Decoupling the Contributions of Different Instability Mechanisms to the PEMFC Performance Decay of Non-noble Metal O2-Reduction Catalysts - Institut National de l'Energie Solaire Accéder directement au contenu
Article Dans Une Revue Journal of the American Chemical Society Année : 2023

Decoupling the Contributions of Different Instability Mechanisms to the PEMFC Performance Decay of Non-noble Metal O2-Reduction Catalysts

Résumé

Non-noble metal catalysts (NNMCs) hold the potential to replace the expensive Pt-based materials currently used to speed up the oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC) cathodes, but they feature poor durability that inhibits their implementation in commercial PEMFCs. This performance decay is commonly ascribed to the operative demetallation of their ORR-active sites, the electro-oxidation of the carbonaceous matrix that hosts these active centers, and/or the chemical degradation of the ionomer, active sites, and/or carbon support by radicals derived from the H 2 O 2 produced as an ORR byproduct. However, little is known regarding the relative contributions of these mechanisms to the overall PEMFC performance loss. With this motivation, in this study, we combined four degradation protocols entailing different cathode gas feeds (i.e., air vs N 2), potential hold values, and durations to decouple the relative impact of the above deactivation mechanisms to the overall performance decay. Our results indicate that H 2 O 2-related instability does not depend on the operative voltage but only on the ORR charge. Moreover, the electro-oxidation of the carbon matrix at high potentials (which for the catalyst tested herein triggers at 0.7 V) seems to be more detrimental to the NNMCs' activity than the demetallation occurring at low potentials.

Domaines

Catalyse Matériaux
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Dates et versions

hal-04089928 , version 1 (05-05-2023)

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Seçil Ünsal, Robin Girod, Christian Appel, Dmitry Karpov, Michel Mermoux, et al.. Decoupling the Contributions of Different Instability Mechanisms to the PEMFC Performance Decay of Non-noble Metal O2-Reduction Catalysts. Journal of the American Chemical Society, 2023, 145 (14), pp.7845 - 7858. ⟨10.1021/jacs.2c12751⟩. ⟨hal-04089928⟩
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