Cathodic and anodic deposition of mercury and silver at boron-doped diamond electrodes

• Published in: Journal of the Electrochemical Society 1999, Vol.146 (1), p.125-130
• Main Authors: VINOKUR, N, MILLER, B, AVYIGAL, Y, KALISH, R
• Format: Article
• Language: English
• Subjects: Chemistry; Electrochemistry; Electrodeposition; Exact sciences and technology; General and physical chemistry; Study of interfaces
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1391574

The mechanisms of silver and mercury metal deposition on boron-doped diamond electrodes were investigated using a prior model of three-dimensional diffusion controlled nucleation/growth to interpret the data. The mechanism of nucleation depends upon the nucleation overpotential and metal ion concentration. At low overpotentials, instantaneous nucleation can be observed and, at high overpotentials or concentrations, the process becomes progressive. No underpotential phenomena are observed, consistent with exceptionally weak interaction between the deposited metal and the diamond surface. Active sites corresponding to a low density of surface sites on the electrode which act as critical nuclei during the electrodeposition. Anodic reactions of silver were also investigated. It was found that the resulting product depends on the silver concentration in the solution. Soluble Ag(II) forms only at low concentration ( < 0.5 mM Ag exp + ). Increasing concentration leads to formation of sparingly soluble oxysalts of formula Ag sub 7 O sub 8 X, where X is NO sub 3 exp - or ClO sub 4 exp - , with voltammetric characteristics and adhesion similar to these found for cathodic metal deposits.