Dual sulfur and indium vacancies-engineered ZnIn2S4 with p-n type built-in electric field for boosted photocatalytic hydrogen production

The development of highly efficient photocatalysts for solar-driven hydrogen evolution is critically important for addressing global energy and environmental challenges. In this study, a dual-vacancy system comprising cooperatively interacting sulfur vacancies (V S ) and indium vacancies (V In ) was constructed in ZnIn 2 S 4 (ZIS) through a combined hydrothermal-acid etching strategy. This approach enabled site-selective enrichment of the two distinct vacancies within the [ZnS] 4 and [InS] 4 structural units, respectively, leading to the increment of the active sites for catalytic reaction. Systematic characterization and theoretical calculations confirm that the unique vacancy configuration induces a substantially enhanced built-in electric field (BIEF), oriented from the n-type V S region toward the p-type V In region, which effectively promotes spatial separation and directional migration of photogenerated electron-hole pairs while significantly suppressing non-radiative recombination. The optimized ZIS catalyst with dual-vacancies (ZIS-D) achieves an exceptional hydrogen evolution rate of 9.68 mmol·h −1 ·g −1 under simulated solar illumination, representing 7-fold and 4-fold enhancements compared to pristine ZIS and ZIS-V S samples, respectively. This study provides new perspectives and theoretical foundations for vacancy engineering in the design of advanced photocatalytic systems.