Artificial Photosynthesis of H₂O₂ by Synergistically Interplayed ZnIn₂S₄ and K⁺-Incorporated Polymeric Carbon Nitride

On-site production of H2O2 from O2 and H2O by way of artificial photosynthesis is highly desirable for facilitating the application of H2O2-based advanced oxidation processes. Achieving descent H2O2 production efficiency is challenging, due to the severe recombination of the photoinduced charges and the sluggish kinetics of the water oxidation reaction. In this work, a heterojunction of exfoliated K+-doped polymeric carbon nitride (K-CN) and zinc indium sulfide (ZnIn2S4, ZIS) is constructed; an interfacial electric field is induced, and partial charge transfer from ZIS to K-CN is verified via a spectroscopic technique. The spatial separation of the photoinduced charges is significantly enhanced, and a remarkable photocatalytic H2O2 production from O2 and H2O is thus achieved, e.g., 1729.9 μmol h–1 g–1 and apparent quantum yield of 2.43% under irradiation of 420 nm. Mechanistic investigations reveal the essential role of superoxide radical (O2·–) in O2 to H2O2 conversion.