Scaling Low-Temperature CO2-to-Syngas Electroreduction: Failure Modes, Engineering Bottlenecks, and Mitigation Strategies

Pachamuthu S, Gao J, Ozden A, Legrand U, Favaro M, Isaacs M, García de Arquer FP, Azenha C, Mendes A, Sargent EH, Janáky C, Grätzel M, Jiménez-Calvo P (2026)

Publication Type: Journal article, Review article

Publication year: 2026

Journal

ACS Energy Letters American Chemical Society

Book Volume: 11

Pages Range: 4813-4836

Journal Issue: 7

DOI: 10.1021/acsenergylett.6c00886

Abstract

Low-temperature CO2 electroreduction (CO2eR) to syngas offers tunable H2:CO ratios and a renewable route to decarbonized syngas production, yet catalyst-level advances rarely translate to scalable, durable systems. This review addresses that disconnect with a systems-engineering perspective. We first establish the component foundations, electrolytes, membranes, and cell architectures of flow cells and zero-gap membrane electrode assembly (MEA) electrolyzers, together with integrated versus decoupled syngas production modes, then analyze the engineering failure modes that dominate at scale: non-uniform current distribution, localized hotspots, electrode flooding, salt precipitation, and thermal gradients. Single-pass CO2 conversion efficiency (SPCE) is introduced as a co-equal metric alongside Faradaic and energy efficiency (FE/EE). Original contributions include a standardized accelerated stress test (AST) protocol, a lifecycle sustainability assessment (LCSA) framework with quantitative carbon footprint benchmarking, a mitigation strategy compatibility matrix, and three-benchmark design pathways targeting high EE, high stability, and high SPCE, providing an actionable systems-engineering roadmap toward CO2eR systems sustaining >5000 h at industrially relevant current densities.

Involved external institutions

École Polytechnique Fédérale de Lausanne (EPFL) CH Switzerland (CH) Universidade do Porto PT Portugal (PT) University of Toronto CA Canada (CA) eChemicles HU Hungary (HU) Khalifa University of Science, Technology & Research (KUSTAR) / جامعة خليفة AE United Arab Emirates (AE) Electro Carbon Inc. CA Canada (CA) Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) DE Germany (DE) Rutherford Appleton Laboratory GB United Kingdom (GB) Institute Of Photonic Sciences / Instituto de Ciencias Fotónicas / Institut de Ciències Fotòniques (ICFO-CERCA) ES Spain (ES)

How to cite

APA:

Pachamuthu, S., Gao, J., Ozden, A., Legrand, U., Favaro, M., Isaacs, M.,... Jiménez-Calvo, P. (2026). Scaling Low-Temperature CO2-to-Syngas Electroreduction: Failure Modes, Engineering Bottlenecks, and Mitigation Strategies. ACS Energy Letters, 11(7), 4813-4836. https://doi.org/10.1021/acsenergylett.6c00886

MLA:

Pachamuthu, Senthilkumar, et al. "Scaling Low-Temperature CO2-to-Syngas Electroreduction: Failure Modes, Engineering Bottlenecks, and Mitigation Strategies." ACS Energy Letters 11.7 (2026): 4813-4836.

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