Novel porous flower-like NiO@graphene composites with superior microwave absorption properties dues to good impedance matching, the special porous flower-like structure, polarization effects and conductivity loss.

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SnO2 nanocrystals were introduced into Fe3O4/MWCNTs to tune the complex permittivity. The synergistic interaction of different components and special net-like structure contribute to a highly efficient MA.

ZnO nanocrystals were introduced into Fe 3 O 4 /MWCNTs composites to improve the impedance matching and electromagnetic (EM) wave attenuation of the system. The as-synthesized ZnO/ Fe 3 O 4 /MWCNTs composites were characterized by X-ray di®raction, vibrating sample magnetometer,¯eld-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy. SEM and TEM images showed that Fe 3 O 4 microspheres 100-200 nm in size connected MWCNTs. Analysis of EM parameters revealed that the impedance matching of the ZnO/Fe 3 O 4 /MWCNTs composites was considerably improved after ZnO nanocrystals were introduced. The ZnO/Fe 3 O 4 /MWCNTs composites exhibited a highly e±cient microwave absorption (MA) capacity within the tested frequency range of 2-18 GHz. The optimal re°ection loss of EM waves was À38:2 dB at 6.08 GHz with an absorber thickness of 3.5 mm. The excellent MA properties of the composites could be attributed to the improved impedance matching, interfacial polarization, and combined e®ects of dielectric and magnetic losses.

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