CO2 -Philic Separation Membrane: Deep Eutectic Solvent Filled Graphene Oxide Nanoslits.

CO2 capture and sequestration is an energy-intensive industry to deal with the global greenhouse effect. Membrane separation is considered a cost-effective method to mitigate the emission of CO2 . Though good separation performance and stability have been reported, supported ionic liquid membranes are still not widely applied for CO2 separation due to the high cost. As a novel analogous solvent to ionic liquid, deep eutectic solvent retains the excellent merits of ionic liquid and is cheap with facile preparation. Herein, a highly CO2 -philic separation membrane is constructed by nanoconfining choline chloride/ethylene glycol (ChCl/EG) deep eutectic solvent into graphene oxide nanoslits. Molecular dynamic simulation results indicate that the confinement makes a difference to the structure of the nanoconfined ChCl/EG liquid from their bulk, which remarkably facilitates CO2 transport. By tuning the molar ratio of ChCl/EG and thickness of the membrane, the resultant membrane exhibits outstanding separation performance for CO2 with excellent selectivity over other light gases, good long-term durability, and thermal stability. This makes it a promising membrane for selective CO2 separation.