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

Abstract

Structural properties of Ag n Rh (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 threedimensional 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 Ag n Rh clusters with n ≤ 8 is considerably higher than that for the larger homologues. Further, the results show that doping Ag n clusters with Rh increases the reactivity toward NO adsorption.

Study of odd–even effects in physisorption and chemisorption of Ar, N2, O2and NO on open shell Ag11–13+clusters by means of self-consistent van der Waals density functional calculations

“…2,[11][12][13][14] The reactivity of bimetallic Ag n M m 0AE clusters towards small particles has been also explored. [15][16][17][18] The interaction of pure and bimetallic clusters with noble gases, like argon, has been studied in order to infer the particle morphology and to characterize its physisorption activity. 2,19 Bréchignac and coworkers 2,12 have extracted and rationalized general size-dependent trends about the reactivity of cationic silver clusters by analyzing the mass spectra of gas phase Ag n + X clusters (n r 70), X being one or more of Ar, N 2 , and O 2 adsorbed molecules.…”

“…23 Small silver clusters are supposed to be the active phase in the Ag/Al 2 O 3 catalyst for selective catalytic reduction of nitrous oxides, NO x , in the presence of hydrocarbons 24,25 and ammonia. 26 As a first step to understand these processes, apart from the action of the support, density functional calculations have been done to explore NO x adsorption on pure and doped silver clusters, 7,18 as well as the Ag(111) surface 27 and AlN(0001) surface. 28 DFT calculations show that NO interacts weakly with Ag n clusters (n r 8) and is preferably adsorbed in atop sites.…”

Bonding and properties of superatoms. Analogs to atoms and molecules and related concepts from superatomic clusters

“…Small sized silver clusters exhibit an enhanced reactivity toward NO binding as relevant pollutants in greenhouse gases, when a Rh atom is included as dopant. Silver‐rhodium clusters of the form Ag n Rh with n = ≤15 were evaluated by Merino and coworkers, providing interesting examples of Superatoms that can be further developed . Their results indicate the relevance of keeping the dopant atom lying on the cluster surface, and thus, further efforts in the characterization of cage doped clusters should be pertinent in catalytic application, in addition to endohedral doping.…”

“…It is important to stress that besides the favorable electronic structure and geometrical shape, further analysis of possible isomers should be carried out to pursue energy minima geometries. [51] Soto and coworkers [52,53] [54] Their results indicate the relevance of keeping the dopant atom lying on the cluster surface, and thus, further efforts in the characterization of cage doped clusters should be pertinent in catalytic application, in addition to endohedral doping.…”

Effect of Water Molecule on Photo-Assisted Nitrous Oxide Decomposition over Oxotitanium Porphyrin: A Theoretical Study

“…The catalytic deN 2 O has been studied to a greater extent than selective catalytic reduction (SCR) over a large variety of catalysts, including noble metals [4,[8][9][10][11], perovskites [12][13][14], metal oxides [15][16][17][18], and zeolites [19][20][21][22]. It is also important to note that in deN 2 O processes, tolerance to various substances coexisting in the exhaust gases (e.g.…”