Covalent modification is commonly used to tune the channel size and functionality of 2D membranes. However, common synthesis strategies used to produce such modifications are known to disrupt the structure of the membranes. Herein, we report less intrusive yet equally effective non-covalent modifications on Ti₃C₂T_x MXene membranes by a solvent treatment, where the channels are robustly decorated by protic solvents via hydrogen bond network. The densely functionalized (-O, -F, -OH) Ti₃C₂T_x channel allows multiple hydrogen bond establishment and its sub-1-nm size induces a nanoconfinement effect to greatly strengthen these interactions by maintaining solvent-MXene distance and solvent orientation. In sub-1-nm ion sieving and separation, as-decorated membranes exhibit stable ion rejection, and proton-cation (H⁺/Mⁿ⁺) selectivity that is up to 50 times and 30 times, respectively, higher than that of pristine membranes. It demonstrates the feasibility of non-covalent methods as a broad modification alternative for nanochannels integrated in energy-, resource- and environment-related applications.

Membrane‐based enantioselective separation is a promising method for chiral resolution due to its low cost and high efficiency. However, scalable fabrication of chiral separation membranes displaying both high enantioselectivity and high flux of enantiomers is still a challenge. Here, the authors report the preparation of homochiral porous organic cage (Covalent cage 3 (CC3)‐R)‐based enantioselective thin‐film‐composite membranes using polyamide (PA) as the matrix, where fully organic and solvent‐processable cage crystals have good compatibility with the polymer scaffold. The hierarchical CC3‐R channels consist of chiral selective windows and inner cavities, leading to favorable chiral resolution and permeation of enantiomers; the CC3‐R/PA composite membranes display an enantiomeric excess of 95.2% for R‐(+)‐limonene over S‐(−)‐limonene and a high flux of 99.9 mg h⁻¹ m⁻². This work sheds light on the use of homochiral porous organic cages for preparing enantioselective membranes and demonstrates a new route for the development of next‐generation chiral separation membranes.

High‐performance proton exchange membranes (PEMs) play a vital role in the efficiency of high‐temperature proton exchange membrane fuel cells. In this study, a novel PEM with a hyperbranched interpenetrating hydrogen bond network (HIHBN) is developed by incorporating hyperbranched poly(benzyl‐triptycene) (PBT) and SnP₂O₇ hydrogen bond networks. This innovative design significantly enhances the proton conductivity. Additionally, the unique structure of the hyperbranched PBT polymer with a branching point (triptycene, a π‐conjugated aromatic ring compound with a three‐cyclic configuration) contributes to an impressive glass transition temperature exceeding 400 °C, enabling the membrane to operate at elevated temperatures (above 220 °C) in fuel cell applications. This membrane shows promise as an alternative to commonly used polybenzimidazole (PBI)‐based membranes, offering improved mechanical strength and a reduced swelling ratio. When applied in fuel cells, the HIHBN PEM achieves an excellent through‐plane proton conductivity of 0.108 S cm⁻¹ and a peak power density of 0.75 W cm⁻² at 220 °C under dry H₂/O₂ conditions. Notably, it exhibited minimal degradation after ≈33 h under harsh operating conditions, demonstrating its stability and long‐term durability. These findings highlight the potential of HIHBN PEMs for high‐efficiency, durable performance in high‐temperature fuel cell environments.

An ultrathin carbon molecular sieve membrane with superior H ₂ /CO ₂ separation performance was fabricated by using metal oxyhydroxide nanosheets as a scaffold.