Photocatalytic activity of BiFeO₃/ZnFe₂O₄ nanocomposites under visible light irradiation

Herein, BiFeO₃/ZnFe₂O₄ nanocomposites were synthesized via a glyoxylate precursor method using a two-pot approach. Phase evolution is investigated by X-ray diffraction and Raman spectroscopy, which confirm that no impurity phases are formed between BiFeO₃ and ZnFe₂O₄ following calcination at 600 °C. The specific surface area characterized by N₂ adsorption-desorption isotherms decreases from 30.56 to 13.13 m² g^-1 with the addition of zinc ferrite. In contrast, the magnetization increases from 0.28 to 1.8 emu g^-1 with an increase in the amount of ZnFe₂O₄. The composites show strong absorption in the visible region with the optical band gap calculated from the Tauc's plot in the range from 2.17 to 2.22 eV, as measured by diffuse reflectance spectroscopy. Furthermore, the maximum efficiency for the photodegradation of methylene blue under visible light is displayed by the composite containing 25 wt% ZnFe₂O₄ due to the synergic effect between BiFeO₃ and ZnFe₂O₄, as confirmed by photoluminescence spectroscopy.