Oxidation of CO adlayers on Pt(111) at low potentials: an impinging jet study in H2SO4 electrolyte with mathematical modeling of the current transients

The const. potential oxidn. of adlayers of CO on a bead type Pt(111) electrode created by the impinging jet flow technique has been studied in 0.5 and 0.05 mol dm-​3 H2SO4 electrolyte.  Washing procedures were developed which allowed work to be carried out for long periods of time without contamination problems.  At low potentials (<680 mV vs.RHE) in 0.5 mol dm-​3 H2SO4 the compact adlayers were slowly oxidized in a process which first involved a const. current plateau followed by a single sym. peak.  The total oxidn. charges of the transients corresponded to that of a compact CO adlayer and the peak charges to that calcd. from data reported in the literature for a looser adlayer structure.  In 0.05 mol dm-​3 H2SO4 the adlayers oxidize much faster and the oxidn. process is more complex.  The current-​time traces for the stronger electrolyte were described well by an equation esp. derived for the oxidn. kinetics under the particular conditions used in this work.  Values for a potential dependent rate const. for the oxidn. were detd. by means of curve fitting.