Optical, Magnetic, Ferroelectric Properties and Photocatalytic Activity of Bi2Fe4O9 Nanoparticles through a Hydrothermal Assisted Sol–Gel Method

Abstract

Polycrystalline Bi2Fe4O9 nanoparticles were successfully prepared by a hydrothermal assisted sol-gel method. X-ray diffraction (XRD) data, Fourier transform infrared (FTIR) spectra, and Raman spectra reveal that Bi2Fe4O9 nanoparticles has orthorhombic mullite structure without other impurities such as Bi2O3, Fe3O4, BiFeO3, Fe2O3. Scanning electron microscopy (SEM) shows that the synthesized polycrystalline Bi2Fe4O9 particles have regular spherical shape and the average particle size of 50 nm. Optical properties of the Bi2Fe4O9 nanoparticles were studied by UV–Vis absorption spectroscopy, and the bandgap energy (Eg) value is found to be 1.75 eV. Magnetic characterization shows that the Bi2Fe4O9 nanoparticles exhibit a paramagnetic behavior at 300 K and undergo an antiferromagnetic transition at 190 K. Ferroelectric hysteresis loops with rounded corners at room temperature at 50 Hz are observed for the Bi2Fe4O9 nanoparticles due to the large electrical leakage. Photocatalytic experiments indicate that the Bi2Fe4O9 nanoparticles exhibit excellent photocatalytic activity and stability in degradation of methylene blue (MB) and methyl red (MR) dyes under visible light irradiation.