Two-dimensional carbon nanomesh membrane for ultrafast molecular sieving

Abstract

Two-dimensional membranes assembled with two-dimensional materials have been widely used in water purification, but there are problems of poor permeability and low water flux. To address this issue, herein, a novel strategy for preparing the 2D carbon nanomesh (CNM) has been developed by simple high-temperature chlorination of MXene. It has been found that pore size distribution of resultant CNM is heavily dependent upon MXene type. When three membranes (∼100 μm in thickness) assembled from Nb2C-CNM, Ti3C2-CNM and Nb4C3-CNM were used to sieve dye solutions, they all exhibit high rejection rates of up to 99.9% for organic dyes and extremely high water permeance, which are two orders of magnitude higher than the reported GO-based membranes. The realization of this ultrafast dye molecular sieving in such thick membranes is unexpected, which can be ascribed to the unique hierarchical structure of the interconnected nanochannels inside the assembled CNM membrane. This discovery may open up novel perspectives for the construction of thick membranes with ultrafast molecular separation performance. More interestingly, after long-term soaking treatment in acidic solution, the CNM membranes can exhibit further significantly increased water flux while keeping their high dye rejection rates, which may suggest a strategy for preparing membranes with excellent separation performance.