Effect of heat treatment on ultrasonic synthesized bismuth ferrites: an effective visible light-driven photocatalyst

Even though it is a potential visible-light responsive photocatalyst, the application of BiFeO₃ (BFO) is restricted because of the presence of residual impurities in the synthesis process. To alleviate this problem, in this work, BiFeO₃ was synthesized by the sonochemical method and calcined at different temperatures. Morphologies and phases of the samples were evaluated by using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) techniques. UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) was used to analyze the absorption properties. The photocatalytic activities of the samples were evaluated via the photocatalytic degradation of rhodamine-B (RhB) aqueous solution under simulated solar light irradiation. The results revealed that the phase transformation from amorphous to crystalline phase has occurred during heat treatment. The formation of pure BFO occurred only at about 600 °C, indicating the importance of heat treatment during the synthesis process. On the other hand, the decolorization of RhB solution was completed by pure BFO photocatalyst within 1 h of simulated solar light irradiation.