The Electrode Behavior of Platinum

A potential of −0.305 ± 0.005 volt (relative to a saturated calomel electrode) was obtained at a freshly prepared platinum surface within 30 sec. of immersion in oxygen-free N/5 sulphuric acid saturated with hydrogen. In electrolytes saturated with nitrogen or oxygen potentials of +0.05 ± 0.01 volt and +0.745 ± 0.005 volt respectively were more slowly attained. The times required for the electrode to reach maximum potentials, t max , when it was made a cathode, and corresponding values of t max when it was rendered anodic, were determined over a range of currents. The values of t max appear to provide a method of determining the surface areas of platinum electrodes.