Adsorption of a single gold or silver atom on vanadium oxide clusters.

The bonding properties between a single atom and its support have a close relationship with the stability and reactivity of single-atom catalysts. As a model system, the structural and electronic properties of bimetallic oxide clusters MV3Oy(q) (M = Au or Ag, q = 0, ±1, and y = 6-8) are systematically studied using density functional theory. The single noble metal atom Au or Ag tends to be adsorbed on the periphery of the V oxide clusters. Au prefers V sites for oxygen-poor clusters and O sites for oxygen-rich clusters, while Ag prefers O sites for most cases. According to natural population analysis, Au may possess positive or negative charges in the bimetallic oxide clusters, while Ag usually possesses positive charges. The bonding between Au and V has relatively high covalent character according to the bond order analysis. This work may provide some clues for understanding the bonding properties of single noble metal atoms on the support in practical single-atom catalysts, and serve as a starting point for further theoretical studies on the reaction mechanisms of related catalytic systems.