An experimental investigation by electrochemical impedance spectroscopy for the study of mechanism of copper electrodeposition from an acidic bath

Abstract The mechanism of copper electrodeposition with varying potential investigated by using electrochemical impedance spectroscopy (EIS) has been reported in this current study. The bath of the deposit has limited and unlimited supply of copper ions to the substrate by using two counter electrodes i.e., platinum (Pt) and copper (Cu) respectively. The electrodeposition of copper on graphite electrodes was investigated by utilizing cyclic voltammetry (CV), potentiostatic and EIS methods. On the Nyquist plots, copper ion charge transfer is represented by a single capacitive constant at high frequencies while copper ion diffusion from the solution to the electrode surface is represented by a Warburg-type contribution at low frequencies. The corresponding Bode plots represent a decent matching between the experimental and fitting data. The effect of potential on double-layer capacitance, diffusion coefficient, and diffusion layer thickness along the interface of electrode and electrolyte has been discussed extensively. The morphologies of the copper particles depositing on the surface of the electrode were also studied and it shows a transition from spherical to dendritic structure as a function of deposition potential.