Fluorine-induced gradient electric field in mesoporous covalent organic frameworks for efficient separation of polarized perfluorinated gases

The challenge of effectively capturing and separating perfluorinated gases is critical due to environmental concerns and the potential to recover these gases as high-value products in the silicon semiconductor industry. Various strategies have been developed to enhance the mass transfer capabilities of microporous adsorbents, which are vital for producing high-performance adsorbent materials. However, slow mass transfer within micropores significantly limits their performance in applications. In this study, we introduce two isostructural mesoporous covalent organic frameworks (COFs) characterized by high crystallinity, porosity, and stability. Compared to non-fluorinated COFs, the highly fluorinated COF demonstrates superior storage capacity for octafluoropropane (C3F8) and perfluorocyclobutane (c-C4F8). It also achieves remarkable separation efficiencies for C3F8 (or c-C4F8)/N2 (or Ar, H2, O2) mixtures under ambient conditions, establishing a standard in the field. This study highlights the significance of strategically modifying pore surface chemistry based on the polarizability differences of guest molecules. Such modifications enable the efficient separation of mixed gas molecules in mesoporous materials.