ELECTROSORPTION OF SORBITOL AT PLATINUM-ELECTRODES - EFFECT OF THE SUPERFICIAL STRUCTURE

The electrosorption of sorbitol was investigated at polycrystalline an d single-crystal platinum electrodes in an acidic medium. The coverage degree and the number of electrons per site involved in the electro-o xidation of the adsorbed species coming from the sorbitol were estimat ed from voltammetric measurements carried out at high sweep rates and for adsorption times varying from 0.1 to 500 s. The adsorption process depends on the superficial structure. The electrode surface was never saturated by the organic species coming from sorbitol adsorption and the number of electrons per site was found to be around 3, though this decreased to about 2 after long adsorption times. One of the main ads orbed species present at the electrode surface for long adsorption tim es is linearly adsorbed CO, as confirmed by in situ IR reflectance spe ctroscopy. The presence of other kinds of adsorbed species is also dis cussed.