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

Wang, Huijie; Shi, Miaomiao; Wang, Chong; Chu, Zhenyu; Yin, Zongyou; Wang, Chen · Nano Lett · 2025

basic_science · Level V

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Abstract

High-purity H<sub>2</sub> 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, H<sub>2</sub> can pass through while CO<sub>2</sub> is blocked by the size-exclusion principle. Abundant carboxylic acid groups in pores hinder the mobility of CO<sub>2</sub> via electrostatic interaction, integrating adsorption and molecular sieving to enable excellent H<sub>2</sub> transport and separation. The HOF-S membrane combines size exclusion and HOF-CO<sub>2</sub> interactions, exhibiting excellent selectivity for H<sub>2</sub>/CO<sub>2</sub> (164) and a ternary gas mixture (H<sub>2</sub>/CO<sub>2</sub> selectivity: 154; H<sub>2</sub>/CH<sub>4</sub> 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.