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.