Electro-oxidation of oxalic acid

• Published in: Electrochimica acta 1986-06, Vol.31 (6), p.645-655
• Main Authors: Vassiliev, Yu.B., Sarghisyan, S.A.
• Format: Article
• Language: English
• Subjects: Chemistry; Electrochemistry; Exact sciences and technology; General and physical chemistry; Kinetics and mechanism of reactions
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/0013-4686(86)87031-1

The major regularities of the oxalic acid adsorption and electro-oxidation on a smooth platinum electrode have been investigated. The effects of the electrode-catalyst nature (platinum, palladium, iridium, rhodium, gold, glassy carbon GC-12, OPTA-platinum—titanium oxide, nickel, osmium) as well as the solvent nature (water, methanol, acetonitrile, N-methylpyrrolidone, dimethylformamide and their mixtures) upon the electro-oxidation rate have been studied. The anion-type particle reversibly adsorbed on the electrode surface has been shown to undergo electro-oxidation. A direct comparison of the results of the adsorption and kinetic measurements carried out under the same conditions has led to the conclusions regarding the mechanism of the electro-oxidation process. The slow step of the process appears to be the transfer of the first electron from the adsorbed anion-type particles to the electrode. Consideration of these particles adsorption energy changes with the surface coverage change due to the presence of repulsive forces as well as a strong inhibition of the process by the adsorbed oxygen enabled us to interpret the kinetic regularities (influence of concentration, pH, potential, etc.). The absence of oxidation in alkaline solutions is accounted for by the fact that due to the shift of the region of oxygen adsorption toward less anodic potentials the adsorbed anion particles of oxalic acid or its monoester are removed from the surface.