Polymer-Scaffold Induced Extensive Hydrogen-Bond Network: Enabling High Transport of Proton and Oxygen in Cathode Catalyst/Ionomer Interfaces

Uneven ionomer coverage in the cathode catalyst layer of proton exchange membrane fuel cells (PEMFCs) impedes proton conduction and oxygen diffusion, particularly at low platinum loadings. Here, a functionalized polymer-scaffold is designed and constructed by using hydroxy-pyridine polybenzimidazole (PyOHPBI) with abundant hydrogen-bond sites, thereby proposing a hydrogen-bond synergistic strategy to address the challenges of optimizing ionomer distribution and enhancing the transport of protons and gas through the catalyst layer. By integrating molecular dynamics simulations, in situ and ex-situ characterization methods, the design achieves 144.4% of the peak power density compared to commercial Pt/C catalysts, alongside an exceptionally low local oxygen transport resistance of only 7.81 s·m^-1 in membrane electrode assemblies (MEAs). This study highlights how surface chemical modifications of carbon supports leverage hydrogen bonds to optimize ionomer coverage, significantly enhancing PEMFC performance and offering insights for developing more efficient and sustainable fuel cell technologies.