Magnetically recyclable visible-light-responsive MoS2@Fe3O4 photocatalysts targeting efficient wastewater treatment

Novel magnetically recyclable MoS2@Fe3O4 nanocomposite with remarkable photocatalytic capability was prepared by virtue of a rational hydrothermal route. The as-synthesized nanocomposites were well characterized by various spectroscopic and microscopic techniques, including X-ray powder diffraction, field-emission scanning electron microscope, transmission electron microscopy, energy-dispersive spectrometer, X-ray photoelectron spectroscopy, N2 adsorption–desorption isotherm (BET), ultraviolet–visible diffuse reflectance spectroscopy, fluorescence spectrophotometer and vibrating sample magnetometer, showing good structural, compositional, optical and magnetic properties. Photocatalytic activity was evaluated by degrading rhodamine B (RhB) and methylene blue (MB) aqueous solution under visible-light irradiation. In comparison with pure MoS2, the MoS2@Fe3O4 with 17 wt% dosage of Fe3O4 (MF-17) possessed superior photocatalytic performance. The photocatalytic degradation showed an evident dependence on the initial pH value with respect to the RhB and MB solutions, where the optimal degradation efficiency was obtained at pH 3.0 and 11.0, respectively. More importantly, magnetic MoS2@Fe3O4 hybrid can be well separated and easily recycled by an external magnetic field, still maintaining advanced activity after eight photoreaction cycles.