Issue 2, 2021

Hydration effects and negative dielectric constant of nano-confined water between cation intercalated MXenes

Abstract

Using electrochemical methods a profound enhancement of the capacitance of electric double layer capacitor electrodes was reported when water molecules are strongly confined into the two-dimensional slits of titanium carbide MXene nanosheets [A. Sugahara et al., Nat. Commun., 2019, 10, 850]. We study the effects of hydration on the dielectric properties of nanoconfined water and supercapacitance properties of the cation intercalated MXene. A model for the electric double layer capacitor is constructed where water molecules are strongly confined in two-dimensional slits of MXene. We report an abnormal dielectric constant and polarization of nano-confined water between MXene layers. We found that by decreasing the ionic radius of the intercalated cations and in a critical hydration shell radius the capacitance of the system increases significantly (ā‰ƒ200 F gāˆ’1) which can be interpreted as a negative permittivity. This study builds a bridge between the fundamental understanding of the dielectric properties of nanoconfined water and the capability of using MXene films for supercapacitor technology, and in doing so provides a solid theoretical support for recent experiments.

Graphical abstract: Hydration effects and negative dielectric constant of nano-confined water between cation intercalated MXenes

Article information

Article type
Paper
Submitted
23 May 2020
Accepted
27 Nov 2020
First published
07 Dec 2020

Nanoscale, 2021,13, 922-929

Hydration effects and negative dielectric constant of nano-confined water between cation intercalated MXenes

H. Jalali, F. Khoeini, F. M. Peeters and M. Neek-Amal, Nanoscale, 2021, 13, 922 DOI: 10.1039/D0NR03953E

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