Selective high-temperature CO2 electrolysis enabled by oxidized carbon intermediates

Theis L. Skafte, Zixuan Guan, Michael L. Machala, Chirranjeevi B. Gopal, Matteo Monti, Lev Martinez, Eugen Stamate, Simone Sanna, Jose A. Garrido Torres, Ethan J. Crumlin, Max García-Melchor, Michal Bajdich, William C. Chueh, Christopher R. Graves*

*Corresponding author for this work

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Abstract

High-temperature CO2 electrolysers offer exceptionally efficient storage of renewable electricity in the form of CO and other chemical fuels, but conventional electrodes catalyse destructive carbon deposition. Ceria catalysts are known carbon inhibitors for fuel cell (oxidation) reactions; however, for more severe electrolysis (reduction) conditions, catalyst design strategies remain unclear. Here we establish the inhibition mechanism on ceria and show selective CO2 to CO conversion well beyond the thermodynamic carbon deposition threshold. Operando X-ray photoelectron spectroscopy during CO2 electrolysis—using thin-film model electrodes consisting of samarium-doped ceria, nickel and/or yttria-stabilized zirconia—together with density functional theory modelling, reveal the crucial role of oxidized carbon intermediates in preventing carbon build-up. Using these insights, we demonstrate stable electrochemical CO2 reduction with a scaled-up 16 cm2 ceria-based solid-oxide cell under conditions that rapidly destroy a nickel-based cell, leading to substantially improved device lifetime.
Original languageEnglish
JournalNature Energy
Volume4
Pages (from-to)846-855
Number of pages10
ISSN2058-7546
DOIs
Publication statusPublished - 2019

Cite this

Skafte, T. L., Guan, Z., Machala, M. L., Gopal, C. B., Monti, M., Martinez, L., Stamate, E., Sanna, S., Garrido Torres, J. A., Crumlin, E. J., García-Melchor, M., Bajdich, M., Chueh, W. C., & Graves, C. R. (2019). Selective high-temperature CO2 electrolysis enabled by oxidized carbon intermediates. Nature Energy, 4, 846-855. https://doi.org/10.1038/s41560-019-0457-4