Comparative study of carbon monoxide adsorption and oxidation of the chemisorbed species at smooth and platinized platinum electrodes

The adsorption of carbon monoxide and the anodic oxidation of the chemisorbed species were investigated at room temperature under the same experimental conditions on foils of smooth and platinized platinum for which hydrogen adsorption is very similar. Both the weakly and strongly bonded species (type II and type I species) were formed to the same extent on the two electrodes in acidic electrolytes. While the freshly platinized platinum electrode behaved like the smooth electrode with predominance of the one-site adsorption of CO, the aging of the platinized electrode led to an increase of the two-site adsorption. The oxidation rate of strongly bonded species at constant potential decreased when the extent of two-site adsorption increased. The electrochemical results are discussed in the light of recent work in the gas phase.