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Abstract
The production of nanostructured systems with adjustable physical-chemical properties for advanced photocatalytic applications is one of the important issues of recent years. In this study, Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@TiO2 composites were synthesized and characterized by TEM, SEM-EDS, XRD, FT-IR, UV-Vis, VSM and XPS. The TEM and SEM results showed that the produced Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@TiO2 composites have spherical structure and its average diameters are 210, 220, and 240 nm, respectively. The crystal structures of prepared composites were determined with XRD analysis. The results showed a good agreement with the standard diffraction data cards. The calculated average particle sizes of the composites by using Debye-Scherrer’s formula showed agreement with the TEM and SEM results. The FT-IR and UV-Vis analysis of the composites gave information about its bond structures and bandgap energies. The bandgap energies of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@TiO2 composites were found 1.3, 1.68, and 2.1 eV, respectively. The XPS analysis of the composites was used to determine the surface composition and bonding and the results showed agreement with the other studies. The photocatalytic activities of synthesized composites were determined on the decomposition of Acid Blue 161. The results show that Fe3O4@SiO2@TiO2, which can be recycled by an external magnet, represented more efficient photocatalytic activity than the commercial TiO2 (Degussa-25). While the rate of dye decomposition over TiO2 nanoparticles is 84%, the rate of dye decomposition over Fe3O4@SiO2@TiO2 composites is 100% within 105 min. The high photocatalytic activity of Fe3O4@SiO2@TiO2 composites makes these composites promising candidates for the decomposition of dye contaminants.