Journal of Applied Electrochemistry, Vol.47, No.11, 1251-1260, 2017
Electroreduction and solubility of CO2 in methoxy- and nitrile-functionalized imidazolium (FAP) ionic liquids
Ionic liquids with cyano (-CN)- and methoxy (-OCH3)-functionalized imidazolium cations paired with a fluorine-containing common anion Tris(pentafluoroethyl)trifluorophosphate or [FAP] were evaluated as solvent and electrolyte in the electroreduction of carbon dioxide. The measured reduction potentials of CO2 in both ionic liquids were observed to occur at ca.-1.1 V versus Cc(+)/Cc internal reference standard, which are significantly lower when compared to that of the non-functionalized analog [pmim][FAP], with an observed reduction potential of ca. -1.6 V versus Cc(+)/Cc. This decrease in the potential required for CO2 reduction in the cation-functionalized [FAP] ionic liquids suggests that the presence of functional groups methoxy and cyano effectively decreased the free energy of formation of the radical anion CO (2) (center dot-) . Results using pressure drop measurement and IR spectroscopy verify the ability of the ILs to dissolve carbon dioxide. Such solvents may be used as carbon capture agents and organocatalysts in the reduction of carbon dioxide.
Keywords:Chronoamperometry;CO2 reduction;Methoxy-functionalized ionic liquid;Nitrile-functionalized ionic liquid;Pressure drop method;IR spectroscopy