Operando Laboratory X-Ray Imaging of Silver-Based Gas Diffusion Electrodes during Oxygen Reduction Reaction in Highly Alkaline Media

Operando laboratory X-ray radiographies were carried out for imaging of two different silver-based gas diffusion electrodes containing an electroconductive Ni mesh structure, one gas diffusion electrode composed of 95 wt.% Ag and 5 wt.% polytetrafluoroethylene and one composed of 97 wt.% Ag and 3 wt...

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Bibliographic Details
Published in:Materials 2019-08, Vol.12 (17), p.2686
Main Authors: Paulisch, Melanie Cornelia, Gebhard, Marcus, Franzen, David, Hilger, André, Osenberg, Markus, Kardjilov, Nikolay, Ellendorff, Barbara, Turek, Thomas, Roth, Christina, Manke, Ingo
Format: Article
Language:English
Subjects:
Cellulose
Diffusion electrodes
Droplets
Electrochemical analysis
Electrodes
Electrolytes
Gas flow
Gaseous diffusion
Grain boundaries
Investigations
Ion beams
Laboratories
Medical imaging
Microstructure
Oxygen reduction reactions
Polytetrafluoroethylene
Radiography
Silver
Synchrotrons
Tomography
X ray imagery
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Summary:Operando laboratory X-ray radiographies were carried out for imaging of two different silver-based gas diffusion electrodes containing an electroconductive Ni mesh structure, one gas diffusion electrode composed of 95 wt.% Ag and 5 wt.% polytetrafluoroethylene and one composed of 97 wt.% Ag and 3 wt.% polytetrafluoroethylene, under different operating parameters. Thereby, correlations of their electrochemical behavior and the transport of the 30 wt.% NaOH electrolyte through the gas diffusion electrodes were revealed. The work was divided into two parts. In the first step, the microstructure of the gas diffusion electrodes was analyzed ex situ by a combination of focused ion beam technology and synchrotron as well as laboratory X-ray tomography and radiography. In the second step, operando laboratory X-ray radiographies were performed during chronoamperometric measurements at different potentials. The combination of the ex situ microstructural analyses and the operando measurements reveals the impact of the microstructure on the electrolyte transport through the gas diffusion electrodes. Hence, an impact of the Ni mesh structure within the gas diffusion electrode on the droplet formation could be shown. Moreover, it could be observed that increasing overpotentials cause increasing electrolyte transport velocities and faster droplet formation due to electrowetting. In general, higher electrolyte transport velocities were found for the gas diffusion electrode with 97 wt.% Ag in contrast to that with 95 wt.% Ag.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma12172686