Covalent Organic Framework Membranes with Asymmetric Wettability for Efficient Photocatalytic H 2 O 2 Synthesis

Abstract Photocatalytic H 2 O 2 synthesis from air and water is a sustainable route but hindered by mass transport and charge separation issues. Here, covalent organic framework (COF) membranes with asymmetric wettability are developed to construct triphase interfaces, locally enriching O 2 and H 2 O for efficient reactions. Converting COF powders into nanostructured membranes enhances light absorption and band alignment, promoting water oxidation and charge separation. These synergistic effects boost H 2 O 2 production to 52.5 mmol g −1 h −1 under O 2 , with an apparent quantum yield 27.8 times higher than powders, and up to 148.9‐fold under air. The flexible membranes can be integrated into reactors, and the in situ generated H 2 O 2 enables pollutant degradation. This work demonstrates a versatile strategy for high‐performance triphase photocatalysis and multifunctional membrane catalysts toward sustainable chemical synthesis.