Formic Acid Electrooxidation on Platinum, Resolution of the Kinetic Mechanism in Steady State and Evaluation of the Kinetic Constants

Abstract

A kinetic mechanism recently proposed for the formic acid oxidation (FAO) on platinum in acid solutions was analytically solved in order to verify its capability to correlate experimental measurements in steady state conditions. It involves three adsorbed reaction intermediates (COad, HCOOad, OHad) and two reaction pathways. The derived kinetic equations enabled the fitting of the experimental current-potential curves at three different formic acid concentrations, as well as the evaluation of the corresponding kinetic constants of the elementary steps involved in the mechanism. An expression for the variation of the COad surface coverage on potential was included in the calculations, obtained from measurements of the oxidation charges by voltammetric stripping. Finally, the dependences of the surface coverages of OHad and HCOOad on potential could be simulated, which are consistent with results obtained by other authors through spectroscopic techniques.