Sulfur‐Rich Vacancies in SnIn 4 S 8 Accelerating Surface Reaction Kinetics for Photocatalysis

ABSTRACT Photocatalytic hydrogen production coupled with simultaneous pollutant degradation offers a sustainable solution to global energy and environmental crises, yet suffers from sluggish surface reaction kinetics that limit practical implementation. Here, we report the synthesis of sulfur‐vacancy‐rich SnIn 4 S 8 (V S ‐SnIn 4 S 8 ) with significantly enhanced photocatalytic performance of hydrogen evolution coupling organic pollutants degradation. The V S ‐SnIn 4 S 8 catalyst exhibits a hydrogen evolution rate of 596.35 µmol/h/g, representing a 2.6‐fold improvement over pristine SnIn 4 S 8 (227.02 µmol/h/g). Remarkably, when employing tetracycline (TC) as a sacrificial agent, V S ‐SnIn 4 S 8 achieves substantial hydrogen production activity (50.35 µmol/h/g). Experimental characterization reveals that sulfur vacancies optimize the conduction band potential of SnIn 4 S 8 , thereby strengthening its reduction capability and catalytic activity. Furthermore, these vacancies function as electron capture sites, suppressing photogenerated charge carrier recombination. Density functional theory (DFT) calculations confirm that sulfur vacancies facilitate water molecule adsorption and dissociation, directly contributing to accelerated hydrogen evolution kinetics. Our findings demonstrate that engineering vacancy defects offers a viable strategy for enhancing surface reaction kinetics in dual‐function photocatalytic systems targeting both pollutant remediation and hydrogen production.