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Oxygen Absorption in Electrocatalyst Layers Detected by Scanning Electrochemical Microscopy
Mahdi Moghaddam1,2, Pekka Peljo1,2
1Research Group of Physical Electrochemistry and Electrochemical Physics Department of Chemistry and Materials Science Aalto University Kemistintie 1, PO BOX 16100 00076 Aalto Finland.
Chemelectrochem
|September 30, 2021
Summary
Scanning electrochemical microscopy (SECM) reveals oxygen is absorbed in fuel cell catalyst layers. This oxygen is confined by Nafion ionomer and carbon black, likely in hydrophobic regions.
Area of Science:
- Electrochemistry
- Materials Science
- Energy Conversion
Background:
- Polymer electrolyte membrane (PEM) fuel cells and electrolyzers rely on efficient electrocatalyst layers.
- Understanding oxygen behavior within these layers is crucial for performance and durability.
- Scanning electrochemical microscopy (SECM) offers high spatial resolution for probing electrochemical processes.
Purpose of the Study:
- To investigate the presence and distribution of oxygen within the electrocatalyst layers of PEM fuel cells and electrolyzers.
- To determine the factors influencing oxygen confinement in these materials.
- To elucidate the role of ionomer and support materials on oxygen behavior.
Main Methods:
- Utilized scanning electrochemical microscopy (SECM) with an ultra-micro-electrode (UME).
- Performed approach curve measurements on electrocatalyst layers.
- Set the UME tip potential for oxygen reduction detection.
Main Results:
- SECM approach curves indicated significant oxygen absorption within the electrocatalyst layers.
- Confirmed that the combination of Nafion ionomer and carbon black leads to oxygen confinement.
- Observed oxygen confinement within the hydrophobic domains of Nafion self-assembled on carbon black.
Conclusions:
- Oxygen is present and confined within the electrocatalyst layers of PEM fuel cells and electrolyzers.
- Nafion ionomer and carbon black synergistically contribute to oxygen confinement.
- Hydrophobic regions of Nafion on carbon black surfaces are suggested as the primary sites for oxygen confinement.
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