Molecular sieving membranes with sufficient and uniform nanochannels that break the permeability-selectivity trade-off are desirable for energy-efficient gas separation, and the arising two-dimensional (2D) materials provide new routes for membrane development. However, for 2D lamellar membranes, disordered interlayer nanochannels for mass transport are usually formed between randomly stacked neighboring nanosheets, which is obstructive for highly efficient separation. Therefore, manufacturing lamellar membranes with highly ordered nanochannel structures for fast and precise molecular sieving is still challenging. Here, we report on lamellar stacked MXene membranes with aligned and regular subnanometer channels, taking advantage of the abundant surface-terminating groups on the MXene nanosheets, which exhibit excellent gas separation performance with H2 permeability >2200 Barrer and H2/CO2 selectivity >160, superior to the state-of-the-art membranes. The results of molecular dynamics simulations quantitatively support the experiments, confirming the subnanometer interlayer spacing between the neighboring MXene nanosheets as molecular sieving channels for gas separation.

Two-dimensional (2D) materials are promising candidates for advanced water purification membranes. A new kind of lamellar membrane is based on a stack of 2D MXene nanosheets. Starting from compact Ti AlC , delaminated nanosheets of the composition Ti C T with the functional groups T (O, OH, and/or F) can be produced by etching and ultrasonication and stapled on a porous support by vacuum filtration. The MXene membrane supported on anodic aluminum oxide (AAO) substrate shows excellent water permeance (more than 1000 L m h bar ) and favorable rejection rate (over 90 %) for molecules with sizes larger than 2.5 nm. The water permeance through the MXene membrane is much higher than that of the most membranes with similar rejections. Long-time operation also reveals the outstanding stability of the MXene membrane for water purification.

Ti 3 C 2 T x MXene, through exposing more edge sites, is demonstrated to be an efficient catalyst for electrochemical nitrogen fixation at an ultralow overpotential under ambient conditions. On the edge plane, the nitrogen is spontaneously absorbed on the middle Ti and overcomes a low energy barrier to be converted into ammonia compared to that on the basal plane with an unfavorable energy barrier. This proposed strategy is readily applicable to other two-dimensional catalysts to optimize the surface properties for efficient electrochemical nitrogen fixation under ambient conditions.

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An efficient one-pot multienzyme approach has been developed for the synthesis of structural diverse LacNAc, lactose, and their derivatives including those containing negatively charged 6-O-sulfated GlcNAc and C2-substituted GlcNAc or Glc analogs. Two bacterial β1–4-galactosyltransferases, NmLgtB and Hp1–4GalT, exhibits promiscuous and complementary acceptor substrate specificity. The application of these enzymes in the one-pot multienzyme system allows the access to complex disaccharides with diverse structural modifications from monosaccharide derivatives and inexpensive Glc-1-P without using expensive sugar nucleotide. Bacterial carbohydrate-biosynthetic enzymes have been proven as efficient tools in novel synthesis of diverse and complex carbohydrates.