Synthesis and characterization of Fe3O4/BiOI n-p heterojunction magnetic photocatalysts

The visible-light-driven Fe3O4/BiOI n-p heterojunction photocatalysts were successfully synthesized by a facile and economical solve-thermal method. The as-prepared samples were systematically characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, and vibrating sample magnetometer. The methyl orange and sulfadiazine sodium salt were taken as the model pollutants to estimate the photocatalytic activities of the Fe3O4/BiOI composites with different Fe3O4 contents. The results revealed that the photocatalytic properties of photocatalysts within the appropriate loading range were superior to pure BiOI. Among them 7 wt% Fe3O4/BiOI composite exhibited the highest photocatalytic activity both on degradation of MO and SD-Na. The increase in photodegradation activity may be attributed to the moderate loading of Fe3O4, which could promote the separation of electron–hole pairs effectively. Furthermore, the introducing of Fe3O4 provides the composite a good magnetic property, which greatly promotes the practical application of Fe3O4/BiOI composite photocatalysts in water purification.