Two-dimensional Ti2CTx MXene membranes with integrated and ordered nanochannels for efficient solvent dehydration

Abstract

Two-dimensional (2D) material membranes have shown great potential for molecular separation. However, it remains challenging to controllably tune 2D material membrane structures with ordered nanochannels without non-selective defects. Herein, for the first time, 2D Ti₂CT_x MXene membranes were designed and fabricated for efficient solvent dehydration via a new strategy. Specifically, positively charged hyperbranched polyethylenimine was intercalated between negatively charged MXene nanosheets to assemble regular stacking structures via electrostatic interactions, followed by interfacial polymerization with trimesoyl chloride to seal possible non-selective defects. This strategy realized integrated Ti₂CT_x membranes as thin as ∼100 nm with highly ordered 2D nanochannels, thereby exhibiting outstanding separation performance: the water content was enriched to >99 wt% in permeate from 10 wt% water/isopropanol mixtures. Compared with commonly studied Ti₃C₂T_x MXene membranes prepared by the same approach, the Ti₂CT_x membranes showed higher selectivity with similarly high flux. The membrane fabrication approach developed herein offers a powerful platform for the rational design of 2D material thin films for precise molecular separation and other applications.