Modulating Molecular Interactions in Bulk and Electrochemical Interfaces of Deep Eutectic Solvent-Based Tailored Electrolytes for Facilitating Reactive CO2 Capture

The conventional CO₂ capture and utilization (CCU) uses aqueous amine solutions, but its environmental hostility and energy-intensive process to regenerate CO₂ are major hurdles toward sustainability. Alternatively, electrochemical reactive CO₂ capture (eRCC) that integrates CO₂ capture and its conversion has been considered a promising method for economical and sustainable CO₂ valorization. However, designing a suitable electrolyte system with tailored electrochemical interfaces for efficient eRCC is a major challenge. Herein, we report a tailored deep eutectic solvent (DES)-based electrolyte containing a superbase (DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene), an aprotic diluent (DMSO: dimethyl sulfoxide), and ethaline (Eth) for an efficient and low-cost eRCC. The tailored DES electrolyte depicts multifold improvement in eRCC performance compared to pristine Eth with good CO₂ capture capacity and a superior conversion rate (363.6 μmol cm^–2 h^–1) at elevated temperatures (i.e., 50 °C). The spectroscopic, electrochemical, and theoretical (AIMD) investigations suggest that the modulated molecular interactions between DES and CO₂ boost its capture and facilitate the release of captured CO₂ for subsequent reduction. Overall, the facile mass transport, higher concentration of CO₂ at the electrode surface, and greater stabilization of intermediates due to the formation of a compact electrical double layer in a tailored DES resulted in relatively high eRCC performance.