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Revealing in-plane movement of platinum in polymer electrolyte fuel cells after heavy-duty vehicle lifetime


Fuel cell heavy-duty vehicles (HDVs) require increased durability of oxygen-reduction-reaction electrocatalysts, making knowledge of realistic degradation mechanisms critical. Here identical-location micro-X-ray fluorescence spectroscopy was performed on membrane electrode assemblies. The results exposed heavy in-plane movement of electrocatalyst after HDV lifetime, suggesting that electrochemical Ostwald ripening may not be a local effect. Development of local loading hotspots and preferential movement of electrocatalyst away from cathode catalyst layer cracks was observed. The heterogeneous degradation exhibited by a modified cathode gas diffusion layer membrane electrode assembly after HDV lifetime was successfully quantified by the identical-location approach. Further synchrotron micro-X-ray diffraction and micro-X-ray fluorescence experiments were performed to obtain the currently unknown correlation between electrocatalyst nanoparticle size increase and loading change. A direct correlation was discovered which developed only after HDV lifetime. The work provides a route to engineer immediate system-level mitigation strategies and to develop structured cathode catalyst layers with durable electrocatalysts.

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Fig. 1: Single-cell voltage cycle of the AST and ECSA loss pathways.
Fig. 2: Electrochemical characterization after 0, 10,000, 30,000, 60,000 and 90,000 AST cycles.
Fig. 3: IL-micro-XRF spectroscopy of the standard MEA.
Fig. 4: In-plane movement of platinum.
Fig. 5: IL-micro-XRF spectroscopy of the modified membrane electrode assembly.
Fig. 6: Synchrotron micro-XRD and micro-XRF spectroscopy of identical locations in the standard MEA after the AST.

Data availability

The authors declare that the data supporting the findings of this study are available within the article and its Supplementary Information. Source data are provided with this paper.


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XRF was performed at the HIMaC2 Analytic Laboratory, a user facility operated by the Horiba Institute for Mobility and Connectivity, University of California Irvine. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under contract number DE-AC02-05CH11231. We thank D. Parkinson for beamline support.

Author information

Authors and Affiliations



K.K. and A.Z. were chiefly responsible for most of the experiments. L.C. and N.T. performed combined XRD and XRF experiments at the synchrotron. M.C. and S.P. performed microscopy experiments. P.A., L.C., J.B., C.J. and I.V.Z. helped with data interpretation and study conception. K.K. produced the first manuscript draft, which all the authors edited. L.C., C.J., P.A., I.V.Z. and M.S. obtained funding support and oversaw the study.

Corresponding authors

Correspondence to Lei Cheng, Christina Johnston or Iryna V. Zenyuk.

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Nature Catalysis thanks Jong-Sung Yu, Lin Gan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–14 and Tables 1 and 2.

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Source Data Fig. 1

A schematic drawing of the process.

Source Data Fig. 2

Source data for Fig. 2.

Source Data Fig. 3

Source data for Fig. 3.

Source Data Fig. 5

Source data for Fig. 5.

Source Data Fig. 6

Source data for Fig. 6.

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Khedekar, K., Zaffora, A., Santamaria, M. et al. Revealing in-plane movement of platinum in polymer electrolyte fuel cells after heavy-duty vehicle lifetime. Nat Catal 6, 676–686 (2023).

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