Effects of Gas Adsorption on the Graphite-Supported Ag Nanoclusters: A Molecular Dynamics Study

Molecular dynamics simulations were used to investigate the adsorption effects of different gas phases on structural and dynamical properties of graphite-supported Ag nanoclusters at various pressures, temperatures, and cluster sizes. Three Ag nanoclusters with N = 38, 108, and 256 atoms in vacuum and under pressure of five gases (He, Ar, Xe, H-2, and CO) were simulated. The effect of each gas on nanoclusters at four temperatures and at various numbers of gas atoms (various pressures) was investigated. The adsorption, structural changes, and dynamic properties were monitored as a function of cluster size, pressure, and temperature. The adsorption isotherms, density profiles, deformation parameter, mean-square displacement, and diffusivity were calculated to study structural changes and dynamical properties of nanoclusters. It was found that the adsorption isotherms comply from the Langmuir type I. Also, the gas phase changes the vacuum cluster structure irreversibly. Furthermore, the gas phase increases the diffusivity of nanoclusters on the substrate surface, and this diffusivity increases with gas pressure.