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Mechanistic Insight into the Chemical Exfoliation and Functionalization of Ti3C2 MXene

Srivastava, Pooja and Mishra, Avanish and Mizuseki, Hiroshi and Lee, Kwang-Ryeol and Singh, Abhishek K (2016) Mechanistic Insight into the Chemical Exfoliation and Functionalization of Ti3C2 MXene. In: ACS APPLIED MATERIALS & INTERFACES, 8 (36). pp. 24256-24264.

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Official URL: http://dx.doi.org/10.1021/acsami.6b08413

Abstract

MXene, a two-dimensional layer of transition metal carbides/nitrides, showed great promise for energy storage, sensing, and electronic applications. MXene are chemically exfoliated from the bulk MAX phase; however, mechanistic understanding of exfoliation and subsequent functionalization of these technologically important materials is still lacking. Here, using density-functional theory we show that exfoliation of Ti3C2 MXene proceeds via HF insertion through edges of Ti3AlC2 MAX phase. Spontaneous dissociation of HF and subsequent termination of edge Ti atoms by H/F weakens Al-MXene bonds. Consequent opening of the interlayer gap allows further insertion of HF that leads to the formation of AlF3 and H-2, which eventually come out of the MAX, leaving fluorinated MXene behind. Density of state and electron localization function shows robust binding between F/OH and Ti, which makes it very difficult to obtain controlled functionalized or pristine MXene. Analysis of the calculated Gibbs free energy (Delta G) shows fully fluorinated MXene to be lowest in energy, whereas the formation of pristine MXene is thermodynamically least favorable. In the presence of water, mixed functionalized Ti3C2Fx(OH)(1-x) (x ranges from 0 to 1) MXene can be obtained. The Delta G values for the mixed functionalized MXenes are very close in energy, indicating the random and nonuniform functionalization of MXene. The microscopic understanding gained here unveils the challenges in exfoliation and controlling the functionalization of MXene, which is essential for its practical application.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Depositing User: Id for Latest eprints
Date Deposited: 28 Oct 2016 07:15
Last Modified: 28 Oct 2016 07:15
URI: http://eprints.iisc.ac.in/id/eprint/55147

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