Nafion content in the catalyst layer of polymer electrolyte fuel cells: effects on structure and performance

The influence of Nafion content of PEFC gas diffusion electrodes with intermixed ionomer in the catalyst was evaluated. Electrochemical studies were carried out in a 50 cm2 single cell in H2/air operation at 70œC. Low platinum load (0.1 mg/cm2) electrodes with a Nafion content changing from 14 to 66 wt% were studied. The performance of PEFC electrodes is affected from the Nafion content and an optimal content of about 33 wt% of ionomer was found. Hg intrusion porosimetry and cyclic voltammetry were carried out to evaluate the pore size distribution and the electrochemical surface area, respectively. These data were correlated with single cell performance. The electrochemical experimental data were analysed using a theoretical equation and the obtained kinetics parameters were related to the catalytic layer structure.