorphous NiWO4 nanoparticles modified on NiS2 cocatalysts to construct a NiS2/NiWO4/ZnIn2S4 hollow microsphere photocatalyst. The close contact arrangement between NiS2/NiWO4 microspheres and ZnIn2S4 nanosheets undeniably enhances charge separation of carriers. Meanwhile, the amorphous NiWO4 interlayer functions excellently in conductivity, as an "electron bridge," for accelerating charge carrier transfer. Significantly, amorphous NiWO4 strongly interacts electronically with NiS2, reducing the local electron density of Ni and S atoms. This promotes the adsorption of water by Ni sites and optimizes of adsorption/desorption of hydrogen atoms at the adjacent S sites where S-Hads are weakened. The hierarchical ZnIn2S4/NiWO4/NiS2 photocatalyst remarkably boosts the hydrogen production rate. It was 11.919 mmol·g−1·h−1 compared to bare ZnIn2S4, and ZnIn2S4/NiS2 only showed 1.8 times increase, while ZnIn2S4/NiWO4/NiS2 increased by 12.5 times. The optimization of the active center in the study provides a beneficial strategy for designing efficient photocatalysts for water splitting with great potential for hydrogen evolution cocatalysts.