Bipolar membrane electrolyzers enable high single-pass CO<sub>2</sub> electroreduction to multicarbon products.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35750665.
- Also identified by DOI 10.1038/s41467-022-31295-3 and PMC identifier 9232613.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
In alkaline and neutral MEA CO<sub>2</sub> electrolyzers, CO<sub>2</sub> rapidly converts to (bi)carbonate, imposing a significant energy penalty arising from separating CO<sub>2</sub> from the anode gas outlets. Here we report a CO<sub>2</sub> electrolyzer uses a bipolar membrane (BPM) to convert (bi)carbonate back to CO<sub>2</sub>, preventing crossover; and that surpasses the single-pass utilization (SPU) limit (25% for multi-carbon products, C<sub>2+</sub>) suffered by previous neutral-media electrolyzers. We employ a stationary unbuffered catholyte layer between BPM and cathode to promote C<sub>2+</sub> products while ensuring that (bi)carbonate is converted back, in situ, to CO<sub>2</sub> 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<sub>2</sub> to ~10 μm balances the CO<sub>2</sub> diffusion flux with the regeneration rate. We report a single-pass CO<sub>2</sub> utilization of 78%, which lowers the energy associated with downstream separation of CO<sub>2</sub> by 10× compared with past systems.