Superparamagnetic Plasmonic Nanohybrids: Shape-Controlled Synthesis, TEM-Induced Structure Evolution, and Efficient Sunlight-Driven Inactivation of Bacteria

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• 作者：Yueming Zhai ; Lei Han ; Ping Wang ; Gaiping Li ; Wen Ren ; Ling Liu ; Erkang Wang ; Shaojun Dong
• 刊名：ACS Nano
• 出版年：2011
• 出版时间：November 22, 2011
• 年：2011
• 卷：5
• 期：11
• 页码：8562-8570
• 全文大小：1030K
• 年卷期：0
• ISSN：1936-086X

文摘

Magnetic materials and noble metal-based multifunctional hybrids have attracted much attention recently due to their unique properties and potential applications in a variety of fields. However, substantial challenges remain to directly obtain water-soluble hybrids with well-defined structures and to directly combine magnetic nanoparticles with nonspherical noble metals. We describe here for the first time a simple solvothermal method to synthesize a series of novel water-soluble nanohybrids composed of shape-tuned Ag cores and a Fe₃O₄ shell. We found that small Fe₃O₄ grains can be well-distributed directly on the surface on the Ag seeds. Such hybrids have both plasmonic and significant superparamagnetic properties, enabling magnetic separation. The plasmon resonance frequency of Ag nanostructures can be fine-tuned through the interactions between the two components. In addition, the decorated Fe₃O₄ nanoparticles stabilized the Ag nanostructures when exposed to air and natural light for a long time. Furthermore, an interesting structural transformation is observed in the one-dimensional Ag–Fe₃O₄ nanowires under high-energy electron beam. The Ag core can diffuse through the porous iron oxide shell, break away, and result in the formation of Ag nanocluster-decorated iron oxide tubes. Finally, the hybrids acted as a chemical template for the synthesis of Fe₃O₄/Au-AgCl double-layer nanotubes that display obvious near-infrared absorption. Importantly, the double-layer nanotubes exhibited enhanced photocatalytic inactivation of bacteria at very low concentrations under natural sunlight.