Evaluation of the influence of impurities on the oxygen sensitivity of monocrystalline antimony electrodes

Measurements are presented which show that the oxygen sensitivity of ultra pure (6N) monocrystalline antimony electrodes presents an improved reproducibility and constancy as compared with monocrystalline electrodes containing impurity inclusions in the electrode surface. The former electrodes also present a higher potential stability. The time to reach a pseudo-stable potential level (drift <0.6 mV/h) is also faster for this type of electrodes. The improved characteristics of the ultra pure electrodes are thought to be due to a uniform distribution of the anodic and the cathodic areas over the electrode surfaces. On the electrodes with impurity inclusions exposed in the surfaces, a high degree of local corrosion was noted. The oxygen sensitivity of the ultra pure electrodes, dE/d(log p_O2), was found to be 15.3 ± 0.7 and 15.7 ± 0.8 mV, 5 and 25 h after immersion of the electrodes in the electrolyte respectively.