Grant Johnson - Influence of charge state on the mechanism of CO oxidation on gold clusters

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      Volume:   130

        Issue: 5

        Pages: 1694-1698


    Published: FEB 6 2008


        We present results from our joint experimental and theoretical   study of the reactivity of anionic and cationic gold oxide   clusters toward CO, focusing on the role of atomic oxygen,   different charge states, and mechanisms for oxidation. We show   that anionic clusters react by an Eley-Rideal-like mechanism   involving the preferential attack of CO on oxygen rather than   gold. In contrast, the oxidation of CO on cationic gold oxide   clusters can occur by both an Eley-Rideal-like and a   Langmuir-Hinshelwood-like mechanism at multiple collision   conditions as a result of the high adsorption energy of two CO   molecules. This large energy of CO adsorption on cationic gold   oxide clusters is the driving force for the CO oxidation.   Therefore, in the presence of cationic gold species at high   pressures of CC, the oxidation reaction is self-promoting (i.e.,   the oxidation of one CO molecule is promoted by the binding of a   second CO). Our findings provide new insight into the role of   charge state in gold-cluster-based nanocatalysis.

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