Nucleation and Growth of Zinc from Chloride Concentrated Solutions

Abstract
The electrodeposition of metals is a complex phenomenon influenced by a number of factors that modify the rates of nucleation and growth and determine the properties of the deposits. In this work we study the influence of the zinc chloride concentration on the zinc nucleation process on glassy carbon, in a KCl electrolyte under conditions close to those employed in commercial acid deposition baths for zinc. The electrochemical study was performed using cyclic voltammetry and potentiostatic current‐time transients. The charge‐transfer coefficient and the formal potential for reduction were evaluated from cyclic voltammetry experiments. The nucleation process was analyzed by comparing the transients obtained with the known dimensionless (i/i m)2 vs. t/t m reponse for instantaneous or progressive nucleation. The results show that the nucleation process and the number density of sites are dependent on concentration. Scanning electron microscopy analysis of the deposits shows that the deposits are homogeneous and compact although a change in the morphology is observed as a function of concentration. Evaluation of the corrosion resistance reveals the influence of the nucleation process on the subsequent corrosion resistance of the zinc deposits.