Pt/Fe3O4 Core/Shell Triangular Nanoprisms by Heteroepitaxy: Facet Selectivity at the Pt鈥揊e3O4 Interface and the Fe3O4 Outer Surface

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• 作者：Maowei Jiang ; Wei Liu ; Xiaoli Yang ; Zheng Jiang ; Tao Yao ; Shiqiang Wei ; Xiaogang Peng
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：9
• 期：11
• 页码：10950-10960
• 全文大小：785K
• ISSN：1936-086X

文摘

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鈥揊e₃O₄ interface, existence of both lattice and chemical mismatch resulted in facet-selective epitaxy along 鉄?11鉄?directions of two lattices. X-ray absorption fine structure measurements demonstrated that the Pt seed nanocrystals were composed of an iron-rich Pt鈥揊e metallic thin layer sandwiched between the Pt core and a Fe鈥揙 outer-surface. The Fe鈥揙 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.