VOLTAMMETRIC STUDY OF THE ELECTROCHEMICAL-BEHAVIOR OF GLYCOLIC ACID-SOLUTIONS IN SULFURIC-ACID ON PLATINUM SINGLE-CRYSTAL ELECTRODES WITH BASAL ORIENTATIONS

The electrochemical behaviour of glycolic acid has been studied on platinum single crystals with basal orientations in sulphuric acid. The bulk oxidation of glycolic acid proceeds at high potential values, where extensive adsorption of oxygen exists on the electrode surface, making the preservation of surface structure impossible. The observed behaviour at lower potentials can be summarized by two points. Evidence exists of specific adsorption of the glycolate anion, which is more strongly adsorbed than bisulphate. Blocking of electrode surfaces is also observed for the three planes studied, although no significant surface poisoning was observed under open-circuit conditions. Experimental data indicate the absence of a CO-like adsorbed species on Pt(111) and Pt(110), and suggest the existence of structures preserving the C-C bond. Conversely, CO(ads) is the main poison on Pt(100).