Shearing Liquid-Crystalline MXene into Lamellar Membranes with Super-Aligned Nanochannels for Ion Sieving

authored by
Lingzhi Huang, Haoyu Wu, Li Ding, Jürgen Caro, Haihui Wang
Abstract

Ion-selective membranes are crucial in various chemical and physiological processes. Numerous studies have demonstrated progress in separating monovalent/multivalent ions, but efficient monovalent/monovalent ion sieving remains a great challenge due to their same valence and similar radii. Here, this work reports a two-dimensional (2D) MXene membrane with super-aligned slit-shaped nanochannels with ultrahigh monovalent ion selectivity. The MXene membrane is prepared by applying shear forces to a liquid-crystalline (LC) MXene dispersion, which is conducive to the highly-ordered stacking of the MXene nanosheets. The obtained LC MXene membrane (LCMM) exhibits ultrahigh selectivities toward Li+/Na+, Li+/K+, and Li+/Rb+ separation (≈45, ≈49, and ≈59), combined with a fast Li+ transport with a permeation rate of ≈0.35 mol m−2 h−1, outperforming the state-of-the-art membranes. Theoretical calculations indicate that in MXene nanochannels, the hydrated Li+ with a tetrahedral shape has the smallest diameter among the monovalent ions, contributing to the highest mobility. Besides, the weakest interaction is found between hydrated Li+ and MXene channels which also contributes to the ultrafast permeation of Li+ through the super-aligned MXene channels. This work demonstrates the capability of MXene membranes in monovalent ion separation, which also provides a facile and general strategy to fabricate lamellar membranes in a large scale.

Organisation(s)
Institute of Physical Chemistry and Electrochemistry
External Organisation(s)
Tsinghua University
Type
Article
Journal
Angewandte Chemie - International Edition
Volume
63
ISSN
1433-7851
Publication date
31.01.2024
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Catalysis, General Chemistry
Electronic version(s)
https://doi.org/10.1002/anie.202314638 (Access: Open)