Comparative Investigation on the Adsorption Properties of Precious Metal Clusters toward NO:  A Density Functional Study

Abstract

The adsorption properties of precious metal clusters such as Rh, Pd, Ag, Ir, Pt, and Au toward NO were systematically investigated using the density functional calculations. It was found that the most energetically stable adsorption state of NO on the tetrahedral M 4 clusters was found to be the NO/Ir 4 system. The ability of the precious metal clusters to activate the N-O bond was also discussed mainly from a geometric point of view. The entire linear behavior of the elongation of the N-O bond of NO molecules adsorbed on M 4 clusters was observed with increasing values of the molecular charge on the NO molecules, which suggests the back-donation of an electron to the 2π* orbital of the NO molecules. The substantial elongation of the N-O bond was found on the NO/Ir 4 system, which was nearly equal to that on the NO/Rh 4 systems. These results indicate that the Ir cluster has the best properties for the adsorption and activation of NO.

Adsorption of small molecules on helical gold nanorods: A relativistic density functional study

“…The AuAN bond length is 2.27 Å and the stretching frequency is 310.9 cm 21 . This is similar to ammonia adsorption on Au 20 , in which NH 3 interacts via the N atom at the apex site of Au 20 and the adsorption energy is 11.70 kcal/mol and the AuAN bond length is 2.349 Å . [53] This is in accordance with the result that the anchoring AuAN interaction is dominant for gold clusters and is stronger for larger gold clusters.…”

“…[28][29][30][31][32][33] Although impressive progress has been achieved in understanding the adsorption of small molecules on small gold clusters, computational studies for large gold clusters are generally lacking. A notable exception is the study of Gao et al [34] which examined the adsorption of CO on free subnanometer gold clusters (Au 16 -Au 18 , Au 20 , and Au 27 -Au 35 ).…”

Interplay between bonding and magnetism in the binding of NO to Rh clusters

“…The lowest-energy configuration found by us corresponds to a tetrahedron with a spin multiplicity of 7; this is in agreement with one set of earlier calculations. 25 We find two energetically degenerate isomers that lie higher than this by an amount of 0.05 eV/atom: a square geometry with a spin multiplicity of 5, and a non-magnetic tetrahedron. We note that some previous studies 7, 21,23 have claimed that the latter configuration corresponds to the lowest-energy isomer.…”

The simple cubic structure of Ir clusters and the element effect on cluster structures

“…The group 8-10 precious metals (Ru, Rh, Pd, Os, Ir, Pt) are well known as effective catalysts in chemical and automobile industries [1][2][3][4][5]. It has been found that small clusters of these metals are better catalysts with a strong dependence on the cluster size [1,2].…”