Enhanced oxygen reduction electrocatalysis on PtCoSn alloy nanocatalyst mediated by Ta-doped SnO2 support for polymer electrolyte fuel cells

•The PtCoSn/Ta-SnO2 catalyst exhibits remarkably improved ORR kinetics and specific ORR activity.•The incorporation of Sn favors O2 adsorption and dissociation.•The PtCoSn/Ta-SnO2 catalyst shows exceptional load cycle durability. For polymer electrolyte fuel cells (PEFCs), platinum-based catalysts f...

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Veröffentlicht in:Electrochimica acta 2021-09, Vol.390, p.138894, Article 138894
Hauptverfasser: Shi, Guoyu, Hashimoto, Takuma, Tryk, Donald A., Tano, Tetsuro, Iiyama, Akihiro, Uchida, Makoto, Kakinuma, Katsuyoshi
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Sprache:eng
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Zusammenfassung:•The PtCoSn/Ta-SnO2 catalyst exhibits remarkably improved ORR kinetics and specific ORR activity.•The incorporation of Sn favors O2 adsorption and dissociation.•The PtCoSn/Ta-SnO2 catalyst shows exceptional load cycle durability. For polymer electrolyte fuel cells (PEFCs), platinum-based catalysts for the air cathode supported on metal oxides such as SnO2 exhibit highly promising durability. Yet, the activity for the oxygen reduction reaction (ORR) has still not been sufficiently high toward widespread application. Here, we report a new type of catalyst with significantly boosted ORR activity, based on PtCoSn alloy nanostructures formed on Ta-doped SnO2 support (PtCoSn/Ta-SnO2). The ORR activity of the PtCoSn/Ta-SnO2 catalyst is evaluated in acidic media (0.1 M HClO4) from 20 to 80 °C. The apparent rate constants (kapp) for the ORR on PtCoSn/Ta-SnO2 are found to be about 4.5 and 1.5 times greater than those of commercial Pt and Pt3Co alloy catalysts supported on carbon black (c-Pt/C and c-Pt3Co/C), respectively, and increase with temperature, in accordance with an Arrhenius-type relation from 20 to 60 °C. The enhanced ORR rates of the PtCoSn/Ta-SnO2 catalyst can be correlated with an increase in the preexponential factor of the Arrhenius equation, together with a lowered activation energy. Experimental and density functional theory results reveal that the incorporation of Sn facilitates O2 adsorption and dissociation, which is beneficial to overcome the kinetic limitation of ORR. Moreover, the durability of PtCoSn/Ta-SnO2 examined by potential-step cycling between 0.6 and 1.0 V at 80 °C has been found to be much higher as compared with c-Pt/C and c-Pt3Co/C. [Display omitted]
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2021.138894