Membrane and Active Layer Degradation upon PEMFC Steady-State Operation<br>I. Platinum Dissolution and Redistribution within the MEA - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of The Electrochemical Society Année : 2007

Membrane and Active Layer Degradation upon PEMFC Steady-State Operation
I. Platinum Dissolution and Redistribution within the MEA

Résumé

We studied proton exchange membrane fuel cell membrane electrode assemblies (MEAs) degradation after fuel-cell operation. Anode and cathode pronounced degradation was monitored by chemical [energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS)], physical [scanning electron microscopy (SEM), transmission electron microscopy], and electrochemical (ultramicroelectrode with cavity) techniques. Aged MEAs underwent severe redistribution of most elements (Pt, C, F), coupled to a dramatic change of Pt particles shape, mean particle size and density over the carbon substrate. Among the various scenarios for Pt redistribution, Pt dissolution into Ptz+ species and transport in the ionomer or the proton exchange membrane play important roles. The Ptz+ dissolution/transport is likely favored by activators/ligands (F- or SOx-containing species) originating from the alteration of the polymers contained in the MEA. From SEM observations, the source of Ptz+ species is the cathode, while EDS and XPS show some SOx- and F-containing species origin from the anode. Local chemical analyses (SEM-EDS and XPS) revealed the excess Pt monitored in aged MEAs is associated with F excess. For instrumental limitation concerns, we could not detect the S element, but SOx-containing species could also act as counter ions during Ptz+ transport within the MEA. Pt corrosion/redistribution is associated with the decrease of Pt-active area as revealed by COad-stripping voltammograms.
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Dates et versions

hal-00386380 , version 1 (21-05-2009)

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Elodie Guilminot, Audrey Corcella, Marian Chatenet, Frédéric Maillard, Frédéric Charlot, et al.. Membrane and Active Layer Degradation upon PEMFC Steady-State Operation
I. Platinum Dissolution and Redistribution within the MEA. Journal of The Electrochemical Society, 2007, 154 (11), pp. B1106-B1114. ⟨10.1149/1.2775218⟩. ⟨hal-00386380⟩
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