Dihydroxyl-Cooperative 1,2,4-Triazole-Based Ionic Liquid for Robust Reversible CO2 Absorption

The development of aqueous absorbents for CO2 capture is significantly important to reduce global industrial gas emissions through high regeneration efficiency and low energy consumption. Herein, we newly designed and prepared a dihydroxylated ionic liquid (IL) bis(2-hydroxyethyl)dimethylammonium 1,2,4-triazole ([N1,1,2OH,2OH][TZ]) for highly efficient CO2 absorption through anion–cation cooperative interactions. A superior capacity of 1.33 mol of CO2 per mol of IL and excellent reversibility have been achieved by the introduction of dihydroxy sites on the ammonium-based Tz IL. 1H and 13C nuclear magnetic resonance, Fourier transform infrared, and quantum chemical calculations demonstrate bihydroxyl-cooperative absorption of CO2 via hydrogen bond interaction between the cation and anion of the IL. The theory calculation shows that IL displays a superlow reactive absorption enthalpy, favorable to the reversible CO2 absorption, which can maintain an initial absorption capacity of 98.5% with the cycle numbers of 100, implying the facile regeneration and superlow energy consumption. Thus, the functionalized ILs toward group cooperative gas absorption and excellent reversibility may open a door to designing new materials for enhancing CO2 absorption and utilization.