Insights into Carbon Dioxide Electroreduction in Ionic Liquids: Carbon Dioxide Activation and Selectivity Tailored by...

Electroreduction of carbon dioxide (CO₂ ) into high value-added products is a potential solution to a reduction in CO₂ levels and its utilization. One major challenge is the lack of an efficient system that can highly selectively reduce CO₂ into desirable products with low energy consumption. Ionic liquids (ILs) have been used as electrolytes for the electroreduction of CO₂ , and it has been proven that the CO₂ -cation complex results in a low-energy pathway. In this work, an ionic microhabitat (IMH) has been built for CO₂ electroreduction, and a novel anion-functionalized IL, 1-butyl-3-methylimidazolium 1,2,4triazolide ([Bmim][124Triz]), has been designed as the reaction medium. The results showed that the IMH played a key role in enhancing the performance of CO₂ electroreduction, especially in dominating the product selectivity, which is recognized to be a great challenge in an electroreduction process. New insights into the role of the IMH in higher CO₂ solubility, bending linear CO₂ by forming the [124Triz]-CO₂^- adduct, and transferring activated CO₂ into the cathode surface easily were revealed. The Faradaic efficiency for formic acid is as high as 95.2 %, with a current density reaching 24.5 mA cm^-2 . This work provides a promising way for the design of robust and highly efficient ILs for CO₂ electroreduction.