Catalytic Electrochemical Reduction of CO2 in Ionic Liquid EMIMBF3Cl

A novel ionic liquid EMIMBF3Cl that contains a BF3Cl− anion has been synthesized. This is the first report of an ionic liquid with a BF3Cl− anion. It was found that CO2 gas can be dissolved and electrochemically reduced at ambient pressure, and room temperature in the ionic liquid EMIMBF3Cl. The reduction of CO2 occurred at a relatively less negative electrode potential of −1.8 V vs. silver wire, compared to previous reported values that are between −2.4 and −2.0 V. The reduction current density can be as high as ∼5.7 mA/cm2. The BF3Cl− anion may catalyze the CO2 reduction by forming a Lewis acid-base adduct BF3-CO2.