Redox dual-cocatalysts modified ZnIn2S4 hollow sphere with spatially separated carrier for photocatalytic H2 production coupled with selective benzyl alcohol oxidation
The effective separation and utilization of photo-generated carriers are critical for advancing photocatalysis, particularly in coupled reactions of H2 production and value-added chemical synthesis. Here, a sandwich-structured MnO2@ZnIn2S4@Ti3C2 hollow sphere was designed, with MnO2 and Ti3C2 loaded on the inner and outer surfaces of ZnIn2S4, respectively. MnO2 acts as an oxidation cocatalyst collecting photo-generated holes, while Ti3C2 serves as a reduction cocatalyst for electrons, promoting spatial separation of carriers and enabling spatially separated redox reactions. The hollow structure enhances light harvesting. The optimal catalyst achieves photocatalytic H2 production rate of 6.29 mmol g−1 h−1 and benzaldehyde production rate of 5.26 mmol g−1 h−1 from benzyl alcohol oxidation, significantly outperforming ZnIn2S4, MnO2@ZnIn2S4, and ZnIn2S4@Ti3C2. In situ irradiated X-ray photoelectron spectroscopy confirms effective carrier separation. In situ electron paramagnetic resonance and diffuse reflectance infrared Fourier transform spectroscopy reveal reaction intermediates. This work provides a strategy for designing efficient photocatalysts for coupled H2 production and selective oxidation.