Charge separation in CO oxidation involving supported gold clusters

The character of the catalytic oxidation of CO by supported gold cluster catalysts is analyzed with emphasis on the unique characteristics of this process. The scheme of this process used here has the reagent CO molecule captured in the interface between the cluster and support, with oxygen molecules or atoms located on the support surface to react with the CO. (Other models have also been presented.) The experimental data indicate that, together with configurational transitions that lead to the CO molecule joining an oxygen atom to form the CO2 molecule, the charge separation due to capture of the CO molecule by the supported gold cluster is important. The process of release of the CO2 molecule results in charge exchange; the time for this process is relatively long because of the large distance separating positive and negative charges, a distance exceeding the cluster radius. This provides a high efficiency of the oxidation of CO with this catalyst despite the relatively high activation energy for the configurational transition.