A density functional theory study of the dissociation of H2 on gold clusters: Importance of fluxionality and ensemble effects

Abstract

Density functional theory was employed to calculate the adsorption/dissociation of H2 on gold surfaces, Au(111) and Au(100), and on gold particles from 0.7 (Au14) to 1.2 nm (Au29). Flat surfaces of the bulk metal were not active towards H2, but a different effect was observed in gold nanoclusters, where the hydrogen was adsorbed through a dissociative pathway. Several parameters such as the coordination of the Au atoms, ensemble effects and fluxionality of the particle were analyzed to explain the observed activity. The effect of the employed functional was also studied. The flexibility of the structure, i.e., its adaptability towards the adsorbate, plays a key role in the bonding and dissociation of H2. The interaction with hydrogen leads to drastic changes in the structure of the Au nanoparticles. Furthermore, it appears that not only low coordinated Au atoms are needed because H2 adsorption/dissociation was only observed when a cooperation between several (4) active Au atoms was allowed.

Structure and local reactivity of the Au(111) surface reconstruction

“…At the same time, gold nanoparticles are known to be very reactive and make excellent catalysts for a wide variety of substances. [1][2][3][4][5] These apparently contradictory properties of the same material are at the heart of an active research field in current surface science. While pristine Au surfaces are unable to dissociate hydrogen and oxygen molecules, 2,6 they significantly lower the temperature for dehalogenation reactions that are an important step in the assembly of covalently bonded molecular nanostructures [7][8][9][10][11] and graphene nanoribbons.…”

STM-induced desorption of hydrogen from Co nanoislands

“…Moreover, as nanoparticles show unusual properties as compared to bulk, adsorption of a chemical species on a geometrical confined area may eventually lead to new properties. [11][12][13][14][15] Contrary to bulk metals and thin films, only a few studies have been devoted to the adsorption on magnetic nanoparticles. [16][17][18][19] Therefore, it is of fundamental interest to study adsorption on magnetic nanoparticles and its effect on their electronic properties.…”

Optical, Electrical, and Catalytic Properties of Metal Nanoclusters Investigated by ab initio Molecular Dynamics Simulation: A Mini Review

“…Those bonded hydrogen atoms are the clear evidence of the formation of a semi-bounded H 2 molecule, Pd•••H−H, on the surface of Pd nanocluster. Less migration and bonding of hydrogen atoms was observed in the Pt 13 H 24 model, indicating less active hydrogen on Pt nanocluster surface (26).…”

“…In this sense, this AIMD approach is more general and can be applied to simulate other reactions, such as fusion, fragmentation, etc. In the future work, the most challenging research interests will be on how to combine the simulation of photon absorption (70,71), and charge transfer from a substrate to the surface of nanocatalyst (72,73) and charge-facilitated surface reaction (26). One is able to complete the pathways of subsequent elementary processes contributing to the photocatalytic water splitting.…”

“…Small Pd nanoclusters deposited on solid supporting surfaces, such as MgO (21) or TiO 2 (22,23), were also theoretically studied since it was believed to be responsible for the majority of catalytic activity. The behavior characteristic to the clusters comes from a large fraction of surface atoms and the discrete nature of electronic states, which makes the electronic state of the cluster quite different from those of the bulk structure (24,25).Metal clusters with an appropriate size would be an excellent representation of the metal nanoparticles (26). The 13-atom clusters have drawn much attention because it can form closed-shell icosahedral structure (27,28)and are considered as being representative of highly dispersed metal catalysts (29)(30)(31).…”