Nickel Nanoparticles Encapsulated in N-Doped Carbon Nanotubes for Microwave Absorption

Transition metal composites doped with heteroatomic nitrogen and having a hierarchical porous structure are considered to be an effective way to improve the electromagnetic wave absorption ability of carbon-based absorbent materials. In this work, a mixture of melamine, glucose, and nickel nitrate was used as a precursor to synthesize a multi-interface carbon nanotube network with tubular morphology by one-step catalytic pyrolysis. The absorption mechanism was further discussed in detail. The composite materials have a better complementary loss mechanism and good matching impedance capability by combining carbon and magnetic Ni nanoparticles. Notably, 6.4Ni/CNTs-900 exhibits a strong reflection loss (RL) of −49.3 dB at 8.88 GHz with a low filling content of 15% and an effective bandwidth (EAB, RL < −10 dB) of 2.96 GHz. The excellent microwave absorption properties of these materials can be attributed to the multiple scattering, interface polarization, dipole polarization, and conductivity loss induced by the unique structure of the multi-interface carbon nanotube network. This work provides a method for managing electromagnetic radiation pollution, which has great potential for efficient microwave absorption.