Scaling the Electrochemical Conversion of CO₂ to CO

The key challenges for the industrial electrolysis of CO 2 into CO are the low CO 2 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 CO 2 electrolysis. In this study, we employed a bipolar membrane (BPM) in a pressurized electrolyzer with a 25 cm 2 active area to achieve a maximum FE CO of 93% with a cell voltage of 3.5 V and a maximum CO 2 single-pass conversion of 70% without detecting CO 2 crossover. In addition, we upscaled the system active area from 5 to 250 cm 2 and showed that this increase did not result in a loss of performance. In particular, the performance on the pressurized 100 cm 2 electrolyzer established an average FE CO of 85% with a CO 2 single-pass conversion of 60% for over 120 h. This provides practical approaches for transitioning from laboratory-scale to industrial-scale electrolysis.