Nonelectrochemical pathway of methanol oxidation at a platinum-catalyzed oxygen gas diffusion electrode

Potentiostatic investigations of the methanol oxidation in the absence and presence of oxygen at the three-phase boundary of a Pt-catalyzed gas diffus ion electrode were carried out at several electrode potentials. In the pres ence of oxygen, a purely chemical reaction between oxygen and methanol was observed, with the products being CO2 and water. A study of the rate of CO2 formation and of the electrochemical currents for methanol oxidation showe d that the rate of fuel consumption at the electrode is strongly increased by this chemical pathway. This is accompanied by a considerable decrease in the electrochemical currents for oxygen reduction. In the absence of oxyge n and for potentials above 1.1 V vs. RHE, current oscillations were observe d during the anodic process, which were attributed to the formation of an u nstable layer of surface platinum oxides. (C) 2001 The Electrochemical Soci ety.