This paper presents our most recent results on the durability of Pt3Co/C nanoparticles operated in real polymer electrolyte fuel cell conditions (16-cells short stacks, hydrogen/air, constant current or start/stop). The stacks were disassembled after different life stages and the cathode catalyst was analyzed with physical and (electro)chemical techniques. It was found that Co atoms dissolve continuously from the fresh alloyed Pt3Co/C nanoparticles, and that their structure after > 1000 hours of operation strongly depends on the cathode potential. At low cathode potential below the onset of surface oxide formation, the Pt-Co/C nanoparticles are depleted in Co but remain homogeneous in chemical composition. At cathode potential above the onset of surface oxide formation, the decrease of the Co content is much faster, yielding the formation of compact, spherically shaped �hollow� nanoparticles, devoid of any Co. The electrocatalytic activity of the fresh/aged electrocatalysts will be discussed at the light of these changes.

Kirkendall effect-induced formation of Pt “hollow” particles from Pt<sub>3</sub>Co/C nanoparticles in real PEFC conditions

243rd National Meeting (2012)

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Kirkendall effect-induced formation of Pt “hollow” particles from Pt3Co/C nanoparticles in real PEFC conditions

Kirkendall effect-induced formation of Pt “hollow” particles from Pt₃Co/C nanoparticles in real PEFC conditions