Pyrolysis‐Free Covalent Organic Polymer Efficiently Driving Proton‐Exchange‐Membrane Fuel Cells by Covalent Grafting Strategy

Covalent organic polymers (COPs) have emerged as promising oxygen reduction reaction (ORR) catalysts due to their structural tunability and well-defined active sites. However, their practical application is hindered by inherent electrical conductivity and restricted active site accessibility in bulk configurations. While van der Waals-assembled COP-carbon composites enhance conductivity, persistent stacking, and weak interfaces still impede electron/mass transport during ORR. Herein, a covalent grafting strategy is proposed to fabricate a lamellar COP network COP@G, which is achieved by edge-functionalizing COP with aromatic primary amine groups, followed by diazotization reactions and covalent attachment of graphene dispersions. The resulting hybrid exhibits significantly improved active site accessibility and a tenfold increase in conductivity compared to pristine COP. As a result, in 0.1 M HClO₄, COP@G delivers an exceptional acidic ORR performance, with a record half-wave potential of 801 mV, surpassing van der Waals-assembled COP-G by 194 mV. When integrated into proton-exchange-membrane fuel cell (PEMFC) cathodes, COP@G demonstrates an order-of-magnitude enhancement in maximum power density compared to conventional COP-carbon composites.