Adsorption of Tunable aryl alkyl ionic liquids (TILs) on the graphene and Defective graphene nanosheets: A DFT Study

Optical and electronic characteristics of the graphene nanosheets (GNS) could be altered by some structural defects such as double-vacancy and Stone-Wales ones. The physisorption manner of [MPI][BF₄], [MPT1][BF₄], [MPT2][BF₄], and [MPTT][BF₄] ionic liquids on intact and defective GNS surfaces were investigated using M06-2X/cc-pVDZ computational method. Capability for adsorption on the DV and SW graphene surfaces by TILs is increased by about 1.0-4.3 and 0.4-2.0 kcal/mol respectively. The electrostatic potential of the GNS-DV surface is more negative than the GNS-SW one which enables it to interact with cation parts of the adsorbed TILs so extensively. The highest adsorption energy belongs to the [MPI][BF₄]/GNS-DV system. Adsorption of the TILs on the GNS surfaces leads to a decrease in the energy of the LUMO molecular orbital as well as their energy gap of them. Results revealed that the electrical conductivity, as well as absorption spectra of the GNS surfaces, are affected by TILs adsorption and defect nature.