Rapid, Microwave-Assisted, and One-Pot Synthesis of Magnetic Palladium-CoFe2O4-Graphene Composite Nanosheets and Their Applications as Recyclable Catalysts

Here, a microwave-assisted approach has been demonstrated to rapidly prepare magnetic Pd-CoFe2O4-graphene (GE) composite nanosheets in ethylene glycol (EG) solvent. The generation of both Pd and CoFe2O4 nanoparticles is accompanied with the reduction process of graphene oxide (GO) by EG. The surface morphologies and chemical composition of the composite nanosheets are characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) measurements. The as-prepared Pd-CoFe2O4-GE composite nanosheets exhibit a remarkable catalytic activity towards the reduction of 4-nitrophenol by sodium borohydride (NaBH4) at room temperature. The apparent kinetic rate constant (K-app) of this catalytic reaction could reach about 11.0 x 10(-3) s(-1). Moreover, the CoFe2O4 component exhibits a magnetic property, which could make the Pd-CoFe2O4-GE composite nanocatalysts separated from the suspension system. The catalytic conversion of the 4-nitrophenol to 4-aminophenol could reach 87.2% after four cycles. This work presents a simple, rapid, and versatile method to fabricate both metal and spinel-type complex oxides on GE nanosheets, providing a new opportunity for their applications in the recyclable catalytic reaction.