Theoretical Investigation of the Stabilities and Reactivities of Au m Cu n ${\rm Au}_m{\rm Cu}_n$ Metallic Clusters (m+n = 13).

Abstract

AuCu nanoclusters have widespread application in reactions like activation of ${\mathrm{CO}}_2$ , selective oxidation, and cross-coupling reactions. In this study, we investigate the stepwise doping of copper atoms in a pure 13-atom gold cluster, denoted as ${\mathrm{Au}}_m{\mathrm{Cu}}_n$ (m+n = 13). The genetic algorithm based on the artificial bee colony algorithm has been utilized to model various isomers of each composition. The potential energy landscape of these clusters was analyzed by means of the density functional theory method with pure Perdew-Burke-Ernzerhof (PBE) functional. We identify the minimum energy isomer for each cluster composition to evaluate molecular properties like HOMO-LUMO gap, binding energy/atom, second order difference in energy, vertical ionization energy, and vertical electron affinity. Notably, the introduction of copper atoms in these clusters enhances their stability and reactivity. Distinct odd-even oscillations due to close shell electronic configurations are absent, as all cluster compositions have an overall open shell configuration. To assess the catalytic activity of the clusters, we study the adsorption energies of small molecules like $O_2$ and $C_2{H}_4$ on all available sites on the cluster. This study thereby comprehensively explores the range of copper-doped 13-atom gold cluster compositions and their implications on their structure-property relationships vital for catalysis and nanomaterial applications.