Preparation of magnetic composite photocatalyst Fe3O4/SiO2/Bi2WO6 and its photocatalytic activity

Abstract:

Bismuth tungstate (Bi₂WO₆), one of the simplest Aurivillius phase oxides, has been used as a new photocatalyst that works under visible light irradiation. However, it is not easy to reuse the photocatalyst due to difficulty in its recovery from the reaction media. Indeed, reusability and recyclability of photocatalyst are major factors considered in industrial applications. In the paper, magnetically recoverable photocatalyst Fe₃O₄/SiO₂/Bi₂WO₆ was synthesized by a three-step approach. After a hydrothermal process of preparing ferroferric oxide (Fe₃O₄), these Fe₃O₄ nanoparticles were coated with SiO₂ by sol-gel method. Finally, Fe₃O₄/SiO₂ nanoparticles were immobilized onto the surface of Bi₂WO₆ by a second hydrothermal process. The morphology, structure and properties of the composite were characterized by XRD, SEM, PL spectra and UV-vis absorption spectrum. The results show that the Bi₂WO₆ nanosheets structures with average diameters of 500nm are further decorated by Fe₃O₄ nanoparticles with an average diameter of 500nm. The photocatalytic activity of Fe₃O₄/SiO₂/Bi₂WO₆ to degrade rhodamine B was close to that of pure Bi₂WO₆. The photocatalyst with appropriate superparamagnetism can be easily re-collected by applying an external magnetic field. It shows potential applications in pollutant degradation.

Key words:Bi₂WO₆, Fe₃O₄, magnetic;photocatalyst, composite