Integrating two-dimensional MXene fillers into nanocellulose for the fabrication of CO2 separation membranes.

• Mixed matrix membranes comprised of MXenes and nanocellulose were fabricated. • Incorporation of MXene nanosheets provided the membranes with gas transfer channels. • The hydrogen bonds boosted the interfacial affinity between MXenes and cellulose. • The intercalation of nanocellulose can enlarge the interlayer spacing of MXenes. • The optimal MMMs present CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 42.6 and 47.8. To achieve high capability mixed matrix membranes for CO 2 separation, it is vital to construct the suitable transport channels to enhance the diffusivity-enabled selectivity as well as an excellent affinity toward target gas molecules to increase the solubility-based selectivity. Herein, composite membranes were constructed by integrating two-dimensional MXene nanosheets into a carboxylated nanocellulose matrix. The carboxyl-rich cellulose interacts with the surface groups of MXene, which contributes to a superior interface compatibility and repairs the non-selective voids. In particular, one-dimensional nanocellulose can intercalate into MXene laminates to regulate the interlayer spacing and suppress the re-stacking of MXenes. The resulting MC-3 membrane (with a MXene loading of 15.4 wt%) possesses the optimal separation performance, bearing a CO 2 permeability of 156.7 Barrer with ideal selectivities of 47.8 for CO 2 /CH 4 and 42.6 for CO 2 /N 2. For the mixed gas separation, the MC-3 membrane exhibits separation factors of 48.5 and 55.3 for CO 2 /N 2 and CO 2 /CH 4 , respectively. This excellent separation performance is resulted from the enhanced interfacial property, suitable MXene channel size and good CO 2 -solubility of nanocellulose. [ABSTRACT FROM AUTHOR]