A Facile Approach for the Synthesis of Ag-Coated Fe3O4@TiO2 Core/Shell Microspheres as Highly Efficient and Recyclable Photocatalysts

A facile, green, and efficient approach for the fabrication of Ag-coated Fe3O4@TiO2 microspheres with a good core/shell structure has been demonstrated. The protocol employed involves the coating of successive layers of TiO2 nanoparticles on to a magnetic core using a vaporthermal method at low temperature followed by the deposition of silver nanoparticles on the surface of the Fe3O4@TiO2 microspheres through a photochemical route. The Ag-coated Fe3O4@TiO2 microspheres show excellent magnetic properties at room temperature. The photocatalytic properties of the products were investigated for the degradation of organic dyes. The loading of Ag nanoparticles coated on to the surface of the Fe3O4@TiO2 microspheres was controlled by changing the UV photoreduction time. The photocatalytic degradation rates were found to increase with the Ag nanoparticle loading until a maximum photodegradation rate was reached, further increasing the Ag loading led to a decrease in the photodegration rate. Furthermore, compared with that of Degussa P25 titania and uncoated Fe3O4@TiO2 microspheres, the products have better photocatalytic activity. The renewable photocatalytic activity of the microspheres was also examined. The results indicate that the catalytic activity was still present after recycling the photocatalysts five times. Thus, the Ag-coated Fe3O4@TiO2 core/shell microspheres can serve as effective and conveniently recyclable photocatalysts.