In‐Situ Infrared Spectroscopic Studies of Methanol Electrooxidation on Pt

Nature of the methanol adsorbate on platinum electrode and its role in methanol electrooxidation have been studied by in‐situ infrared spectroscopy.—The infrared adsorption intensities of linear CO(a) derived from CO and methanol respectively on a platinum electrode in 0.5 M sulfuric acid were determined as a function of the total adsorbate coverage.—It has been confirmed based on the quantitative comparison of the infrared absorption intensities that the linear CO(a) is the predominant surface species derived from methanol on a smooth platinum electrode in acidic media. However, presence of minor surface species besides the linear CO(a) has also been suggested for the coverages higher than 0.3.—The linear CO(a) acts as the so called catalysis poison for methanol electrooxidation, which has been confirmed by the following two observations; firstly oxidation of the linear CO(a) observed around 0.5 V is accompanied by a sharp increase of the methanol electrooxidation current, secondly rapid decrease of the methanol electrooxidation current observed while the electrode was held at 0.4 V is accompanied by a steady build up of the infrared absorption band of the linear CO(a).