Ordered Array of Gold Nanoshells Interconnected with Gold Nanotubes Fabricated by Double Templating
Ordered Array of Gold Nanoshells Interconnected with Gold Nanotubes Fabricated by Double Templating
复制标题
DOI：
10.1002/adma.200501304
复制
发表时间：
2006-03
影响因子：
29.4
通讯作者：
Wen Dong;H. Dong;Zhenlin Wang;P. Zhan;Ziqin Yu;Xiaoning Zhao;Yong‐yuan Zhu;N. Ming
中科院分区：
文献类型：
--
作者：
Wen Dong;H. Dong;Zhenlin Wang;P. Zhan;Ziqin Yu;Xiaoning Zhao;Yong‐yuan Zhu;N. Ming
Metal nanostructures are of great interest because of their important applications in catalysis, sensing, surface-enhanced Raman scattering (SERS), optoelectronics, information storage, and optics. Further processing of these nanostructures into ordered arrays or entities with a hollow interior is technically important as it could lead to a significant improvement of their optical, catalytic, biosensing, or SERS performances. For example, ordered metal microstructures have been demonstrated to exhibit a photonic bandgap in which the propagation of electromagnetic waves is prohibited. In another example, Halas and co-workers have demonstrated that the surface plasmon resonance (SPR) of gold nanoshells can be tuned from the visible to near-infrared region of the electromagnetic spectrum. For potential applications, it is highly desirable to develop new strategies to arrange hollow metal units into ordered structures and to allow control of their separation on a nanometer scale. Hollow metal nanostructures are often prepared by templating against sacrificial templates, such as colloidal microspheres, or channels in anodized aluminum oxide and track-etched polycarbonate membranes. A convenient method to prepare ordered metal nanomaterials is to deposit metal against colloidal crystal templates. Although new strategies have been developed to fabricate isolated units of metallic hollow nanostructures, there are few methods that can allow the preparation of highly monodisperse hollow metal nanostructures and their ordered arrays. One of the successful methods is the so-called lost-wax approach demonstrated by Colvin and co-workers. This method uses a silica colloidal crystal as the starting template to create a macroporous polymer membrane. Highly monodisperse and ordered inorganic, polymeric, and metallic hollow nanostructures can be generated within the uniform voids in the membranes. In this communication, the preparation of a novel ordered gold network with hollow interiors by a two-step replication procedure is reported. A non-close-packed (NCP) silica colloidal crystal, first introduced by Fenollosa and Meseguer, is used as the primary template. Macroporous polystyrene (PS) membranes are prepared by replication of the NCP silica opals, which contain spherical voids that are interconnected with nanochannels. Monodisperse hollow gold spheres interconnected with gold nanonecks with a hollow interior are electroless-plated within the PS membranes. More importantly, an indirect seeding method is adopted so as to confine plating mainly to the void surface of the PS template. A wide reflectance minimum band is observed in the near-infrared specular reflectivity spectra of the gold nanoshell/nanotube networks. It is believed that these highly ordered nanostructures may have applications in areas such as plasmonics, biophysics, and nanophotonics. The method to fabricate a NCP gold nanoshell network involves several distinct steps, which are summarized in Figure 1. First, a high quality silica colloidal crystal is prepared. Several successful approaches can be used to self-organize monodisperse silica microspheres into a colloidal crystal. Recently, Ozin and co-workers developed an isothermal heating evaporation-induced self-organization technique for the assembly of large silica microspheres. Here, a modification of a microchannel method is adopted to prepare monolayer and multilayer colloidal crystals with large single domains from silica spheres with diameters near or larger than one micrometer. Second, NCP silica templates are fabricated, following the method reported by Fenollosa and Meseguer. In short, the close-packed silica colloidal crystal is first sintered at a high temperature and then chemically etched with HF acid. After that, a thin layer of gold of about 5–8 nm in thickness is thermally evaporated onto the surfaces of the NCP template in step c. After the seeding process, a freestanding macroporous PS membrane is prepared by encapsulating the NCP silica template with PS, followed by removal of the silica template. The prepared PS membranes have uniform spherical pores that are interconnected with nanochannels, due to the presence of silica nanonecks between adjacent silica spheres. Another important feature of the PS template is that, after this replication, the gold nanoseeds are transferred from the surface of the NCP silica template onto the inside walls of the polymer film. These as-deposited metal nanoparticles are accessible C O M M U N IC A IO N S
