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

The increasing CO 2 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 CO 2 absorption and desorption behavior of a kind of imidazole-based ionic liquid for reversible CO 2 capture from ambient air via hydrogen bonding interaction was reported. By adding different hydrogen bond donors, the CO 2 capacities and absorption enthalpies of imidazole-based IL ([N 2224 ][Im]) were well tuned. Between them, [N 2224 ][Im]-Car exhibited a relatively high CO 2 capacity at the atmospheric CO 2 concentration of 0.4 mbar at 30 °C up to 0.6 mol CO 2 per mol IL and excellent reversibility. Compared with pure [N 2224 ][Im], the regeneration performance of [N 2224 ][Im]-Car was immensely enhanced, making it more promising for energy-efficient CO 2 capture and practical application in direct air capture.