Electrochemical Behavior of Copper in CuCl2 Silica Sol and Aqueous Solutions

Electrodeposition and electrocrystallization of copper on glass carbon electrode from both CuCl2 silica sols and aqueous solutions were investigated by utilizing cyclic voltammetry and chronoamperometry, respectively. The experiment results indicated that copper electrodeposition involved the two-step reaction in both electrolytes, and the deposition rate determining step (Cu2+ reduced to Cu+) in silica sol was easier than that in aqueous solution. An adsorption-nucleation model was proposed to analyze quantitatively the current-time transients (CTTs), which could separate the i(DL) and i(nucleation) Perfectly. By the proposed model, copper electrocrystallization mechanism was characterized as progressive nucleation with 3D growth (3DP) under diffusion control. The diffusion coefficient of copper ions in silica sol was smaller than that in aqueous solution. However, the saturated nuclear number density in sol was larger than that in the aqueous solution at the same potential.