ELECTROCHEMICAL OXIDATION OF ETHANOL IN AQUEOUS CARBONATE SOLUTIONS

The electrochemical oxidation of ethyl alcohol has been studied at pla tinum electrodes in aqueous carbonate solutions employing cyclic volta mmetry (CV), chronoamperometry, chronocoulometry, and impedance measur ements. Two anodic CV peaks are observed during the positive scan and only one cathodic peak is observed during the negative scan when the a lcohol concentration is low. At higher alcohol concentrations, only on e anodic CV peak is observed during the anodic scan due to the electro de passivation beyond the first anodic peak potential, and an anodic p eak attributable to the depassivation of the electrode is observed dur ing the reverse scan. The results are consistent with the formation of passive films of the electrode surface by a reaction of platinum or i ts oxide with ethoxy free radicals. The formation of passive films has been confirmed by the temperature dependency of voltammograms and imp edance measurements.