DETERMINATION OF POSSIBLE REACTION-MECHANISMS OF METHANOL ELECTRO-OXIDATION IN AQUEOUS ACIDIC SOLUTIONS

Methanol electro-oxidation has been extensively studied in view of methanol fuel cell applications. In this work the mechanism of methanol electro-oxidation is generally discussed on the basis of Horiuti's rate theory, in which the reaction processes under steady-state conditions are taken into account. In the analysis, the interaction between the adsorbed species was found to be expressed by a linear approximation (Temkin) adsorption isotherm. As a result, adsorbed CH3O or CH3OH with adsorbed H2O or OH, respectively, is suggested to be the intermediate of the reaction under steady-state conditions; their reaction step is the rate-determining step (rds). The present analysis is supported by evidence of the absence of a deuterium-protium exchange reaction between CD3OD and H2O; the hydrogen of the methyl group is not released by the preceding steps of the rds.