Reporter-Embedded TiO2 Core鈭扢ixed Metal Shell Nanoparticles with Enormous Average Surface-Enhanced Raman Scattering Enhancement Factors

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• 作者：Wenbing Li ; Xiaoyu Miao ; Ting Shan Luk ; Peng Zhang
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：March 3, 2011
• 年：2011
• 卷：115
• 期：8
• 页码：3318-3326
• 全文大小：1143K
• 年卷期：v.115,no.8(March 3, 2011)
• ISSN：1932-7455

文摘

We report the development of Raman reporter-embedded TiO₂ nanoparticles coated with mixed Ag and Au shells, showing enormous ensemble surface-enhanced Raman scattering (SERS) enhancement factors (up to 10¹⁰). Effects of shell composition on the enhancement are investigated both experimentally and theoretically. Colloidal TiO₂ nanoparticles are first tagged with meso-tetra(4-carboxyphenyl)porphine or tris(2,2鈥?bipyridyl)ruthenium(II) chloride, used as reporter molecules. They are subsequently coated with either a Ag shell or a mixed Au鈭扐g shell with different compositions. The resulting nanostructures are characterized by UV鈭抳isible spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, particle size analyzer, and Raman spectroscopy. These Raman reporter-embedded TiO₂ core鈭抦etal shell nanoparticles exhibit reproducible SERS signals of the reporter molecules with very high average enhancement factors. Interestingly, depending on the excitation wavelength, bimetallic Au鈭扐g shell nanostructures with proper Au/Ag ratios display higher enhancement factors than Ag-only shell. Simulation results based on equivalent dielectric functions show a very good match with the experimental observations.