THE INFLUENCE OF METHANOL ON O(2) ELECTROREDUCTION AT A ROTATING PT DISK ELECTRODE IN ACID ELECTROLYTE

Using a rotating Pt electrode, the simultaneous electro-oxidation of m ethanol and electroreduction or O2 was studied in O2 saturated 0.5M H2 SO4 solutions containing dissolved methanol. The two processes occurre d with no apparent interaction above 0.8 V vs. a reversible H-2 electr ode. At potentials below 0.8 V the net oxidation/reduction current is smaller (i.e., less cathodic) than would be expected if the reactions occurred with no interaction. The evidence suggests that the effect is due to partial poisoning of the O2 reduction process by adsorbed meth anol. At sufficiently low potentials (approximately 0.4 V), O2 electro reduction reaches the same diffusion-limited whether or not methanol i s added. The mechanism of O2 electroreduction appears to remain unchan ged in the presence of methanol.