Molecular dynamics simulations of simple aromatic compounds adsorption on single-walled carbon nanotubes

Abstract

The adsorption of three simple aromatic compounds (benzene, phenol and 4-chlorophenol) on single-walled carbon nanotubes (SWCNTs) has been investigated at a molecular level using molecular dynamics (MD) simulation. The adsorption energies of adsorbates on SWCNTs were calculated. The effects of adsorbate substituents and SWCNT size on the adsorption energy were analysed. The adsorption capacities of SWCNTs for adsorbates are positively correlated with the corresponding adsorption energy. The configurations of adsorbed molecules show that a second layer was formed on (5, 5) SWCNT and diminished with the increase in SWCNT diameter. The orientations of adsorbed molecules inside were limited by the pore size of the SWCNT. The angular distribution of adsorbed molecules indicates that small angles are more likely to be formed on a less curved surface. The non-bond interaction energy is negatively correlated with the binding strength of adsorbates to the SWCNT. The distances between adsorbed molecules and tube surface were determined by radial distribution function (RDF). The distances for benzene, phenol and 4-chlorophenol were 5.00 Å, 4.85 Å and 4.75 Å respectively, longer than those in vacuum conditions. The visualisation of non-bond interactions indicates that the π–π interaction is rather complicated, consisting of attractive and repulsive interactions.