Adsorption of CO and O2 on AumCun clusters: First principles calculations

The adsorption of CO and O2 molecules on Aun (n = 2-5), Cun(n = 2-5), and AumCun (m = 1, 2, 3; 1 ≤ n ≤ 6) clusters is investigated in the framework of density functional theory. The equilibrium atomic geometry and electronic structure of each cluster are determined. It is found that Aun (n = 2-5) clusters show strong reactivity toward CO, while they do not bind to molecular oxygen. High adsorption energy values can be obtained for odd number of Cun clusters for both CO and O2 adsorptions. Cu top site is energetically preferred for the adsorption of both CO and O2 molecules in AumCun clusters. The results of electronic density of states show an sp hybridization between Cu and O atoms in O2 adsorbed AumCun clusters. This interaction plays a major role in their binding. The highest occupied molecular orbital and the lowest unoccupied molecular orbital energy gap values and charge density differences are presented. There are charge transfers from s and d orbital electrons of Cu to p orbitals of C and of O atoms. It is observed that O2 adsorption on some clusters can induce half metallicity which is an ideal property for possible applications in spintronics.