Hierarchical Ag2O–ZnO–Fe3O4 composites with enhanced visible-light photocatalytic activity

Abstract Efficient visible-light-driven Ag 2 O–ZnO–Fe 3 O 4 photocatalysts with hierarchical structures are synthesized. The as-prepared products are characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectra (DRS). XRD and XPS confirm the presence of Ag 2 O. DRS reveals that the adsorption edge of the Ag 2 O–ZnO–Fe 3 O 4 photocatalysts is redshifted as compared with that of the ZnO–Fe 3 O 4 . Visible-light photocatalytic experiments are also conducted. By coupling with Ag 2 O, ZnO became responsive to visible light. The results show that the photocatalytic activity of the products is closely related to the mass ratio of Ag 2 O and ZnO, which is tunable and controlled by the amount of AgNO 3 added during the fabrication process. The highest photocatalytic activity of the Ag 2 O–ZnO–Fe 3 O 4 composites is achieved by adding 1.2 mol of AgNO 3 . The enhancement of photocatalytic activity can be attributed to the inhibition of electron–hole recombination. Furthermore, the as-prepared products can be easily attracted by an external magnetic field, which makes the composites recyclable.