Channel-Pocket Ultra-Micropore Configuration in a Hydrogen-Bonded Organic Framework for Simultaneous High Xe Capture...

Development of energy-efficient physisorbents for xenon/krypton (Xe/Kr) separation is highly essential to produce high-purity noble gases and control the pollution of radioactive isotopes. Porous organic materials are very promising for gas separation due to their advantages of low regeneration energy, high moisture resistance, good solution processability and easy regeneration. However, their nonpolar pore surfaces lack strong sorbate-sorbent interactions, leading to the intrinsic trade-off between Xe capacity and selectivity that severely delimit their separation efficiency. Herein, we report a strategy of designing channel-pocket ultra-micropore configuration in a threefold interpenetrated HOF (ZJU-HOF-6a) for achieving simultaneous high Xe capture and Xe/Kr separation. This channel-pocket ultra-micropore structure can provide the size-matched pore channels and cavities (4.7 and 4.4 Å) to offer strong pore confinement for highly selective binding of Xe, and also maximize the usage of pore spaces for high surface area (1113 m² g^-1) to target large Xe adsorption. ZJU-HOF-6a thus achieves a rare combination of simultaneous high Xe uptake (3.3 mmol g^-1) and record Xe/Kr selectivity (23.5) at 298 K and 1 bar, surpassing all the reported porous organic materials. The adsorption binding of Xe and Kr was visualized by gas-loaded ZJU-HOF-6a crystal structures. Breakthrough experiments demonstrate its exceptional separation capacities for actual Xe/Kr mixtures under ambient conditions, affording the record-high dynamic selectivity (13.7) among porous organic materials.