Reactivity of Ionic Liquid-Based Phenolate Zwitterions for CO₂ Capture in the Aqueous Phase

Ideal liquid sorbents, such as phenolate zwitterions, represent a novel and promising technology for CO₂ capture. To enhance their design and reactivity with CO₂, two types of substituents, electron-donating groups (EDGs) and electron-withdrawing groups (EWGs) were investigated. Using density functional theory (DFT) with a large basis set, their effectiveness as reactivity modulators was assessed through energy decomposition analysis, noncovalent interaction, natural bond orbitals (NBO), evaluation of reaction energy barriers, and pK_a. EDGs, in general, enhance phenolate reactivity and stability, highlighting their potential in the design of advanced zwitterionic sorbents for CO₂ capture. Conversely, EWGs demonstrated mixed effects, providing lower CO₂ capture effectiveness but enhancing recyclability of the phenolates. In summary, our findings provide a framework to investigate substituent efficacy and design next-generation carbon capture materials.