Elucidating the Ultrafast Molecular Permeation through Well-defined 2D Nanochannels of Lamellar Membranes.

Abstract

Lamellar membranes with well-defined 2D nanochannels exhibit fast, selective permeation. However, the underlying molecular transport mechanism remains unexplored. Here in , regular and robust MXene Ti 3 C 2 T x lamellar membranes are prepared, and the size and wettability of nanochannels are manipulated by chemically grafted hydrophilic (-NH 2 ) or hydrophobic (-C 6 H 5 , -C 12 H 25 ) groups. These nanochannels have sharp difference in mass transfer behaviors. Hydrophilic nanochannels , in which polar molecules form orderly aligned aggregate s along channel walls , impart ultrahigh permeance of over 3000 L m -2 h -1 bar -1 , which is over 3 times higher than that in hydrophobic nanochannels with disordered molecular configuration . In contrast, nonpolar molecules with disordered configuration in both hydrophilic and hydrophobic nanochannels have comparable permeance. Finally , two phenomenological transport model s to correlate t he permeance with the mass transport mechanism of molecules that display ordered and disordered configuration are established, which is conductive to designing high performance 2D channel materials .