Synthesis, characterization and enhanced electromagnetic properties of NiFe2O4@SiO2-decorated reduced graphene oxide nanosheets

Abstract A ternary composite of NiFe 2 O 4 @SiO 2 @RGO was synthesized using a three-step method. A facile hydrothermal route (NiFe 2 O 4 )was used in the first step, and the modified Sto¨ber method (NiFeO 4 @SiO 2 )in second step, followed by reduced reaction of GO using a hydrothermal reaction (NiFe 2 O 4 @SiO 2 @RGO). The obtained samples were characterized by various instruments and The TEM analysis indicated that NiFe 2 O 4 particles were homogenously enwrapped by SiO 2 . The NiFe 2 O 4 particles with a size of about 10–15 nm are core, SiO 2 forms shell and the core-shell structured NiFe 2 O 4 @SiO 2 disperses on the surface of RGO. The ternary composite shows the best microwave absorption properties (−42.9 dB), which is higher than NiFe 2 O 4 (−11.3 dB)and NiFe 2 O 4 @SiO 2 (−25.9 dB). This is mainly attributed to the synergistic effects between permittivity and permeability and enhanced effects at the interfaces. For the NiFe 2 O 4 @SiO 2 @RGO composite, the maximum reflection loss can reach −42.9 dB at 12.2 GHz and the absorption bandwidth with the reflection loss below −10 dB is 6.2 GHz(from 10.1to 16.3 GHz)for a thickness of 3 mm. Our results indicate that the core-shell structured NiFe 2 O 4 @SiO 2 on graphene is a promising microwave absorbent with thin thickness, light weight, strong absorption, and broad bandwidth.