Regulation of impedance matching feature and electronic structure of nitrogen-doped carbon nanotubes for high-performance electromagnetic wave absorption

In this study,we developed a facile method to fabricate three-dimensional(3D)structures composed of FeNi alloy nanoparticles encapsulated in N-doped carbon nanotubes that grafted on the SiO_(2) spheres(Fe_(x)Ni_(y)@NCNT@SiO_(2))for electromagnetic wave(EMW)absorption.The experimental results suggest that the impedance matching characteristic can be tuned by the introduction of SiO_(2) spheres in the 3D structure.Density functional theory(DFT)calculations showed that the introduction of Ni improved the polarization and conductive losses of the Fe_(x)Ni_(y)@NCNT@SiO_(2).As a result,the optimal 3D structure exhibits excellent EMW absorption property with a reflection loss and effective absorption bandwidth are-49.39 dB and 4.32 GHz,respectively,even though the matching thickness is only 1.6 mm,superior to most magnetic carbon-based composites.Thus,our current approach opens up an effective way to the development of low-cost,high-performance EMW absorbers.