Facile Synthesis of Carbon-Encapsulated Ni Nanoparticles Embedded into Porous Graphite Sheets as High-Performance Microwave Absorber

The Ni@C nanohybrids were prepared by a unique and efficient method of annealing the organic carbon compound and metal nitrate. Morphology detection demonstrated the Ni nanoparticles were uniformly encapsulated into the carbon network. The microwave absorption of 10 wt % Ni@C nanohybrids with paraffin matrix was measured over the range of 1-18 GHz. The complex permittivity was adjusted by changing the carbon proportions because of the superior conductivity of graphite. The minimum reflection loss (RL) value of -56 dB was obtained at 15.8 GHz with a thickness of 1.8 mm and the effective absorption bandwidth (RL <= -10 dB) was 5.4 GHz. Therefore, the Ni@C nanohybrids have great potential to be utilized as a high-efficiency and lightweight microwave absorber.