3D hierarchically ordered porous carbon frameworks/Co nanoparticles for Broadening electromagnetic wave absorption bandwidth

With the rapid development of communication technology and the widespread use of high-frequency equipment, electromagnetic interference and irradiation have become increasingly serious, posing risks to human health and the operation of electronic devices. In this work, the 3D hierarchically ordered porous carbon frameworks with magnetic Co nanoparticles (Co–OPCs) are synthesized using the template-assisted method and a pyrolysis process to address these challenges. By adjusting the pyrolysis temperatures, the average size of Co nanoparticles in Co–OPCs ranged from 12.4 to 44.7 nm. The optimal Co–OPCs exhibited stronger electron transfer capability, stronger interface polarization loss of abundant Co/C heterogeneous interfaces, more dipole polarization loss ability from carbon defects and N-doping sites, multiple reflections contributed by the unique hollow structural characteristics and excellent impedance matching degree balanced by dielectric-magnetic loss. Consequently, the optimal Co-OPC sample's minimum reflection loss (RLmin) can reach −43.19 dB at a thickness of 1.70 mm and an effective absorption bandwidth (EAB) up to 6.86 GHz at a thickness of 2.00 mm. This work aims to clarify the electromagnetic loss mechanism of 3D hierarchically ordered porous carbon framework with magnetic nanoparticles and provide an effective method for designing and manufacturing lightweight, high-performance carbon-based absorbers.