Ultrapermeable, Durable CO2-Selective Ionogel Membranes via Photothermal-Steered Confined Gelation and Locking Engineering

Ionic liquids (ILs) featuring excellent selective solubility for CO 2 have led to versatile development and applications of gas separation membranes for CO 2 capture. Over the past decade, a myriad of ILs-based membranes have been exploited; however, they normally suffer from a formidable conflict between CO 2 permeance and stability as imposed by their mutually exclusive design requirements. Herein, a photothermal-steered confined gelation and locking engineering (CGLE) is proposed to fabricate ultrathin dual-confined ionogel membranes (DCIMs) that empower ultrapermeable and durable CO 2 separation. In the CGLE, coupling CNTs-enabled photothermally confined reactor with ILs-regulated gelation behavior, ionogel precursors consisting of poly(ethylene glycol) diacrylate and 1-butyl-3-methylimidazolium tetrafluoroborate experience in situ confined polymerization and gelation within CNTs-stacked skeleton, thus making free ILs dually locked via dual confinement of CNTs skeleton and gel network. These DCIMs have a greatly decreased thickness to 1–3 µm by ≈100 folds over counterparts, yet exhibiting an enhanced pressure resistance and long-term stability. Moreover, DCIMs give an ultrahigh CO 2 permeance of 113 GPU, a rewarding CO 2 /N 2 and CO 2 /CH 4 selectivity of 68 and 88, respectively, transcending most ILs-based membranes. These findings represent a paradigm shift in developing advanced ionogel membranes beyond gas separation.