Pushing Rubbery Polymer Membranes To Be Economic for CO Separation: Embedment with TiCT MXene Nanosheets.

Sustainable and energy-efficient molecular separation requires membranes with high gas permeability and selectivity. This work reports excellent CO separation performance of self-standing and thin-film mixed matrix membranes (MMMs) fabricated by embedding 2D TiCT MXene nanosheets in Pebax-1657. The CO/N and CO/H separation performances of the free-standing membranes are above Robeson's upper bounds, and the performances of the thin-film composite (TFC) membranes are in the target area for cost-efficient CO capture. Characterization and molecular dynamics simulation results suggest that the superior performances of the Pebax-TiCT membranes are due to the formation of hydrogen bonds between TiCT and Pebax chains, leading to the creation of the well-formed galleries of TiCT nanosheets in the hard segments of the Pebax. The interfacial interactions and selective TiCT nanochannels enable fast and selective CO transport. Enhancement of the transport properties of Pebax-2533 and polyurethane when embedded with TiCT further supports these findings. The ease of fabrication and high separation performance of the new TFC membranes point to their great potential for energy-efficient CO separation with the low cost of $29/ton separated CO.