Highly selective and stable electro-catalytic system with ionic liquids for the reduction of carbon dioxide to carbon monoxide

•Excellent synergy was observed for the electrochemical reduction of CO2 to CO.•The electro-catalytic system exhibited continuous activity for more than 150 h.•The Faraday efficiency for CO formation was > 98%.

In this study, the electrochemical reduction of CO2 was examined using a Ag-modified Cu catalyst cathode in a series of mixed ionic liquids (ILs) in the presence or absence of cobalt chloride (CoCl2). These results indicate that the Ag-modified Cu electrode in EMIMBF4 + BMIMNO3 with CoCl2 exhibited the excellent synergy for the electrochemical reduction of CO2 to CO with a stable area specific activity, with continuous production for at least 150 h. In such a system, a CO selectivity of 98% was achieved. According to the obtained results, a possible mechanism was proposed. The synergistic effect between the Ag-modified Cu electrode, serving as the main catalyst, and CoCl2 and ILs, serving as the co-catalysts, is probably responsible for the highly selective and stable electrocatalytic reduction of CO2 to CO.

Graphical abstractThe electrochemical reduction of CO2 to CO over a silver-modified copper electrode in a mixed IL system of 24 g EMIMBF4 + 1 g BMIMNO3 (containing 0.25 mg CoCl2) exhibited excellent synergy with > 98% selectivity, and a stable area specific activity with continuous activity for at least 150 h.Figure optionsDownload full-size imageDownload as PowerPoint slide