Adsorption of SO, CO, O2, and N2 on the most stable small Fe clusters

Abstract

Electronic, structural, and magnetic properties of small Fen aggregates with n < 15 atoms were investigated in the framework of the density functional theory (DFT). Our results indicate that spin–orbit coupling has little effect on the structural properties. The magnetic moment of each atom in the cluster is greater than the magnetic moment of their bulk material and the average binding energy value rises monotonically with the size of the cluster and approaches the bulk value. As well as Fe7 and Fe13 are the two first magic numbers in good agreement with experimental reports. We studied the adsorption of diatomic SO, CO, O2, and N2 molecules on the Fe7 and Fe13 nanoclusters. The most stable adsorption sites, binding energies, and the effect of adsorption on the electronic properties of the Fe clusters were studied. The different aspects of the adsorption mechanism were also investigated. The interaction intensity order is SO, O2, CO, and N2, and the bond length of the molecules increased after adsorption. X@Fe13 (X = SO, O2, CO, and N2) systems represent higher magnetization compared to the X@Fe7 systems. The maximum effect of absorption on the magnetization of the Fe13 cluster was about 2.4% and on the Fe7 cluster was about 9.6%. These results provide insights into the application of iron-based catalysts and the understanding of the real reactions and experimental reports.