Carbon monoxide adsorption on Pt/Pt electrodes modified with silver adatoms

Adsorption of carbon monoxide on the Pt/Pt surface in the presence of preliminarily accumulated different amounts of UPD silver (θAg) is studied by using voltammetry, electrode washings, and analytical techniques. It is found that carbon monoxide is adsorbed only on the sites unoccupied by Agad and rather than displacing the latter atoms to the noticeable extent. The fraction of carbon monoxide chemisorbed in the linear form increases with θAg. The shape of anodic voltammetric curves and the number of peaks in the region where the mixed layer COads + Agad is desorbed strongly depend on the COads : Agad ratio; at small and medium θ Ag, three and more peaks are observed. Electroanalytic detection of silver passed to solution in various potential ranges in the course of the mixed-layer oxidation allowed us to identify the processes corresponding to different peaks.