MOF-induced hetero-nucleation engineering enables HOF-based composite membranes for high-permeance hydrogen purification

Herein, we have designed the all-nanoporous composite (ANC) membranes with metal–organic framework (MOF) fillers and hydrogen-bonded organic framework (HOF) matrix, achieving high-permeance H₂ purification. The hetero-MOF facilitates the heterogeneous nucleation, offsetting the need for a highly supersaturated solution to achieve sufficient nucleation density during solution processing. Continuous MOF/HOF ANC membranes are realized by suppressing the homogeneous nucleation, equilibrating the nucleation driving force with the molecular attachment rate, and balancing the nutrient supply and demand. The optimized copper 1,4-benzene dicarboxylate nanosheets (ns-CuBDC)/HOF-30-100 (30 means that HOF monomer concentration is 30 mg·mL⁻¹ and 100 represents that the temperature for solvent evaporation is 100 °C) ANC membrane shows synchronously improved H₂ permeance and H₂/CH₄ selectivity by 562% and 241% compared to the pristine HOF membrane. The ns-CuBDC/HOF-30-100 ANC membrane inherits the pressure-responsive behavior from the parent HOF, exhibiting further improved H₂ permeance up to 9842 gas permeation units (GPU) and slightly changed H₂/CH₄ selectivity of 30.01 at 2.0 bar. The MOF/HOF ANC membrane manifests that incorporating a porous hetero-phase effectively upgrades the gas separation performance, and the HOF matrix circumvents the performance constraints of the traditional polymer matrix while preserving the solution-processability.