Ionic liquid-decorated COF and its covalent composite aerogel for selective CO2 adsorption and catalytic conversion†
Atmospheric CO2 is closely related to the greenhouse effect. Therefore, new practical materials and techniques for highly selective CO2 adsorption and catalytic conversion are imperative. Covalent composites of covalent organic frameworks (COFs) with polymers (oligomers) might be a promising approach to meeting the multifaceted requirements of CO2 treatment. Herein, a novel COF–chitosan composite aerogel (COF-IL@chitosan) was designed and fabricated by chemical crosslinking of an allyl-imidazolium ionic liquid-decorated COF (COF-IL) with a thiol-attached chitosan (chitosan–SH) binder via a photoinduced thiol–ene reaction. The crystalline structure, highly selective CO2 adsorption and catalytic conversion features of COF-IL were found to be well maintained in the composite aerogel. The generated covalently coupled COF–chitosan composite material COF-IL@chitosan was found to be robust, uniform and processable even with a remarkably high COF loading (up to 80 wt%). More importantly, the processable COF-IL@chitosan aerogel could be readily shaped into a simplified fixed-bed reactor model via a facile templated freeze-drying procedure, and a scaled-up recyclable CO2 cycloaddition reaction was realized.