Zinc electrodeposition from chloride solutions onto glassy carbon electrode

Abstract

An electrochemical study of zinc deposition was carried out in baths containing 0.5 M ZnCl2 and 0.4 M H3BO3. From the voltammetric study it was found that, in our experimental conditions, zinc electrodeposition is quasi-reversible and occurs under charge transfer control. The average coefficient diffusion calculated was D = 7.14 x 10-6 cm2s-1 while the standard constant at electrode charge was 8.78 x 10-3 cms-1. The nucleation and growth parameters determined from the potentiostatic study showed that, at bigger overpotentials, a vertical growth is favored, suggesting a dendritic growth. The critical cluster's size calculated was 2, indicating that each active site is formed by two zinc atoms on the glassy carbon electrode (GCE) surface, while the ΔG for the formation of stable nucleus was 1.35 x 10-20 J/nuclei. The Scanning Electron Microscopy images showed thin platelets of hexagonal crystals and dendrites at lower and higher overpotentials applied, respectively. © 2009, Sociedad Química de México.