Tailing size and impedance matching characteristic of nitrogen-doped carbon nanotubes for electromagnetic wave absorption

Abstract Carbon nanotubes (CNTs) have important application in electromagnetic wave absorption due to their unique tubular structure, lightweight feature and high electrical conductivity. However, sole CNTs suffer from bad impedance matching characteristic, leading to unsatisfactory absorption performance. Herein we propose a universal SiO2-assisted strategy to fabricate Ni nanoparticle-encapsulated nitrogen-doped CNTs on the SiO2 spheres (Ni@NCNT@SiO2). Due to the spatial separating effect, the formation of large metal aggregates and large-sized NCNTs in the products are avoided effectively. In the meanwhile, the ideal impedance matching characteristic is also achieved due to the introduction of the non-conductive SiO2 spheres. As a result, even with a low matching thickness (1.3–2.0 mm), the reflection loss values of Ni@NCNT@SiO2 reaches −30 dB. Furthermore, the proposed method can be also used to fabricate Fe3C/Fe@NCNT@SiO2 and Co@NCNT@SiO2 with satisfactory absorption properties, demonstrating its universality for synthesis of high-performance absorbers based on CNTs.