(91g) Electrochemical Impedance Analysis of Formic Acid Electrooxidation

Formic acid has drawn increased interest for use in direct liquid fuel cells as well as serving as a model compound for other small organic molecules. In this work, electrochemical impedance spectroscopy is utilized to investigate the electro-oxidation of formic acid on a smooth polycrystalline platinum electrode in a sulfuric acid solution. While there is broad agreement about the basic aspects of the mechanism of formic acid electrooxidation, there remains some disagreement on some specific aspects, in particular the nature of some of the intermediates formed. Equivalent circuits are derived from the various proposed mechanisms and the quality of the fit of these to the impedance data is examined. Key kinetic parameters have also been extracted from the impedance data.