Synthesis and characterization of magnetic-photocatalytic Fe3O4/SiO2/a-Fe2O3 nano core-shell

In this study, novel magnetic-photocatalytic core/double-layershell of Fe3O4/SiO2/a-Fe2O3 particles were synthesized by a developed sol-gel method. Initially, Fe3O4 magnetic nano-particles, as cores, were synthesized. Then, SiO2 and alpha-Fe2O3 layers were deposited on the cores. After that, a post-deposition heat treatment was performed to modify phase compositions and crystal structures of the particles. In each stage, characterization of core and each of shells were performed by X-Ray Diffraction (XRD), Fourier-Transform Infrared spectroscopy (FTIR), and Vibrating-Sample Magnetometer (VSM). XRD results confirmed the formation of all three desired phases. Besides, from the XRD pattern of the Fe3O4 magnetic core, the average crystallite size was found around 12 nm. The FTIR spectrum of iron (III) oxide and silicon dioxide confirmed the formation of the Fe-O-Si bonds. Also, Saturation magnetization (Ms) of nano core/double-shell showed an increase in the magnetic response. The morphology and particle size of particles were analyzed by a Field Emission Scanning Electron Microscope (FESEM) and High-Resolution Transmission Electron Microscope (HRTEM). The average size of core/double-shell particles was about 250 nm. The degradation of methylene blue (MB), as dye contaminations, under UV irradiation in particular times were investigated to demonstrate the photocatalytic properties. The result illustrated the high photo-degradation (60% in 80 min) by nano Fe3O4/SiO2/a-Fe2O3 core-shell particles .