Enzyme-Click Postsynthetic Modification of Covalent Organic Frameworks for Photocatalytic H₂O₂ Production

Postsynthetic modification (PSM) is a powerful strategy for tailoring the structure and functionality of covalent organic frameworks (COFs). In this work, we present a novel enzymatic PSM strategy for functional group engineering within COFs. By taking advantage of enzymatic catalysis, 2-hydroxyethylthio (-S-EtOH) and ethylthio (-S-Et) groups were covalently implanted within the COF pore channels with high grafting efficiency under ambient aqueous conditions, highlighting the mild, efficient, and ecofriendly nature of this approach. Theoretical calculations and in situ experiments revealed that the incorporation of -S-EtOH not only promotes exciton dissociation with a superior charge separation efficiency but also strengthens the proton supply for the formation of hydrogenation intermediates and lowers the Gibbs free energy difference (ΔG), thereby facilitating the photocatalytic H₂O₂ production. Our work bridges the gap between enzymatic catalysis and reticular materials engineering, offering a conceptual breakthrough in COF postsynthetic modification and functionalization.