Oxygen-tolerant electroproduction of C2 products from simulated flue gas

The electroreduction of carbon dioxide (CO2) to C-2 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 (O-2) impurities. We demonstrate that pressurization enables efficient CO2 electroreduction of dilute CO2 streams (15% v/v); however, with the inclusion of O-2 (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 O-2 transport and stabilizes the copper catalyst. Applying this strategy, we convert an O-2-containing flue gas to C-2 products at a faradaic efficiency (FE) of 68% and a non-iR-corrected full cell energetic efficiency (EE) of 26%.