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Editors’ Choice—Flooded by Success: On the Role of Electrode Wettability in CO 2 Electrolyzers that Generate Liquid Products
Name
Leonard_2020_J._Electrochem._Soc._167_124521.pdf
Description
Published version
Size
3.11 MB
Format
Adobe PDF
Checksum (MD5)
15f716f37611bd4c5e2c1bf118dbabc5
Author(s)
Leonard, McLain E
Orella, Michael J
Aiello, Nicholas
Román-Leshkov, Yuriy
Forner-Cuenca, Antoni
Brushett, Fikile R
Date Issued
2020
Journal
Journal of the Electrochemical Society
Publisher
The Electrochemical Society
Version
Final published version
Abstract
© 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. Economic operation of carbon dioxide (CO2) electrolyzers generating liquid products will likely require high reactant conversions and product concentrations, conditions anticipated to challenge existing gas diffusion electrodes (GDEs). Notably, electrode wettability will increase as lower surface tension products (e.g., formic acid, alcohols) are introduced into electrolyte streams, potentially leading to flooding. To understand the hydraulically stable operating envelopes in mixed aqueous-organic liquid domains, we connect intrinsic electrode wettability descriptors to operating parameters such as electrolyte flow rate and current. We first measure contact angles of water-organic product dilutions on polytetrafluoroethylene (PTFE) and graphite surfaces as planar analogues for GDE components. We then use material balances around the reactive gas-liquid-solid interface to calculate product mass fractions as functions of water sweep rate and current. Product composition maps visualize the extent to which changes in cell performance influence capillary pressure, a determinant of GDE saturation. Analyses suggest that formic acid mixtures pose little risk for GDE flooding across a wide range of conditions, but effluents containing <30% alcohol by mass may cause flooding. This study reveals opportunities to integrate microstructural features and oleophobic surface treatments into GDEs to repel aqueous-organic mixtures and expand the window of stable operating conditions.
Terms of Use
Creative Commons Attribution 4.0 International license
Persistent DSpace Link
DOI of Published Version
10.1149/1945-7111/ABAA1A
