MgIn2S4/COF S-scheme heterostructure for improved photocatalytic H2O2 production under pure water and air

Photocatalytic H 2 O 2 production from O 2 and H 2 O is an economical and environmentally sustainable approach. However, the reliance on sacrificial agents and pure O 2 greatly limits the practical application of numerous photocatalysts. Herein, a novel S-scheme photocatalyst composed of MgIn 2 S 4 and covalent organic framework (COF) was developed toward efficient photocatalytic H 2 O 2 evolution under pure water and air. MgIn 2 S 4 /COF (MC) S-scheme heterojunction was constructed by decorating MgIn 2 S 4 nanosheets on hollow spherical COF using wet chemistry. The H 2 O 2 yield of the optimal MC composite in pure water and air was 4.52 mmol⸱g −1 ⸱h −1 under pure water and air, which was separately 6.6 times and 9.4 times higher than that of pristine MgIn 2 S 4 and COF. Photocatalytic mechanism characterizations confirmed that the continuous 2e − O 2 reduction and 4e − H 2 O oxidation simultaneously occurred within this reaction system, and both ·O 2 – and e – were pivotal intermediates for H 2 O 2 evolution. The MC S-scheme heterojunction was advantageous to the effective separation and transfer of photogenerated electrons and holes, thereby enhancing the photocatalytic H 2 O 2 production activity. This work offers important guidance for constructing high-efficiency COFs-based S-scheme heterojunction for H 2 O 2 production. • MgIn 2 S 4 /COF S-scheme photocatalysts were successfully prepared by wet chemical method. • MgIn 2 S 4 /COF composites exhibit high photocatalytic H 2 O 2 production performance under pure water and air. • Construction of S-scheme heterojunction facilitates light absorption, reactant adsorption and photogenerated carrier separation. • Photocatalytic H 2 O 2 production undergoes a dual-channel pathway consisting of ORR and WOR.