Promoting CO₂ reduction in the presence of oxygen with polymer-based gas diffusion electrodes

The electrochemical reduction of CO₂ is a promising technology that holds the potential to convert waste CO₂ into valuable products. High carbon capture and purification costs hamper economic feasibility and drive scientists to explore the viability of directly using flue gas exhaust streams. However, flue gas impurities, such as O₂, pose a great challenge because O₂ is preferentially reduced over CO₂. Here, we show that careful design of the gas diffusion electrode (GDE) can significantly improve Faradaic efficiency. This work not only unravels how commonly used carbon-based GDEs facilitate O₂ reduction but also succeeds in devising polymer-based alternatives that significantly improve the Faradaic efficiency (>40%) of CO₂ reduction with 5% O₂-containing feed streams while showing excellent stability for >2 days. These results demonstrate that it is feasible to engineer suitable GDEs for CO₂ reduction with impure feed streams.