Task-specific ionic liquids for carbon dioxide absorption and conversion into value-added products

Ionic liquids (ILs), by virtue of their special properties such as functional designability and high thermal stability, have been widely used as absorbent to CO₂ and catalyst for CO₂ conversion. This review summarizes the recent developments from 2019 to 2021 on task-specific ionic liquids (TSILs) with modulable properties by introducing specific functional groups to anions or/and cations for CO₂ absorption and conversion. The increase of basicity in TSILs by introducing amino/or amine groups or collaboration with multiple active sites of carboxyl, imidazolyl, pyridyl, and hydroxyl groups achieve high CO₂ affinity and absorption capacity. To solve the defects of high viscosity, ether groups are introduced to TSILs for CO₂ absorption. Besides, recent studies on CO₂ thermal catalytic conversion focused on the construction of C–O bonds and C–N bonds are also summarized. The catalytic activity of TSILs is enhanced by improving the synergy effect of different functional groups on anions and cations. It is expected that this minireview will provide the understanding of the current developments and perspective for practical CO₂ absorption and transformation by TSILs.