Confinement of ultrasmall CoFe₂O₄ nanoparticles in hierarchical ZnIn₂S₄ microspheres with enhanced interfacial charge separation for photocatalytic H₂ evolution

The charge carriers’ separation efficiency, light absorption capacity and microstructure of photocatalysts are important factors affecting the photocatalytic performance. Herein, we prepared the hierarchical ZnIn₂S₄ (ZIS) microspheres-confined CoFe₂O₄ nanoparticles (CFO NPs) p-n junction (CFO/ZIS) with enhanced charge carriers’ separation and extensive visible light response. Surprisingly, the 1% CFO/ZIS exhibits the optimal photocatalytic H₂ evolution (PHE) activity, which is about over 3.7 times higher than pure ZIS. Furthermore, the apparent quantum yield (AQY) of the1% CFO/ZIS reaches 5.0% at 420 nm. In addition, the effects of various sacrificial reagent on the PHE were investigated in depth. And the formed photocatalytic reaction path of p-n junction effectively prevents the photocorrosion of ZIS. Hence, the photocatalytic activity and crystalline structure of 1% CFO/ZIS have no obvious change after five photocatalytic cycles, which shows that the photocatalyst possesses excellent chemical stability. Moreover, the as-prepared p-n junction shows outstanding photocatalytic performance for the degradation of 2-mercaptobenzothiazole (MBT). According to a series of experiments and characterizations, a possible photocatalytic mechanism for the CFO/ZIS p-n junction was proposed.