ZnIn2S4/MIL-53-NH2 composite photocatalysts for H2O2 production: Synergistic effect of sulfur vacancy and heterostructure

Defect engineering is used in the development of photocatalysts and has received widespread attention for achieving efficient photocatalysis. Here, ZnIn 2 S 4 with rich sulfur vacancies (V S -ZnIn 2 S 4 ) was integrated with MIL-53-NH 2 for photocatalytic H 2 O 2 production from O 2 reduction under visible light. The sulfur vacancy could effectively promote charge separation and O 2 capture, and the heterostructure between ZnIn 2 S 4 and MIL-53-NH 2 further inhibits charge recombination, which promises highly boosted photocatalytic activities. In ambient air and pure water, V S -ZnIn 2 S 4 /MIL-53-NH 2 heterostructures exhibit superior photocatalytic H 2 O 2 production performance (705 μmol·L −1 ) relative to those of monomeric Znln 2 S 4 (78 μmol·L −1 ), V S -Znln 2 S 4 (210 μmol·L −1 ), MIL-53-NH 2 (38 μmol·L −1 ), as well as ZnIn 2 S 4 /MIL-53-NH 2 (395 μmol·L −1 ). Mechanistic studies have confirmed that the main pathway for H 2 O 2 formation on V S -ZnIn 2 S 4 /MIL-53-NH 2 is ⋅O 2 – -triggered O 2 reduction, and sulfur vacancy can adsorb and activate O 2 to facilitate the production of ⋅O 2 – . This study provides new insights into catalyst design and green synthesis of H 2 O 2 .