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An electrochemical engineering assessment of the operational conditions and constraints for solar-driven water-splitting systems at near-neutral pH

Singh, Meenesh R. and Papadantonakis, Kimberly M. and Xiang, Chengxiang and Lewis, Nathan S. (2015) An electrochemical engineering assessment of the operational conditions and constraints for solar-driven water-splitting systems at near-neutral pH. Energy and Environmental Science, 8 (9). pp. 2760-2767. ISSN 1754-5692. https://resolver.caltech.edu/CaltechAUTHORS:20150918-153945062

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Abstract

The solution transport losses in a one-dimensional solar-driven water-splitting cell that operates in either concentrated acid, dilute acid, or buffered near-neutral pH electrolytes have been evaluated using a mathematical model that accounts for diffusion, migration and convective transport, as well as for bulk electrochemical reactions in the electrolyte. The Ohmic resistance loss, the Nernstian potential loss associated with pH gradients at the surface of the electrode, and electrodialysis in different electrolytes were assessed quantitatively in a stagnant cell as well as in a bubble-convected cell, in which convective mixing occurred due to product-gas evolution. In a stagnant cell that did not have convective mixing, small limiting current densities (<3 mA cm^(−2)) and significant polarization losses derived from pH gradients were present in dilute acid as well as in near-neutral pH buffered electrolytes. In contrast, bubble-convected cells exhibited a significant increase in the limiting current density, and a significant reduction of the concentration overpotentials. In a bubble-convected cell, minimal solution transport losses were present in membrane-free cells, in either buffered electrolytes or in unbuffered solutions with pH ≤ 1. However, membrane-free cells lack a mechanism for product-gas separation, presenting significant practical and engineering impediments to the deployment of such systems. To produce an intrinsically safe cell, an ion-exchange membrane was incorporated into the cell. The accompanying solution losses, especially the pH gradients at the electrode surfaces, were modeled and simulated for such a system. Hence this work describes the general conditions under which intrinsically safe, efficient solar-driven water-splitting cells can be operated.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1039/c5ee01721aDOIArticle
http://pubs.rsc.org/en/Content/ArticleLanding/2015/EE/C5EE01721APublisherArticle
http://www.rsc.org/suppdata/c5/ee/c5ee01721a/c5ee01721a1.pdfPublisherSupplementary Information
ORCID:
AuthorORCID
Singh, Meenesh R.0000-0002-3638-8866
Papadantonakis, Kimberly M.0000-0002-9900-5500
Xiang, Chengxiang0000-0002-1698-6754
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2015 The Royal Society of Chemistry. Received 3rd June 2015, Accepted 29th June 2015, First published online 30 Jun 2015. This material is based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award number DE-SC0004993.
Group:JCAP
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Issue or Number:9
Record Number:CaltechAUTHORS:20150918-153945062
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150918-153945062
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60354
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 Sep 2015 22:50
Last Modified:09 Mar 2020 13:19

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