Synthesis of Fe 3 O 4 @SiO 2 @Ce 0.5 Mn 0.5 O 2 core–shell–shell magnetic submicrospheres as photocatalyst for methyl orange degradation

Abstract

Core-shell-shell composite (Fe 3 O 4 @SiO 2 @Ce 0.5 Mn 0.5 O 2 ) submicrospheres were successfully synthesised by homogeneous precipitation of Ce and Mn on Fe 3 O 4 @SiO 2 spheres, which were prepared by a modified sol-gel method with the presence of Fe 3 O 4 particles. The synthesised multilayer-structured nanocomposites were characterised by X-ray diffraction, Fourier transform infrared spectroscopy, a transmission electron microscope and a vibrating sample magnetometer. The results show that the magnetic Fe 3 O 4 cores were well wrapped by the coating layer of SiO 2 with a thickness of 20 nm in the amorphous phase, and the Ce 0.5 Mn 0.5 O 2 nanoparticles with a diameter of about 20 nm were attached on the SiO 2 shell. The magnetic measurements indicated that the Fe 3 O 4 @SiO 2 @Ce 0.5 Mn 0.5 O 2 submicrospheres had a superparamagnetism property with the saturation magnetisation of 32.5 eum g -1 . At the same time, the composites demonstrated a high photocatalytic activity for methyl orange (MO) degradation with efficiency up to 94.5% under UV irradiation within 1 h. Moreover, the submicrospheres were found to be stable under repeated applications of up to five successive cycles with a nearly constant photocatalytic activity. It is expected that the catalyst could be used for trace pollutants (MO) removal from water and recycled because of its superparamagnetism properties and high photocatalytic activity.