Abstract: Functionalized ionic liquids (ILs) are the most promising approaches to achieve high performing CO₂ capture. This mini-review outlines some important progress for functionalized ILs in CO₂ capture. Ami-no-functionalized ILs exhibit high reactivity with CO₂, and their careful structural design is able to produce high absorption capacity of CO₂. The introduction of intra-molecular hydrogen bonding/proton transfer in ami-no-functionalized ILs is an attractive approach to avoid the formation of intermolecular hydrogen bonded networks generally occurred in traditional amino-functionalized ILs, thus resulting in enhanced absorption capacity of CO₂ and improved uptake rate. Non-amino anion-functionalized ILs such as substituted azolide or phenolate ILs show great potential for rapid and reversible uptake of CO₂ due to their lack of hydrogen bonding, controllable absorption enthalpy and excellent stability. However, there is still a long way to go to construct high performing systems based on functionalized ILs including high capacity of CO₂, rapid absorption kinetics and excellent cycling life. Smart strategies such as dual-tuning methods, multi-site cooperative interactions, and intra-molecular hydrogen bonding/proton transfer would promote the development of CO₂ capture in functionalized ILs significantly.

Key words: functionalized ionic liquids, smart strategies, high CO₂ capacity, rapid uptake kinetics, long cycling life