A new approach has been developed to improve SO₂ sorption by cyano-containing ionic liquids (ILs) through tuning the basicity of ILs and cyano–sulfur interaction. Several kinds of cyano-containing ILs with different basicity were designed, prepared, and used for SO₂ capture. The interaction between these cyano-containing ILs and SO₂ was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO₂ capacity originate from the basicity of the ILs and enhanced cyano–sulfur interaction. Furthermore, the captured SO₂ was easy to release by heating or bubbling N₂ through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO₂ capture.

A strategy for improving CO₂ capture by new anion-functionalized ionic liquids (ILs) making use of multiple site cooperative interactions is reported. An extremely high capacity of up to 1.60 mol CO₂ per mol IL and excellent reversibility were achieved by introducing a nitrogen-based interacting site on the phenolate and imidazolate anion. Quantum-chemical calculations, spectroscopic investigations, and calorimetric data demonstrated that multiple-site cooperative interactions between two kinds of interacting sites in the anion and CO₂ resulted in superior CO₂ capacities, which originated from the π-electron delocalization in the pyridine ring.

A strategy for improving CO₂ capture by new anion-functionalized ionic liquids (ILs) making use of multiple site cooperative interactions is reported. An extremely high capacity of up to 1.60 mol CO₂ per mol IL and excellent reversibility were achieved by introducing a nitrogen-based interacting site on the phenolate and imidazolate anion. Quantum-chemical calculations, spectroscopic investigations, and calorimetric data demonstrated that multiple-site cooperative interactions between two kinds of interacting sites in the anion and CO₂ resulted in superior CO₂ capacities, which originated from the π-electron delocalization in the pyridine ring.

Phenolic ionic liquids for the efficient and reversible capture of CO₂ were designed and prepared from phosphonium hydroxide and substituted phenols. The electron-withdrawing or electron-donating ability, position, and number of the substituents on the anion of these ionic liquids were correlated with the physicochemical properties of the ionic liquids. The results show that the stability, viscosity, and CO₂-capturing ability of these ionic liquids were significantly affected by the substituents. Furthermore, the relationship between the decomposition temperature, the CO₂-absorption capacity, and the basicity of these ionic liquids was quantitatively correlated and further rationalized by theoretical calculation. Indeed, these ionic liquids showed good stability, high absorption capacity, and low absorption enthalpy for CO₂ capture. This method, which tunes the physicochemical properties by making use of substituent effects in the anion of the ionic liquid, is important for the design of highly efficient and reversible methods for CO₂-capture. This CO₂ capture process using diverse phenolic ionic liquids is a promising potential method for CO₂ absorption with both high absorption capacity and good reversibility.

The search for a better carbon dioxide (CO₂) capture material is attracting significant attention because of an increase in anthropogenic emissions. Porous materials are considered to be among the most promising candidates. A series of porous, nitrogen-doped carbons for CO₂ capture have been developed by using high-yield carbonization reactions from task-specific ionic liquid (TSIL) precursors. Owing to strong interactions between the CO₂ molecules and nitrogen-containing basic sites within the carbon framework, the porous nitrogen-doped compound derived from the carbonization of a TSIL at 500 °C, CN500, exhibits an exceptional CO₂ absorption capacity of 193 mg of CO₂ per g sorbent (4.39 mmol g⁻¹ at 0 °C and 1 bar), which demonstrates a significantly higher capacity than previously reported adsorbents. The application of TSILs as precursors for porous materials provides a new avenue for the development of improved materials for carbon capture.