Fine-tuning of imidazole-based ionic liquid for highly efficient and reversible direct air capture via hydrogen bonding interaction

The increasing CO₂ concentration in the atmosphere has caused a lot of environmental problems. However, absorbents for highly efficient and reversible carbon capture, especially direct air capture, are still under development. Herein, a strategy of improving the CO₂ absorption and desorption behavior of a kind of imidazole-based ionic liquid for reversible CO₂ capture from ambient air via hydrogen bonding interaction was reported. By adding different hydrogen bond donors, the CO₂ capacities and absorption enthalpies of imidazole-based IL ([N₂₂₂₄][Im]) were well tuned. Between them, [N₂₂₂₄][Im]-Car exhibited a relatively high CO₂ capacity at the atmospheric CO₂ concentration of 0.4 mbar at 30 °C up to 0.6 mol CO₂ per mol IL and excellent reversibility. Compared with pure [N₂₂₂₄][Im], the regeneration performance of [N₂₂₂₄][Im]-Car was immensely enhanced, making it more promising for energy-efficient CO₂ capture and practical application in direct air capture.