Electrodeposition of Cobalt Nanoclusters from Ammonical Chloride Solutions onto HOPG Electrodes. A Kinetical and Morphological Study.

A kinetical study about the Co electrodeposition onto Highly Oriented Pyrolytic Graphite electrodes from an aqueous solution containing 0.01 M CoCl2 + 1 M NH4CI (pH = 7) was conducted at overpotential conditions through potentiostatic studies. The entire chronoamperograms were adequately predicted, considering the contribution to the total current of three different processes: a Langmuir-type adsorption process, a three-dimensional nucleation and growth and a proton reduction process. In all cases, the nucleation rate and the number of active nucleation sites are potential dependent. The Atomic Force Microscopy study revealed the presence of homogeneous cobalt clusters of less of 100 nm in height and 50 nm in diameter at different potential values.