Meta-Hybrid Density Functional Theory Study of Adsorption of Imidazolium- and Ammonium-Based Ionic Liquids on Graphene Sheet

Abstract

In this study, two types of ionic liquids (ILs) based on 1-butyl-3-methylimidazolium [Bmim]+ and butyltrimethylammonium [Btma]+ cations, paired to tetrafluoroborate [BF4]−, hexafluorophosphate [PF6]−, dicyanamide [DCA]−, and bis(trifluoromethylsilfonyl)imide [Tf2N]− anions, were chosen as adsorbates to investigate the influence of cation and anion type on the adsorption of ILs on the graphene surface. The adsorption process on the graphene surface (circumcoronene) was studied using M06-2X/cc-pVDZ level of theory. Empirical dispersion correction (D3) was also added to the M06-2X functional to investigate the effects of dispersion on the binding energy values. The graphene···IL configurations, binding energies, and thermochemistry of IL adsorption on the graphene surface were investigated. Orbital energies, charge transfer behavior, the influence of adsorption on the hydrogen bond strength between cation and anion of ILs, and the significance of noncovalent interactions on the adsorption of ILs on the graph...