Mechanism of the electrooxidation of methanol on an iridium electrode

1. The slow step of the electrooxidation of methanol on an iridium electrode is the oxidation of chemisorbed carbon-containing particles, formed as a result of adsorption, with dehydrogenation of the methanol by the adsorbed OH particles. 2. All the kinetic principles of the oxidation of methanol on an iridium electrode correspond to the kinetics of processes on an exponentially inhomogeneous surface. 3. In contrast to platinum, the adsorption of oxygen on iridium begins at more negative potentials; therefore the process of oxidation probably proceeds in the presence of coverage by OH particles >0.1, as a result of which the true Tafel slope is equal to 0.120 V. 4. The rate of oxidation of methanol on iridium is 1.3–1.5 orders of magnitude lower than on platinum under the same conditions.