Kinetics and mechanism of silver chloride electroformation during the localized electrodissolutions of silver in solutions containing chloride

FERNÁNDEZ LORENZO DE MELE, M; SALVAREZZA, R; VAZQUEZ MOLL, V.D.; ARVIA, A.J.

JOURNAL OF THE ELECTROCHEMICAL SOCIETY

ELECTROCHEMICAL SOC INC

Año: 1986 vol. 133 p. 746 - 752

0013-4651

The electroformation of Formula during electro‐oxidation of Ag in neutral Formula solutions is investigated by using potentiostatic and potentiodynamic techniques complemented with SEM observation and EDAX. The kinetics of the electroformation of Formula is interpreted through a complex model that implies the formation of adsorbed Formula species at the submonolayer level, the electrodissolution of Ag through the Formula submonolayer diffusing out of the electrode as a complex ion, and the nucleation and growth of a tridimensional Formula phase. This layer is formed initially as an island‐type deposit that includes Formula precipitation from the solution adjacent to the electrode. The overall process is discussed in terms of a sum of nucleation and growth reactions under diffusion control (multiple region process). The electrode surface is considered as a sum of regions, each one involving its own characteristic growth rate. A probabilistic distribution of regions is postulated to calculate the current transients under a constant potential step. Fitting parameters can be reasonably interpreted at the molecular level. The proposed mechanism correlates with the complex chemical and electrochemical reactions expected for Ag in Formula solutions