Deciphering the Role of Solvents in the Liquid Phase Exfoliation of Hexagonal Boron Nitride: A Molecular Dynamics Simulation Study

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• 作者：Titas Kumar Mukhopadhyay ; Ayan Datta
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：811-822
• 全文大小：780K
• ISSN：1932-7455

文摘

Boron nitride (BN) nanosheets are promising candidates for device applications because of structural stability and large in-plane conductivity that require highly scalable and efficient preparatory routes. Liquid phase exfoliation (LPE), the best known method for the synthesis of two-dimensional nanosheets, demands an understanding of the solvent preferences for exfoliation and colloidal dispersion of the individual layers. The nature of solvent–BN interactions during LPE remains elusive to date. Herein, we investigate the liquid phase exfoliation of hexagonal boron nitride (h-BN) in various polar and relatively nonpolar solvents using classical molecular dynamics (MD) simulations. It is shown that, upon intercalation, polar solvents get strongly adsorbed on the surfaces and in between h-BN layers forming “quasi-stable” states through electrostatic interactions which reduce interlayer binding and favor exfoliation. Preference for parallel mechanism of exfoliation over the perpendicular path has been established in terms of free energy calculations. The best exfoliants are the polar and sterically less demanding solvents such as dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), and water that can intercalate between the BN layers. DMSO and IPA also act as excellent dispersing agents. These findings offer a new guideline for the a priori choice of a solvent during LPE of h-BN as well as other polar two-dimensional materials.