Impact of Accelerated Stress Tests on the Cathodic Catalytic Layer in a Proton Exchange Membrane (PEM) Fuel Cell Studied by Identical Location Scanning Electron Microscopy
Journal article, 2022

Platinum is the most used electrocatalyst in proton exchange membrane fuel cells (PEMFCs). Nonetheless, it suffers from various types of degradation. Identical location electron microscopy has previously been used to observe local catalyst changes under accelerated stress tests (ASTs), giving insight into how individual catalyst particles degrade. However, it is important that such studies are carried out under relevant reaction conditions, as these can differ substantially between liquid half-cells and real PEMFC conditions. In this work, a single cell PEMFC was used to study the degradation of a commercial Pt-catalyzed membrane electrode assembly by performing square wave voltage ASTs in a potential range of 0.6 to 1.0 V. Identical location scanning electron microscopy (IL-SEM) was used to follow the degradation of the cathodic catalytic layer (CL) throughout 14,000 AST cycles. From the IL-SEM, we can conclude that the Pt nanoparticles degrade via Ostwald ripening, crystal migration, and coalescence. Small Pt nanoparticles agglomerate to larger particles or dissolve and redeposit to more stable particles, increasing the average particle size during the ASTs. In addition, cross-sectional TEM images show thinning of the ionomer layer during the AST procedure. The IL-SEM technique facilitates observation of local degradation of the CL in real PEMFCs, which will help to understand different degradation mechanisms, allowing for better solutions to be designed.

accelerated stress test

identical location-SEM

catalyst deactivation

PEMFC

catalytic layer degradation

platinum

Author

Victor Shokhen

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Competence Centre for Catalysis (KCK)

Linnéa Strandberg

Competence Centre for Catalysis (KCK)

Chalmers, Physics, Chemical Physics

Magnus Skoglundh

Competence Centre for Catalysis (KCK)

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Björn Wickman

Chalmers, Physics, Chemical Physics

Competence Centre for Catalysis (KCK)

ACS Applied Energy Materials

25740962 (eISSN)

Vol. 5 9 11200-11212

Subject Categories

Materials Chemistry

Other Chemical Engineering

DOI

10.1021/acsaem.2c01790

More information

Latest update

3/7/2024 9