Novel ZIF-8/ZnIn2S4 heterojunction efficiently generates hydrogen peroxide via dual-channel reactions driven by visible light in air

The photocatalytic synthesis of hydrogen peroxide (H₂O₂) from water and air presents a cost-effective and environmental-friendly alternative to traditional methods. However, single component photocatalysts encounter challenges such as rapid carriers recombination and insufficient oxidation–reduction potential. Furthermore, the unfavorable thermodynamics associated with the water oxidation reaction (WOR) for most photocatalysts complicates the realization of dual-channel photocatalytic reactions. In this study, we successfully fabricated a Z-scheme heterojunction (ZIF-8/ZnIn₂S₄) by in-situ growing the metal–organic framework ZIF-8 on flower-like ZnIn₂S₄ (ZIS) for efficient H₂O₂ production. Under visible light irradiation, the optimized ZIF-8/ZIS demonstrated an impressive H₂O₂ generation rate of 742.7 μmol g⁻¹h⁻¹ in isopropanol solution, showing a 1.8-fold improvement compared to ZIS alone. The excellent photocatalytic performance can be attributed to the efficient separation and transfer of photogenerated electron-hole pairs facilitated by the Z-scheme heterojunction. Femtosecond transient absorption spectroscopy and density function theory analysis confirmed the Z-scheme route for charge transfer in ZIF-8/ZIS. Quenching experiments, electron spin resonance analysis, and in-situ diffuse reflectance infrared Fourier transform spectroscopy studies revealed that the primary reactive species, e⁻ and •O₂⁻, significantly contribute to H₂O₂ production through photocatalytic oxygen reduction reaction and WOR. This investigation provides valuable insights for the rational design and preparation of ZIS-based heterojunctions with efficient solar-driven H₂O₂ synthesis via a dual-channel pathway.