Enhanced Gas Separation through Nanoconfined Ionic Liquid in Laminated MoS2 Membrane

Two-dimensional (2D) materials-based membranes show great potential for gas separation. Herein an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), was confined in the 2D channels of MoS2-laminated membranes via an infiltration process. Compared with the corresponding bulk [BMIM][BF4], nanoconfined [BMIM][BF4] shows an obvious incremental increase in freezing point and a shift of vibration bands. The resulting MoS2-supported ionic liquid membrane (MoS2 SILM) exhibits excellent CO2 separation performance with high CO2 permeance (47.88 GPU) and superb selectivity for CO2/N2 (131.42), CO2/CH4 (43.52), and CO2/H2 (14.95), which is much better than that of neat [BMIM][BF4] and [BMIM][BF4]-based membranes. The outstanding performance of MoS2 SILMs is attributed to the nanoconfined [BMIM][BF4], which enables fast transport of CO2. Long-term operation also reveals the durability and stability of the prepared MoS2 SILMs. The method of confining ILs in the 2D nanochannels of 2D materials may pave a new way for CO2 capture and separation.