Superior Hydrogen Separation in Nanofluidic Membranes by Synergistic Effect of Pore Tailoring and Host-Guest Interaction

High-purity H₂ production accompanied by precise decarbonization paves the way for a carbon-neutral society. Hydrogen-bonded organic frameworks (HOFs) are promising materials for advanced gas separation membranes, but their broad nanoscale pores limit selective separation. High-quality carboxylic acid-based HOF membranes (HOF-S, HOF-M, HOF-L) with pore sizes of 6.2, 16, and 24 Å were synthesized using an innovative pore-tailoring strategy. Under optimized conditions, H₂ can pass through while CO₂ is blocked by the size-exclusion principle. Abundant carboxylic acid groups in pores hinder the mobility of CO₂ via electrostatic interaction, integrating adsorption and molecular sieving to enable excellent H₂ transport and separation. The HOF-S membrane combines size exclusion and HOF-CO₂ interactions, exhibiting excellent selectivity for H₂/CO₂ (164) and a ternary gas mixture (H₂/CO₂ selectivity: 154; H₂/CH₄ selectivity: 201). It also displays long-term stability under both dry and wet conditions. This strategy opens new possibilities for customizing nanofluidic membranes for advanced gas separation technologies.