Yhe Study Of RGO/CoFe₂O₄ Nanocomposites By Click Chemistry And Electromagnetic Wave Absorption Properties

Graphene, which owning light-weight, good electrical and mechanical properties, superior stability, high surface area and high complex permittivity, has been used for the microwave absorption because of its dielectric loss. However, as we known too much dielectric loss of microwave absorption materials is not helpful in improving the microwave absorption performance because it results in strong reflection and weak absorption. So, often combination of graphene with magnetic media microwave absorbers to make the composites with both magnetic loss and dielectric loss, it conducive to realize impedance matching and absorption band broadening. This paper is aim to covalent coupling CoFe2O4 NPs on the surface of graphene, and discussed the microwave absorption mechanisms of the CoFe2O4/RGO nanocomposites with click reaction. The main research content is as follows:First of all, graphene oxide was prepared by a modified Hummers method and then treated with ultrasonication as raw material. It was characterized with XRD, SEM and IR spectrum. The results showed that graphene oxide was plicated in the edge and that oxygen group was introduced to the graphene oxide. Furthermore, through ring opening reaction make the azide functional groups grafted onto the surface of graphene oxide.Secondly, using cobalt nitrate and nitric acid iron as raw material, ammonium hydroxide as precipitating agent, the cobalt ferrite was successfully prepared by hydrothermal method. The influence of technological factors on the sturture and morphology of the cobalt ferrite was investigated in detail: temperature was 180?, pH was 9 and time was 10 h. And then using the method of amide reaction make the functional groups grafted on the surface of cobalt ferrite. The magnetic property analysis showed that with the increasing of the cladding layer, the saturation magnetization was decreased. We have test the electromagnetic parameter of pure cobalt ferrite, the minimum RL is-10.8dB at 4.5 GHz when the thickness of 2.0mm.Lastly,the RGO/CoFe2O4 nanocomposites have been successfully synthesized by click coupling the CoFe2O4 nanoparticles onto the surface of RGO, and investigating the effect of different mass ratio of RGO/CoFe2O4.The results showed that the mass ratio of RGO/CoFe2O4 was 1:10, the minimum RL is-24.1dB at 15.2 GHz with a thickness of 2.0 mm, and the effective absorption frequency ranges from 12.8 to 18.0 GHz. When the thickness increases to 4.0 mm, the minimum RL of the composites was-40 dB at 6.8GHz and the bandwidths below-10 dB(90% of EM wave absorption) was range from 5.8 to 8.5GHz. Compared with CoFe2O4/RGO composites with mechanical mixing, the click coupling nanocomposites exhibited better microwave absorption properties at C band and Ku band.