Comparison of the Structural and Photo-catalytic Properties of Nanostructured Fe3O4/TiO2 Core–Shell Composites Synthesized by Ultrasonic and Stöber Methods

Abstract

In the present research, Fe3O4/TiO2 magnetic photo-catalytic nanocomposites with a core/shell structure were successfully synthesized using two techniques of ultrasonic and Stöber. In this way, iron oxide (II, III) nanoparticles as soft magnetic cores of this composite were prepared by utilizing a chemical method assisted by ultrasound with a Fe+3/Fe+2 molar ratio of 1.5 under the nitrogen atmosphere. Thereafter, titanium oxide coating was performed on Fe3O4 nanoparticles by using tetrabutyl orthotitanate (TBOT) and titanium isopropoxide (TTIP) precursors. The resultant nanostructures were characterized by means of X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, energy dispersive X-ray (EDX) analysis, vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Through findings obtained from TEM examinations, the formation of core/shell nanostructure was confirmed in the prepared Fe3O4/TiO2 composites. Analysis of magnetic properties revealed that titanium oxide coating on iron oxide nanoparticles reduces saturation magnetization (Ms). The values of saturation magnetization for Fe3O4 powder and Fe3O4/TiO2 nanocomposite powders achieved via ultrasonic and Stöber methods were 60, 23 and 9 emu/g, respectively. Photo-catalytic properties of Fe3O4/TiO2 nanostructures were evaluated by the use of methylene blue dye under UV light. Results indicated that Fe3O4/TiO2 composite obtained by the Stöber method has a better photo-catalytic property as well as a decreased but acceptable magnetic separation. Degradation of methylene blue dye in the presence of photo-catalytic powder prepared by ultrasonic and Stöber procedures was 61 and 69 %, respectively, within 90 minutes of UV light exposure.