Scaling the Electrochemical Conversion of CO2 to CO

Abstract

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 FE_CO 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 FE_CO 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.