One-pot solvothermal synthesis of magnetically separable rGO/MnFe2O4 hybrids as efficient photocatalysts for degradation of MB under visible light

Efficient and easily separable photocatalysts with visible light response are of great importance for the degradation of organic pollutants in wastewater treatment. In this work, magnetically separable reduced graphene oxide (rGO) supported MnFe2O4 hybrids were prepared using graphene oxide and metal ions (Fe3+ and Mn2+) as starting materials via a one-pot solvothermal synthesis method. The hybrids were characterized by X-ray powder diffraction, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, Fourier Transform Infrared Spectroscopy, Ultraviolet–visible spectroscopy, and vibrating sample magnetometer. The influence of the rGO content on the morphology and catalytic performance was investigated. It was shown that monodispersed MnFe2O4 microspheres with uniform size were successfully embedded in the rGO nanosheets. The photocatalytic activity has been evaluated by photocatalytic degradation of methylene blue under visible light irradiation. Among the hybrids with various rGO contents, the hybrid (10% rGO/MnFe2O4) prepared with 10 wt% GO showed the best performance with reaction rate of 0.01443 min−1, around 6 times higher than that of MnFe2O4 (0.00248 min−1), demonstrating the important role of rGO for the photocatalytic activity. Benefiting from their considerable saturation magnetization, lower remanence and coercivity, the hybrids can be easily separated and recycled from the solution by an external magnet. This research would provide a strategy for designing efficient and magnetically recycled photocatalysts for wastewater decontamination under visible light.