Molecular design of CO2-binding organic liquids: Experimental and modeling insights into the role of hydroxy compounds in DBU-based water-lean solvents

CO 2 binding organic liquids (CO 2 BOLs) are a promising class of water-lean solvents for CO 2 capture, with improved performance compared to traditional aqueous amines. This study systematically examines the role of hydroxy compounds and their molecular features on CO 2 chemisorption in binary 1,8-diazabicyclo[5.4.0]undec-7-ene-based CO 2 BOLs using a combined density functional theory (DFT) and experimental approach. A series of hydroxy compounds from linear and branched alkanols, polyols, and ether-functionalized alcohols are evaluated to elucidate structure–property relationships governing CO 2 binding, reaction energetics, and absorption performance. DFT-based topological and energetic analyses reveal that CO 2 uptake is controlled by a balance between strong DBU–hydroxy hydrogen bonding and weaker, reversible CO 2 –oxygen interactions. Experimental measurements of CO 2 loading and absorption enthalpy confirm a pronounced thermodynamic–kinetic trade-off, where polyols exhibit strong CO 2 binding but suffer from high activation barriers and regeneration penalties, whereas linear alkanols favor faster kinetics with weaker thermodynamic driving forces. Branched alkanols and ether-containing alcohols provide an optimal intermediate regime, achieving higher CO 2 loadings with moderate absorption enthalpies. The combined experimental–computational framework presented here provides mechanistic insight and practical guidelines for the rational design of next-generation CO 2 BOLs, advancing the development of efficient and regenerable water-lean solvents for CO 2 capture.