Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Reduction of oxygen and oxidation of hydrogen peroxide at the dropping mercury electrode are electrochemical processes strongly influenced both by the pH value and the anions in solution. With decreasing pH, both processes become irreversible, especially in the presence of anions with a negative φ₂ potential of the diffusion part of the double layer. In the case of irreversible oxygen reduction, the concept that the rate-controlling step of the electrode process is the acceptance of the first electron with the formation of the superoxide anion, O₂^-, was substantiated. Oxidation of hydrogen peroxide becomes irreversible at a lower pH value than the reduction of oxygen. The slowest, i.e. rate-controlling step of the electrode process in borate buffers at pH 9-10 is the transfer of the second electron, i.e. oxidation of superoxide to oxygen.