Charge Transfer Stage during Potentiostatic Formation of Zinc Nuclei on Carbon Electrode from Zincate Solution

Abstract

This work is devoted to an investigation of the dynamics of charge transfer ηD and crystallization ηc overpotentials during potentiostatic formation of zinc atoms adsorbed on an isotropic pyrolytic carbon electrode in a zincate solution. We found two reasons for time dependent decrease of ηD. The first, the exchange current increases due to gradual activation of the electrode surface by the applied potential pulse. The second reason is increase of the supersaturation. Activation of the electrode is suggested to consist in reduction of oxygen- containing carbon compounds followed by adsorption of water molecules, which participate in the rate-controlling stage of [Zn(OH)3H2O]- ion reduction. The time dependent change of the crystallization overpotential as a constituent of the total overpotential η causes redistribution of the ηD and ηc terms.