Novel magnetically separable ZnO/AgBr/Fe3O4/Ag3VO4 nanocomposites with tandem n–n heterojunctions as highly efficient visible-light-driven photocatalysts

Abstract

In the present work, novel magnetically separable ZnO/AgBr/Fe₃O₄/Ag₃VO₄ nanocomposites with different weight percentages of Ag₃VO₄ were successfully prepared. The preparation method is a facile large-scale method with a low temperature of 96 °C. Characterization techniques of XRD, EDX, SEM, TEM, UV-vis DRS, FT-IR, PL, and VSM were applied to study the microstructure, purity, morphology, spectroscopic, and magnetic properties of the resultant samples. Photocatalytic activity was evaluated by degradation of rhodamine B under visible-light irradiation. The results indicated that the nanocomposite with 10% Ag₃VO₄ has the best activity. The photocatalytic activity of this nanocomposite is about 2.8 and 3.5-fold higher than those of the ZnO/AgBr/Fe₃O₄ and ZnO/Ag₃VO₄/Fe₃O₄ nanocomposites, respectively. The highly enhanced activity was attributed to the formation of tandem n–n heterojunctions between ZnO, AgBr, and Ag₃VO₄ which suppresses recombination of the photogenerated electron–hole pairs. Furthermore, the enhanced activity of the nanocomposite for degradation of two more dye pollutants and a colorless pollutant was confirmed. Finally, the magnetic photocatalyst was recycled using an external magnetic field with reasonable activity after four runs.