Enhancing Electrochemical CO₂-to-CO Conversion in a Nonaqueous Amine-Based Electrolyte at Elevated Temperature via Pulsed Electrolysis and EDTA

This study represents a first step toward integrating CO2 capture and electrochemical conversion by investigating the use of 0.5 M monoethanolamine (MEA)─a widely used industrial CO2 absorbent─in a nonaqueous electrolyte composed of choline chloride and ethylene glycol (1:4 mole ratio). This electrolyte was selected to enhance the CO2 solubility and catalytic performance while minimizing the water content and suppressing hydrogen evolution. This electrolyte was tested in a compact two-compartment H-cell electrolyzer operating at 65 °C─a temperature reflecting industrially relevant conditions. To further improve the stability and selectivity of the CO2RR to CO, pulsed electrolysis was employed. This approach effectively addressed key drawbacks of static electrolysis by modulating the electric field, enhancing mass transport, and inducing electrode surface restructuring. Additionally, ethylenediaminetetraacetic acid (EDTA) was introduced to chelate trace metal impurities and further stabilize the process. The combined use of EDTA and pulsed electrolysis (pulse potential of 0 V vs. Ag/AgCl for 20 s) effectively restructured the electrode surface, resulting in improved current stability and a notable increase in faradaic efficiency for CO up to 60%. Overall, our findings demonstrate the potential of pulsed electrolysis and EDTA in overcoming the limitations of static electrolysis and provide a foundational framework for integrated CO2 capture and conversion processes using multifunctional nonaqueous electrolytes.