Fabrication of magnetically separable NiFe2O4/BiOI nanocomposites with enhanced photocatalytic performance under visible-light irradiation

A series of novel flower-like NiFe2O4/BiOI (NFO/BOI) nanocomposites have been synthesized via a facile solvothermal method. The structure, morphology and magnetic, optical and visible-light photocatalytic properties of the as-prepared nanocomposite were respectively characterized by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, vibrating sample magnetometry and UV-visible diffuse reflectance spectroscopy. Experimental results revealed that the weight percent of NiFe2O4 has a considerable effect on the photodegradation of rhodamine B, methylene blue and crystal violet under visible-light irradiation. Compared with pure NiFe2O4 and BiOI, all the heterogeneous NFO/BOI nanocomposites exhibited significantly enhanced photocatalytic efficiency. Among these prepared samples, the NiFe2O4/BiOI nanocomposite with 15% wt NiFe2O4 displayed the best photocatalytic activity. The enhanced photocatalytic performance was mainly ascribed to the efficient separation of photo-induced electron–hole pairs and the formation of highly active species, superoxide radicals (˙O2˙−), in the NFO/BOI photocatalytic oxidation system. Furthermore, the NFO/BOI nanocomposites could be easily separated and recycled from contaminant solution using a magnet, which exhibited great potential application in the treatment of various pollutants in wastewater by utilizing solar energy effectively.