Potentiostatic investigation of the vitreous carbon / RbCu₄Cl₃I₂ interface

Abstract

The electrochemical processes occurring at vitreous carbon electrodes in contact with the solid electrolyte RbCu₄Cl₃I₂ has been investigated. The reaction

$$Cu^ + - e \leftrightarrow Cu^{2 + } $$

in the range of potentials −0.05...+ 0.57 V on the electrode takes place. The exchange current density of this reaction is about 25·10⁻² A·m⁻². The rate of the electrode processes is controlled by the slown diffusion of Cu²⁺ ions near the electrode. The diffusion coefficient of Cu²⁺ ions in the electrolyte is about 1.5·10⁻¹² m²·s⁻¹.

At potentials higher than 0.57 V on the electrode surface, a divalent copper phase is deposited. The rate of this process is controlled by the instantaneous nucleation and the two-dimensional growth of the phase.

At potentials lower than −0.05 V, the reaction

$$Cu^ + - e \to Cu^0 $$

begins at the electrode and metallic copper is deposited. The rate of this reaction is controlled by the instantaneous nucleation and the three-dimensional growth of the deposit. Perpendicular to the electrode surfaces, the growth rate of the deposition has the order of magnitude of 10⁻⁹ m·s⁻¹ and the quantity of nuclei is not less than 10¹² m⁻².