Advanced microscopy for evaluating realistic fuel-cell degradation
Researchers from the Laboratory for Electrocatalysis have developed an advanced approach for monitoring catalyst degradation in proton-exchange membrane fuel cells. In an article published in ACS Catalysis, they showed that the presence of a membrane in half-cell measurements plays a key role in the realistic evaluation of catalyst stability. By combining identical-location scanning electron microscopy with automated nanoparticle size-distribution analysis, they were able to directly follow how catalyst nanoparticles change during accelerated degradation tests.
Fuel cells are an important technology for converting hydrogen into electricity, but their wider implementation is still limited, among other factors, by the long-term stability of the catalysts. These catalysts are often based on platinum or platinum alloys, which can dissolve, migrate and redeposit during operation. This leads to nanoparticle growth, loss of active surface area and reduced fuel-cell performance.
In the study, the researchers compared a gas diffusion electrode (GDE) without a membrane with an electrode covered by a proton-exchange membrane. The results showed that the membrane-free half-cell system, which is commonly used for laboratory testing, leads to more pronounced degradation because the catalyst layer is directly exposed to the liquid electrolyte. This promotes platinum dissolution and migration, resulting in excessive nanoparticle growth. In contrast, the presence of the membrane limits transport pathways and better mimics the conditions in an operating fuel cell. This approach therefore provides a more realistic insight into how catalysts change during operation.
In more complex and realistic systems, such as gas diffusion electrodes, standard identical-location particle analysis using transmission electron microscopy (TEM) is not directly applicable. One of the key features of this research is therefore the use of identical-location scanning electron microscopy (SEM), which enables changes in catalyst nanoparticles to be monitored within the actual catalyst layer. The researchers analysed the same areas of the electrode before and after testing, allowing direct comparison of morphological changes at the nanoparticle level. Automated particle size-distribution analysis further enabled the processing of a larger number of microscopy images, providing a statistically more reliable evaluation of degradation-induced changes.
The study demonstrates that reliable evaluation of catalyst stability requires testing under conditions that closely resemble the actual operation of a fuel cell. The presented approach enables a more precise understanding of degradation mechanisms and represents an important step towards the development of more durable catalysts and more efficient hydrogen fuel cells.
The research, published in ACS Catalysis (impact factor 13.6), is the result of the work of Mitja Kostelec, Goran Dražić, Ana Rebeka Kamšek, Jan Vidergar, Gregor Kapun and Nejc Hodnik. The article, entitled Realistic Fuel Cell Catalyst Degradation via Automated Identical Location SEM-PSD Analysis with the GDE Half-Cell Setup, was also selected for the journal cover.
Kostelec, M.; Dražić, G.; Kamšek, A. R.; Vidergar, J.; Kapun, G.; Hodnik, N. Realistic Fuel Cell Catalyst Degradation via Automated Identical Location SEM-PSD Analysis with the GDE Half-Cell Setup. ACS Catal. 2026, 16 (12), 11207–11218.
Link to publication: https://doi.org/10.1021/acscatal.6c01369
Contact: Mitja Kostelec, Mitja.Kostelec(at)ki.si