Excellent S-band microwave absorption of 3D Ni/NPCF@CS composite material

The escalating demand for effective electromagnetic interference shielding, particularly in the challenging low-frequency microwave range such as S-band, underscores the need for advanced high-performance electromagnetic absorbing materials. Herein, three-dimensional (3D) nickel/nitrogen-doped porous carbon foam decorated with carbon spheres (3D Ni/NPCF@CS) was synthesized for S-band microwave absorption. This unique design capitalizes on the synergistic interplay between the highly conductive and porous 3D carbon skeleton, the magnetic properties of encapsulated Ni nanoparticles, and the enhanced interfacial polarization provided by the conductive polypyrrole coating. This engineered hierarchical architecture created abundant heterogeneous interfaces and microwave loss pathways. Detailed electromagnetic analysis revealed that the optimized Ni/NPCF@CS composite material exhibited exceptional reflection loss (RL) performance of −57.8 dB at 3.44 GHz. The dominant absorption mechanisms, including dielectric loss from dipole polarization, conductive loss, and magnetic loss from Ni nanoparticles, were thoroughly investigated and discussed. This study provides valuable insights into the development of 3D-foam-based microwave-absorbing materials, particularly for their practical implementation in the S-band.