A contribution to the kinetics of hydrogen transport through Pd foil electrode during hydrogen extraction under self-discharge and potentiostatic conditions

Abstract

This paper contributes to the kinetics of hydrogen transport through the Pd foil electrode in 0.1 mol l(-1) NaOH solution during the hydrogen extraction from the foil electrode under the self-discharge and potentiostatic conditions by the analysis of open-circuit potential and anodic current transients, respectively. The hydrogen oxidation rate calculated based upon the mixed potential theory just equals the rate of hydrogen self-discharge from the electrode during the OCP transient. When the electrode surface is subjected even to a constant discharging potential, the hydrogen concentration gradient at the surface is given by the Butler-Volmer equation combined with the decay in actual potential jump with time below the transition discharging potential; however, the constant hydrogen concentration condition is satisfied at the surface above this potential. By taking the hydrogen oxidation rate during the OCP transient and the two constraints during the anodic current transient as the boundary condition at the surface, the hydrogen concentration profile transients have been derived during the hydrogen extraction under the self-discharge and potentiostatic conditions, respectively.