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

Abstract

Defect engineering is used in the development of photocatalysts and has received widespread attention for achieving efficient photocatalysis. Here, ZnIn2S4 with rich sulfur vacancies (VS-ZnIn2S4) was integrated with MIL-53-NH2 for photocatalytic H2O2 production from O2 reduction under visible light. The sulfur vacancy could effectively promote charge separation and O2 capture, and the heterostructure between ZnIn2S4 and MIL-53-NH2 further inhibits charge recombination, which promises highly boosted photocatalytic activities. In ambient air and pure water, VS-ZnIn2S4/MIL-53-NH2 heterostructures exhibit superior photocatalytic H2O2 production performance (705 μmol·L−1) relative to those of monomeric Znln2S4 (78 μmol·L−1), VS-Znln2S4 (210 μmol·L−1), MIL-53-NH2 (38 μmol·L−1), as well as ZnIn2S4/MIL-53-NH2 (395 μmol·L−1). Mechanistic studies have confirmed that the main pathway for H2O2 formation on VS-ZnIn2S4/MIL-53-NH2 is ⋅O2–-triggered O2 reduction, and sulfur vacancy can adsorb and activate O2 to facilitate the production of ⋅O2–. This study provides new insights into catalyst design and green synthesis of H2O2.