The kinetics of zinc dissolution in chloride electrolytes: Impedance measurements and electrode morphology
Résumé
Complex plane impedance plots, obtained during the anodic dissolution of zinc in NH4Cl and in NH4Cl+ZnCl2 electrolytes, reveal three relaxation processes at low frequencies. It is concluded that the mechanism of zinc dissolution involves two adsorbed intermediates and implies a slow electrode activation with increasing anodic polarization. The strong stimulation of zinc dissolution by chloride anions appears to be consequent on their influence on several elementary steps of the reaction mechanism. Different steps of this reaction mechanism are decelerated in the presence of tetrabutylammonium bromide which inhibits both the formation of an insoluble oxidation product and the dissolution of zinc.