Facile Synthesis of MFe₂O₄/RGO (M = Ni, Co) Nanocomposites and Their Application in the Reduction of 4-Nitrophenol

In this study, magnetic MFe₂O₄ (MFO, M = Ni, Co)/RGO heterogeneous catalysts have been synthesized by a facile solvothermal method. To characterize their morphological, structural, magnetic, and optical properties, the materials were analyzed by complementary chemical–physical methods. Moreover, the obtained results were compared with those obtained from pristine MFe₂O₄ and individual synthesized RGO. The MFO/RGO composites are composed of thin RGO layers and approximatively spherical aggregates of small crystalline MFO nanoparticles. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of sodium borohydride was applied to access the catalytic activity of the synthesized composites. Among these synthesized materials, NiFe₂O₄/RGO was highly active in this reaction. The combination of RGO layers and NiFe₂O₄ nanoparticles is assumed to be responsible for its high activity. Furthermore, NFO/RGO was catalytically active for six cycles adding fresh 4-nitrophenol (4-NP) to the reaction mixture.