ELECTROCHEMICAL AND SURFACE CHARACTERIZATION OF ELECTROCATALYTICALLY ACTIVE AMORPHOUS NI-CO ALLOYS

The electrochemical behaviour of electrocatalytically active amorphous Ni-Co alloys together with their crystalline counterparts have been studied by means of cyclic voltammetry (cv) in conjunction with X-ray photoelectron spectroscopy (XPS). The cv profiles of these alloys are quite different when tested after steady state polarization compared with potential cycling. The electrochemical behaviour of Ni-Co alloys shifted substantially from characteristics of Co to those of Ni. XPS analysis was used to identify the changes in surface oxidation species caused by electrochemical treatments. The oxides formed on amorphous alloys are different from those on crystalline alloys, in terms of their oxidation states, the amount of hydroxyl ions and solvent, film thickness, and ratio of components in the film. Furthermore, a hydrous oxide film, consisting of a micro-porous structure filled with solvent and hydroxyl ions, which is electrocatalytically active for the oxygen evolution reaction, was formed on potential cycled amorphous Ni-Co alloys.