Qualitative Analysis of the Frumkin Adsorption Isotherm of the Over-Potentially Deposited Hydrogen at the Poly-Ni/KOH Aqueous Electrolyte Interface Using the Phase-Shift Method

Abstract

The phase-shift method of the Frumkin adsorption isotherm of the over-potentially deposited hydrogen (OPD H) for the cathodic evolution reaction (HER) at the poly-Ni/0.05 M KOH aqueous electrolyte interface has been studied using cyclic voltammetric and ac impedance techniques. The behavior of the phase shift for the optimum intermediate frequency corresponds well to that of the fractional surface coverage at the interface. The phase-shift method, i.e., the phase-shift profile vs. for the optimum intermediate frequency, can be used as a new method to estimate and analyze the Frumkin adsorption isotherm (θ vs. of the OPD H for the cathodic HER at the interface. At the poly-Ni/0.05 M KOH aqueous electrolyte interface, the rate of change of the standard free energy of the OPD H with θ, the interaction parameter for the Frumkin adsorption isotherm, the equilibrium constant for the OPD H with θ, and the standard free energy of the OPD H with θ are 24.8 kJ/mol, 10, and respectively. The electrode kinetic and thermodynamic parameters depend strongly on θ © 2002 The Electrochemical Society. All rights reserved.