A Structural and Stability Evaluation of Au₁₂ from an Isolated Cluster to the Deposited Material

Abstract

The morphology and charged state of gold clusters play a crucial role in heterogeneous catalysis. The selection and optimization of theoretical approaches are necessary for the investigation of active sites on isolated and supported gold clusters. In the present paper, a study of the potential isomers of the Au12 cluster is performed within the DFT/PBE framework using a scalar-relativistic approach. We have found Au12 to be a dynamic cluster with at least 24 isomers due to the Jahn–Teller distortion. The majority of these isomers exhibit low symmetry, resulting in the formation of low-coordinated atoms, which are discussed in terms of frontier molecular orbitals and a Hirschfeld analysis of their atomic charges. The energy difference between the most energetically stable 2D (D 3h ) and 3D (C 2v ) isomers of Au12 is small (equal to 25 kJ/mol), which is evidence of their coexistence. The influence of the support on properties of the cluster is investigated using Au12/MgO(100). The 2D isomer of Au12 can interact with the surface either in an upright position, with two (E ads/atom = 24 kJ/mol) or three atoms (E ads/atom = 25 kJ/mol); the preferred position is planar (E ads/atom = 30 kJ/mol). The small deformation energy is required to distort a dynamic structure of Au12 compared to rigid gold clusters. The 3D isomer interacts with MgO(100) with two of its atoms (E ads/atom = 24 kJ/mol). The Au–Au distances across the surface increase, whereas the Au–Au distances at an angle to the surface are compressed with respect to the distances in the free clusters. The weak adsorption energies of Au12 on MgO and the low activation barriers for gold atom migration (15 kJ/mol) between oxygen sites facilitate the diffusion of nanoparticles on the MgO surface.

Sites for the selective hydrogenation of ethyne to ethene on supported NiO/Au catalysts

“…Au 12 cluster was considered as a model. It has a dynamic structure [23] and co-exists in flat (two-dimensional (2D)) and three-dimensional (3D) structures that allowed us to study the dependence of adsorption properties on the structural features of gold particles.…”

“…The calculation of all the structures was performed in singlet ground state. The types of stationary points on the potential energy surface were determined from the analysis of Hess matrix; the second derivatives were calculated analytically [23].…”

CO oxidation on h-BN supported Au atom

“…can considerably influence the catalytic properties of gold clusters and modify (enhance or suppress) their reactivity. 2,9,12,17 Such supports usually stabilize gold particles and can modify considerably their geometric structure and morphology, [18][19][20][21][22] which in turn can affect catalytic properties of the supported particles. Charge transfer from the metal oxide support to the a) On gold results in formation of the highly reactive charged gold clusters.…”

Ligand-protected gold clusters: the structure, synthesis and applications

“…34 The Au 12 cluster also has a dynamic structure both in the gas phase and on a regular MgO(111) surface. 143 Probably, it is the dynamic properties of gold clusters that are responsible for the high catalytic activity of these species. Indeed, they can vary the structure on activation of the reactant molecule or on the formation of an intermediate.…”