Task-specific deep eutectic solvents: Intelligent molecular design for on-demand CO2 capture and release

Achieving carbon neutrality demands advanced CO 2 capture technologies that overcome the limitations of conventional amine-based solvents, such as high energy consumption and environmental toxicity. Here, a task-specific deep eutectic solvent (DES) engineered for on-demand CO 2 capture and release, combining high efficiency, low energy consumption, and environmental sustainability was reported in this work, which employing an ionic liquid as a hydrogen bond acceptor (HBA) and ethanol as a dual-function solvent/hydrogen bond donor (HBD). The [AEP][Pro]-Ethanol system achieved a high capacity of 1.10 mol CO 2 ·mol absorbent −1 while a low viscosity of 13.06 mPa·s after saturated absorption, and kept 87 % regeneration efficiency after five regeneration cycles at 363.15 K. Mechanistic insights from combined experimental characterization and density functional theory (DFT) calculations revealed a unique CO 2 absorption pathway, enabling ultralow regeneration energy (1.94 GJ·ton −1 CO 2 )—nearly 50 % lower than monoethanolamine (MEA, 3.77 GJ·ton −1 CO 2 ). This DES platform merges molecular tunability, exceptional cycling stability, and industrial scalability, offering a breakthrough solution for next-generation carbon capture technologies. • Designed and developed functionalized deep eutectic solvent [AEP][Pro]-Ethanol for energy-efficient CO 2 capture • Achieved a high CO 2 absorption capacity of 1.10 mol CO 2 ·mol absorbent -1 with a low viscosity of 13.06 mPa·s at saturation • Maintains 87% regeneration efficiency after 5 cycles at low temperature (363.15 K) • The [AEP][Pro]-Ethanol absorbent achieved an exceptionally low regeneration energy consumption of 1.94 GJ·ton -1 CO 2 • Combined experimental and quantum chemical calculations elucidate the absorbent's molecular structure and low-temperature regeneration mechanism