Structure and Interaction of Ionic Liquid Monolayer on Graphite from First-Principles

Journal Article · Mon Dec 10 00:00:00 EST 2018 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.8b10664· OSTI ID:1507862

Zhang, Shaoze ^[1]; Lu, Yunxiang ^[2]; Peng, Changjun ^[2]; Liu, Honglai ^[2]; Jiang, De-en ^[3]

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1. Univ. of California, Riverside, CA (United States); East China Univ. of Science and Technology, Shanghai (China)
2. East China Univ. of Science and Technology, Shanghai (China)
3. Univ. of California, Riverside, CA (United States)

The ionic-liquid/graphite interface is important in understanding the behaviors of the ionic-liquid electrolyte in carbon-based supercapacitors and Li-ion batteries. A row-like cation–anion structure of the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([BMP][TFSA]) ionic liquid (a popular choice for interfacial studies) on the graphite surface has been suggested on the basis of scanning tunneling microscopy images, but it is unclear if this structure is the most stable one. Herein, we explore alternative models of the [BMP][TFSA] monolayer on graphite basal plane with first-principles density functional theory. We find that the checkerboard type of structure is in fact more stable than the row-like structure. We further use simulated annealing based on classical molecular dynamics simulations to obtain more stable conformations of ions on the surface. Both charge-density-difference and noncovalent-interaction analyses show that the higher stability of the checkerboard structure than the row-like structure is due to the stronger anion–surface interactions in the former. Furthermore, our work therefore suggests a new structure of the [BMP][TFSA] monolayer on the graphite basal plane.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Fluid Interface Reactions, Structures and Transport Center (FIRST); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1507862
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 1 Vol. 123; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY