Carbon dioxide capture and its electrochemical reduction study in deep eutectic solvent (DES) via experimental and molecular simulation approaches

Electrochemical reduction of carbon dioxide (ERCO2) is one of the potential ways to tackle the problems associated with climate change due to this greenhouse gas. However, poor solubility of CO2 in the commonly used aqueous as well as organic electrolytes limits the availability of CO2 at the electrode surface for its efficient capture and conversion. In this regard, deep eutectic solvents (DES) offer new avenues to enhance the electrochemical reduction of carbon dioxide due to very good solubility of CO2 (1.3 mol CO2/mol DES; 329 K, 76.5kPa) in DES, which is tuneable with the DES composition. Nevertheless, the understanding about the mechanistic aspects of capture and electrochemical conversion of CO2 in DES are not clearly understood. Herein, we present the results from our systematic theoretical plus experimental investigations on CO2 capture and electrochemical conversion using a DES, i.e. Ethaline. Ethaline when used as electrolyte at gold sheet working electrode reveals enhanced current response, reduced charge transfer resistance, and lowering of the overpotential by 440 mV as compared to DMF (dimethyl formamide). The CO2 electrolysis in Ethaline gives CO as the main product with a high faradic efficiency of 81.8%. The theoretical studies using Molecular Dynamics (MD) simulation was performed to investigate the microscopic properties of the DES along with its ability for CO2 capture.