Facile synthesis of cobalt nanoparticles embedded in a rod-like porous carbon matrix with excellent electromagnetic wave absorption performance

A rod-like porous Co/C composite was successfully fabricated by carbonizing a Co-based MOF-74 precursor. Due to significant synergy between the porous carbon framework (dielectric loss) and cobalt nanoparticles (magnetic loss) coupled with the multiple polarization loss (interfacial or dipole polarization loss) due to the porous nature of the structure, the Co/C composites showed extremely favorable microwave absorption performance. When the as-prepared cobalt-based MOF precursor was annealed at 700 °C (S700), the supreme EM wave reflection performance was −38.46 dB at 7.82 GHz with a coating thickness of 2.5 mm, whereas the broadest effective absorption bandwidth (3.3 GHz) was obtained with a coating thickness of 1.5 mm. Moreover, S600 samples exhibited an expansive absorption bandwidth range of 14.82 GHz (3.18–18 GHz) as the coating thickness was varied from 1.0 mm to 5.5 mm. The unique rod-like porous Co/C samples prepared in this study have significant potential for application in the field of the EM wave absorption.