The determination of kinetics parameters of the hydrogen evolution on Pd-Ni alloys by ac impedance

The hydrogen evolution reaction (HER) at a Pd-Ni electrodeposited alloy ele ctrode has been studied by means of ac impedance spectrum measurements and by de polarization current behavior in 0.5 mol dm(-3) NaOH solution at 25 d egrees C, The rate constants of the forward and backward reactions of the c orresponding steps were estimated by a nonlinear fitting method, It has bee n found that the overall reaction proceeds through a Volmer-Heyrovsky mecha nism, with Heyrovsky as the rate determining step. The coverage vs potentia l relation is discussed comparing the results of ac impedance calculations with the same of potential decay determinations. (C) 2000 International Ass ociation for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.