Efficient Electrocatalytic CO 2 Reduction Driven by Ionic Liquid Buffer-Like Solutions

Electrocatalysis of CO 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 CO per mol IL could be absorbed into the electrolyte at atmospheric pressure, forming bicarbonate and providing a constant supply of dissolved CO to the surface of the electrode. Electrocatalysis of CO reduction in the electrolyte was facilitated by stabilization of CO radical anions by the imidazolium cations of the IL and buffer-like effects with bicarbonate.