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Molecular Foundry

HIGHLIGHTSAnisotropic phase segregation and migration of Pt in nanocrystals en route to nanoframe catalysts
November 15, 2016

The Pt-Ni alloy formed during synthesis begins as Pt-rich, becomes Ni-rich as RD is formed, and then enriches in Pt as time is prolonged.


Scientific Achievement

Control of nanoscopic segregation of the elements in Pt-Ni rhombic dodecahedra (RD) was discovered to create a 3-D Pt3Ni nanoframe.

Significance and Impact

Being able to control the element spatial distribution within nanocrystals is an advanced strategy for obtaining catalysts with new morphologies and structure.

Research Details

Elemental mapping shows distribution of the elements in nanocrystals at various stages of the synthesis.

  • Initial Pt-rich alloy grows in <111> and <200> directions, providing compositional anisotropy
  • Pt segregates to axes of RD such that when Ni-rich phase is corroded, tetradecapod (14 arm) structure is obtained
  • Pt migrates to edges of RD after certain time such that when Ni-rich phase is corroded, nanoframe can be obtained
Niu, Z.; Becknell, N.; Yu, Y.; Kim, D.; Chen, C.; Kornienko, N.; Somorjai, G. A.; Yang, P. Nat. Mater. (2016) DOI: 10.1038/NMAT4724

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