OXYGEN EVOLUTION IN 30-PERCENT KOH AT 70-DEGREES-C ON NICKEL ANODICALLY COATED WITH COOOH CO3O4

The oxygen evolution reaction (OER) was investigated on polished pure nickel electrodes preanodized for 30 min in nonpurified 30 wt % KOH at 70-degrees-C prior to determinating the kinetic parameters of the OER. The electrolyte contained up to 0.8 mM dissolved cobalt and the preanodization current, i(a), ranged from 0.05 to 5 A cm-2. In the presence of dissolved cobalt, an anodic coating of CoOOH/Co3O4 is formed on the nickel substrate. The electrocatalytic activity increases as i(a) or the concentration in dissolved cobalt is increased. With 0.4 mM dissolved cobalt, the improved electrocatalytic activity is due to a linear increase in exchange current density through the charge associated with the reduction of the loading. The Tafel slope remains unaffected.