Atomic-scale compositional mapping and 3-dimensional electron microscopy of dealloyed PtCo3 catalyst nanoparticles with spongy multi-core/shell structures

Zhongyi Liu, Huolin Xin, Zhiqiang Yu, Ye Zhu, Junliang Zhang, Julia A. Mundy, David A. Muller, Frederick T. Wagner

Research output: Journal article publicationJournal articleAcademic researchpeer-review

22 Citations (Scopus)

Abstract

Advanced electron microscopy techniques, i.e., high angle annular dark field (HAADF) imaging, elemental mapping based on electron energy loss spectroscopy (EELS), and three-dimensional (3D) reconstructions from electron tomography, have been used to characterize the complex spongy core-shell structures observed in a high-performing fuel cell catalyst, a dealloyed PtCo3 catalyst supported on high surface carbon (or D-PtCo 3/HSC). HAADF imaging showed that multiple dark-contrast patches were randomly decorated on the D-PtCo3 nanoparticles, a type of image that had previously been reported for other catalysts and had been referred to as a spongy structure. In this work, EELS-based elemental mapping revealed that not all of the dark-contrast patches were simple holes (as had been reported for other catalysts). Rather, in this material, while some of the dark-contrast patches corresponded to voids or divots, others were Co-rich cores. The probability of a dark-contrast patch in an HAADF being a Co-rich core was statistically determined to be 58% ± 15%. 3D tomography further confirmed the existence of voids and divots in the multi-core/shell-structured D-PtCo3 nanoparticles. Possible formation mechanisms of the spongy multi-core/shell structure are discussed. All right reserved.
Original languageEnglish
JournalJournal of the Electrochemical Society
Volume159
Issue number9
DOIs
Publication statusPublished - 1 Dec 2012
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Materials Chemistry
  • Electrochemistry

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