Magnetic photocatalysts composed of titania catalyst and magnetic support are of great interest due to
their easy recovery and recyclability by magnetic separation. By using layer-by-layer chemical technique,
a core–shell structure of Fe3O4/SiO2/TiO2 composite was prepared by coating magnetite core particles
with silica and photoactive titania. An amorphous silica shell was coated on magnetite nanoparticles
firstly to form SiO2/TiO2 composite. In the next step of synthesis, we found that the polyacrylic acid treatment
on silica surface played an important role in the coating of the anatase nanoparticles: no any anatase
nanoparticles could be attached to the silica surface without the polyacrylic acid treatment. The
structure and morphology of the as-prepared composites were characterized by X-ray diffraction, infrared
spectroscopic analysis and transmission electron microscopy. Experimental results proved that the
treatment of silica surface with polyacrylic acid contributed to the formation of covalent bond between
titania nanocrystals and silica. The as-prepared photocatalyst presented good photocatalytic activities in
the degradation of rhodamine B under UV illusion, while it could be easily separated by external magnetic
field.