SOME ASPECTS OF THE REDUCTION OF OXYGEN AT A PLATINUM-OXYGEN ALLOY DIAPHRAGM

The steady-state galvanostatic polarization curve was obtained on the front side of a Pt diaphragm in contact with O2-stirred 2N H2SO4 solution while the back side was in contact with concentrated HNO3. From low oxygen overvoltage (O2-n) measurements it is shown that the rest potential is the reversible O2 potential. The rate of O2 reduction on the Pt-O alloy diaphragm is lower at high current densities than on a bright Pt cathode. At very high current densities the system is driven into the H2-evolution region where the H2-n is close to the literature values for the Ha-n on bright Pt. When the system was returned to open-circuit, the rest potential returned to the normal oxygen potential after about 24 hr. This time delay represents the time required to repair the complete layer of adsorbed oxygen atoms which had been removed by the strong cathodic current. © 1979, The Electrochemical Society, Inc. All rights reserved.