Metal‐Organic Framework‐Templated Construction of Internal Electric Field and S‐Vacancy Defect‐Engineered S‐Scheme Heterojunction for Enhanced Photocatalytic Hydrogen Evolution

ABSTRACT Constructing a heterojunction photocatalyst can effectively enhance photocatalytic hydrogen evolution (PHE) activity. Here, we report a novel multidimensional strategy to construct S‐scheme heterojunctions with internal electric field (IEF) regulation and S‐vacancy defects via MOF‐templated in situ synthesis. MOF templates enable atomic‐level interfacial contact, precise heterostructure size control, and abundant vacancy formation during pyrolysis. Systematic characterization verifies that this strategy preserves a large specific surface area, generates abundant S vacancies to expose more active sites, and synergistically strengthens the interfacial IEF. Density functional theory (DFT) calculations and photoelectrochemical measurements reveal that the Bi 2 S 3 @ZnIn 2 S 4 heterojunction drives S‐scheme charge transfer and preserves a high conduction‐band (CB) reduction potential for H + reduction and that S vacancies act as electron traps to suppress carrier recombination. Benefiting from the triple synergy of MOF templating, IEF regulation, and S‐vacancy engineering, the optimized heterojunction shows outstanding photocatalytic H 2 evolution (5.13 mmol g −1 h −1 ), which is 3.8, 6.7, 11.7, and 244.3 times higher than that of Bi 2 S 3 /ZnIn 2 S 4 , Bi 2 S 3 ‐ZnIn 2 S 4 , pure ZnIn 2 S 4 , and Bi 2 S 3 , respectively. It retains high activity over seven cycles, confirming its structural and catalytic stability. This work offers a new paradigm for designing high‐performance photocatalysts via multidimensional synergistic engineering and deepens insights into charge transfer and reaction kinetics in defect‐mediated S‐scheme systems.