Téléchargement | - Voir le manuscrit accepté : Compositional and morphological changes for ordered PtxFey/C oxygen electroreduction catalysts (PDF, 2.4 Mio)
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DOI | Trouver le DOI : https://doi.org/10.1002/cctc.201200614 |
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Auteur | Rechercher : Chen, Liang1; Rechercher : Chan, Mickey C. Y.; Rechercher : Nan, Feihong; Rechercher : Bock, Christina1; Rechercher : Botton, Gianluigi A.; Rechercher : Mercier, Patrick H. J.1; Rechercher : Macdougall, Barry R.1 |
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Affiliation | - Conseil national de recherches du Canada. Énergie, les mines et l'environnement
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Format | Texte, Article |
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Sujet | iron; platinum; carbon; supported catalysts; reduction |
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Résumé | Changes in O₂ reduction activity (orr) and structural changes of carbon supported catalysts upon electrochemical stress testing are investigated. Focus is placed on two alloy catalysts of nominal Pt₃Fe/C and Pt₃Fe₂/C compositions. Energy dispersive X-ray Spectroscopy (EDXS) spot and line analyses reveal a dependence of the Fe composition on the particle size particularly for he two as-prepared catalysts. Catalyst particles are shown to exist of a Pt enriched shell and a PtxFey alloy core. Larger (>≈10 nm) particles are shown to have a higher Fe content that approaches the nominal composition suggesting that the smaller (<≈6 nm) Pt catalyst particles are more difficult to alloy. HAADF-STEM, XRD, and scanning electron microscope (SEM) with EDXS show that Fe is gradually lost from the catalyst particles as a result of extensive potential (E)-cycling. Changes upon E-cycling are most clearly observed for the small (smaller than 3 nm) particles, for which, Fe is almost entirely depleted. However, the catalytic orr activities remain constant over an extensive cycling period for the PtxFey/C catalysts. In fact, the mass orr activities are seen to decrease proportionally with the Pt surface area (Apt). The histograms before and after cycling are compared to observed changes in APt, and are also discussed in comparison to E-holding experiments. It is concluded that the dissolution of Pt is a strong contributor for the observed drop in APt and mass orr activity for the PtxFey/C catalysts. The continuous transition between Pt-oxide formation and its reduction to Pt metal is suggested to play a major role for the degradation of the PtxFey/C catalysts studied in this work. |
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Date de publication | 2013-03-01 |
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Dans | |
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Langue | anglais |
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Publications évaluées par des pairs | Oui |
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Numéro du CNRC | NRC-EME-53170 |
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Numéro NPARC | 21268530 |
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Exporter la notice | Exporter en format RIS |
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Signaler une correction | Signaler une correction (s'ouvre dans un nouvel onglet) |
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Identificateur de l’enregistrement | 6ecb0940-ab05-4ad0-92f5-0d90b8587288 |
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Enregistrement créé | 2013-09-13 |
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Enregistrement modifié | 2020-08-31 |
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