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Modeling the electrochemical behavior and interfacial junction profiles of bipolar membranes at solar flux relevant operating current densities

Lin, Meng and Digdaya, Ibadillah A. and Xiang, Chengxiang (2021) Modeling the electrochemical behavior and interfacial junction profiles of bipolar membranes at solar flux relevant operating current densities. Sustainable Energy and Fuels, 5 (7). pp. 2149-2158. ISSN 2398-4902. doi:10.1039/d1se00201e. https://resolver.caltech.edu/CaltechAUTHORS:20210401-090557418

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Abstract

A 1-dimensional, multi-physics model that accounts for the migration and diffusion of solution species, electrostatics, and chemical reactions, in particular water dissociation (WD), at bipolar membrane (BPM) interfaces was developed to study the electrochemical behavior of bipolar membranes (BPMs) at solar flux relevant operating current densities (tens of mA cm⁻²). Significant partial current densities for WD were observed at BPM voltages much less than the equilibrium voltage, e.g., 59 mV × ΔpH from both experiments and modeling. The co-ion leakage across the BPM at pH differentials accounted for the early presence of the partial current density for WD. Two distinctive electric field dependent WD pathways, the un-catalyzed pathway and the catalyzed pathway, were quantitatively and parametrically studied to improve the turn-on potential of the BPM. The catalyzed pathway accounted for the majority of the partial current density for WD at low voltages, while the un-catalyzed pathway dominated the WD at relatively high voltages. Significant WD was observed only within the interfacial CL (<5 nm), in which a large electric field was present. To improve the electrochemical behavior and the turn-on potential of BPMs, the impacts of the pK_a of the immobilized WD catalysts, the electric-field dependent rate constant, the thickness of the catalyst layer and fixed charge density in BPMs on the partial current densities for WD were studied systematically. In addition, the electrochemical behavior and concentration profiles of BPMs in a buffered electrolyte were studied and contrasted with those in an un-buffered electrolyte from both modeling and experiments.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1039/d1se00201eDOIArticle
http://www.rsc.org/suppdata/d1/se/d1se00201e/d1se00201e1.pdfPublisherSupplementary Information
ORCID:
AuthorORCID
Lin, Meng0000-0001-7785-749X
Digdaya, Ibadillah A.0000-0001-7349-0934
Xiang, Chengxiang0000-0002-1698-6754
Additional Information:© The Royal Society of Chemistry 2021. Submitted 09 Feb 2021; Accepted 14 Feb 2021; First published 23 Feb 2021. This material is based on work performed by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, and Fuels from Sunlight Hub under Award Number DE-SC0021266. Meng Lin acknowledges support from the Swiss National Science Foundation through the Early Postdoc Mobility Fellowship, grant no. P2ELP2_178290. There are no conflicts to declare.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0021266
Swiss National Science Foundation (SNSF)P2ELP2_178290
Issue or Number:7
DOI:10.1039/d1se00201e
Record Number:CaltechAUTHORS:20210401-090557418
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210401-090557418
Official Citation:Modeling the electrochemical behavior and interfacial junction profiles of bipolar membranes at solar flux relevant operating current densities. Sustainable Energy Fuels, 2021, 5, 2149-2158; DOI: 10.1039/d1se00201e
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108600
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Apr 2021 17:13
Last Modified:12 Apr 2021 14:57

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