Precise Pore Engineering at Picometer Scale on Nanofluidic Membrane for Efficient Hydrogen Purification

Hydrogen, a carbon-free energy carrier is mainly produced through methane steam reforming, generating CO₂ as the primary byproduct alongside H₂O and CH₄, complicating efficient hydrogen purification. Nanofluidic Hydrogen-bonded framework (HBF) membranes are promising for gas separation, while methods to precisely tailor pores for enhance performance remain scarce. Herein, a series of HBF membranes (SIFHBF-Cu, GeFHBF-Cu and TIFHBF-Cu) are successfully fabricated for H₂ purification. Pore size is precisely tuned at the picometer scale (< 1 Å) by altering the anion linkers (SiF₆ ^2-, GeF₆ ^2- and TiF₆ ^2-), enabling efficient H₂ purification through the synergy between subtle window adjustments and F-site-enhanced CO₂ affinity. The SIFHBF-Cu membrane combines the optimal size-exclusion and strongest HBF-CO₂ interactions, exhibiting excellent H₂/CO₂ selectivity (501) and ternary gas separation (H₂/CO₂: 477, H₂/CH₄: 557), with stable performance under dry/wet conditions. This study provides a strategy for ultra-precise pore engineering, showing potential for other challenging separations like seawater desalination and isomer separation.