Controlled synthesis of BiFeO3, Bi2Fe4O9 and BiFeO3/Bi2Fe4O9 nanostructures with enhanced photocatalytic activity on degradation of Eosin Yellow under visible light.

Multiferroic BiFeO₃, Bi₂Fe₄O₉ and BiFeO₃/Bi₂Fe₄O₉ nanostructures were synthesised by a low-temperature hydrothermal method by varying the reaction temperature and time without any further post-heat treatment procedure. The as-prepared nanostructures were examined utilising X-ray diffraction (XRD), UV-Visible spectroscopy (UV-Vis), Fourier transform-infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM) and vibration sample magnetometry (VSM) techniques to assess their physicochemical and magnetic properties. XRD analysis revealed the formation of BiFeO₃, Bi₂Fe₄O₉ and BiFeO₃/Bi₂Fe₄O₉ with an average crystallite size in the range of 44-52 nm, and the lattice strains due to crystal imperfections were also investigated by W-H analysis. From UV-Visible analysis, the as-prepared samples have bandgaps in the range of 2.02-2.17 eV for direct and 1.82-1.94 eV for indirect bandgaps. The photocatalytic activity was analyzed by photocatalytic degradation of Eosin Yellow solution at ambient temperature. In comparison to pure BiFeO₃ and Bi₂Fe₄O₉, the modified BiFeO₃/Bi₂Fe₄O₉ composite displayed higher photocatalytic activity when exposed to visible light. About 77.14% of the EY dye was degraded after 180 minutes of light exposure. The observed rate constant for BF-200 was 0.00889/min, which was about 1.95 and 1.82 times higher than that of pure BiFeO₃ and pure Bi₂Fe₄O₉ samples, respectively. Because of the compounds' synergistic effect, there was an increase in light absorption and an improvement in charge separation that contributed to the increased photocatalytic activity, which could be a suitable candidate for the photocatalytic decomposition of organic contaminants.