Rational Design of MXene Hollow Fiber Membranes for Gas Separations

One scalable and facile dip-coating approach was utilized to construct a thin CO2-selection layer of Pebax/PEGDA-MXene on a hollow fiber PVDF substrate. An interlayer spacing of 3.59 angstrom was rationally designed and precisely controlled for the MXene stacks in the coated layer, allowing efficient separation of the CO2 (3.3 angstrom) from N2 (3.6 angstrom) and CH4 (3.8 angstrom). In addition, CO2-philic nanodomains in the separation layer were constructed by grafting PEGDA into MXene interlayers, which enhanced the CO2 affinity through the MXene interlayers, while non-CO2-philic nanodomains could promote CO2 transport due to the low resistance. The membrane could exhibit optimal separation performance with a CO2 permeance of 765.5 GPU, a CO2/N2 selectivity of 54.5, and a CO2/CH4 selectivity of 66.2, overcoming the 2008 Robeson upper bounds limitation. Overall, this facile approach endows a precise controlled molecular sieving MXene membrane for superior CO2 separation, which could be applied for interlayer spacing control of other 2D materials during membrane construction.

Automated summary

A scalable and easy dip-coating method was used to create a thin CO2-selection layer of Pebax/PEGDA-MXene on a hollow fiber PVDF substrate. The interlayer spacing of the MXene stacks in the coating was designed to be 3.59 angstrom, allowing efficient separation of CO2 from N2 and CH4. CO2-philic nanodomains were constructed in the layer to enhance CO2 affinity, while non-CO2-philic nanodomains promoted CO2 transport. The membrane showed excellent separation performance, surpassing the 2008 Robeson upper bounds limitation.