Interlayer Polymerization Enables Cross-Plane Conjugation in COFs for Efficient Photocatalytic H₂O₂ Production

Abstract

Conventional two-dimensional covalent organic frameworks (2D COFs) are limited by the absence of continuous charge-transfer pathways between layers, which hinders their photocatalytic efficiency. To overcome this limitation, two types of polymer-bridged COFs are synthesized using an interlayer polymerization strategy, with polypyrrole and polyaniline serving as bridging materials. These materials facilitate directional charge transport and modulate excited-state dynamics. The resulting COFs maintain high crystallinity and porosity while exhibiting significantly improved charge separation. PPy-COF achieves a high H₂O₂ production rate of 1614.9 μmol·g⁻¹·h⁻¹ under visible-light irradiation. Mechanistic studies reveal a singlet-oxygen-mediated oxygen reduction pathway with high selectivity, promoted by intersystem crossing and facilitated by the polymer bridges. This design effectively addresses the intrinsic anisotropic charge-transport limitation of 2D COFs. These findings position interlayer conjugation as a promising strategy for enhancing the photocatalytic performance of COF-based materials for sustainable H₂O₂ generation.