Hydrogen peroxide (H2O2) is a green oxidant widely used in a variety of industries. Photocatalytic generation of H2O2 from water and oxygen by sunlight is an appealing strategy compared to the high energy consumption of the industrial anthraquinone process. However, the low activity and selectivity of the two-step single-electron oxygen reduction reaction (ORR) during the photocatalytic process greatly restricts the H2O2 production efficiency. Here, we demonstrated that the redox centers in MOFs (NMFS-M, single-atom M linked to an iron-oxo cluster in NH2-MIL-101(Fe) by a molecular linker cysteine, M = Co, Ni, Cu, and Zn) for the production of H2O2 from water and oxygen. The optimal NMFS-Cu stably generates H2O2 under simulated sunlight irradiation with a nearly 2% solar-to-chemical conversion efficiency under AM1.5 spectrum and an apparent quantum yield of 19.6% at 420 nm. Combined with density functional theory calculations, isotopic experiments, and advanced spectroscopic characterizations, the high photocatalytic performance is ascribed to the notably promoted sequential two-step ORR to H2O2 by forming μ-peroxide and desorption of *H2O2 at the single-atom Cu sites. The in situ generated O2 via water oxidation reaction is rapidly consumed by ORR, leading to a boosted photocatalytic generation of H2O2.
Meng et al. (Mon,) studied this question.