Adsorbate Effects on Structure and Shape of Supported Nanoclusters:  A Molecular Dynamics Study

Abstract

Classical molecular dynamics simulations are used to examine the effects of adsorption of inert-gas atoms (Ar, Xe, and He) at various pressures and temperatures on the shape, structure, and diffusion of a 256-atom platinum nanocluster supported on a graphite substrate. The many-body Sutton Chen potential is used to model the Pt−Pt interactions, and the Lennard-Jones potential is employed for the rest of the pair interactions. Gas adsorption on the metal cluster is monitored as a function of pressure at constant temperature, and the evolution of the structure is analyzed as the pressure is increased and then as the gas phase is gradually removed. It is found that the gas phase substantially alters the vacuum cluster structure, and the changes are mostly irreversible in the time frame of the simulations (2 ns), especially at temperatures well below the cluster melting point, where the low energy structures determined under high pressures are very stable. The dynamic properties are also modified by the gas phase; the cluster diffusion depends on the inert gas pressure, being lower at high gas pressures. Although the contact area cluster−substrate is significantly smaller compared to the vacuum case, the size mismatch is reduced because of the presence of the gas-adsorbed layer that forces the rearrangement of the metal atoms leading to distorted structures which favor the Pt−C interactions.

H2adsorption on Ag-nanocluster/single-walled carbon nanotube composites: A molecular dynamics study on the effects of nanocluster size, diameter, and chirality of nanotube

“…Therefore, at higher temperatures, more H 2 pressure is needed to reach saturation state, as reported earlier by Zhang et al Also this result is consistent with the fact that increasing of temperature decreases the coverage due to the more ability of adsorbates to be desorbed from the surface at higher temperatures . Moreover, these adsorption isotherms are according to those of the Langmuir type‐I …”

“…[65] Moreover, these adsorption isotherms are according to those of the Langmuir type-I. [66][67][68] The adsorption isotherms of H 2 on Ag N /(19,0) composite with (N 5 32, 108, 256, 500, and 864) at 300 K are given in Figure 2. The similar conditions are also observed for other nanotubes studied in this work.…”

A molecular dynamics study of cooling rate during solidification of metal nanoparticles

“…In addition to experiments over many years [1,[8][9][10][11], numerical simulations such as molecular dynamics (MD) and Monte Carlo (MC) simulations have contributed to interpreting the configuration and thermodynamic properties of nanoparticles. These atomic simulations have revealed interesting properties unique to nanoparticles such as a stable structure for small particles with a specific magic number [12,13], depression of the melting point [14][15][16][17][18][19][20][21], the effect of substrates on the phase stability of nanoparticles [17,18,20,[22][23][24][25], and the effect of orientation of the substrate on nanoparticle epitaxy [24][25][26][27], the solid-to-liquid transition region of binary nanoparticles [28][29][30][31] and the structural properties of binary nanoparticles [32].…”

The Interactions of Oxygen with Small Gold Clusters on Nitrogen-Doped Graphene

“…As discussed in Section 3.2.1, the geometrical structures of pure Au 7 and Au 9 clusters would be greatly changed after O 2 is adsorbed on their bridge sites. It is reported that the shape changes could modify the O 2 bonding mode, therefore alter the cluster's catalytic activity [50]. Thus, enhancing the cluster's stability without decreasing its catalytic activity is an important issue for catalytic applications.…”