Analysis of Oxygen Transport Resistance of Nafion Thin Film on Pt Electrode

To clarify the rate determining process for the oxygen transport in a catalyst layer of polymer electrolyte fuel cells, the oxygen transport resistance of a Nafion thin film was precisely evaluated using a microelectrode technique for cast Nafion films with 30-150 nm thickness and data analysis on the relationship between the Nafion thickness on the Pt electrode and the diffusion-limited current density on the electrode. While the oxygen transport resistivity inside the Nafion thin film was roughly equal to that of Nafion thick membrane, the interfacial resistance at the Pt/Nafion or Nafion/gas interface was estimated to be equivalent to 60-80 nm thickness of Nafion film and to account for the dominant part of the total oxygen transport loss in a real PEFC electrode, especially with a low platinum loading.