Preparation and characterization of magnetic core–shell ZnFe2O4@ZnO nanoparticles and their application for the photodegradation of methylene blue

Magnetically separable ZnFe2O4@ZnO nanoparticles with enhanced photocatalytic activity were successfully synthesized by two steps. First, ZnFe2O4 nanoparticles (NPs), which served as seeding materials, were synthesized using a solvothermal method. Second, wurtzite ZnO was coated on the ZnFe2O4 particle surfaces on the basis of a chemical precipitation method. The as-prepared samples were characterized with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM) and Energy-dispersive X-ray spectroscopy (EDS). Photodegradation experiments of the samples were carried out by choosing Methylene Blue (MB) as a model target under UV irradiation with homemade photocatalytic apparatus. The results indicated that the obtained core–shell ZnFe2O4@ZnO NPs exhibited higher photocatalytic activity than pure ZnO. In addition, when the molar ratio of ZnFe2O4 to ZnO was 1:10, the obtained product showed the highest photocatalytic activity. Furthermore, the core–shell ZnFe2O4@ZnO NPs could be conveniently separated by using an external magnetic field and the photocorrosion of ZnO was inhibited to some extent.

► A novel ZnFe2O4@ZnO core–shell photocatalyst was successfully prepared.
► The photocatalyst exhibited higher photocatalytic activity than pure ZnO.
► The composite photocatalyst inhibited the photocorrossion of ZnO to some extent.
► The novel photocatalyst could be easily separated by external magnetic field.