Effect of active S of ZnIn2S4 on the photocatalytic H2 production by water splitting under visible light irradiation

Active S atoms of sulfides play key roles in photocatalytic H2 production. This study reports a visible-light-driven ZnIn2S4 photocatalyst with abundant active S atoms achieved by exposing more (110) plane via adjusting S contents in reactants. The prepared samples exhibit flower-like microparticles aggregated by nanosheets (∼10 nm thick). The aggregation increases with the S contents. XRD and XPS results indicate that ZIS-1 exposes more (110) planes and active S atoms than other samples. Photocatalytic H2 production tests indicate that ZIS-1 exhibits the highest H2 production rate (19.81 mmol g−1 h−1) and AQY value (19.36 %) among the prepared samples. The underlying reason for the high performance of ZIS-1 is attributed to the active S mechanism, which is confirmed by the phenomenon that the photocatalytic performance decreases when secondary materials are modified on its surface. Furthermore, the optical and electrochemical experiments suggest that the ZIS-1 owns more photogenerated electrons, less electron-hole recombination rates, higher donor density, and better charge transfer ability. This study may provide a new idea for rational design and simple synthesis of high-performance and cost-effective metal sulfide semiconductor photocatalysts for solar-hydrogen energy conversion.