Two-Dimensional Membranes: New Paradigms for High-Performance Separation Membranes

Two-dimensional (2D) materials with atomic thicknesses have aroused great interest as promising building blocks for the preparation of ultrathin 2D membranes. These 2D membranes can exhibit unprecedentedly high separation permeance owing to their ultrasmall membrane thicknesses and superior selectivity because of their size-selective nanopores and/or nanochannels. Until now, a large number of 2D membranes with good performance have been reported, highlighting the potential of these novel membranes for efficient liquid and gas separations. Summarized in this review are the latest advances in 2D membranes, with a special focus on industrially attractive separation processes, fabrication methods of laminar membranes, choices of membrane materials, designs of membrane structures, and unique membrane transport properties. Opportunities and challenges of 2D membranes for commercial applications are also briefly discussed.