Synthesis of hollow Fe3O4 at ZnO at anatase TiO2 core–shell structured spheres

Hollow Fe3O4 at ZnO at anatase TiO2 core–shell structured spheres have been successfully synthesized through a simple two-step sol–gel method and the synthesis process is illustrated as an explicit schematic diagram. Surfactant cetyltrimethylammonium bromide was employed to realize the mesoporous anatase TiO2 shell on the surface of Fe3O4 at ZnO composite spheres. Electron microscopy examinations indicate that the composite core–shell structured hollow spheres have a homogeneous ZnO interlayer and an anatase TiO2 shell outside the ZnO layer, both of which have a thickness of about 20 nm. The magnetization hysteresis curves of the samples show that the core–shell structured composites have a magnetic saturation value of 41.5 emu/g, suggesting that the obtained product can be separated easily from reaction system and put into recyclable applications.