Nucleation and growth of cobalt onto different substrates Part I.: Underpotential deposition onto a gold electrode

The formation and stripping of a cobalt adlayer were studied by electrochemical techniques at underpotential conditions, monitoring the deposition/dissolution onto/from a polycrystalline gold electrode. The kinetics of the former process fit a model where adsorption and diffusion-controlled two-dimensional instantaneous nucleation of cobalt occurs simultaneously onto the gold electrode surface. The latter involves a complex mechanism where adsorption/desorption competes with two processes, an instantaneous nucleation and growth of two-dimensional holes under charge transfer control and a progressive one. However, it was found that the relative contribution of the instantaneous nucleation was the most important independently of the applied potential. (C) 2002 Elsevier Science B.V. All rights reserved.