Electrochemical Reduction of Molecular Oxygen on Hg Adatom-Modified Au Electrode in Organic Media Containing a Small Amount of Water

Electrochemical reduction of molecular oxygen (O2) on an Hg adatom-modified Au electrode in an organic medium was subjected to cyclic voltammetry in order to clarify the catalytic effect of the surface of the Hg adatom-modified Au electrode in the reduction of O2 to hydrogen peroxide (HO2−). Acceleration of the disproportionation of superoxide ions (O2−) could be observed on the Hg adatom-modified Au electrode in organic media (DMF, AN) containing 2.5~3.5 mM H2O, whereas quasireversible O2/O2− redox reaction was observed on a bare Au electrode in the organic solution and on the Hg adatom-modified Au electrode in an organic medium, which had been thoroughly dehydrated. In addition, the extent of acceleration of the disproportionation of O2− was found to depend on the surface coverage (θ) of Hg on the Au electrode surface. These results suggest that the Hg adatom-modified Au electrode surface efficiently catalyzed the disproportionation of O2− by use of a small amount of H2O in an organic medium.