title: Pt/Fe₃O₄ Core/Shell Triangular Nanoprisms by Heteroepitaxy: Facet Selectivity at the Pt-Fe₃O₄ Interface and the Fe₃O₄ Outer Surface.
abstract: Pt/Fe3O4 core/shell triangular nanoprisms were synthesized using seed-mediated heteroepitaxy. Their well-defined shape, facets, and ordered-assembly allowed detailed analysis of mechanism of the heteroepitaxy. At the Pt-Fe3O4 interface, existence of both lattice and chemical mismatch resulted in facet-selective epitaxy along ⟨111⟩ directions of two lattices. X-ray absorption fine structure measurements demonstrated that the Pt seed nanocrystals were composed of an iron-rich Pt-Fe metallic thin layer sandwiched between the Pt core and a Fe-O outer-surface. The Fe-O outer-surface of the seed nanocrystals presumably offered epitaxial sites for the following deposition of the Fe3O4 shell. Each tip and side of a triangular nanoprism respectively possessed a groove and a ridge, and a (111) plane parallel to the basal planes linked all grooves and ridges. This interesting (111) plane approximately bisected the triangle nanoprisms and located near the Pt-seed. The outer surface of the hybrid nanocrystals was also found to be facet-selective, that is, solely {111} facets of Fe3O4 lattice. These polar {111} facets allowed the surface to be only occupied with high-density iron ions, and thus offered best surface coordination for the electron donating ligands in the solution.
authors.affiliation: Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China.
authors.forename: Maowei
authors.initials: M
authors.lastname: Jiang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei 230029, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Yang
authors.affiliation: Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201204, P. R. China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei 230029, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yao
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei 230029, P. R. China.
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei
authors.affiliation: Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Peng
keywords: core/shell; facet-selectivity; heteroepitaxy; interface; nanoprism; surface