Multifunctional Matrix‐Activated Electrodes Enabling Efficient Proton Transport and Durable Low‐Pt Operation for High‐Temperature Proton Exchange Membrane Fuel Cells

ABSTRACT Phosphoric acid (PA)‐related challenges, including PA loss, redistribution, and flooding, critically limit the performance and long‐term durability of high‐temperature proton exchange membrane fuel cells (HT‐PEMFCs) based on PA‐doped membrane electrode assemblies. Although these issues can be partially mitigated using proton‐conducting additives and hydrophobic polytetrafluoroethylene, practical commercialization remains impeded by restricted high‐temperature operability and the requirement for high Pt loadings. To address these challenges, here we report a cerium hydrogen phosphate (CeHP)‐integrated multifunctional matrix‐activated electrode (MME) that stabilizes PA‐containing electrode microenvironments and preserve electrochemical pathways under severe high‐temperature operation above 200°C, where acid evaporation, dehydration, and migration become increasingly pronounced. This integrated matrix combines high‐temperature proton‐conduction, radical scavenging, and structural reinforcement of the porous catalyst layer, consequently alleviating the degradation at such high temperature. As a result, the optimized MME delivers a 38% increase in peak power density and a 62% reduction in voltage decay rate at 240°C, while requiring only 40% of the Pt loading of a Celtec commercial HT‐PEMFC electrode (0.4 vs. 1.0 mg Pt cm −2 per electrode). These results establish multifunctional catalyst‐layer matrix engineering as an effective strategy for enabling durable, low‐Pt HT‐PEMFC operation in acid‐doped polymer electrochemical systems under harsh high‐temperature conditions.