O2 adsorption and dissociation on neutral, positively and negatively charged Aun (n = 5–79) clusters

Abstract

The adsorption and dissociation of an O₂ molecule on gas-phase gold clusters of size varying from 5 to 79 atoms have been investigated by means of first principles density functional theory calculations. The adsorption energies and dissociation barriers have been determined for neutral, positively and negatively charged gold clusters in order to analyze in a systematic way the role of the charge on the cluster reactivity. While there is beneficial effect on O₂ activation of an extra electron on the small gold clusters (Au₅ and Au₁₃), the effect is absent for positively charged clusters. The effect of the charge vanishes rapidly by increasing the cluster size and is not visible for clusters containing about 40 atoms or more. Au₃₈ appears to be the most reactive among the clusters considered and strong oscillations in adsorption energies and dissociation barriers are found even for clusters containing several tens of atoms like Au₃₈, Au₅₅, and Au₇₉.