Hydrogen, oxygen and nitrogen adsorption on Rhn−1X (n = 2–5, X = 3d, 4d atoms) clusters: A DFT study

Abstract

The ground state geometries and electronic properties of Rhn−1X (n=2–5; X=3d, 4d atoms) and Rhn−1X–Y (Y=H, O and N) clusters are systematically investigated by using density functional theory calculations. As compared to that of pure Rhn clusters, the lowest-energy geometries of Rhn−1X clusters have different degree of distortion, which are especially obvious in n=5. The magnetic moments of the mixed clusters with doping Mn and Fe are obviously enhanced, which are mainly derived from the strong spin splitting of d electrons on the doped atoms. By analyzing the adsorption of H, O and N on the mixed clusters, H atom is found to adsorb on the top or bridge site rather than the hollow site, but the adsorption sites of O and N are much more complex. The adsorption energies of O and N are all larger than that of H. The adsorption energies of O are generally stronger than that of N, but in a few cases the opposite is true, which can be attributed to the significant difference in the interaction between the s–p electrons of O, N and the d electrons of the doped clusters. The adsorption energies of O on clusters with doping the early 3d and 4d transition metal atoms are significantly stronger than that with doping the late 3d and 4d transition metal atoms.