Efficient CO2/Pure Water Co-Electrolysis for CO Production at 100 °C

Polyelectrolyte-based CO2 electrolyzers are generally limited to operation below 80 °C, primarily restricted by the thermal instability of alkaline polyelectrolyte (APE) membranes and the rapid evaporation/boiling of water at elevated temperatures. Herein, we successfully increased the CO2/pure water co-electrolysis temperature to 100 °C by employing a custom-designed membrane electrode assembly (MEA) electrolyzer. This was enabled by employing a high-temperature-resistant APE membrane (QAPPT) and implementing a back-pressurized cell configuration to avoid water boiling. Using this setup, we systematically investigated the effects of temperature and backpressure on CO2/pure water co-electrolysis performance. Our results demonstrate that elevated temperature and applied backpressure synergistically promote Ag-catalyzed CO2 reduction to CO. Under optimized conditions, the CO2 MEA electrolyzer achieves state-of-the-art CO production performance, exceeding reported benchmarks and highlighting the critical role of operating conditions in CO2 electrolysis.