Oxygen-vacancy-enriched MoO3 quantum dots anchored on sulfur-vacancy-rich Zn3In2S6 heterostructures for boosted hydrogen peroxide photosynthesis from pure water

The development of efficient photocatalytic systems for hydrogen peroxide (H 2 O 2 ) production from pure water remains a huge challenge due to rapid charge recombination and insufficient redox capability in single-component photocatalysts. Herein, we successfully constructed the S-scheme oxygen-vacancy-enriched MoO 3 quantum dots (Ov-MoQDs)/sulfur-vacancy-rich Zn 3 In 2 S 6 (Sv-ZIS) heterostructures by coupling Sv-ZIS nanosheets with Ov-MoQDs. The optimized 3Ov-MoQDs/Sv-ZIS sample achieves an outstanding H 2 O 2 production rate of 85.8 ± 3.1 μM under visible light illumination for 1 h in the pure water, which is about 3.5 and 45.1 times higher than those of Sv-ZIS and Ov-MoQDs, respectively. Through comprehensive in situ and ex situ characterizations combined with theoretical calculations, we demonstrate that the enhanced activity stems from efficient charge separation and transfer across the heterogeneous interfaces via an S-scheme mechanism. Furthermore, the H 2 O 2 photosynthesis over Ov-MoQDs/Sv-ZIS heterostructures is found to proceed through a two-step single-electron oxygen reduction reaction (ORR) pathway. This work provides valuable insights into the rational design of advanced heterostructured photocatalysts for sustainable chemical synthesis.