SPATIAL DISTRIBUTIONS AND SATURATION NUMBER DENSITIES OF LEAD NUCLEI DEPOSITED ON VITREOUS CARBON ELECTRODES

The nucleation of lead onto vitreous carbon electrodes has been investigated. Diffusion-controlled growth of nuclei inhibits nucleation, giving rise to saturation with nuclei and introducing correlations in their location on the electrode surface. Similar nuclear number densities were obtained from direct, microscopic observation of the surface and from analysis of potentiostatic current transients considering the development of nucleation exclusion zones around already established nuclei. At low overpotentials nuclei were found to be uniformly distributed on the surface, whereas at high overpotentials the results were found to be consistent with simulations of the process that allowed for the existence of exclusion zones around nuclei, with radii proportional to the square root of their age.