Abstract

The activity of Pt, Pt + Pb and Pt + Ir deposits on Ti, for ethylene glycol (EG) oxidation, was studied in both 0.5 M H2SO4 and 0.5 M NaOH solutions. The metallic deposits were prepared by electrolysis at constant current on Ti, with their morphology studied by scanning electron microscopy. These electrodes revealed higher activities in alkaline medium than in acid solutions, the Pt deposits being the most active for EG electro-oxidation. In acid medium, although the electrodes generally showed low electrocatalytic activities, among them Pt + Ir codeposits presented the best performance. Additionally, from activity measurements in acid medium, a synergistic effect for Pt + Ir electrodes was observed. The effect of the supporting electrolyte on the activity of these electrodes is discussed in terms of a reaction path, which is dependent on the OH- anions in alkaline solutions and on the adsorbed (OH)ad species in sulfuric acid solution.