De novo contrived three-in-one oriented graft molecule for high-performance GO nanofiltration membranes with ultra-low friction 2D nanochannels

Abstract

The realistic application promotion of two-dimensional graphene oxide (GO) membranes is hampered by the trade-off between permeance and stability due to the mismatching nanochannel structure and wall chemistry enabled by the current decoration strategy. To address this, we de novo contrive a three-in-one oriented graft molecule, 1-(3-aminopropyl)-2,3-dimethylimidazolium bromide. In this compound, amino groups can reduce GO while acting as covalently grafting sites, thereby expanding the graphene region and decreasing the molecular transport resistance. Imidazolium cation moieties can interact with oxygen-containing groups of GO to enhance membranes’ anti-swelling ability. The whole molecules act as pillars to maintain the interlayer spacing. The modified GO (AIMGO) membranes show one-order-of-magnitude permeance improvements over GO membranes, with equally promising rejections. Furthermore, AIMGO membranes display ideal stability, remaining intact after 20-day water and ethanol immersion, unlike rapidly swollen GO membranes. AIMGO membranes are effective in the realistic pharmaceutical area achieving a separation factor of 9.8, with ethanol permeance of 513 L m−2 h−1 bar−1, which far exceeds the state-of-the-art polymeric membranes for drug purification. Herein, we highlight the rational combination of wide interlayer distance, low wall friction, and strong interlayer interactions to establish an efficient pathway for overcoming the permeance-stability trade-off in GO membranes and other two-dimensional membranes.