Morphological, Structural, and Compositional Evolution of Pt–Ni Octahedral Electrocatalysts with Pt-Rich Edges and Ni-Rich Core: Toward the Rational Design of Electrocatalysts for the Oxygen Reduction Reaction

Meital Shviro, Martin Gocyla, Shlomi Polani, Marc Heggen, David Zitoun, Rafal E. Dunin-Borkowski

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The progress in colloidal synthesis of Pt–Ni octahedra has been instrumental in rising the oxygen reduction reaction catalytic activity high above the benchmark of Pt catalysts. This impressive catalytic performance is believed to result from the exposure of the most active catalytic sites after an activation process, chemical or electrochemical, which leads to a Pt surface enrichment. A foremost importance is to understand the structure and the elemental distribution of Pt–Ni octahedral, which leads to an optimal catalytic activity and stability. However, the factors governing the synthesis of the Pt–Ni octahedra are not well understood. In this study, unprecedented surface atomic segregation of Pt atoms in a Ni-rich Pt–Ni octahedral nanoparticle structure is established by advanced electron microscopy. The Pt atoms are almost exclusively located on the edges of the Pt–Ni octahedra. This structure is formed in a pristine form, i.e., prior to any chemical or electrochemical etching. A new growth mechanism is revealed, which involves the transformation from an octahedron with a Pt-rich core to a Ni-rich octahedron with Pt-rich edges. This observation may pave the way for a deeper understanding of this class of Pt–Ni octahedral nanoparticles as an electrocatalyst.

Original languageEnglish
Article number1800442
JournalParticle and Particle Systems Characterization
Volume36
Issue number3
DOIs
StatePublished - Mar 2019

Bibliographical note

Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

  • Pt–Ni octahedra
  • nanoparticles
  • phase segregation
  • structural evolution

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