Pt-Ru Bulk Phase Diagram

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Pt-Ru Bulk Phase Diagram
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Nanoscale Phase Behavior
Characterization of final nanoparticles X-ray
Photoelectron Spectroscopy (XPS) Scanning
Transmission Electron Microscopy (STEM) Energy
Dispersive X-ray Analysis (EDAX) Electron
Microdiffraction
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X-ray Photoelectron Spectroscopy (XPS)
X-Ray Photoelectron Spectroscopy (XPS) probes the
composition of the bulk sample. These figures
show that bimetallic nanoparticles are formed
upon reduction of a a metallic salt in the
presence of supported nanoparticles (Ru or Pt).
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Growth of Nanoparticles after Reduction
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Particle Size Distribution Ru Pt/C
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Compositional Analysis Energy Dispersive X-ray
Analysis (EDAX)
Relative Abundance
Atomic Composition (at. Ru)
Using EDAX, the composition of individual
particles is probed. The figure on the left
shows sample EDAX spectra for both the carbon
support and a particle of ca. 80 Ruthenium.
The figure on the right shows the representative
composition distribution for all bimetallic
samples.
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Atomic Ordering in Solids
Adapted from http//chemed.chem.purdue.edu/genche
m/topicreview/bp/ch13/structureframe.html
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Sample X-Ray Diffraction Patterns
Intensity
Intensity
2 ? (deg)
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Electron Microdiffraction
66 Å particle with a composition of 16 Ru
35 Å particle with a composition of 66 Ru
41 Å particle with a composition of 42 Ru
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Template Effects in the Binary Phase Diagram of
Pt-Ru Nanoparticles
Nano-phase diagram of bimetallic particles
formed on supported Ru clusters.
Nano-phase diagram of bimetallic particles
formed on supported Pt clusters.
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Binary Nano-Phase Diagram

• Supported bimetallic nanoparticles can be
  synthesized by reducing metallic salts onto
  pre-existing metallic nanoparticles.
• XPS, EDAX, and STEM provide evidence of the
  formation of bimetallic particles with wide size
  and compositional distributions.
• These bimetallic nanoparticles have an
  organized close-packed structure that shows
  phase-sensitive behavior across the compositional
  space. Microdiffraction results show template
  effects via the coexistence of both (fcc) and
  (hcp) structures within the same samples.