Anisotropic Growth of One-Dimensional Silver Rod-Needle and Plate-Belt Heteronanostructures Induced by Twins and hcp Phase

摘要

Heteronanostructures, which are nanosized single structures consisting of more than one component, can possess multiple properties simultaneously. Since noble-metal nanostructures exhibit shape- and size-dependent properties, single-component noble-metal nanostructures with one or more domains of different shapes or sizes epitaxially extended can be categorized as another type of heteronanostructure. In this regard, Klajn et al. reported the synthesis of heterodimeric sphere-prism nanostructures via meta-stable gold supraspheres. In addition, Chen et al. reported the fabrication of Au rod-sheath heteronanostructures that exhibit a significant electromagnetic enhancement at the junction of the rod and sheath. Here we report a one-step, high-yield synthesis of one-dimensional (1D) Ag heteronanostructures in aqueous solution. Besides the usual fec phase of Ag, the heteronanostructures also contain a rare hcp (4H polytypic) phase, which favors the asymmetrical growth. We have found the variance of crystal structures in different segments of the heteronanostructures to be correlated with the formation process of such novel nanostructures.