Synergistic enhancement of photocatalytic H2 evolution via Fe doping and S-scheme heterojunction of MIL-68(Fe)/ZnIn2S4

Solar-driven photocatalytic hydrogen evolution represents a promising strategy, yet constructing photocatalysts that simultaneously deliver high activity and efficient visible-light utilization remains challenging. In this work, an Fe-ion-doped metal–organic framework, MIL-68(Fe), was synthesized and employed as substrate template for in-situ growth of ZnIn₂S₄ nanosheets. Subsequent one-pot synthesis yielded hollow tubular MIL-68(Fe)/ZnIn₂S₄ composite uniformly coated with ZnIn₂S₄ nanosheets, effectively mitigating severe stacking inherent to pure ZnIn₂S₄. Characterization confirmed successful Fe-ion doping, which significantly enhanced visible-light absorption. The optimal composite achieved photocatalytic hydrogen evolution rate of 10.04 mmol·g −1 ·h −1 , representing 9.84-fold enhancement over pristine ZnIn₂S₄. Density functional theory calculations revealed that interfacial Fe O and in O bonds facilitate built-in electric field formation within [ZnS₄] layers, confirming successful S-scheme heterojunction construction. This unique structure preserves photogenerated charge carriers with stronger redox potentials, thereby substantially boosting overall photocatalytic activity. This study offers novel approach for photocatalyst modification and demonstrates synergistic combination of ion doping with S-scheme heterojunction engineering as highly promising research direction