Functional Hierarchical Nanocomposites Based on ZnO Nanowire and Magnetic Nanoparticle as Highly Active Recyclable Photocatalysts

A novel magnetic hierarchical nanocomposite based on ZnO nanowire/Fe 3 O 4 @SiO 2 nanoparticle has been successfully synthesized by multistep chemical methods without calcinations. The magnetic cores of Fe 3 O 4 act as the center for the growth of ZnO nanowires. As a result, the zinc oxide nanowires grown around Fe 3 O 4 magnetic cores form a chestnut-like hybrid structure. The length of these ZnO nanowires was controlled by growth time. When used in the photodegradation of rhodamine B (RhB), these ZnO–Fe 3 O 4 @SiO 2 nanocomposites show high photocatalytic activity. The large surface areas and the presence of nanowires, in which the electron transport rate is fasten to reduce the recombination of the photogenerated electrons and holes, are considered to make the major contribution to the enhanced photocatalysis. In addition, the as-obtained nanocomposites inherit the magnetic property from the Fe 3 O 4 nanoparticles with the saturation magnetization ( M s ) about 3 emu/g. It has been demonstrated that this photocatalyst can be easily recycled by applying an external magnetic field and its high photocatalytic properties remain well after several recycles. This paper provides a convenient approach to synthesize recyclable magnetic photocatalysts.