Structural Evolution of the Rhodium-Doped Silver Clusters AgnRh (n ≤ 15) and Their Reactivity toward NO

Structural properties of AgnRh (n <= 15) clusters are investigated using a successive growth algorithm coupled with density functional theory computations. The structures of the clusters are revisited, including a detailed discussion of their electronic properties. In contrast to these previous contributions, the lowest energy structures of the clusters are planar for n = 3-6, while three-dimensional for n = 7 onward. Our present searches identify new lowest energy structures for n = 3-6 and 9-13. The most stable isomers are selected to study the adsorption of NO. The size-dependent reactivity of the clusters indicates that Rh atom acts as a more effective adsorption site for NO than Ag. Since the transition from Rh-exposed to Rh-encapsulated structures occurs at n = 9, the reactivity toward NO for AgnRh clusters with n = 8 is considerably higher than that for the larger homologues. Further, the results show that doping Agn clusters with Rh increases the reactivity toward NO adsorption.