Core–shell Ag@SiO2 nanoparticles of different silica shell thicknesses: Preparation and their effects on photoluminescence of lanthanide complexes

Abstract Three kinds of almost spherical core–shell Ag@SiO 2 nanoparticles of different silica shell thicknesses (10, 25 and 80 nm) were prepared via the Stober process. The Ag core nanoparticles were prepared by reducing silver nitrate with sodium citrate. The size, morphology and structure of core–shell Ag@SiO 2 nanoparticles were characterized by transmission electron microscopy. Subsequently, eight kinds of lanthanide complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. The composition of the lanthanide complexes was characterized by elemental analysis, IR and UV spectra. Finally, lanthanide complexes were attached to the surface of Ag@SiO 2 nanoparticles to form lanthanide-complex-doped Ag@SiO 2 nanocomposites. The results show that the complex-doped Ag@SiO 2 nanocomposites display much stronger luminescence intensities than the lanthanide complexes. Furthermore, the luminescence intensities of the lanthanide-complex-doped Ag@SiO 2 nanocomposites with SiO 2 shell thickness of 25 nm are stronger than those of the nanocomposites with SiO 2 shell thickness of 10 and 80 nm.