Structural, electronic and catalytic properties of AgnSnn (n = 2-14) clusters by density functional theory.

Density functional theory (DFT) calculations of clusters were carried out to investigate the structural and electronic properties of AgnSnn (n = 2-14) clusters. Their lowest energy structure, average binding energy, second-order differential energy, HOMO-LUMO energy gap and density of states were analyzed. The reactions of carbon monoxide and oxygen on the Ag8 cluster and Ag4Sn4 cluster were compared to measure the adsorption and catalytic properties of the Ag4Sn4 cluster. The results show that Ag atoms gather together and are encapsulated by peripheral Sn atoms. The Ag4Sn4 cluster has a magic size. The sp-hybridization plays a crucial role in AgnSnn clusters. For both CO and O2 adsorption, the effect of the Ag4Sn4 cluster is better than that of the Ag8 cluster. The addition of an equal proportion of Sn atoms enhanced the catalysis compared to the Ag8 cluster with the same number of atoms. Our results suggest that the addition of Sn atoms can be an efficient and attractive way of tuning the adsorption ability and reactivity of silver clusters and can provide constructive input for the design of efficient nanocatalysts.