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Formation of Gold and Silver Nanoparticle Arrays and Thin Shells on Mesostructured Silica Nanofibers
Author(s) -
Zhang S.,
Ni W.,
Kou X.,
Yeung M. H.,
Sun L.,
Wang J.,
Yan C.
Publication year - 2007
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200700366
Subject(s) - nanofiber , materials science , nanoparticle , nanostructure , raman spectroscopy , chemical engineering , nanotechnology , surface plasmon resonance , colloidal gold , bifunctional , organic chemistry , physics , optics , engineering , chemistry , catalysis
Mesostructured silica nanofibers synthesized in high yields with cetyltrimethylammonium bromide as the structure‐directing agent in HBr solutions are used as templates for the assembly of Au and Ag nanoparticles and the formation of thin Au shells along the fiber axis. Presynthesized spherical Au and Ag nanoparticles are adsorbed in varying amounts onto the silica nanofibers through bifunctional linking molecules. Nonspherical Au nanoparticles with sharp tips are synthesized on the nanofibers through a seed‐mediated growth approach. The number density of nonspherical Au nanoparticles is controlled by varying the amount of seeded nanofibers relative to the amount of supplied Au precursor. This seed‐mediated growth is further used to form continuous Au shells around the silica nanofibers. Both the Au‐ and Ag‐nanoparticle/silica‐nanofiber hybrid nanostructures and silica/Au core/shell fibers exhibit extinction spectra that are distinct from the spectra of Au and Ag nanoparticles in solution, indicating the presence of new surface plasmon resonance modes in the silica/Au core/shell fibers and surface plasmon coupling between closely spaced metal nanoparticles assembled on silica nanofibers. Spherical Au‐ and Ag‐nanoparticle/silica‐nanofiber hybrid nanostructures are further used as substrates for surface‐enhanced Raman spectroscopy, and the enhancement factors of the Raman signals obtained on the Ag‐nanoparticle/silica‐nanofiber hybrid nanostructures are 2 × 10 5 for 4‐mercaptobenzoic acid and 4‐mercaptophenol and 7 × 10 7 for rhodamine B isothiocyanate. These hybrid nanostructures are therefore potentially useful for ultrasensitive chemical and biological sensing by using molecular vibrational signatures.