Electrochemical Tuning of CO₂ Reactivity in Ionic Liquids Using Different Cathodes: From Oxalate to Carboxylation Products

Abstract

There is currently quite a lot of scientific interest in carbon dioxide (CO2) capture and valorization with ionic liquids (ILs). In this manuscript, we analyze the influence of the potential applied, the nature of the cathode and the electrolyte using different organic mediators, such as nitro or cyano aromatic derivatives, to promote the electrochemical activation of CO2. An electrocatalytic process using a homogeneous catalysis is seen when nitroderivatives are used, yielding to oxalate in organic electrolytes and ILs. Turnover frequency (TOF) values and Farafay efficiencies were slightly higher in N,N’-dimethylformamide (DMF) than in ILs probably due to the viscosity of the electrolyte. The use of cyano derivatives allows to tune the electrochemical reactivity in function of the reduction potential value applied from electrocarboxylated products (via a nucleophile-electrophile reaction) to oxalate. These electrochemical reactions were also performed using three different cathodes, organic electrolytes and ionic liquids. The use of copper, as a cathode, and ionic liquids, as electrolytes, would be a cheaper and greener alternative for activating carbon dioxide.

Keywords

• CO₂
• electrochemistry
• ionic liquid
• catalysis
• carboxylation
• green chemistry