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.

Electrocatalytic nitrogen fixation is considered a promising approach to achieve NH3 production. However, due to the chemical inertness of nitrogen, it is necessary to develop efficient catalysts to facilitate the process of nitrogen reduction. Here, molybdenum carbide nanodots embedded in ultrathin carbon nanosheets (Mo2C/C) are developed to serve as a catalyst candidate for highly efficient and robust N2 fixation through an electrocatalytic nitrogen reduction reaction (NRR). The as‐synthesized Mo2C/C nanosheets show excellent catalytic performance with a high NH3 yield rate (11.3 µg h−1 mg−1 Mo2C) and Faradic efficiency (7.8%) for NRR under ambient conditions. More importantly, the isotopic experiments using 15N2 as a nitrogen source confirm that the synthesized ammonia is derived from the direct supply of nitrogen. This result also demonstrates the possibility of high‐efficiency nitrogen reduction even though accompanied with vigorous hydrogen evolution.

ZIF-8 membranes with inborn-suppressed linker mobility sharpen molecular sieving with C3H6/C3H8 separation factor above 300.

Two-dimensional (2D) graphitic carbon nitride (g-C N ) nanosheets show brilliant application potential in numerous fields. Herein, a membrane with artificial nanopores and self-supporting spacers was fabricated by assembly of 2D g-C N nanosheets in a stack with elaborate structures. In water purification the g-C N membrane shows a better separation performance than commercial membranes. The g-C N membrane has a water permeance of 29 L m h bar and a rejection rate of 87 % for 3 nm molecules with a membrane thickness of 160 nm. The artificial nanopores in the g-C N nanosheets and the spacers between the partially exfoliated g-C N nanosheets provide nanochannels for water transport while bigger molecules are retained. The self-supported nanochannels in the g-C N membrane are very stable and rigid enough to resist environmental challenges, such as changes to pH and pressure conditions. Permeation experiments and molecular dynamics simulations indicate that a novel nanofluidics phenomenon takes place, whereby water transport through the g-C N nanosheet membrane occurs with ultralow friction. The findings provide new understanding of fluidics in nanochannels and illuminate a fabrication method by which rigid nanochannels may be obtained for applications in complex or harsh environments.