Covalent Organic Frameworks Regulating the Catalyst Interfacial Microenvironment for High‐Power Proton Exchange Membrane Fuel Cells

Abstract Platinum (Pt)‐based proton exchange membrane fuel cells (PEMFCs) hold promise as clean and efficient energy conversion devices. However, their widespread application is hindered by low Pt utilization and substantial mass transport resistance within the cathode catalyst layer (CCL). Herein, a strategy is developed to incorporate nitrogen‐rich covalent organic frameworks (COFs) into the CCL, aiming to regulate the triple‐phase boundaries (TPB) microenvironment and enhance catalytic performance. The intrinsic nanoporous architecture of COFs facilitates oxygen diffusion, while positively charged nitrogen sites promote favorable electrostatic interactions with Nafion ionomers. These interactions suppress the undesired sulfonic acid group adsorption and clustering on the Pt surface, leading to a more homogeneous Nafion distribution within the CCL. Consequently, both oxygen and proton transport are significantly improved, enhancing the effective utilization of Pt sites. The resulting PEMFCs achieve a 1.46‐fold increase in peak power density and a 1.59‐fold enhancement in Pt mass activity (MA) compared to conventional systems. This work not only provides a novel interface engineering approach for high‐performance PEMFCs but also broadens the application scope of COFs in electrochemical energy devices.