Density functional theory study of FePdn (n = 2–14) clusters and interactions with small molecules

First-principles calculations have been conducted to investigate the properties of FePdn (n = 2–14) clusters. In the lowest energy structures of FePdn clusters, the Fe atom gradually moves from the convex to the surface, and then to the interior site with the number of Pd atoms increasing from 2 to 14. The magnetic moments of Pdn clusters have been enhanced by the doping of Fe impurity. Furthermore, the adsorption of small molecules, including NH3, H2O, CO, H2, and O2, on the higher stability of FePdn (n = 5, 7, 10, and 12) clusters were studied. The lowest energy adsorption structures are obtained for each molecule. On the whole, the adsorption energies vary as the order of Ea(H2O) < Ea(H2) < Ea(NH3) < Ea(O2) < Ea(CO). NH3, CO and H2 molecules prefer to adsorb on the FePd10 cluster with the highest adsorption energy, while H2O and O2 are more like to adsorb on the FePd5. The magnetic moments of FePdn clusters are reduced with the adsorption of molecules.