Highly selective electrocatalytic reduction of carbon dioxide to carbon monoxide on silver electrode with aqueous ionic liquids

•Metal Ag in BMImCl aqueous solution shows the excellent synergy.•The electro-catalytic system is relatively simple.•The electro-catalytic system presents better stability.•The selectivity of reduction of CO2 to CO (FE >99%) is higher.

In this study, the electrochemical reduction of carbon dioxide (CO2) was examined in a series of aqueous solutions of ionic liquids on metal (silver (Ag), copper, platinum and gold) catalyst cathode. The results indicated that Ag metal cathode in 1-butyl-3-methylimidazolium chloride (BMImCl) with 20 wt.% water showed excellent synergy in electrochemical reduction of CO2 to carbon monoxide (CO) with extremely high selectivity (> 99%) and efficiency, and with stable area specific activity (ca. 2.4 mA·cm− 2). The behavior of electrocatalytic reduction of CO2 to CO on Ag electrode in ionic liquids (ILs) was examined by cyclic voltammogram. The study revealed that the chloride containing IL could be the most effective candidate for reduction of CO2 to CO and for inhibiting the hydrogen evolution reaction probably due to the dominated water–anion and water–cation interactions in aqueous BMImCl.

Graphical abstractThe electrochemical reduction of CO2 to CO over metal Ag cathode in BMImCl aqueous solution showed the excellent synergy with > 99% selectivity and with stable area specific activity (ca. 2.4 mA·cm− 2).Figure optionsDownload full-size imageDownload as PowerPoint slide