Electrochemical nucleation and growth of rhodium on gold substrates

The mechanism of rhodium adlayer formation on the (100) face of a gold single crystal and on a polycrystalline gold electrode has been studied using cyclic voltammetry and chronoamperometry. The voltammogram shows the presence of two peaks associated with the deposition of rhodium from the Na3RhCl6 salt in 0.1 M HClO4. The results obtained on the (100) face of a gold single crystal indicate that the two monolayers of rhodium can be deposited before the nucleation and growth of the three-dimensional (3D) rhodium clusters. The experimental results described in this paper show that the bulk rhodium electrodeposition on a gold electrode includes a nucleation process combined with a diffusion-controlled growth of the stable rhodium crystals. The nucleation kinetics is compared for the 3D electrodeposition on the 〈100〉 face of a single crystal gold electrode and on a polycrystalline gold electrode.