1D/0D heterostructured ZnIn2S4@ZnO S-scheme photocatalysts for improved H2O2 preparation

Solar photocatalysis is a promising, green, and sustainable technique for the synthesis of H2O2. In this study, low-dimensional ZnO/ZnIn2S4 S-scheme heterojunction photocatalysts are fabricated using electrostatic spinning and chemical bath deposition methods for the efficient photocatalytic production of H2O2. ZnO nanofibers loaded with 20 wt% ZnIn2S4 exhibit a superior H2O2 production rate of 928 μmol g−1 h−1, which is more than four times higher than that seen in pristine hexagonal phase ZnO and ZnIn2S4. First-principles calculations and in-situ X-ray photoelectron spectroscopy reveal the charge separation and transfer mechanisms in the S-scheme heterojunction. The construction of the S-scheme heterojunction facilitates the spatial separation of charge carriers, and electrons and holes with higher redox abilities are retained. Photoelectrochemical and photoluminescence tests further show that the formation of an S-scheme heterojunction is beneficial for the separation of photoinduced charge carriers. Electrochemical tests and electron paramagnetic resonance measurements indicate that H2O2 production is primarily via a two-step single-electron O2 reduction path. This study provides a new approach for the construction of S-scheme heterojunction materials that can efficiently produce H2O2 under solar irradiation.