Efficient sacrificial-agent-free solar H2O2 production over all-inorganic S-scheme composites

Solar H2O2 generated from O-2 and H2O is an economical and green protocol. However, most photocatalysts only perform well in the presence of sacrificial donors or the photocatalysts are composed by organic materials, thus hindering their applicability. Herein, an inorganic matrix, i.e. ZnIn2S4@BiVO4 (ZIS@BVO), is constructed as model catalyst for photocatalytic H2O2 production in non-sacrificial systems. Excellent performance (1.8 mmol g(-1) h(-1)) under visible-light is realized, and an apparent quantum yield of 5.18% is realized at 420 nm. Thorough investigation helps us to rationalize its exceptional performance and structural characteristics. Of note, the electron spin resonance spectroscopy results, in combination with scavenger capture experiments, reveal the discovery of an overlooked pathway. Specifically, except for the well-known two-electron oxygen reduction reaction (ORR), the involvement of O-1(2) intermediate is verified during the H2O2 generation. Beyond presenting high performance of the inorganic composites, this finding also discloses a different reaction path for H2O2 production.