Reactant-Promoted Oxygen Dissociation on Gold Clusters

The molecular and dissociative adsorption of O₂ on pure odd-size Au_n (n = 1, 3, 5, 7, 9) clusters and Au_n with a coadsorbed C₂H₄ molecule has been studied theoretically using density functional theory. It is demonstrated that catalytic activation of the adsorbed O₂ on pure gold clusters in the considered size range cannot lead to O₂ dissociation. Coadsorption of C₂H₄, however, involves an extra charge transfer from the gold cluster to O₂, energetically promoting oxygen dissociation. Our finding indicates that O₂ dissociation on the surface of small gold clusters is sensitive to the presence of other adsorbates, including the reactant molecule itself. This effect can be particularly important for understanding the mechanism of catalytic oxidation on gold clusters.