Cathodic processes in the ligand-deficient Cu/Cu(II) ethylenediamine system

A plateau of a limiting current observed on voltammograms in the ligand-def icient Cu/Cu(II) ethylenediamine system is a prewave resulting from abrupt changes in the solution composition at the electrode surface. Voltammograms may be described quantitatively by equations of formal kinetics accounting for two consecutive one-electron transfers provided that the process of Cu 2+ + e(-) --> Cu+ is a rate-determining step. Cu2O developed under open-cir cuit conditions exhibits properties typical of an adsorbed layer. The excha nge current density of Cu(II) reduction decreases with the thickness of suc h layers. The irreversible reduction of Cu2O occurs at sufficiently high ca thodic overvoltages, resulting in a significant activation of the electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.