The last decade has seen an explosion of interest in the use of ionic liquids (ILs) in CO2 capture and conversion, in large part because of their unique properties such as negligible vapor pressure, high thermal and chemical stability, and the feasibility of structural and functional tunability. One of the primary goals in this area is to design functional ILs with high absorption capacity for CO2 capture. In this context, amine-functionalized ILs have become one of the most popular IL types and have attracted much attention. The absorption mechanism of IL with CO2 is crucial for its absorption capacity; however, the absorption mechanism of amine-functionalized IL is still a subject of debate. Davis and co-workers first reported an amine-functionalized IL with a primary amine on the imidazolium cation, which reacts with CO2 similarly to standard amine scrubbing agents. As shown in Eqs. (1) and (2), one CO2 reacts with two amines to form carbamate and ammonium ions (1:2 reaction mechanism).
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