Scaling the Electrochemical Conversion of CO2 to CO

The key challenges for the industrial electrolysis of CO2 into CO are the low CO2 conversion, restricted scale-up, and poor long-term operation. Systematic process design and electrolyzer engineering are essential for addressing these challenges and exploiting the full potential of commercial CO2 electrolysis. In this study, we employed a bipolar membrane (BPM) in a pressurized electrolyzer with a 25 cm2 active area to achieve a maximum FECO of 93% with a cell voltage of 3.5 V and a maximum CO2 single-pass conversion of 70% without detecting CO2 crossover. In addition, we upscaled the system active area from 5 to 250 cm2 and showed that this increase did not result in a loss of performance. In particular, the performance on the pressurized 100 cm2 electrolyzer established an average FECO of 85% with a CO2 single-pass conversion of 60% for over 120 h. This provides practical approaches for transitioning from laboratory-scale to industrial-scale electrolysis.