Synthesis and properties of magnetically separable Fe3O4/TiO2/Bi2O3 photocatalysts

The Fe3O4/TiO2/Bi2O3 composites were synthesized by a sol–gel method and used as improved photocatalysts for the degradation of methyl orange (MO) under simulated sunlight at room temperature. The as-prepared Fe3O4/TiO2/Bi2O3 composites were characterized by X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). TEM analysis reveals that the composite has a core–shell structure and diameters of Fe3O4 core is about 200 nm. DRS results reveal that all composites showed red shift in optical absorption. TiO2, Fe3O4, and Bi2O3 exist mainly as separate phases in the Fe3O4/TiO2/Bi2O3 composites based on XPS analysis. The photocatalytic degradation of MO with the prepared photocatalysts was studied under simulated sunlight illumination. Photocatalytic reactivity test indicated that the removal efficiency of MO with the Fe3O4/TiO2/Bi2O3 photocatalyst was higher than that of pure TiO2 and Fe3O4/TiO2. Recovery rate of Fe3O4/TiO2/Bi2O3 photocatalysts achieved 80 % after five times reuse.