ELECTROCHEMICAL INTERCALATION AND OXIDATION OF GLYOXYLIC-ACID INTO A HIGHLY ORIENTED PYROLYTIC-GRAPHITE (HOPG) ELECTRODE

The intercalation and electrooxidation of glyoxylic acid in 0.1 M KOH solutions in a highly oriented pyrolytic graphite electrode (HOPGE) ha ve been studied. The values of Tafel slopes, reaction orders and appar ent activation enthalpy determined resulted in an experimental rate eq uation as follows: I = nFK C-Glycox exp [0.44 FE/RT]. A five step mech anism can be given to explain the expression, where a first intercalat ion step is followed by a single electron transfer from the inserted g lyoxylate ions towards the host graphite layers. At the end, CO2, CO a nd water are obtained as reaction products which give rise to localize d strains with the result of a sudden exfoliation of the electrode.