Molecular oxygen adsorption and dissociation on Au₁₂M clusters with M = Cu, Ag or Ir

Abstract

In this work, we present a density functional theory study of the structural and electronic properties of isolated neutral clusters of the type Au₁₂M, with M = Cu, Ag, or Ir. On the other hand, there is experimental evidence that gold-silver, gold-copper and gold-iridium nanoparticles have an enhanced catalytic activity for the CO oxidation reaction. In order to address these phenomena, we also performed density functional calculations of the adsorption and dissociation of O₂ on these nanoparticles. Moreover, to understand the effects of Cu, Ag, and Ir impurity atoms on the dissociation of O₂, we also analyze this reaction in the corresponding pure gold cluster. The results indicate that the substitution of one gold atom in a Au₁₃ cluster by Ag, Cu or Ir diminishes the activation energy barrier for the O₂ dissociation by nearly 1 eV. This energy barrier is similar for Au₁₂Ag and Au₁₂Cu, whereas for Au₁₂Ir is even lower. These results suggest that the addition of other transition metal atoms to gold nanoclusters can enhance their catalytic activity towards the CO oxidation reaction, independently of the effect that the substrate could have on supported nanoclusters.

Graphical abstract