In-Depth Investigation on THz Spectrum of 1-Butyl-3-Methylimidazolium Dicyanamide Spreading on Graphene Surface by Computational Calculation

Published in Journal of Molecular Liquids, 2020

Yongii Guan, Jiao Zhang, Jinyuan Wang, Fulong Yang, Huanwang Jing, Xiaoping Zhang, Youquan Deng. Journal of Molecular Liquids, 2020, 311, 113353.

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Abstract

Understanding dynamic change of ionic liquid (IL) THz spectrum under certain conditions is a real challenge. Herein, through spreading 1-butyl-3-methylimidazolium dicyanamide ([Bmim][DCA]) nanodroplet on graphene surface, dynamic change of [Bmim][DCA] THz spectrum in the range from 30 to 300 cm-1 is probed by computational calculation at 300 K. Analyzing the calculated THz spectra it can be found that vibrational bands at 49.95 (cation-anion bend), 216.45 cm-1 (rocking of CH3 in alkyl chain) show a 16.65 cm-1 blue shift as spreading time increases from 0 to 5 ns and further blue-shift 16.65 cm-1 as spreading time increases from 10 to 20 ns, while vibrational band at 266.40 cm-1 (bend of CH3 in methyl) only blue-shifts 16.65 cm-1 as spreading time increases from 0 to 20 ns. The underlying mechanism is revealed to be the stronger adsorbed layer forming on graphene-IL interface which enhances the hydrogen bonds between cations and anions, and constrains the torsion and out-of-plane bend of CH3 group in alkyl chain and methyl respectively. The findings described here represent an important step in developing a comprehensive understanding of dynamic manipulation IL THz spectrum by spreading IL nanodroplet on graphene surface.

Yongii Guan, Jiao Zhang, Jinyuan Wang, Fulong Yang, Huanwang Jing, Xiaoping Zhang, Youquan Deng. In-Depth Investigation on THz Spectrum of 1-Butyl-3-Methylimidazolium Dicyanamide Spreading on Graphene Surface by Computational Calculation. Journal of Molecular Liquids, 2020, 311, 113353.