Relationship between Membrane Thickness and Stability of Pt/C Catalyst for Oxygen Reduction Reaction in a Gas Diffusion Electrode
Authors: Marsel Aleš , Hotko Miha , Hodnik Nejc 
Published: December 2024

In the quest towards a hydrogen-powered future, the longevity of electrocatalysts emerges as a pivotal challenge for both real-world deployments and laboratory evaluation1, given, in part, to the extended duration of traditional testing protocols. This challenge has led to the widespread adoption of accelerated stress tests (ASTs) as a substitute for long-term stability assessment of catalysts for the oxygen reduction reaction (ORR). However, conventional methods, such as those employing rotating disk electrodes (RDEs), encounter limitations related to oxygen transport, resulting in data that may not accurately reflect performance in practical applications. Furthermore, RDEs fall short by not accommodating membrane integration, a factor critical for understanding catalyst dissolution dynamics in fuel cells2,3. Addressing these limitations, the gas diffusion electrode (GDE) methodology offers a promising alternative. By facilitating direct exposure to gaseous oxygen, the GDE approach effectively bypasses the oxygen transport constraints inherent to RDE systems. Additionally, it accommodates the incorporation of a membrane4, aligning more closely with the conditions experienced by membrane electrode assemblies (MEAs) in real-world fuel cell environments. This compatibility enhances the relevance of our stability assessments for catalysts and catalyst layers, bringing us closer to replicating operational conditions.

In this investigation, we utilize the potential of the GDE to explore the impact of membrane thickness on the stability of the catalyst layer within fuel cells. Utilizing an array of Nafion membranes, spanning thicknesses from 12 to 125 microns, we performed a series of stability measurements adhering to the standard protocol defined by the U.S. Department of Energy (DoE) for accelerated stress tests. This study aims to shed light on how variations in membrane thickness influence the stability of the catalyst layer, offering insights that could steer the development of more durable and efficient fuel cell technologies.

References:

(1) Borup, R. L.; Kusoglu, A.; Neyerlin, K. C.; Mukundan, R.; Ahluwalia, R. K.; Cullen, D. A.; More, K. L.; Weber, A. Z.; Myers, D. J. Recent Developments in Catalyst-Related PEM Fuel Cell Durability. Current Opinion in Electrochemistry
2020, 21, 192–200. https://doi.org/10.1016/j.coelec.2020.02.007.

(2) Ehelebe, K.; Escalera-López, D.; Cherevko, S. Limitations of Aqueous Model Systems in the Stability Assessment of Electrocatalysts for Oxygen Reactions in Fuel Cell and Electrolyzers. Current Opinion in Electrochemistry
2021, 29, 100832. https://doi.org/10.1016/j.coelec.2021.100832.

(3) Ehelebe, K.; Knöppel, J.; Bierling, M.; Mayerhöfer, B.; Böhm, T.; Kulyk, N.; Thiele, S.; Mayrhofer, K. J. J.; Cherevko, S. Platinum Dissolution in Realistic Fuel Cell Catalyst Layers. Angew. Chem. Int. Ed.
2021, 60 (16), 8882–8888. https://doi.org/10.1002/anie.202014711.

(4) Alinejad, S.; Inaba, M.; Schröder, J.; Du, J.; Quinson, J.; Zana, A.; Arenz, M. Testing Fuel Cell Catalysts under More Realistic Reaction Conditions: Accelerated Stress Tests in a Gas Diffusion Electrode Setup. J. Phys. Energy
2020, 2 (2), 024003. https://doi.org/10.1088/2515-7655/ab67e2.