Investigation of structural and electronic properties of small Au n Cu m (n+m≤5) nano-clusters for Oxygen adsorption

In this study, the structures, the IR spectroscopy, and the electronic properties of AunCum (n≤5) bimetallic clusters were studied and compared with those of pure gold and copper clusters using the generalized gradient approximation (GGA) and exchange correlation density functional theory (DFT). The study of an O2-AunCum system is important to identify the promotion effects of each of the two metals and their effect in catalysts, sensors, energy sources, or many other applications. This study also demonstrated that the O2 molecule preferred to adsorb at the Cu site rather than at the Au site in bimetallic clusters. O2 adsorption at a bridge site is energetically more favored over the other sites (1- both oxygen atoms are bonded to the same substrate atom 2- O2 is connected to a Cu atom through a single bond) for oxygen adsorption on these clusters. Further, it was concluded that after the adsorption of the O2 molecule on the bimetallic clusters, the Au-Cu interaction is strengthened and the O-O interaction is weakened; the reactivity improvement of the oxygen molecule was clear.