Abstract
Highly stable Ag–SiO2 nanoparticle composites were first obtained by laser ablation of a silver target in an aqueous colloidal dispersion of silica and examined by UV–vis absorption spectroscopy, transmission electron microscopy and Raman spectroscopy. The surface enhanced Raman scattering (SERS) activity of these nanocomposites was tested using 2,2’-bipyridine as a molecular reporter and excitation in the visible and near-IR spectral regions. The computational DFT approach provided evidence of ligand adsorption on positively charged adatoms of the silver nanostructured surface, in a very similar way to the metal/molecule interaction occurring in the corresponding Ag(I) coordination compound.
Highlights
Silica nanoparticles in an aqueous suspension are known to be inert and dispersible – properties which can be quite useful in the preparation of colloidal nanocomposites with silver
The shift of the maximum from 395 nm, as observed in Ag colloid obtained by ns-pulsed laser ablation [33], to 399 nm is consistent with the effect due to the higher refractive index of silica as compared to that of water [34]
The silver/silica suspensions obtained by laser ablation are very stable, even after several months
Summary
Silica nanoparticles in an aqueous suspension are known to be inert and dispersible – properties which can be quite useful in the preparation of colloidal nanocomposites with silver For this reason, there are a significant number of studies in the literature on colloidal substrates formed with silica and silver, especially in recent years [1,2,3,4,5,6,7,8,9,10,11,12,13,14], which have found various applications in medicine, catalysis and environmental research. The second motivation is to exploit the adsorption capability of the colloidal silica for various
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