Exchange-coupled Core/shell Structure CoFe2O4@NiFe2O4/CNFs Composites with Enhanced Microwave Absorption Performance

One strategy to solve the electromagnetic pollution is proposed to fabricate electromagnetic wave absorption materials. The CoFe2O4@NiFe2O4/CNFs composites with magnetic exchange-coupled core/shell structure were synthesized by a facial solvothermal method. The CoFe2O4@NiFe2O4 particles with core/shell structure was anchored on surface of carbon nanofibers. Compared with CoFe2O4 /CNFs whose the minimum reflection loss is -39.17 dB at 15.45 GHz and the effective absorbing band is 3.32 GHz at 1.5mm, the composite exhibits excellent microwave absorption performance that the minimum reflection loss at 12.32 GHz reaches -51.46 dB when the mass ratio of CoFe2O4 to NiFe2O4 is 3:1 and the thickness is 1.80 mm and the effective absorbing bandwidth reaches 3.85 GHz at 1.5 mm. The results indicate that the exchange coupling effect could enhance the electromagnetic wave absorption. Also, the content of NiFe2O4 could influence the properties if its content is too heavy, the exchange coupling effect will decrease and the impedance will be mismatched. Therefore, CoFe2O4@NiFe2O4/CNFs particles can be used as thin layer materials with strong absorption of low frequency microwave. The study provides a novel way to improve electromagnetic wave absorption properties based on exchange-coupled core/shell structure and the composition control.