Efficient Electrocatalytic CO₂ Reduction Driven by Ionic Liquid Buffer-Like Solutions

Electrocatalysis of CO₂ reduction in aqueous electrolytes containing the ionic liquid (IL) 1-n-butyl-2,3-dimethylimidazolium acetate ([BMMIm][OAc]) and DMSO proceeded at low overpotentials (-0.9 V vs. Ag/AgCl) at commercially-available Au electrodes, with high selectivity for CO production (58 % faradaic efficiency at -1.6 V vs. Ag/AgCl). 0.43 mol CO₂ per mol IL could be absorbed into the electrolyte at atmospheric pressure, forming bicarbonate and providing a constant supply of dissolved CO₂ to the surface of the electrode. Electrocatalysis of CO₂ reduction in the electrolyte was facilitated by stabilization of CO₂ radical anions by the imidazolium cations of the IL and buffer-like effects with bicarbonate.