Engineering multi-channel water transport in surface-porous MXene nanosheets for high-performance thin-film nanocomposite membranes

Two-dimensional (2D) nanosheets are emerging as promising nanofillers for high-performance nanocomposite membranes, but their non-porous surfaces often impede water permeation. This study addresses this limitation by generating surface nanopores on MXene nanosheets via a synergistic method combining site-specific catalysis and etching. Surface nanopores enable direct water penetration, providing additional pathways for improved water transport through the membrane. The surface-porous MXene (SPMXene) polyamide nanofiltration membranes exhibit a 64 % increase in water permeance compared to control thin-film composite (TFC) membranes, while maintaining up to 99.7 % of sodium sulfate (Na₂SO₄) rejection, outperforming other MXene-based membranes reported in the literature. Molecular dynamics (MD) simulations confirm that the SPMXene polyamide membranes exhibits facilitation of fast water transport. As a direct modification, surface etching method preserves the interlayer channels of MXene nanosheets and significantly boosts membrane permeance by introducing multiple water transport pathways.