ATTEMPTS TO REDUCE THE OXYGEN OVERPOTENTIAL OF Ni ANODES USING ION BEAM MIXING AND ION IMPLANTATION TECHNIQUES

Ni electrodes have been prepared with evaporated surface layers of Ru, Rh, Pd, Ag, Ir and Pt. These are subjected to 80 keV Ar+ bombardment for fluences ranging from 1-6×1016 cm-2. Ni electrodes have also been prepared by direct ion implantation of 50 keV Ru+, Rh+, Pd+, Ag+, Ir+ and Pt+ over the fluence range 0.5-2×1016 cm-2. The distributions of the impurity metals in the Ni are determined by backscattering (RBS) before and after electrochemical polarization measurements. These polarization tests are carried out in an all Teflon electrolysis cell over a range of current densities (0.1-~2000 mA cm-2) using aqueous KOH solution (30%) at 80°C. Initial results have shown that the overpotential can be reduced by up to ~30% at high current densities (1 A/cm2) but this decrease is not reproducible. This appears to be correlated to the growth of an oxide corrosion layer producing an increase in the depth of the impurity atoms and, in some cases, to a dissolution of the impurity atoms into the electrolyte.