How is CO2 absorbed into a deep eutectic solvent?

Deep eutectic solvents show great potential as CO2 absorbents, which is highly desirable for the sustainable development of CO2 reduction and prevention of global climate changes. Ab initio molecular dynamics simulations in the isothermal-isobaric ensemble at pressures of 1 MPa and 5 MPa and at the corresponding experimental density are carried out to investigate the CO2 absorption in choline chloride: ethylene glycol deep eutectic solvent. Based on the structural analysis, there is a strong anion and hydrogen bond donor effect and a minor cation effect on CO2 solvation in the solvent. Instead of cooperation, a competition between the anion and the hydrogen bond donor (ethylene glycol) for the interaction with CO2 is indicated. While at a lower pressure, the ethylene glycol-CO2 interaction dominates, at a higher pressure, it is the chloride-CO2 interaction. Thus, it is possible to use the same advantages within the deep eutectic solvent as the CO2 absorbent as in ionic liquids, but in the hydrogen bond, a donor can be exploited.