Fabrication of magnetically separable NiFe2O4/Bi24O31Br10 nanocomposites and excellent photocatalytic performance under visible light irradiation

Novel multifunctional NiFe2O4/Bi24O31Br10 nanocomposites were synthesized by a thermal decomposition process and hydrothermal route. The structures, morphologies, as well as the magnetic, optical and visible-light photocatalytic properties of the as-prepared nanocomposites were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, vibrating sample magnetometer (VSM) and UV–visible diffuse reflectance spectroscopy (DRS). The experimental results reveal that the NiFe2O4/Bi24O31Br10 composites exhibit an enhanced photocatalytic activity for photo-degradation of crystal violet (CV) under visible light irradiation. Among the prepared samples, the 20% NiFe2O4/Bi24O31Br10 nanocomposite displays the best photocatalytic activity, which is mainly ascribed to the efficient separation of photo-induced electron-hole pairs. Hydroxyl (•OH) radicals and holes are confirmed to be the dominant active species in the NiFe2O4/Bi24O31Br10 photocatalytic system. Furthermore, due to their excellent ferromagnetism and stability, NiFe2O4/Bi24O31Br10 nanocomposites can be easily separated from contaminant solution by using a magnet, implying that they have promising application in treatment of various dyestuff wastewaters on a large scale.