Understanding the Effect of Doping on Energetics and Electronic Structure for Au₂₅, Ag₂₅, and Au₃₈ Clusters

Abstract

We investigate the doping process theoretically for singly doped MAu24, MAg24, and MAu37 (M = Ni, Pd, Pt, Cu, Ag/Au, Zn, Cd, Hg, Ga, In, and Tl) clusters using density functional theory (DFT). For all clusters, the group X dopants (Ni, Pd, and Pt) prefer the central location due to the relative stability of d electrons in the dopant. For dopants in groups XI–XIII, doping on the surface of the core and the ligand shell in MAu24 becomes thermodynamically more preferable as a result of symmetry-dictated coupling between dopant atomic orbitals and superatomic levels as well as because of relativistic contraction of s and p orbitals. The same mechanisms are also found to be responsible for the relative isomer energies in MAu37 clusters. For these clusters, DFT calculations predict that it is unlikely for the dopant atom to occupy the central location. We found similar trends for different dopants across the periodic table in relative isomer energies of MAu24 and MAg24; however, center-doped clusters are somewhat more stable in the case of MAg24 due to the smaller relativistic stabilization of s and p levels in Ag compared to Au. We also found that the metallic radii of the dopant can affect the geometries and relative stabilities of the isomers for the doped clusters significantly.

Elucidating ligand effects in thiolate-protected metal clusters using Au24Pt(TBBT)18 as a model cluster

“…However, for [Au 24 Pt(SR) 18 ] 0 , density functional theory (DFT) calculations predicted that the geometrical structure in which Pt is located at the center of the metal core is thermodynamically most stable. 51 The optical absorption spectrum of cluster 1 is similar to the theoretical absorption spectrum that is predicted for [Au 24 Pt(SR) 18 ] 0 with the geometry described above. 48 The optical absorption spectrum of cluster 2 is similar to that of cluster 1 (Fig.…”

“…Because the d orbital of Pt is largely involved in HOMO−1, 56 the energy of HOMO−1 changes considerably if the substitution position of Pt is different. 51 However, Pt is located at the center of the metal core in clusters 1 and 2. Therefore, there is a minimal difference in the positions of this orbital between the two clusters, which results in no substantial change in the position of peak α in the spectrum between the two clusters.…”

Metal Doping of Au25(SR)18– Clusters: Insights and Hindsights

“…Very recently, the Aikens group used DFT to study the doping process in a few clusters, including Au24M(SR)18. 36 Whereas group X dopants (Pd, Pt) resulted stable when at the central position, for dopants in groups XI− XIII (and thus also for Cd and Hg, group XII) the icosahedral position was found thermodynamically preferable mainly due to group theory and relativistic effects. As to the staple position compared to the central position, whereas for Cd the former has a slightly lower energy, for Hg the results point to Hg(c) as being quite more stable than Hg(s).…”

Metal Nanoclusters Stabilized by Selenol Ligands

“…However, an atomic‐level understanding of surface coordination chemistry in large nanoparticles (e.g., >1000 metal atoms) remains challenging, for two natures of nanoparticles—the poly‐disperse sizes (i.e., hard to be prepared uniformly at the atomic level), and the uncertain surface chemistry (e.g., metal–ligand interactions) . In view of this, metal nanoclusters have been served as model nanosystems, and precise molecular tools, for investigating the surface coordination chemistry at the atomic level owing to the monodisperse sizes and accurately characterized structures of these nanomaterials . Thiolates are most frequently used in protecting metallic kernels of nanoclusters; selenols, cognate derivatives of thiols by replacing the sulfur in thiols into selenium, have embodied their superiority in stabilizing metal nanoclusters and shown distinctively surface coordination mode.…”