Safdari

Density Functional Theory Study of Gas Adsorption on metal-Graphene Surface

Safdari1, A. N. Shamkhali*,2 and G. A. Parsafar1

1.Department of Chemistry, Sharif University of Technology, 11155-9516 Tehran, Iran

2.Department of Chemistry, University of Mohaghegh Ardabili, 56199-11367 Ardabil, Iran

* Email: shamkhali@uma.ac.ir

Carbon nanostructures are of great importance in academic research and industry, which can be mentioned to chemical sensors, catalytic processes, pharmaceutical and environmental issues [1,2]. Common point in all of these applications, is the occurrence of adsorption of molecules on these structures [3, 4]. Important carbon nanostructures in this case are mainly nanotubes and graphene. To modify pure graphene, recently, many experimental and theoretical studies have carried out to investigate of metal adsorption on graphene [4]. In this work, the adsorption of CO molecules on pure graphene and on metal adatom on graphene surface has been simulated based on density functional theory (DFT). All calculations were performed by PBE functional and Troullier-Martins pseudopotentials. The geometry of CO adsorbates on the pure graphene surface, is shown in (figure 1). CO molecules are adsorbed from oxygen side on the surface of graphene. The 5×5×1 k-point mesh is selected for optimization of the supercell. As seen in (figure 2), density of states (DOS) for graphene-CO, graphen and CO around the Fermi energy have been moved and very small mixing occurred which implies the physisorption of CO on the bare graphen surface. While, the results have showed that CO adsorption on metal adatom on graphene surface is chemisorption. In order to better representation of CO dynamics on the surface, its internal stretching frequency on the surface was calculated.

Keywords: Adsorption, density functional theory, graphene, metal adatom, CO dynamics

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