Identification of different silver nucleation processes on vitreous carbon surfaces from an ammonia electrolytic bath

We performed an electrochemical study of silver electrodeposition from an electrolytic bath containing 1 M NH4OH and 1 M KNO3 (pH = 11), over a Ag(I) concentration range of 10(-4) to 0.3 M, and identified silver nucleation processes on the vitreous carbon surface. Depending upon the silver concentration in the deposition bath, growth occurred either two-dimensionally (2D), controlled by adatom incorporation, or three-dimensionally (3D), controlled by diffusion or lattice incorporation. Qualitative and quantitative characterization of the observed nucleation processes were based on the results of cyclic voltammetry and chronoamperometry analysis. For quantitative characterization, different theoretical models related to electrocrystallization processes were used. Atomic force microscopy (AFM) was employed to probe the surface morphology of the silver deposit. AFM images revealed that silver deposits formed from ammonia baths with different concentrations of Ag(I) ion possess different morphological characteristics. Indeed, many of the surface characteristics clearly corroborated the mechanism of silver deposition proposed by electrochemical analysis. (C) 1998 Elsevier Science S.A.