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Etude du vieillissement des assemblages membrane-électrodes pour piles à combustible basse température

Abstract : The durability of Pt3Co/C PEMFC cathode catalysts is investigated under real operating conditions (16-cell short stacks, hydrogen/air, constant current or start/stop, ageing time > 1000 hours). Using atomically resolved physical techniques such as HRSTEM-HAADF, and XAS, a detailed picture of how atomic structure, chemical composition and morphology of these cathode catalysts are changing over time has been drawn. In addition to 3D Ostwald ripening, these Pt-alloy catalysts undergo irreversible decrease of their cobalt content upon aging, yielding formation of “hollow” Pt/C nanoparticles. In the meantime, a great amount of Co2+ species is released within the MEA, which influences the catalyst surface reactivity and its ORR activity. Finally, structural markers of the degradation of the cathode catalyst have been used to unveil aging heterogeneities within the MEA: “through-the-plane” heterogeneities of aging (i.e. from the PEM/cathode interface to the cathode/GDL interface), and “in-the-plane” heterogeneities of ageing (i.e. from the gas inlet to the gas outlet) have been evidenced. The latter was confirmed using a cathode catalytic layer segmented in 20 segments along the gas flow channel.
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https://tel.archives-ouvertes.fr/tel-00923165
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Submitted on : Thursday, January 2, 2014 - 1:56:08 AM
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  • HAL Id : tel-00923165, version 1

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Julien Durst. Etude du vieillissement des assemblages membrane-électrodes pour piles à combustible basse température. Autre. Université de Grenoble, 2012. Français. ⟨NNT : 2012GRENI027⟩. ⟨tel-00923165⟩

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