Preparation and characterization of Fe₃O₄/SiO₂/Bi₂MoO₆ composite as magnetically separable photocatalyst

Highlights: • Fe₃O₄/SiO₂/Bi₂MoO₆ composite was prepared by a hydrothermal method. • The composite has an enhanced visible absorption compared with pure Bi₂MoO₆. • The magnetic photocatalyst displayed excellent stability and reusability. • O₂^·− and ^·OH play a major role during the photocatalytic process. - Abstract: In this paper, Fe₃O₄/SiO₂/Bi₂MoO₆ microspheres were prepared by a facile hydrothermal method. The scanning electron microscope (SEM) results revealed that flower-like three dimensional (3D) Bi₂MoO₆ microspheres were decorated with Fe₃O₄/SiO₂ magnetic nanoparticles. The UV–vis diffuse reflection spectra showed extended absorption within the visible light range compared with pure Bi₂MoO₆. We evaluated the photocatalytic activities of Fe₃O₄/SiO₂/Bi₂MoO₆ microspheres on the degradation of Rhodamine B (RhB) under visible light irradiation and found that the obtained composite exhibited higher photocatalytic activity than pure Bi₂MoO₆ and P25. Moreover, the Fe₃O₄/SiO₂/Bi₂MoO₆ composite also displayed excellent stability and their photocatalytic activity decreased slightly after reusing 5 cycles. Meanwhile, the composite could be easily separated by applying an external magnetic field. The trapping experiment results suggest that superoxide radical species O₂^·− and hydroxyl radicals ^·OH play a major role in Fe₃O₄/SiO₂/Bi₂MoO₆ system under visible light irradiation. The combination of flower-like three dimensional (3D) Bi₂MoO₆ microspheres and Fe₃O₄/SiO₂ magnetic nanospheres provides a useful strategy for designing multifunctional nanostructure materials with enhanced photocatalytic activities in the potential applications of water purification