Amino-Functionalized Ionic-Liquid-Grafted Covalent Organic Frameworks for High-Efficiency CO2Capture and Conversion

Abstract

Rationally integrating desired functional components into a composite material can endow the tailored function to achieve the corresponding purpose. This is the first case where a series of [AeImBr]X%-TAPT-COFs (X = 0, 17, 33, 50, 67, 83, 100) were fabricated by chemically integrating the amino-functionalized imidazole ionic liquid (NH2-IL) onto channel walls of mesoporous covalent organic framework materials ([HO]X%-TAPT-COFs). By virtue of the polar groups (amino groups) and abundant imidazole cations of NH2-IL and its microporous nature, the obtained [AeImBr]X%-TAPT-COFs exhibit higher CO2 capture activity than [HO]X%-TAPT-COFs. Correspondingly, the CO2 equilibrium capture capacity increases from 62.6 to 117.4 mg/g, which is crucial to the storage of enough CO2 around the catalytic active sites. Additionally, the synergistic effect of -NH2 and Br- in NH2-IL can also improve the cycloaddition reaction rate. The characteristics of [AeImBr]X%-TAPT-COFs contribute to the efficient generation of cyclic carbonate through heterogeneously catalyzing CO2-epoxide cycloaddition without any solvents and cocatalysts. Specifically, [AeImBr]83%-TAPT-COF has a CO2 equilibrium capture capacity of 117.4 mg/g and cyclochloroallyl carbonate yield of 99.1%. As a result of the use of the chemical grafting method, [AeImBr]X%-TAPT-COFs possess excellent stability and cycle life. The equilibrium capture capacity and cyclochloroallyl carbonate yield reach 112.7 mg CO2/g adsorbent and 95.0% at the eighth cycle.