Impact of catalyst carbon support on the benefits of high oxygen permeability ionomer for proton exchange membrane fuel cells

In this study, we present a comparative analysis of fuel cell electrochemical performance using platinum catalysts supported on low surface area carbon (Pt/LSC) and high surface area carbon (Pt/HSC) combined with two ionomers: the high oxygen permeability ionomer (HOPI) and the conventional Nafion D2020. We observed that Pt/LSC, when paired with HOPI, achieves superior specific activity and reduced oxygen transport resistance compared to Pt/HSC. This is attributed to the greater surface exposure of platinum particles in Pt/LSC, which enhances ionomer-catalyst interactions. In contrast, Pt/HSC's internal porosity limits these benefits, likely due to restricted ionomer access to internal Pt sites. The results underscore the importance of optimizing ionomer-catalyst interactions, with HOPI demonstrating strong potential for improving fuel cell efficiency and durability. • Pt/HSC has a significant fraction of internal Pt, affecting the impact of ionomer. • HOPI ionomer outperforms traditional PFSA for both Pt/LSC and Pt/HSC catalysts. • Pt/LSC with HOPI shows higher specific activity and reduced O₂ transport resistance. • HOPI reduces the oxygen transport resistance with Pt/HSC catalyst. • The benefit of HOPI on specific activity is reduced with Pt/HSC catalyst.