Preparation and application of magnetic cobalt/SiO2 core/shell nanospheres

Homogeneous SiO2-coated cobalt nanospheres with tunable silica shell thickness from 21.7 nm to 4.5 nm were synthesized by using modified Stöber method. These nanocomposites were used as source materials to prepare SiO2 semi-hollow and hollow nanospheres by partially and completely etching cobalt cores, respectively. A proposed formation mechanism of these Co/SiO2 nanospheres with a core/shell structure was presented in this paper, which is also important for the rational design and synthesis of other monodisperse core/shell nanoarchitectures with uniform size and shape. Furthermore, these Co/SiO2 nanospheres were also used as a substrate for the deposition of CdS nanocrystals to prepare magnetic luminescent Co/SiO2/CdS nanocomposites.

► Preparation of magnetic Co/SiO2 core/shell nanospheres via modified Stöber method. ► The use of APS primer is critical for deposition of silica onto cobalt. ► Both TEOS and CoCl2 contents are dominant to determine the shell thickness. ► Fabrication of SiO2 semi-hollow and hollow spheres by acid etching strategy. ► Synthesis of luminescent Co/SiO2/CdS by using Co/SiO2 spheres as a substrate.