Bipolar membrane electrolyzers enable high single-pass CO2 electroreduction to multicarbon products
Ke Xie, Rui Kai Miao, Adnan Ozden, Shijie Liu, Zhu Chen, Cao‐Thang Dinh, Jianan Erick Huang, Qiucheng Xu, Christine M. Gabardo, Geonhui Lee, Jonathan P. Edwards, Colin P. O’Brien, Shannon W. Boettcher, David Sinton, Edward H. Sargent
Abstract
Abstract In alkaline and neutral MEA CO 2 electrolyzers, CO 2 rapidly converts to (bi)carbonate, imposing a significant energy penalty arising from separating CO 2 from the anode gas outlets. Here we report a CO 2 electrolyzer uses a bipolar membrane (BPM) to convert (bi)carbonate back to CO 2 , preventing crossover; and that surpasses the single-pass utilization (SPU) limit (25% for multi-carbon products, C 2+ ) suffered by previous neutral-media electrolyzers. We employ a stationary unbuffered catholyte layer between BPM and cathode to promote C 2+ products while ensuring that (bi)carbonate is converted back, in situ, to CO 2 near the cathode. We develop a model that enables the design of the catholyte layer, finding that limiting the diffusion path length of reverted CO 2 to ~10 μm balances the CO 2 diffusion flux with the regeneration rate. We report a single-pass CO 2 utilization of 78%, which lowers the energy associated with downstream separation of CO 2 by 10× compared with past systems.