Anodic oxidation of oxalic acid using WOx based anodes

The electrochemical (COOH)(2) oxidation reaction was studied at high potentials (i.e. in the region where O-2 is evolved) in acidic, aqueous solutions using conductive WOx based anodes. The WOx films used as anodes also contained Pt 'micro'-centers. Comparative oxidation studies were also carried out using antimony doped SnO2 anodes. More rapid (COOH)(2) oxidation rates were observed for the WOx based anodes than for the antimony doped SnO2 anodes. The (COOH)(2) oxidation reaction studied under the conditions used in this work was shown to be activation rather than mass transport controlled. The (COOH)(2) oxidation rate constant was found to be independent of the applied potential using the WOx based anodes. This likely suggests that a chemical reaction is involved in the (COOH)(2) oxidation reaction. This chemical reaction is also suggested to be the rate determining step in the (COOH)(2) to CO2 oxidation reaction. Furthermore, it is believed that the (COOH)2 oxidation reaction involves adsorptive interactions of this organic with the Pt/WOx anode surface. (C) 2002 Elsevier Science Ltd. All rights reserved.