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Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films
Published on: December 4, 2014
Skeletal octahedral nanoframe with Cartesian coordinates via geometrically precise nanoscale phase segregation in a
Aram Oh, Hionsuck Baik1, Dong Shin Choi2
1§Korea Basic Science Institute (KBSI), Seoul 136-713, Republic of Korea.
Abstract:
Catalytic properties of nanoparticles can be significantly enhanced by controlling nanoscale alloying and its structure. In this work, by using a facet-controlled Pt@Ni core-shell octahedron nanoparticle, we show that the nanoscale phase segregation can have directionality and be geometrically controlled to produce a Ni octahedron that is penetrated by Pt atoms along three orthogonal Cartesian axes and is coated by Pt atoms along its edges. This peculiar anisotropic diffusion of Pt core atoms along the ⟨100⟩ vertex, and then toward the ⟨110⟩ edges, is explained via the minimum strain energy for Ni-Ni pair interactions. The selective removal of the Ni-rich phase by etching then results in structurally fortified Pt-rich skeletal PtNi alloy framework nanostructures. Electrochemical evaluation of this hollow nanoframe suggests that the oxygen reduction reaction (ORR) activity is greatly improved compared to conventional Pt catalysts.
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