Contribution of Nafion loading to the activity of catalysts and the performance of PEMFC

Different amounts of Nafion loadings (in the range of 0-2.0 mg cm(-2)) were added to a catalyst containing 0.5 mg cm(-2) of pt; these were prepared by spraying a Nafion solution on an electrode surface. The effect of Nafion loading on the activity of the catalyst and the performance of a proton exchange membrane fuel cell (PEMFC) was investigated by using electrochemical methods such as direct current polarization (using an I-V curve), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and linear scan voltammetry (LSV). The results of the I-V and EIS were compared in order to resolve the ohmic resistance (R-Omega, calculated from the T-V curve) into interfacial and internal resistances (R-if and R-S, simulated from the EIS). The analysis of the electrochemical data revealed that the interfacial resistance (R-if) is closely related to the reactive region of three-phase zones (interfaces among the reactants, electrolyte and catalyst), and it provides a major parameter for diagnosing the activity of the catalysts and the performance of the PEMFC. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.