Anatase TiO2 nanolayer coating on strontium ferrite nanoparticles for magnetic photocatalyst

TiO2/SrFe12O19 composite nanoparticles with core-shell structure have been obtained. The core SrFe12O19 nanoparticles were synthesized by citrate precursor technique with Fe/Sr ratio of 10.8, and then the shell TiO2 nanocrystals were derived via sol-gel technology. The presence of a small amount of polyethyleneimine (PEI) on the surface of the strontium ferrite nanoparticles facilitates this coating process. The morphology, crystalline structure, particle size and size distribution of TiO2/SrFe12O19 composite nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and 3000HSA analyzer (MALVERN), respectively. Energy-dispersive spectroscopy (EDS) was utilized for the elemental analysis of the products. The as-prepared composite particles can be utilized as a magnetic photocatalyst, which can be fluidized and recovered by an applied magnetic field enhancing both separating and mixing efficiency for recyclable fluids. Magnetic properties and photocatalytic activities of these powders have been evaluated. The result of the experiments shows that the saturation magnetizations of titania-coated SrFe12O19 nanoparticles decrease as increasing the thickness of the titania coating, while the coercivity does not show any change after coating. Photocatalytic activities of these powders increase with increasing the thickness of TiO2 coating layer. (c) 2006 Elsevier B.V. All rights reserved.