The effect of Nafion film on the cathode catalyst layer performance in a low–Pt PEM fuel cell

A single–pore model for performance of the cathode catalyst layer (CCL) in a PEM fuel cell is developed. The model takes into account oxygen transport through the CCL depth and through the thin Nafion film, separating the pore from Pt/C species. Analytical solution to model equations reveals the limiting current density jNlim due to oxygen transport through the Nafion film. Further, jNlim linearly depends on the CCL thickness, i.e., the thinner the CCL, the lower jNlim. This result may explain unexpected lowering of low–Pt loaded catalyst layers performance, which has been widely discussed in literature. •A model for the cathode catalyst layer (CCL) performance in a PEM fuel cell is developed.•The model includes oxygen transport though the Nafion film separating the pore from Pt/C species.•Analytical solution reveals the limiting current density due to oxygen transport through the Nafion film.•This limiting current linearly depends on the CCL thickness.