Sustainion Imidazolium-Functionalized Polymers for Carbon Dioxide Electrolysis

CO2 electrolysis is a key step in CO2 conversion into fuels and chemicals as a way of mitigating climate change. We report the synthesis and testing of a series of new anion-conductive membranes (tradenamed SustainionS) for use in CO2 electrolysis. These membranes incorporate the functional character of imidazolium-based ionic liquids as co-catalysts in CO2 reduction into a solid membrane with a styrene backbone. We find that the addition of an imidazolium group onto the styrene side-chains increases the selectivity of the reaction from approximately 25% to approximately 95%. The current at 3 V is increased by a factor of 14. So far we have been able to tune these parameters to achieve stable cells that provide current densities higher than 100 mAcm(-2) at 3 V cell potential with a CO product selectivity over 98%. Stable performance was observed for 6 months of continuous operation (> 150 000 000 turnovers). These results demonstrate that imidazolium polymers are ideal membranes for CO2 electrolysis.