Controllable N‑Doped Carbonaceous Composites with Highly Dispersed Ni Nanoparticles for Excellent Microwave Absorption

Microwave absorption materials with great reflection loss and wide absorption band that can provide electromagnetic waves (EMWs) absorption with minimal thickness are highly desirable, particularly when they could be controllably fabricated through a facile process. Herein, N-doped three-dimensional (3D) carbonaceous composites with highly dispersed nickel nanoparticles (N-SA/Ni-X, X = 3%, 6%, 9%) were successfully prepared by a facile one-step encapsulation process and carbonization. The performance of the absorber has a significant enhancement due to the introduction of nitrogen elements into a carbon network for controlling the dispersion and size distribution of Ni nanoparticles. When a 6% Ni2+ mass percentage was used, the maximum reflection loss (RL) could reach −42.2 dB at 9.8 GHz. Moreover, the effective absorption (below −10 dB) bandwidth can be increased by 2.3 GHz, from 8.5 to 10.8 GHz, with the absorber thickness of only 2 mm, and it can be tuned from 2.8 to 14.4 GHz by adjusting the thickness from 1.5 to 5 mm. The excellent electromagnetic-wave-absorbing performance could be assigned to the combinatorial advantages of the lightweight conductive porous network with favorable dielectric loss and magnetic loss features induced by highly dispersed Ni nanoparticles. These newly fabricated N-SA/Ni-X composites could be regarded as promising candidates for lightweight and high-performance microwave absorption materials.