Carbon-Capped PtNi Catalysts for the Oxygen Reduction Reaction in Acidic Environment: A Durability Study
Résumé
Protective-shell catalysts (particularly carbon-capped catalysts), may increase the durability of oxygen reduction catalysts, owing to their supposed anti-degradation effect. The mechanisms promoting this effect are still questioned and further scientific scrutiny is needed to better understand their underlying principle. In this paper, three carbon-capped PtNi/C catalysts with different extents of carbon cap graphitization were synthesized via a one-pot heat-treatment. A precise electrochemical activation was applied, leading to similar intrinsic ORR activity than for a commercial Pt 3 Ni/VC benchmark catalyst and larger activity than for the mother Pt/Gr.C catalyst. To examine their robustness once fully activated, an aggressive accelerated stress test (AST) in an electrochemical half-cell, which emphasizes Pt dissolution/redeposition was performed and coupled with post mortem analyses. The carbon-capped catalyst with the most graphitized shell is able to withstand the AST: its Pt nanoparticle size is less affected than for uncapped catalysts, suggesting a positive action of the protective carbon cap.
Mots clés
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