Properties and applications of silica submicron powders with surface Ag nanoclusters

Spherical silica powders with uniform, submicron grain diameter have been obtained using the sol -gel technology. Subsequently, metallic silver nanoparticles have been produced on the surfaces of the grains. Raman scattering spectra of such SiO2-Ag0 powders impregnated in ethanol solutions of tris(2,2' -bipyridyl)ruthenium(II) can be recorded for solutions four orders of magnitude more diluted than the lowest possible concentration detectable for complex liquid solutions in the same experimental conditions (the SERS effect). Also, such silver-doped silica powders display anti-microbial capabilities and can be used to obtain doped thin-film coatings, e.g. for the production of bacteriostatic textiles.