Synthesis and photocatalytic performance of the electrospun Bi₂Fe₄O₉ nanofibers

Bi₂Fe₄O₉ nanofibers were successfully synthesized by an electrospinning method combined with a sol–gel process. The as-spun nanofibers were annealed at different temperatures ranging from 500 to 700 °C and a pure orthorhombic phase was obtained at 700 °C. The thermo-decomposition behavior, structure, morphology, optical property, and the specific surface area of the nanofibers were characterized by thermogravimetry and differential scanning calorimetry, X-ray diffraction, field emission scanning electron microscopy, UV-vis diffuse reflectance spectroscopy and photoluminescene spectroscopy, and specific surface analyzer, respectively. The results indicated that the diameter and morphology of the fiber changed with different calcination temperatures. Moreover, the results of UV-vis diffuse reflectance spectroscopy revealed that the Bi₂Fe₄O₉ nanofiber could be a photocatalyst under a visible light irradiation and the bandgap value was determined to be 2.1 eV based on the Kubelka–Munk theory. The photocatalytic activity of the obtained nanofibers was evaluated by the degradation of methyl orange. A favorable degradation rate of 45 % was obtained for the sample annealed at 600 °C under the illumination of visible light for 3 h and an enhanced efficiency up to 70 % with recycling stability could be obtained with the aid of H₂O₂ for the pure-phase sample annealed at 700 °C. These results demonstrated that the electrospun Bi₂Fe₄O₉ nanofibers could be a promising visible light photocatalyst.