title: Mechanism of bismuth telluride exfoliation in an ionic liquid solvent.
abstract: Bismuth telluride (Bi2Te3) is a well-known thermoelectric material that has a layered crystal structure. Exfoliating Bi2Te3 to produce two-dimensional (2D) nanosheets is extremely important because the exfoliated nanosheets possess unique properties, which can potentially revolutionize several material technologies such as thermoelectrics, heterogeneous catalysts, and infrared detectors. In this work, ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) is used to exfoliate Bi2Te3 nanoplatelets. In both experiments and in molecular dynamics (MD) simulations, the Bi2Te3 nanoplatelets yield a stable dispersion of 2D nanosheets in the IL solvent, and our MD simulations provide molecular-level insight into the kinetics and thermodynamics of the exfoliation process. An analysis of the dynamics of Bi2Te3 during exfoliation indicates that the relative translation (sliding apart) of adjacent layers caused by IL-induced forces plays an important role in the process. Moreover, an evaluation of the MD trajectories and electrostatic interactions indicates that the [C4mim](+) cation is primarily responsible for initiating Bi2Te3 layer sliding and separation, while the Cl(-) anion is less active. Overall, our combined experimental and computational investigation highlights the effectiveness of IL-assisted exfoliation, and the underlying molecular-level insights should accelerate the development of future exfoliation techniques for producing 2D chalcogenide materials.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ludwig
authors.forename: Lingling
authors.initials: L
authors.lastname: Guo
authors.forename: Parker
authors.initials: P
authors.lastname: McCrary
authors.forename: Zhongtao
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: ⊥Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States.|#St. Mary's College, Notre Dame, Indiana 46556, United States.
authors.forename: Haley
authors.initials: H
authors.lastname: Gordon
authors.forename: Haiyu
authors.initials: H
authors.lastname: Quan
authors.affiliation: ∇Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Stanton
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Frazier
authors.forename: Robin D
authors.initials: RD
authors.lastname: Rogers
authors.forename: Hung-Ta
authors.initials: HT
authors.lastname: Wang
authors.forename: C Heath
authors.initials: CH
authors.lastname: Turner