In situ constructed honeycomb-like NiFe2O4@Ni@C composites as efficient electromagnetic wave absorber.

[Display omitted] • The honeycomb-like NiFe 2 O 4 @Ni@C composites is obtained. • The porous core–shell structure has more interfacial polarization and multiple reflection. • The superior absorption capacity reaches −65.33 dB at 13.63 GHz. Rational excogitation of microstructure and chemical constituents is a superior means of constructing electromagnetic wave (EMW) absorption materials with high performance. In this study, a kind of honeycomb-like NiFe 2 O 4 @Ni@C composite is prepared via an uncomplicated polymerization, pyrolysis and etching. Porous structure and internal cavity of NiFe 2 O 4 @Ni@C contribute to the numerous reflection and scattering of EMW. The strong ferromagnetic resonance of NiFe 2 O 4 core and the multiple relaxation processes of porous carbon shell strongly promote the EMW loss. Additionally, the synergistic effect can improve impedance matching. The results demonstrate that the minimum reflection loss (RL) of honeycomb-like NiFe 2 O 4 @Ni@C composites is −65.33 dB at 13.63 GHz. The effective absorption bandwidth (EAB) is 3.68 GHz when the matching thickness is 4.95 mm. The mechanism of EMW dissipation of the honeycomb-like NiFe 2 O 4 @Ni@C composites is attributed to multiple reflections and scattering, conductive loss, interfacial polarization and ferromagnetism resonance. This work provides a tactic for the excogitation and synthesis of a low cost, light weight and efficient EMW absorber. [ABSTRACT FROM AUTHOR]