Ternary Ionic-Liquid-Based Electrolyte Enables Efficient Electro-reduction of CO2 over Bulk Metal Electrodes

Using bulk metals as catalysts to get high efficiencyin electro-reductionof CO2 is ideal but challenging. Here, we report the couplingof bulk metal electrodes and a ternary ionic-liquid-based electrolyte,1-butyl-3-methyl-imidazolium tetrafluoro-borate/ 1-dodecyl-3-methyl-imidazoliumtetrafluoro-borate/ MeCN to realize highly efficient electro-reductionof CO2 to CO. Over various bulk metal electrodes, the ternaryelectrolyte not only increases the current density but also suppressesthe hydrogen evolution reaction to obtain a high Faradaic efficiency(FE) toward CO. FECO could maintain similar to 100% over awide potential range, and metal electrodes showed very high stabilityin the ternary electrolyte. It is demonstrated that the aggregationbehavior of the ternary electrolyte and the arrangement of two kindsof IL cations with different chain lengths in the electrochemicaldouble layer not only increase the wettability to electrode and CO2 adsorption but also extend the diffusion channel of H+, rendering the high current density and FECO.