Size‐Dependent Structural Evolution and Chemical Reactivity of Gold Clusters

Abstract

Ground-state structures and other experimentally relevant isomers of Au(15) (-) to Au(24) (-) clusters are determined through joint first-principles density functional theory and photoelectron spectroscopy measurements. Subsequent calculations of molecular O(2) adsorption to the optimal cluster structures reveal a size-dependent reactivity pattern that agrees well with earlier experiments. A detailed analysis of the underlying electronic structure shows that the chemical reactivity of the gold cluster anions can be elucidated in terms of a partial-jellium picture, where delocalized electrons occupying electronic shells move over the ionic skeleton, whose geometric structure is strongly influenced by the directional bonding associated with the highly localized "d-band" electrons.

Fluxionality of gold nanoparticles investigated by Born-Oppenheimer molecular dynamics

“…In general when the dimensions of metal particles are reduced to a size comparable to that of the constituent atoms, their electronic structure deviates dramatically from that of the bulk metal. This phenomenon has very relevant effects on both physical and chemical properties of the metal [14,20,21]. In the field of catalysis one particularly striking phenomenon underlying the special properties of size and shape dependence of materials is the ability of finely dispersed gold to catalyse oxidation reactions [22,23].…”

“…An interesting theoretical basis for the nobility of gold has been given by Hammer and Nørskov based on electronic structure calculations [24], while other theoretical and experimental studies have investigated the origin of the decrease of nobility of gold [25,26]. Several studies have been published that aim at understanding the origin of the special reactivity of nano-sized gold particles towards oxygen [21,25,[27][28][29][30][31][32][33][34], but one of the keys to the understanding of the peculiar reactivity of small gold clusters lies in its fluxional character, since structural isomers are in principle able to adapt their structures towards the most favorable free-energy path [25,35].…”

Cluster melting: new, limiting, and liminal phenomena

“…While geometric structural information is not generally directly accessible via experiment, comparison of photoelectron spectra with theoretical predictions has been shown to be a powerful tool for determining the experimental structures in many cases [24,25]. Such studies -including also photoabsortion spectra -have been able to demonstrate the likely coexistence of isomers at finite temperature as well [26].…”

CO chemisorption on the surfaces of the golden cages

“…The structures of gold anion clusters ͑Au n − ͒ with n =3-20 have been extensively studied through combined experimental techniques and density functional theory ͑DFT͒ calculations. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Small Au n − clusters ͑n Ͻ 12͒ were found to exhibit planar structures. 4,6,17 was found to be the critical size for the two-dimensional ͑2D͒ to three-dimensional ͑3D͒ structural transition: 11,13 the global-minimum structure of Au 12 − is 3D with a nearly degenerate 2D isomer coexisting in the cluster beam.…”