Enhanced interfacial adhesion in hydrocarbon membrane MEAs via plasma activation and thin PFSA ionomer coating

Enhancing interfacial compatibility between hydrocarbon membranes and perfluorosulfonic acid (PFSA) ionomer–based catalyst layers remains a major challenge in proton exchange membrane fuel cells (PEMFCs). Here, an interfacial engineering strategy combining plasma surface activation with a thin PFSA ionomer interlayer is developed for fabricating hydrocarbon membrane-based electrode assemblies (MEAs). Oxygen plasma treatment increases membrane surface energy and wettability, promoting the formation of a uniform and continuous PFSA ionomer coating and enabling stable membrane–electrode integration via decal transfer. Key fabrication parameters, including PFSA ionomer coating thickness, ionomer-to-carbon (I/C) ratio, and hot-pressing pressure, are systematically investigated. The optimized condition (4 μm ionomer coating, I/C = 1.0, and 70 bar hot-pressing) yields the highest single-cell performance. The relatively high hot-pressing pressure, which is difficult to apply to conventional unreinforced PFSA membranes, is enabled by the mechanical robustness of the hydrocarbon membrane combined with the engineered interfacial architecture. Under U.S. Department of Energy (DOE) wet–dry accelerated stress testing, the optimized MEA maintains stable electrochemical performance over 15,000 cycles without interfacial failure. This is the first report of a standalone hydrocarbon membrane MEA sustaining 15,000 wet–dry cycles without interfacial delamination, demonstrating that rational interfacial engineering can enable highly durable next-generation PEMFCs.