PVP-assisted Hydrothermal Synthesis of ZnIn2S4 with Optimized Morphology and Sulfur Vacancies for Enhanced Photocatalytic H2O2 Production

Enhancing the photocatalytic efficiency of zinc indium sulfide (ZnIn 2 S 4 , ZIS) for hydrogen peroxide (H 2 O 2 ) production remains a significant challenge. Based on a viscous solvent system, this study innovatively introduced polyvinylpyrrolidone (PVP) to assist the hydrothermal synthesis of ZnIn 2 S 4 . Acting as both a dispersant and stabilizer, PVP guided the self-assembly of nanosheets into a highly ordered petal-like architecture with expanded interlayer spacing, while effectively suppressing random nanoparticle aggregation. This unique structure not only enhanced light harvesting and mass transfer efficiency but also facilitated electron transport through nanosheet bridges. This distinctive architecture enhances light absorption and mass transfer, while the interconnected nanoflake networks provide efficient pathways for electron transport. This integrated design effectively suppresses photogenerated charge recombination and increases the accessibility of active sites. Consequently, the optimized 160-PVP@ZIS sample yielded 843.2 μM of H 2 O 2 , 2.92 times higher than pristine ZIS. Combined XPS and FTIR analyses revealed that sulfur vacancy enrichment and surface hydroxylation synergistically promoted the generation of key reactive oxygen species (·OH and ·O 2 - ), thereby enhancing the photocatalytic performance. This study demonstrates that PVP-assisted hydrothermal synthesis provides an effective strategy to regulate both morphology and surface chemistry, offering new design principles for high-performance ZnIn 2 S 4 -based photocatalysts toward sustainable H 2 O 2 production.