Ultrathin and Stable Ionic Liquid Membranes with Bio-Inspired Interlocking Architecture for CO2 Separation.

The growing demand for energy-efficient carbon capture has spurred significant advancements in supported ionic liquid membranes (SILMs), which utilize ionic liquid (IL) with high CO2 solubility for continuous gas purification processes. However, conventional SILMs are hindered by a persistent limitation: thick IL layers (> 50 µm) significantly reduce CO2 permeance to below 1 GPU, while also causing mechanical failure under prolonged operational pressure. Inspired by the interlocking elytra of Tenebrionidae beetles, which use microscale "teeth" to withstand mechanical stress, locked ionic liquid membranes (LILMs) are engineered by composeing two interpenetrating polyamide nanofilms with biomimetic protrusions. These nanofilms confine ILs within cavities formed by protrusions, thinning IL layers to sub-0.5 µm while resisting shear stresses. The LILMs demonstrate a CO2/N2 selectivity of 55 and an enhanced CO2 permeance of 8.2 GPU, surpassing the performance of conventional SILMs by ≈20-fold while maintaining stability over 168 h of continuous mixed gas separation. By dual-purposing ILs as both solvents for interfacial polymerization and CO2 transporters, this bio-inspired architecture overcomes the thickness-stability limitations, enabling energy-efficient carbon capture.