Polydopamine-Loaded ZnIn 2 S 4 Photocatalyst for H 2 O 2 Production in Water

Reasonably utilizing solar energy to synthesize hydrogen peroxide (H 2 O 2 ) from oxygen and water is a promising and sustainable solution. In this work, we constructed an S-scheme photocatalyst ZnIn 2 S 4 /PDA (ZIS/PDA) by loading polydopamine (PDA) on the surface of ZnIn 2 S 4, which significantly enhanced the separation and transfer of photogenerated charge carriers while retaining excellent oxidation and reduction abilities and exhibited outstanding H 2 O 2 production performance (1747 μmol·g –1 ·h –1 ) under visible light in pure water, which is 39 times the yield of pure ZnIn 2 S 4 . 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 (Δ G ) of *OOH. In addition, ZIS/PDA significantly inhibited the decomposition of H 2 O 2 by promoting the rapid desorption of H 2 O 2, which is conducive to the stable accumulation of H 2 O 2 . In summary, the innovative ZIS/PDA photocatalyst demonstrates remarkable efficiency in H 2 O 2 production, offering a potential solution for the sustainable energy synthesis.