Highly efficient porous MXene desalination membranes controlled by the thickness of the transition metal carbides

Abstract

MXene membrane has the vast potential to alleviate the global freshwater crisis. Herein, a new strategy for improving the desalination performance is proposed through tunable the thickness transition metal carbides of the nano-porous MXene membrane. The thickness of porous MXene is investigated by molecular dynamics (MD) simulation, including the Ti₂CF₂, Ti₃C₂F₂, and Ti₄C₃F₂. The results show that the porous MXene membrane can reach highly efficient desalination. The water density distribution reveals that more water gathers in the thicker transition metal carbides layer, contributing to the poor water flux; the average charge distribution indicates that the transition metal layer plays an essential role in effectively rejecting Na⁺/trapping Cl⁻ ions. Multilayered porous membranes are explored to improve the trade-off desalination performance. The number of pores enhances the water permeability, and the multilayers improve the ion rejection. The two-layered Ti₃C₂F₂ membrane with three nanopores achieves nearly doubled water flux and keeps 100 % ion rejection. Our work reported that the nano-porous MXene membrane offers a prospective strategy to eliminate the current design defects, which provides an innovative method for the desalination semipermeable membrane industry.