Methanol oxidation in a non-aqueous solvent

Abstract

The methanol oxidation reaction has been studied in trifluoromethanesulphonic acid monohydrate solutions containing low concentrations of water. Cyclic voltammetry and potentiostatic polarisation curves clearly indicate the central role of water in the oxidation scheme. Peak methanol oxidation currents obtained during the positive-direction sweep in cyclic voltammograms exhibit a first-order dependence on water concentration. These peak currents occur at potentials more positive than in aqueous sulphuric acid electrolytes and can be attributed to the fact that oxygen is adsorbed at higher potentials in the non-aqueous (or low water) systems. The relationship between peak oxidation potential and water concentration indicates that bulk H₂O is not the active species involved in the current producing reaction. Tafel slopes from the foot of the oxidation peak suggest that an irreversible one-electron transfer process is rate limiting.