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

• Ag@SiO2 nanoparticles of different silica shell thicknesses were prepared via the Stöber process.
• Sm and Dy complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized.
• The complex-doped Ag@SiO2 composites show stronger luminescent intensities than pure complexes.
• The luminescent intensities of the composites strongly depend on the SiO2 shell thickness.

Three kinds of almost spherical core–shell Ag@SiO2 nanoparticles of different silica shell thicknesses (10, 25 and 80 nm) were prepared via the Stöber process. The Ag core nanoparticles were prepared by reducing silver nitrate with sodium citrate. The size, morphology and structure of core–shell Ag@SiO2 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@SiO2 nanoparticles to form lanthanide-complex-doped Ag@SiO2 nanocomposites. The results show that the complex-doped Ag@SiO2 nanocomposites display much stronger luminescence intensities than the lanthanide complexes. Furthermore, the luminescence intensities of the lanthanide-complex-doped Ag@SiO2 nanocomposites with SiO2 shell thickness of 25 nm are stronger than those of the nanocomposites with SiO2 shell thickness of 10 and 80 nm.

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