Scalable nanoconfined ionic liquid membranes with ultrapermeance and ultraselectivity for efficient CO₂ capture

Supported ionic liquid membranes (SILMs) stand attractive for gas separation considering the tunability, high gas selectivity, and ease of fabrication. However, the intrinsic instability of SILMs limited their practical use. Here, we designed, fabricated, and investigated an ultrapermeable, ultraselective, and stable nanoconfined ionic liquid (NCIL) membrane for highly efficient CO₂ capture. Specifically, the combination of a thin, open, and uniform nanoconfined network of single-walled carbon nanotube with highly CO₂–selective ionic liquid carrier enabled the superior CO₂ permeance of 1654 GPU and CO₂/N₂ selectivity of 1132, surpassing most state-of-the-art facilitated transport membranes. The scale-up potential of the NCIL membrane was demonstrated under simulated natural gas flue gas conditions, achieving CO₂ enrichment from 4.2 to 98% in a single step. Given the processability and scalability of NCIL membrane, this work affirms the industrial potential of SILMs and offers a viable strategy for designing and fabricating stable SILMs for gas separation.