Institute of Radio Engineering and Electronics, Ulyanovsk Branch,
Russian Academy of Sciences; 48, Goncharov St., Ulyanovsk 432011, Russia;
E-mail: ufire@mv.ru.
Abstract. The electrochemical processes occurring at vitreous carbon electrodes in contact with the solid electrolyte RbCu4Cl3I2 has been investigated. The reaction
Cu+- e- « Cu2+
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 at 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 ® Cu0
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 m2.