Issue 18, 2024

CO residence time modulates multi-carbon formation rates in a zero-gap Cu based CO2 electrolyzer

Abstract

Carbon dioxide (CO2) electrolysis on copper (Cu) catalysts has attracted interest due to its direct production of C2+ feedstocks. Using the knowledge that CO2 reduction on copper is primarily a tandem reaction of CO2 to CO and CO to C2+ products, we show that modulating CO concentrations within the liquid catalyst layer allows for a C2+ selectivity of >80% at 200 mA cm−2 under broad conversion conditions. The importance of CO pooling is demonstrated through residence time distribution curves, varying flow fields (serpentine/parallel/interdigitated), and flow rates. While serpentine flow fields require high conversions to limit CO selectivity and maximize C2+ selectivity, the longer CO residence times of parallel flow fields achieve similar selectivity over broad flow rates. Critically, we show that parts of the catalyst area predominantly reduce CO instead of CO2 as supported by CO reduction experiments, transport modelling, and achieving a CO2 utilization efficiency greater than the theoretical limit of 25% for C2+ products.

Graphical abstract: CO residence time modulates multi-carbon formation rates in a zero-gap Cu based CO2 electrolyzer

Supplementary files

Article information

Article type
Paper
Submitted
08 May 2024
Accepted
31 Jul 2024
First published
01 Aug 2024
This article is Open Access
Creative Commons BY license

Energy Environ. Sci., 2024,17, 6728-6738

CO residence time modulates multi-carbon formation rates in a zero-gap Cu based CO2 electrolyzer

S. Subramanian, J. Kok, P. Gholkar, A. Sajeev Kumar, H. Iglesias van Montfort, R. Kortlever, A. Urakawa, B. Dam and T. Burdyny, Energy Environ. Sci., 2024, 17, 6728 DOI: 10.1039/D4EE02004A

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