Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate
The electrochemical reduction of bicarbonate to renewable chemicals without external gaseous CO 2 supply has been motivated as a means of integrating conversion with upstream CO 2 capture. The way that CO 2 is formed and transported during CO 2 -mediated bicarbonate reduction in flow cells is profou...
Published in: | Industrial & Engineering Chemistry Research |
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ftosti:oai:osti.gov:1878469 2023-07-30T04:02:56+02:00 Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate Kas, Recep Yang, Kailun Yewale, Gaurav P. Crow, Allison Burdyny, Thomas Smith, Wilson A. 2023-07-10 application/pdf http://www.osti.gov/servlets/purl/1878469 https://www.osti.gov/biblio/1878469 https://doi.org/10.1021/acs.iecr.2c00352 unknown http://www.osti.gov/servlets/purl/1878469 https://www.osti.gov/biblio/1878469 https://doi.org/10.1021/acs.iecr.2c00352 doi:10.1021/acs.iecr.2c00352 30 DIRECT ENERGY CONVERSION 37 INORGANIC ORGANIC PHYSICAL AND ANALYTICAL CHEMISTRY 2023 ftosti https://doi.org/10.1021/acs.iecr.2c00352 2023-07-11T10:13:45Z The electrochemical reduction of bicarbonate to renewable chemicals without external gaseous CO 2 supply has been motivated as a means of integrating conversion with upstream CO 2 capture. The way that CO 2 is formed and transported during CO 2 -mediated bicarbonate reduction in flow cells is profoundly different from conventional CO 2 saturated and gas-fed systems and a thorough understanding of the process would allow further advancements. Here, we report a comprehensive two-phase mass transport model to estimate the local concentration of species in the porous electrode resultant from homogeneous and electrochemical reactions of (bi)carbonate and CO 2 . The model indicates that significant CO 2 is generated in the porous electrode during electrochemical reduction, even though the starting bicarbonate solution contains negligible CO 2 . However, the in situ formation of CO 2 and subsequent reduction to CO exhibits a plateau at high potentials due to neutralization of the protons by the alkaline reaction products, acting as the limiting step toward higher CO current densities. Nevertheless, the pH in the catalyst layer exhibits a relatively smaller rise, compared to conventional electrochemical CO 2 reduction cells, because of the reaction between protons and CO 3 2– and OH – that is confined to a relatively small volume. A large fraction of the CL exhibits a mildly alkaline environment at high current densities, while an appreciable amount of carbonic acid (0.1–1 mM) and a lower pH exist adjacent to the membrane, which locally favor hydrogen evolution, especially at low electrolyte concentrations. The results presented here provide insights into local cathodic conditions for both bicarbonate cells and direct-CO 2 reduction membrane electrode assembly cells utilizing cation exchange membranes facing the cathode. Other/Unknown Material Carbonic acid SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Industrial & Engineering Chemistry Research 61 29 10461 10473 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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ftosti |
language |
unknown |
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30 DIRECT ENERGY CONVERSION 37 INORGANIC ORGANIC PHYSICAL AND ANALYTICAL CHEMISTRY |
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30 DIRECT ENERGY CONVERSION 37 INORGANIC ORGANIC PHYSICAL AND ANALYTICAL CHEMISTRY Kas, Recep Yang, Kailun Yewale, Gaurav P. Crow, Allison Burdyny, Thomas Smith, Wilson A. Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate |
topic_facet |
30 DIRECT ENERGY CONVERSION 37 INORGANIC ORGANIC PHYSICAL AND ANALYTICAL CHEMISTRY |
description |
The electrochemical reduction of bicarbonate to renewable chemicals without external gaseous CO 2 supply has been motivated as a means of integrating conversion with upstream CO 2 capture. The way that CO 2 is formed and transported during CO 2 -mediated bicarbonate reduction in flow cells is profoundly different from conventional CO 2 saturated and gas-fed systems and a thorough understanding of the process would allow further advancements. Here, we report a comprehensive two-phase mass transport model to estimate the local concentration of species in the porous electrode resultant from homogeneous and electrochemical reactions of (bi)carbonate and CO 2 . The model indicates that significant CO 2 is generated in the porous electrode during electrochemical reduction, even though the starting bicarbonate solution contains negligible CO 2 . However, the in situ formation of CO 2 and subsequent reduction to CO exhibits a plateau at high potentials due to neutralization of the protons by the alkaline reaction products, acting as the limiting step toward higher CO current densities. Nevertheless, the pH in the catalyst layer exhibits a relatively smaller rise, compared to conventional electrochemical CO 2 reduction cells, because of the reaction between protons and CO 3 2– and OH – that is confined to a relatively small volume. A large fraction of the CL exhibits a mildly alkaline environment at high current densities, while an appreciable amount of carbonic acid (0.1–1 mM) and a lower pH exist adjacent to the membrane, which locally favor hydrogen evolution, especially at low electrolyte concentrations. The results presented here provide insights into local cathodic conditions for both bicarbonate cells and direct-CO 2 reduction membrane electrode assembly cells utilizing cation exchange membranes facing the cathode. |
author |
Kas, Recep Yang, Kailun Yewale, Gaurav P. Crow, Allison Burdyny, Thomas Smith, Wilson A. |
author_facet |
Kas, Recep Yang, Kailun Yewale, Gaurav P. Crow, Allison Burdyny, Thomas Smith, Wilson A. |
author_sort |
Kas, Recep |
title |
Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate |
title_short |
Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate |
title_full |
Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate |
title_fullStr |
Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate |
title_full_unstemmed |
Modeling the Local Environment within Porous Electrode during Electrochemical Reduction of Bicarbonate |
title_sort |
modeling the local environment within porous electrode during electrochemical reduction of bicarbonate |
publishDate |
2023 |
url |
http://www.osti.gov/servlets/purl/1878469 https://www.osti.gov/biblio/1878469 https://doi.org/10.1021/acs.iecr.2c00352 |
genre |
Carbonic acid |
genre_facet |
Carbonic acid |
op_relation |
http://www.osti.gov/servlets/purl/1878469 https://www.osti.gov/biblio/1878469 https://doi.org/10.1021/acs.iecr.2c00352 doi:10.1021/acs.iecr.2c00352 |
op_doi |
https://doi.org/10.1021/acs.iecr.2c00352 |
container_title |
Industrial & Engineering Chemistry Research |
container_volume |
61 |
container_issue |
29 |
container_start_page |
10461 |
op_container_end_page |
10473 |
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1772813830375604224 |