The selective sieving role of nanosheets in the development of advanced membranes for water treatment: Comparison and performance enhancement of different nanosheets

Abstract Nanosheets have elicited great enthusiasm in the development of advanced membrane with advantages in the balance of permeability and selectivity, reduction of membrane thickness, enhancement of stabilities and improvement of fouling resistance. Although various nanosheets, such as graphene oxide (GO), MXene, MoS2, 2D metal organic frameworks (MOFs) and 2D covalent organic frameworks (COFs), have been explored as membrane materials for water treatment, their superiorities and deficiencies are different in lamellar membranes in terms of pore size, surface charge, hydrophilicity, stability, toxicity, compatibility with substrates and complexities of preparation, exfoliation and modification. All these properties could influence the application of nanosheets in membrane filtration. The selective sieving mechanisms of nanosheets and their impact on membrane performance were summarized. The common challenges of nanosheets as water treatment membranes and various improving strategies along with the future prospect were discussed.