Crumpled Two-Dimensional Ti₃C₂T_x MXene Lamellar Membranes for Solvent Permeation and Separation

Lamellar membranes assembled from two-dimensional (2D) materials represent a type of advanced separation membrane. However, obtaining 2D materials from assembled lamellar membranes with high permeability and selectivity properties is a significant challenge. In this paper, flat Ti3C2Tx MXene nanosheets were crumpled by a facile freeze-drying method with the use of a solvent as a template. After assembly of the crumpled Ti3C2Tx (c-Ti3C2Tx) nanosheets into lamellar membranes, the c-Ti3C2Tx MXene membranes possessed many interfacial voids with enlarged interlayer channels (compared with noncrumpled Ti3C2Tx MXene membranes). As a result, the permeation of both water and organic solvents was significantly enhanced. For example, the c-Ti3C2Tx MXene membranes exhibited ultrafast permeation of 5460 and 3745 L/m2·h·bar for water and acetone, respectively. It was also demonstrated that the trade-off between permeability and selectivity could be efficiently addressed by regulating the thickness of the c-Ti3C2Tx MXene membranes; this process is directly dependent on the mass loading of the c-Ti3C2Tx nanosheets on the support membrane. These results could potentially create possibilities to develop highly efficient membranes based on these types of 2D MXene materials for water treatment and organic solvent filtration.