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

doi:10.1038/s41467-022-31295-3

Bipolar membrane electrolyzers enable high single-pass CO₂ electroreduction to multicarbon products

Nat Commun. 2022 Jun 24;13(1):3609. doi: 10.1038/s41467-022-31295-3.

Authors

Affiliations

¹ Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON, M5S 3G4, Canada.
² Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada.
³ Department of Chemical Engineering, Queen's University, 19 Division Street, Kingston, Kingston, ON, K7L 3N6, Canada.
⁴ Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, 97403, USA.
⁵ Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada. sinton@mie.utoronto.ca.
⁶ Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON, M5S 3G4, Canada. ted.sargent@utoronto.ca.

^# Contributed equally.

Abstract

In alkaline and neutral MEA CO₂ electrolyzers, CO₂ rapidly converts to (bi)carbonate, imposing a significant energy penalty arising from separating CO₂ from the anode gas outlets. Here we report a CO₂ electrolyzer uses a bipolar membrane (BPM) to convert (bi)carbonate back to CO₂, preventing crossover; and that surpasses the single-pass utilization (SPU) limit (25% for multi-carbon products, C₂₊) suffered by previous neutral-media electrolyzers. We employ a stationary unbuffered catholyte layer between BPM and cathode to promote C₂₊ products while ensuring that (bi)carbonate is converted back, in situ, to CO₂ near the cathode. We develop a model that enables the design of the catholyte layer, finding that limiting the diffusion path length of reverted CO₂ to ~10 μm balances the CO₂ diffusion flux with the regeneration rate. We report a single-pass CO₂ utilization of 78%, which lowers the energy associated with downstream separation of CO₂ by 10× compared with past systems.