A study of Cu-Rh electrodeposition

This manuscript reports the simultaneous electrodeposition of Cu and Rh from an aqueous nitrate solution. The early stages of nucleation and growth of the bimetallic layer were explored using techniques such as cyclic voltammetry and current transients. Non-dimensional Scharifker-Hills graphs showed the occurrence of diffusion-controlled three-dimensional nucleation and growth best described by the Volmer-Weber mechanism. Additionally, different ratios of Cu-Rh electrodes were synthesized by varying the potential of deposition and the Rh content in the deposition bath. Characterization techniques including electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy were employed to investigate the chemical composition and structure of the deposits. The results showed a higher amount of Cu2+ species in the layer than Cu+/Cu-0 when a more negative potential was applied, and when Rh was present in high amounts in the deposition bath. The final morphology of the obtained material proved to be dependent on the deposition potentials and the Cu : Rh content, showing interdependency between the metals.