Rational Design of MXene Hollow Fiber Membranes for Gas Separations.

One scalable and facile dip-coating approach was utilized to construct a thin CO 2 -selection layer of Pebax/PEGDA-MXene on a hollow fiber PVDF substrate. An interlayer spacing of 3.59 Å was rationally designed and precisely controlled for the MXene stacks in the coated layer, allowing efficient separation of the CO 2 (3.3 Å) from N 2 (3.6 Å) and CH 4 (3.8 Å). In addition, CO 2 -philic nanodomains in the separation layer were constructed by grafting PEGDA into MXene interlayers, which enhanced the CO 2 affinity through the MXene interlayers, while non-CO 2 -philic nanodomains could promote CO 2 transport due to the low resistance. The membrane could exhibit optimal separation performance with a CO 2 permeance of 765.5 GPU, a CO 2 /N 2 selectivity of 54.5, and a CO 2 /CH 4 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 CO 2 separation, which could be applied for interlayer spacing control of other 2D materials during membrane construction.