  The electrochemical oxidation of carbon monoxide adsorbed (COad) 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 COad was analyzed using stripping voltammetry
that involved the deconvolution of COad oxidation peaks of voltammograms to
quantify the weakly and strongly bound species of COad. 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 COad species. Irrespective of the applied potential or
temperature, the concentration of weakly bound COad species decreased
exponentially with time. In contrast, the strongly bound COad species showed a
gradual transition of mechanisms, from progressive nucleation at relatively low
potentials to exponential decay at high potentials.
