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

• Published in: ChemSusChem Vol. 12; no. 18; pp. 4170 - 4175
• Main Authors: Gonçalves, Wellington D. G., Zanatta, Marcileia, Simon, Nathalia M., Rutzen, Luciane M., Walsh, Darren A., Dupont, Jairton
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 20.09.2019
• Subjects: Aqueous electrolytes; Bicarbonates; buffer-like solutions; Buffers; Carbon dioxide; CO2 reduction; CO2 sequestration; Electrocatalysis; Electrodes; Electrolytes; electroreduction; Gold; Ionic liquids; Ions; Reduction; Selectivity; Silver chloride
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201901076

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. Isn't it ionic? A simple ionic liquid/DMSO/H2O solution is able to decrease the overpotential in a commercial electrode by in situ formation of bicarbonate, providing an alternative way to produce syngas from CO2.