O2 EVOLUTION ON NICKEL AFTER PREANODIZATION IN 30 WT-PERCENT-KOH AT 70-DEGREES-C IN THE PRESENCE OF DISSOLVED COBALT

The in-situ activation of nickel anodes in a non-purified 30 Wt % KOH solution at 70-degrees-C has been investigated in the presence of 1 mM dissolved cobalt in the electrolyte. The electrodes were pre-anodized at a current density of 5 A cm-2 prior to determination of the kinetic parameters of the oxygen evolution reaction (OER). The presence of dissolved cobalt in the electrolyte enhances the OER since the accumulation of an anodic coating of CoOOH/Co3O4 on the electrode surface significantly increases the exchange current density, while the Tafel slope remains practically constant with the cobalt loading. The nature and morphology of the anodic coating were investigated by cyclic voltammetry and scanning electron microscopy.