Synergistic enhancement of CO2 absorption properties in deep eutectic solvents via hydrophobic microinterfaces under humid conditions

This study introduces innovative hydrophobic nanostructured composite deep eutectic solvents (HS-SiO 2 /DBU-EG) to overcome limitations of amine absorbents in humid CO 2 . The HS-SiO 2 /DBU-EG achieved a significantly enhanced CO 2 absorption capacity of 4.14 mol/kg and maintaining a high regeneration efficiency of 95 %, attributed to its inherent synergistically hydrophobic nanostructure. In contrast, while DBU-EG showed improved absorption under humid CO 2 but reduced regeneration performance. Spectroscopic analysis revealed that DBU-EG relies on hydrolysis-induced N-sites for absorption, but the resulting products are challenging to decompose. Conversely, HS-SiO 2 /DBU-EG utilizes the O-sites of EG as the absorption sites, a mechanism supported by thermodynamic analysis and quantum calculations demonstrating a low enthalpy change value of the reaction. Fixed-bed experiments further confirmed its efficient and continuous absorption performance. This research emphasizes the value of low-energy absorption mechanisms and hydrophobic design for advanced industrial CO 2 capture.