(470d) Coupling CO2 Capture and Electrochemical Reduction Using Azolide Ionic Liquids

Electrochemical CO₂ reduction (CO2R) provides a potential route to obtain a variety of carbon containing products. Here, we explore the use of a dilute ionic liquid (IL) solution in aprotic solvent. The use of an aprotic solvent allows us to avoid competition from HER due to a limited amount of easily ionizable protons that could be reduced while the IL could act as a cocatalyst to facilitate CO₂ activation. Pure ILs have also been used as electrolytes for CO₂ electroreduction in recent years. Ionic liquids have physicochemical properties which make them well suited as electrolytes, such as high intrinsic ionic conductivity, wide electrochemical potential windows, and high solubility of CO₂. Almost all previous work on electrochemical CO₂ reduction in ILs has been done where CO₂ is simply physically dissolved in the IL. In this work, our selected set of ionic liquids react reversibly with CO₂ with an enthalpy of reaction that can be tuned over a very wide range by choice of electron donating or withdrawing groups on the anion. The ability to form anion-CO₂ carbamate complex could facilitate CO₂ activation and reduce the required potential for forming CO over Ag catalysts. Looking forward, combining the CO₂ capture ability of ILs with CO2R could produce systems that perform both functions in a single medium. Insights from this work will advance the performance of systems that perform simultaneous CO₂ capture and conversion. Furthermore, this work will show that in addition to modifying catalyst performance through active site engineering, electrocatalytic activity can be controlled by modifying the environment around active sites. The diversity of ILs provide a way to modify this environment, and thus catalyst performance, in a systematic way.