Energy- and cost-efficient salt-assisted synthesis of nitrogen-doped porous carbon matrix decorated with nickel nanoparticles for superior electromagnetic wave absorption

To optimize the impedance matching of carbon-based microwave absorbing materials, avoid skin effect, and improve the absorption performance, three-dimensional (3D) porous nitrogen-doped carbon matrix decorated with nickel nanoparticles (CN-Ni) was prepared via a facile energy- and cost-efficient NaCl-assisted method in this work. The uniquely designed composites offered multiadvantages for boosting electromagnetic wave (EMW) absorption behaviors. First, the interconnected porous structure reduces the dielectric constant of carbon materials, and magnetic particles were added to further optimize the impedance matching. Second, abundant heterogeneous interfaces, including carbon/Ni and air/carbon, are conducive to inducing interface polarization. The 3D network structure is formed inside the porous carbon matrix, which increases the path of electron transmission and enhances the conductivity loss. Furthermore, the doping of nitrogen atoms results in the creation of dipole centers in the carbon matrix, where the disordered dipoles change to ordered arrangement under an applied electromagnetic field, dissipating electromagnetic energy. The synthesized optimal CN-Ni absorber exhibits excellent electromagnetic wave (EMW) absorption performance of an effective absorption bandwidth (EAB) of 5.0 GHz at 2 mm and a minimum reflection loss ( RL min ) of − 43.28 dB. The energy- and cost-efficient NaCl-assisted synthesis strategy will break a new path for exploring efficient carbon-based EMW absorbers with superior EMW absorption property.