A Superhydrophobic Nanotrap Porous Organic Cage for Efficient Capture of SF₆ Under Dry and Humid Conditions

Effective SF₆ capture and recovery are essential for reducing greenhouse gas emissions and promoting resource recycling, yet many porous materials exhibit reduced separation performance for SF₆/N₂ mixtures in humid environments due to water adsorption competition or structural instability. To address this challenge, we propose a "superhydrophobic nanotrap" strategy by designing a nitrogen-rich superhydrophobic porous organic cage (POC) named IMUPOC-DA. This material incorporates a moisture-blocking shield of superhydrophobic isobutyl chains and an inner cavity with a π-system and Lewis base sites that synergistically enhance SF₆ trapping. At 298 K and 1 bar, IMUPOC-DA achieves an SF₆ adsorption capacity of 53.6 cm³ g^-1 and an SF₆/N₂ uptake ratio of 20.02, a record-high reported thus far for POC-based adsorbents. More importantly, the superhydrophobic surface endows the material with an extremely low water uptake (72.1 mg g^-1), a high water contact angle (150.11^°), and excellent water stability. Dynamic column breakthrough experiments under 80% relative humidity show nearly unchanged SF₆ breakthrough time compared with dry conditions, demonstrating outstanding SF₆/N₂ separation performance even in a moist environment. Therefore, this work not only provides a high-performance candidate for industrial SF₆ recovery but also presents a general design strategy for developing moisture-resistant adsorbents for gas separation.