Broad-spectrum response of NiCo2O4–ZnIn2S4 p–n junction synergizing photothermal and photocatalytic effects for efficient H2 evolution†

In this study, we developed a novel approach by creating a flower-like p–n heterojunction, where NiCo₂O₄ (NCO) nanoparticles are deposited onto a flower-like hierarchical ZnIn₂S₄ (ZIS) microsphere, to facilitate photocatalytic H₂ evolution from water. Theoretical calculations and experimental results underscore the synergistic effects of the heterojunction and photothermal properties in the NCO–ZIS composite, leading to a significant enhancement in photocatalytic activity. Detailed investigation of the photocatalytic mechanism elucidates how the heterojunction bolsters carrier separation and suppresses carrier recombination, while the photothermal effect broadens light absorption, elevates reaction temperature, accelerates carrier migration, and reduces activation energy. Therefore, the NCO–ZIS heterojunction exhibits exceptional hydrogen evolution performance, reaching 4507 μmol h⁻¹ g⁻¹, which surpasses ZIS alone by 5.04 times. This research lays the groundwork for designing highly active photothermal catalysts with broaden-spectrum solar energy utilization.