Perforative pore formation on nanoplates for 2D porous MXene membranes via H2O2 mild etching

Abstract

MXene (Ti3C2Tx) is a novel, two-dimensional (2D) layered material that is atomically thin, exhibits good mechanical strength, and is ideal for fabricating efficient membranes for molecular separation. However, the applications of MXene membranes are limited by their low water permeability owing to narrow channels and high tortuosity. A novel strategy for introducing artificial pores on the surface of MXene nanosheets via gentle in situ chemical etching with hydrogen peroxide (H2O2) to prepare porous MXene nanosheets (PMS) is reported herein. This greatly increases the water permeability of MXene membranes while retaining the high rejection of small-molecule dyes. Permeable pores generated on MXene nanosheets transform the transport model of water molecules in the membrane from typical horizontal transport pathways dominated by interlayer channels to longitudinal–lateral three-dimensional transport pathways, affording increased water molecule transport channels and reduced transport distance. Based on different etching conditions, the obtained membranes exhibit high pure-water permeability ranging from 9.37 to 42.48 L m−2 h−1 bar−1. Moreover, mild etching maintains the 2D structure of the membrane and retains a nearly complete rejection of congo red dye. This study provides a novel and effective strategy for preparing high-performance porous laminar MXene membranes for dye-separation applications.