Construction of MoS2@MXene composite membranes with stable laminar structure for superior nanofiltration performance

Two-dimensional (2D) MXene-based membranes have aroused intensive attention for highly efficient water purification, however, most of them are restricted by the classic trade-off effect and structural swelling in an aqueous medium. In this study, a MoS2@MXene membrane with superior nanofiltration (NF) performance and stability by intercalating 2D molybdenum disulfide (MoS2) nanosheet into Ti3C2Tx MXene laminates was reported. With increasing MoS2 nanosheet loading amount, the MoS2@MXene composite membrane surfaces became more hydrophilic and the corresponding water contact angles reduced from 77.2° to 48°. The optimal MoS2@MXene composite membrane showed enhanced water permeability of 172.5 L·bar−1·h−1·m−2 and nearly 99 % Rhodamine B (RhB) rejection in comparison with the pure MXene membrane. The optimal membrane also displayed high salt rejection of 82.5 %, 75 %, 60 %, and 50.8 % for 1000 ppm Na2SO4, MgSO4, NaCl, and MgCl2 solutions, respectively. Due to the weak interaction between MoS2 and water molecules and the strong π-π attraction force between MXene and MoS2 nanosheets, the MoS2@MXene composite membrane was highly stable which could maintain the same separation performance for 5 NF cycles. The molecular dynamics (MD) simulation also demonstrated that the intercalated MoS2 nanosheet can not only accelerate water transport of the formed laminar structure but also strengthen the structural stability of the membrane. These findings might provide valuable insights into precise construction of 2D material-based membranes with excellent stability and separation performance.