Fabrication of conductive network anemone-like Ni@NC/NCNTs composites towards electromagnetic wave absorption

The structural dimensions of the materials and the design of the components are important factor to optimize the electromagnetic wave (EMW) absorption. Herein, Ni nanoparticles and nitrogen-doped carbon-based composites (Ni@NC/NCNTs) were successfully synthesized under high-temperature carbonization by introducing dicyandiamide (DCDA) into flake-assembled flower spherical Ni-based metal-organic framework (Ni-MOF). The influence of the composition and structure of Ni@NC/NCNTs on the absorption properties of EMW are revealed by changing the carbonization temperature. It could be found that the Ni@NC/NCNT-600 composite exhibits a good absorption capacity in the C-band (4–8 GHz). At a filler loading of 30 wt%, its optimal reflection loss (RL) is −34.22 dB at 4.88 GHz. In addition, the effective absorption bandwidth (EAB) of 4.2 GHz could be obtained at 1.8 mm. And Ni@NC/NCNT-1000 composite also achieve the same bandwidth at thin thicknesses (1.21 mm). The reasonable adjustment of the filler loading and carbonization temperature would effectively improve the permittivity and achieve a good impedance matching. The multiple loss mechanisms make Ni@NC/NCNTs have excellent EMW absorption performance. The optimal RL of Ni@NC/NCNTs-800 composite could reach −56.05 dB at 3.32 mm thickness with 25 wt% filler loading. Therefore, it provides some ideas for developing high-performance carbon-based composites with three-dimensional conductive network structure.