CATHODIC OXYGEN REDUCTION AT A ROTATING AMALGAMATED GOLD DISK ELECTRODE IN AQUEOUS ALKALINE-SOLUTIONS OF MIXED IONIC COMPOSITION

Cathodic oxygen reduction in aqueous alkaline solutions of mixed ionic composition but constant ionic strength: 0.05 mM [(CH3)4N]OH + 0.05(1 - m) M[(C4H9)4N]OH and 0. 05 mM Na OH + 0.05 (1 - m) M[(C4H9)4N]. OH, was studied by polarization measurements at a rotating amalgamated gold disk electrode. It was found that in both cases, added tetrabutylammonium (TBA+) ions slow down the oxygen electroreduction reaction. At potentials corresponding to a displacement of the TBA+ ions from the surface by cations of smaller radius (Na+, tetramethylammonium TMA+), the reaction is sharply accelerated, though only at sufficiently high m-values. In aqueous solutions, low added concentrations of the cations mentioned are ineffective, in contrast to systems in aprotic solvents. The contribution provided to acceleration of the reaction by the change in psi1-potential that occurs on account of TMA+ ion adsorption was estimated, and it was found that this change is not the only reason for the accelerating effect of TMA+ ions on the electrode reaction.