Studies in electrocrystallization: Part IV. Experimental investigation of two-dimensional nucleation-growth processes in terms of surface coverages derived from transient measurements

Abstract

The potential step, linear potential ramp and current step perturbation techniques were used to study thin films of calomel, thallous chloride and cuprous oxide on mercury and amalgam electrodes. The electrochemical transients were analysed in terms of surface coverage, the focus being on the presentation of a unified and comparative approach to data analysis. To this end, model-specific normalized variable curves were developed and presented for each perturbation technique and were compared with experimental results. The use of surface coverage as an experimentally accessible parameter has been found to offer certain distinct advantages in characterizing the behaviour of two-dimensional, nucleation-growth processes. The geometric model originated by Fleischmann, Thirsk and their coworkers was critically tested according to this analysis and was found to provide an excellent quantitative description of the transient response of a system perturbed by a potential step. Extension of this model to include potential variation gave successful descriptions of experimental responses to linear potential ramp and current step perturbations.