Electrochemical reduction of supercritical carbon dioxide in ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate

Using 1-n-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) as a solvent and electrolyte, supercritical (SC) CO2 and water were successfully electrolyzed, and the products were CO, H2, and small amount of formic acid. The Faradic efficiency (FE) of CO increases considerably as the pressure is increased. In contrast, the FE for H2 decreases as the pressure of CO2 rises. After the electrolysis, the products were extracted with SC CO2 and the BmimPF6 could be reused. This offers a new and clean route to use SC CO2.