Quantifying oxidation rates of carbon monoxide on a Pt/C electrode

Abstract

The electrochemical oxidation of carbon monoxide adsorbed (CO ad) on platinum-on-carbon electrodes was studied via a methodology in which pre-adsorbed CO was partially oxidized by applying potentiostatic pulses for certain durations. The residual CO ad was analyzed using stripping voltammetry that involved the deconvolution of CO ad oxidation peaks of voltammograms to quantify the weakly and strongly bound species of CO ad. The data obtained for various potentials and temperatures were fit to a model based on a nucleation and growth mechanism. The resulting fit produced potential- and temperature-dependent rate parameters that provided insight into the oxidation mechanism of the two CO ad species. Irrespective of the applied potential or temperature, the concentration of weakly bound CO ad species decreased exponentially with time. In contrast, the strongly bound CO ad species showed a gradual transition of mechanisms, from progressive nucleation at relatively low potentials to exponential decay at high potentials.