Hollow spherical MoO2–C cocatalyst derived from Mo-polydopamine boosts photocatalytic hydrogen evolution of ZnIn2S4

This study developed an amorphous MoO 2 –C hollow spherical cocatalyst (MOC) derived from Mo-polydopamine, and hybridized it with ZnIn 2 S 4 to form ZnIn 2 S 4 /MoO 2 –C (ZMC) composites. Various characterizations were conducted to analyze the crystal structure, morphology, and photoelectrical properties of the ZMC composites. The prepared ZMC composites were evaluated for photocatalytic hydrogen evolution under simulated sunlight. Furthermore, nanorod-like MoO 2 –C cocatalyst (A-MOC) and ZnIn 2 S 4 /A-MOC (A-ZMC) composites were prepared to investigate the impact of carbon source on catalytic activity. Results show that the addition of MOC cocatalyst significantly enhances the hydrogen evolution rate of ZnIn 2 S 4 from 0.54 to 20.61 mmol g −1  h −1 , and increases the apparent quantum efficiency at 420 nm from 1.66 % to 8.63 %. The hydrogen evolution rate of the optimal ZMC is 1.26 times that of the optimal A-ZMC (16.28 mmol g −1  h −1 ). The crystal structure and morphology of MoO 2 –C determined by carbon source affect the photocatalytic hydrogen evolution performance of ZnIn 2 S 4 . Insight mechanism analysis indicates that the formation of a Schottky junction facilitates the separation of photogenerated electron-hole pairs, thereby enhancing the photocatalytic hydrogen evolution activity. Finally, the ZMC composite catalyst retains 89 % of its original hydrogen evolution performance after 5 cycles over 15 h, demonstrating good stability and promising prospects for real-world applications.