Influence of Nafion loading in the catalyst layer of gas-diffusion electrodes for PEFC

The effect of Nafion loading in the catalyst layer of cathodes for polymer electrolyte fuel cells (PEFCs) was investigated. Steady-state galvanostatic polarisation (GP), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements were carried out at 25 degrees C in 1.0 M H2 SO4 on electrodes with different Nafion loadings. EIS supplied information on the polarization resistance and CV on the electrochemical active area fo r the oxygen reduction reaction (ORR). These parameters, together with thos e derived from GP, allowed a better identification of the features governin g the ORR. An optimum Nafion loading was identified. This loading was found to correspond to a minimum in the polarization resistance and in the oxyge n reduction overpotential and ct maximum in the electrochemical active area . (C) 1999 Elsevier Science S.A. All rights reserved.