Fast Crystallization of Fluorinated Covalent Organic Frameworks via a Steam-Assisted Conversion for Xe/Kr Separation

The development of novel covalent organic frameworks (COFs) represents a crucial research hotspot and frontier in contemporary materials science, offering immense potential for advancing applications in catalysis and separation. However, severe restrictions in conventional solvothermal synthesis, including high reaction energy barriers, long reaction times, and stringent experimental conditions, constrain the potential for uncovering novel structures, particularly challenging fluorinated covalent organic frameworks (FCOFs). Consequently, we propose an innovative steam-assisted conversion (SAC) strategy to address this critical bottleneck and fully unlock the application potential of FCOFs. A series of fluorinated COFs (4F-LZU-1-COF, 4F-SHTA-Pa-COF, and 4F-DHTA-Pa-COF) have been successfully synthesized. Real-space imaging of FCOFs using ultralow-dose high-resolution transmission electron microscopy confirmed their superior crystallinity. Notably, our SAC strategy offers a remarkably mild, rapid, and environmentally friendly synthetic route, which effectively addressing the limitations of the traditional solvothermal approach. These materials demonstrate efficient Xe/Kr separation performance due to the presence of the fluorine sites. Most importantly, FCOFs can tolerate high-intensity  γ-irradiation, making them outstanding candidates for the treatment of radioactive effluent gases. These intriguing findings highlight our SAC strategy as a viable and scalable route for the synthesis of robust FCOFs, broadening the scope of COF fabrication, and opens new avenues for their applications.