1. Investigation of Pd-based electrocatalysts for oxygen reduction in PEMFCs operating under automotive conditions
- Author
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Stassi, A., Gatto, I., Baglio, V., Passalacqua, E., and Aricò, A.S.
- Subjects
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PALLADIUM catalysts , *ELECTROCATALYSIS , *OXYGEN , *CHEMICAL reduction , *PROTON exchange membrane fuel cells , *COMPOSITE materials , *SURFACES (Technology) , *PALLADIUM alloys , *METALLIC surfaces - Abstract
Abstract: Composite Pd-based electrocatalysts consisting of a surface layer of Pt (5% wt.) supported on a core Pd3Co1 alloy were prepared. Two preparation approaches were investigated. One consisting of a single-step reduction procedure; in the second method, preparation of the PdCo alloy and deposition of a Pt overlayer occurred in two distinct steps. The catalyst prepared by a one-step process showed oxidised Pt species on the surface even if characterized by a smaller crystallite size with respect to the two-step Pd-based catalyst (4 nm vs. 6 nm). Moreover, the two-step process showed an enrichment of Pt on the surface and a smaller content of Co in the outermost layers. The enhanced surface characteristics of the two-step Pd catalyst resulted in a better performance. At 80 °C, the mass activity was lower than a Pt3Co1 alloy catalyst with the same crystallographic structure. Interestingly, the composite PtPdCo catalyst showed a significant increase of performance as the temperature was increased to 110 °C whereas the Pt3Co1 showed a decrease due to a prevailing effect of ionomer dry-out in the catalytic layer. The composite catalyst appeared sufficiently stable after 104 electrochemical cycles between 0.6 and 0.9 V at 110 °C and 33% R.H. [Copyright &y& Elsevier]
- Published
- 2013
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