Jiao Zhang1, Yongii Guan1, Jinyuan Wang, Fulong Yang, Huanwang Jing, Xiaoping Zhang, Youquan Deng. Journal of Molecular Liquids, 2020, 311, 113340.
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Ionic liquids (ILs) are promising novel solvents for energy harvesting and understanding the graphene/ILs interface structural characteristics is required. In this study, we calculate the vibrational spectrum (VS) of 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]) pair on graphene surface in the range from 10 to 3500 cm-1 and systemically investigate the influence of the graphene on the VS of [Emim][BF4] using density functional theory. The results show 24 vibrational bands (VBs) with obvious shifting. The VBs at 3170.26 and 3033.51 cm-1 show a redshift of 59.46 and 14.95 cm-1 respectively which was mainly caused by the enhanced hydrogen bond strength of C2H···F and F atoms with the CH on the ethyl chain. The VBs at 101.49 and 1417.43 cm-1 show a blueshift of 62.43 and 23.86 cm-1 due to the enhancement of induction effect of [Emim][BF4] on graphene surface (from −44.68 to −45.42 kJ mol-1). The VB at 86.91 cm-1 shows a redshift of 59.43 cm-1 which can be ascribed to the reduction of the whole interaction energy between the cation and anion of [Emim][BF4] on graphene surface (from −367.06 to −356.06 kJ·mol-1). Overall, these shifts of the VS are mainly attributed to the attraction between graphene and anion [BF4]-, which is dominated by the induction and dispersion interaction accounting for 63.43% and 34.37% of the attraction interaction respectively. Due to this attraction, the anion [BF4]- move closer to the surface of graphene.
Jiao Zhang1, Yongii Guan1, Jinyuan Wang, Fulong Yang, Huanwang Jing, Xiaoping Zhang, Youquan Deng. Vibrational Spectrum of 1-Ethyl-3-Methylimidazolium Tetrafluoroborate on Graphene Surface. Journal of Molecular Liquids, 2020, 311, 113340.