Preparation and Stability of Template-Synthesized Metal Nanorod Sols in Organic Solvents

Abstract

Gold and silver nanorods of diameter 40 and 90 nm and having a variety of aspect ratios (length/diameter) were prepared using the template synthesis approach. After template synthesis, the nanorods were freed from the template membrane and dispersed in either hexafluoro-2-propanol (HFIP) or CHCl3. The stability of these nanorod sols was monitored using visible absorption spectroscopy. For both the Au and Ag nanorods (in both solvents), sols prepared from the 90-nm diameter nanorods were found to be less stable than sols prepared from the 40-nm diameter nanorods. The addition of the polymeric stabilizers poly(vinylpyridine) or poly(vinylpyrrolidone) did not enhance the stability of these nanorod sols. In addition to these studies of sol stability, UV−vis absorption spectroscopy was used to investigate the plasmon absorption band of these sols. The wavelength of maximum absorbance of the plasmon resonance band (λmax) for both Ag and Au sols was shifted to higher wavelengths when the nanorod diameter was increased from 40 to 90 nm. In addition, the λmax values for sols prepared in CHCl3 were red-shifted relative to analogous sols prepared in HFIP.

Preparation and Characterization of Inorganic-Organic Nanocomposite Coatings

“…The UV-visible spectrum of as prepared Ag/PVA nanorods showed a broad absorption band at λmax 458 nm. This characteristic peak was due to the oscillation of conduction band electrons of Ag known as the surface plasmon resonance (Cepak et al, 1998;Foss et al, 1994), (Link et al, 1999;Itakura et al, 1995;Jana et al, 2001). The position of plasmon absorption band (Khanna et al, 2005) was dependent of particle size, aspect ratio and diameter of nanorods and the broad nature of the absorption band in this case is indicative of the presence of both nanospheres and nanorods as reported in citrate reduction method (Zhou et al, 2006).…”

“…The results showed that, silica modified PVP is a remarkably powerful capping agent for preparation of 1D arrangement of Ag nanoparticles and this kind of prepared inorganic/organic nanocomposite can now be developed towards optical and medicinal based applications (Elechiguerra et al, 2005;Sondi et al, 2008;Suvorova et al, 2005;Zheng et al, 2001). The broad nature of the UV -Visible absorption band at λ Max = 410 nm due to the oscillation of conduction band electrons of Ag indicated the presence of both embedded sphere and assembled nanospheres in SiO 2 modified PVP (Cepak et al,1998;Jana et al, 2001;Link et al, 1999). Transparency dependent on the Ag nanoparticle size was about 96% in the infra-red region (Fig.…”

Preparation and Characterization of Gold Nanorods

“…The method is based on the electrochemical deposition of Au within the pores of nanoporous polycarbonate or alumina template membranes. The rods could be dispersed into organic solvents through the dissolution of the appropriate membrane followed by polymer stabilization (Cepak & Martin, 1998). The method can be explained as follows: initially a small amount of Ag or Cu is sputtered onto the alumina template membrane to provide a conductive film for electrodeposition.…”

Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

“…In the present work, the shift in the λ max with the tailing of absorption to the longer wavelength can be attributed to the high dielectric constant of water (ε = 80). The particle size, aspect ratio and diameter of nanowires also plays important role in deciding the position of plasmon absorption band [37]. …”