A reduced pressure-assisted vapor penetration of ionic liquid into the laminated graphene oxide membranes for efficient CO2 separation

Tailor-made ultrathin and defect-free supported ionic liquid membranes (SILMs) have great potential for CO2 separation. Herein, we developed a highly perm-selective CO2-philic laminated GO supported ionic liquid membrane (GO-SILM) with a thickness of 100 nm, via a reduced pressure-assisted vapor penetration strategy. Specifically, under reduced pressure condition, the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) vapor can not only seal the possible defects/pores in GO membrane, but also penetrate into the 2D nanochannels of laminated GO membrane. Based on the favorable interaction between IL and GO nanosheets, IL can be confined within the nanochannels of laminated GO membranes, which favors a fast and selective CO2 transport. Besides, the ultrathin selective layer shortens the transport distance extremely. Benefiting from the aforementioned features, the obtained GO-SILMs display a high CO2 permeance of 56.6 GPU with CO2/CH4 selectivity of 53.5, which is superior to other reported SILMs. The groundbreaking membrane fabrication approach through reduced pressure-assisted IL vapor penetration into GO membrane to seal the non-selective defects is facile, effective and IL-saving, which paves a new way for the development of ultrathin and defect-free SILMs for high-efficient CO2 separation.