Oxygen-tolerant electroproduction of C2 products from simulated flue gas†
The electroreduction of carbon dioxide (CO2) to C2 products is a promising approach to divert and utilize CO2 emissions. However, the requirement of a purified CO2 feedstock decreases the economic feasibility of CO2 electrolysis. Direct utilization of industrial flue gas streams is encumbered by low CO2 concentrations and reactive oxygen (O2) impurities. We demonstrate that pressurization enables efficient CO2 electroreduction of dilute CO2 streams (15% v/v); however, with the inclusion of O2 (4% v/v), the oxygen reduction reaction (ORR) displaces CO2 reduction and consumes up to 99% of the applied current in systems based on previously-reported catalysts. We develop a hydrated ionomer catalyst coating strategy that selectively slows O2 transport and stabilizes the copper catalyst. Applying this strategy, we convert an O2-containing flue gas to C2 products at a faradaic efficiency (FE) of 68% and a non-iR-corrected full cell energetic efficiency (EE) of 26%.