Issue 19, 2023

CO2 flow electrolysis – limiting impact of heat and gas evolution in the electrolyte gap on current density

Abstract

Research in CO2 electro-reduction with the aim of providing green chemical feedstock (e.g., CO) has been driven towards optimization of individual components such as CO2-reducing gas diffusion electrodes (GDEs) to achieve stable electrolysis processes. Moving forward, investigation into the performance of electrodes at a cell- and system-level is needed to identify key operational parameters that enhance electrode efficiency. In this study, we characterize self-regulated steady-states within an electrolytic cell. Additionally, we explore the circumstances under which the current density passing through the cell becomes self-limiting. GDE-relevant system parameters and their impact on the overall electrode durability during electrolysis at high current densities up to −1.2 A cm−2 were analyzed on an intermediate time scale. Integration of inline sensors to the electrolysis test setup enabled close monitoring of changes in the electrolyte temperature and electrolyte pH, as well as the detection of pressure changes around the cathode. In the presented study, the GDE did not appear to be the bottleneck to achieving high current density CO2-electrolysis. Instead, electrolyte heating and gas evolution within the electrolyte gap limited the maximum current densities that could be applied to a GDE flow cell. Our results suggest that electrode performance (selectivity, durability) can sometimes be underestimated when electrolysis cells and their periphery are not optimally suited for operation with GDEs yet, thus preventing performance windows from being reached.

Graphical abstract: CO2 flow electrolysis – limiting impact of heat and gas evolution in the electrolyte gap on current density

Supplementary files

Article information

Article type
Paper
Submitted
15 jun 2023
Accepted
30 ago 2023
First published
31 ago 2023
This article is Open Access
Creative Commons BY license

Green Chem., 2023,25, 7794-7806

CO2 flow electrolysis – limiting impact of heat and gas evolution in the electrolyte gap on current density

C. Martens, B. Schmid, H. Tempel and Rüdiger-A. Eichel, Green Chem., 2023, 25, 7794 DOI: 10.1039/D3GC02140H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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