Polydopamine-Loaded ZnIn2S4 Photocatalyst for H2O2 Production in Water

Reasonably utilizing solar energy to synthesize hydrogen peroxide (H2O2) from oxygen and water is a promising and sustainable solution. In this work, we constructed an S-scheme photocatalyst ZnIn2S4/PDA (ZIS/PDA) by loading polydopamine (PDA) on the surface of ZnIn2S4, which significantly enhanced the separation and transfer of photogenerated charge carriers while retaining excellent oxidation and reduction abilities and exhibited outstanding H2O2 production performance (1747 μmol·g–1·h–1) under visible light in pure water, which is 39 times the yield of pure ZnIn2S4. The presence of PDA coating enhanced the adsorption capacity of catalysts for oxygen and improved the selectivity of the direct two-electron oxygen reduction reaction (2e–ORR) and formation rate by effectively reducing the Gibbs free energy (ΔG) of *OOH. In addition, ZIS/PDA significantly inhibited the decomposition of H2O2 by promoting the rapid desorption of H2O2, which is conducive to the stable accumulation of H2O2. In summary, the innovative ZIS/PDA photocatalyst demonstrates remarkable efficiency in H2O2 production, offering a potential solution for the sustainable energy synthesis.