Role of adsorbed species for the anodic methanol oxidation on platinum in acidic electrolytes

Abstract

The effect of anions on the oxidation of chemisorbed carbonaceous species formed during the anodic oxidation of methanol is attributed to a displacement of the discharge of water molecules to more positive potentials with increasing adsorbability of the anions. The efficiency of CO₂ production decreases from about 90% at a methanol bulk concentration of 0·01 M to about 10% at 5 M in 0·5 M H₂SO₄ at constant potential between 0·5 and 0·7 V. The comparison of the maximum rates of individual reactions with the net rate and the efficiency of CO₂ production leads to the conclusion that the CO₂ evolution does not occur predominantly by the formation and oxidation of the carbonaceous species.