Tailoring microstructures in (Ni/NiO)@C composites via facile route for broadband microwave absorption

The pollution of microwave radiation has gradually become a serious problem at the current stage. In the accepted method of material absorption, the rational regulation of electromagnetic parameters in composites via adjustment of their microstructures is an effective strategy to enhance their microwave absorbing ability. Herein, a kind of (Ni/NiO)@C composite with radial structure was obtained by co-hydrothermal and annealing method. The results show that the microstructure of composite could be regulated by adjusting the additional content of PTA, thus the commendable interface and dipole polarization, eddy current and exchange resonance loss, multiple reflection and scattering loss can be gathered together to absorb incident microwave. The optimal effective absorption bandwidth of as-prepared composite can reach an ultra-wide frequency range of 9.07 GHz for a great application at the thickness of only 1.79 mm, although the maximal reflected loss is-18.45 dB at 14.58 GHz for 1.5 mm thickness. The work reported here provides a facile route to modulate the self-organizing microstructure in composite and realize the wider band of microwave absorption.