Kinetic and morphological study of copper electrodeposits onto glassy carbon electrodes from an electrolytic bath containing perchlorate ions
摘要
A kinetic and morphological study of copper electrodeposition onto glassy carbon electrodes (GCE) was performed using cyclic voltammetry and chronoamperometry in an aqueous 0.001 M Cu(ClO4)2·6H2O solution with 0.1 M NaClO4 as supporting electrolyte at pH 5.5. Electrochemical results indicate that copper deposition is diffusion-controlled and proceeds via a progressive nucleation mechanism. Cyclic voltammograms display a well-defined cathodic peak corresponding to the Cu2⁺/Cu⁰ redox couple, preceded by a distinct cathodic pre-peak at more positive potentials, associated with the initial stages of nucleation. A kinetic analysis based on potentiostatic transients allowed the determination of key parameters, including the nucleation rate constant (A), the number of active nucleation sites (N0), and the diffusion coefficient (D). Morphological characterization by scanning electron microscopy (SEM) shows that at low overpotentials (0.020 and 0.0 V), copper deposits consist of well-defined cubic and prismatic nanocrystals with sizes ranging from 100 to 200 nm, exhibiting faceted morphologies dominated by {100} planes. The presence of these faceted structures indicates crystallographically controlled growth during the early stages of deposition. As the applied overpotential becomes more negative, a transition to a high-density nucleation regime is observed, leading to the formation of a larger number of smaller nuclei and a progressive loss of faceting. This morphological evolution is accompanied by a systematic decrease in particle size, reaching values between 15 and 25 nm at − 0.100 V, consistent with a shift from growth-dominated to nucleation-dominated deposition. Energy-dispersive X-ray spectroscopy (EDS) confirms that the observed nanostructures are composed exclusively of copper.