Study of Dielectric Constant effects on preparation conditions of gas diffusion electrodes for Oxygen Reduction Reaction in polymer electrolyte membrane fuel cells

The effect of solvent dielectric constant that used for preparation of catalyst layer of gas diffusion electrode (GDE) in Proton exchange membrane fuel cell (PEMFC) cathodes for oxygen reduction was investigated. Electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), Chronoamperometry (CA) and Cyclic Voltammetry (CV) measurements were carried out at 298K in 2.0 M H2SO4 on electrodes with same nafion loading and Pt loading but different solvent dielectric constant for ink preparation. In all electrodes nafion loading of 0.5 mgcm-2 and Pt loading of 1 mgcm-2 were chose. EIS supplied information on the charge transfer resistance and CV on the electrochemical active area for the oxygen reduction reaction (ORR) showed optimum results in states that dielectric constant was 4.2. The results indicate that, under optimized conditions the (solvent dielectric constant of 4.2) exchange current density and Tafel slope are 9.8×10-5mA cm-2 and 66.0 mVdec-1, respectively. Examination of morphology of the prepared electrodes using SEM confirmed that the microstructure of the catalyst layer affected with different solvent dielectric constant. Keywords: PEMFC; Gas Diffusion Electrode; Catalyst layer; Oxygen Reduction Reaction; Dielectric Constant.