Co/C Nanoparticle-Embedded Carbon Aerogels for Lightweight and High-Efficiency Electromagnetic Wave Absorption

The development of lightweight, broadband, and high-efficiency electromagnetic wave (EMW) absorbing materials requires both strong attenuation and effective impedance matching. To address this challenge, ZIF-67 was introduced into a resorcinol-formaldehyde (RF) sol–gel system and carbonized at 600–800 °C to construct nanoscale Co/C nanoparticle-embedded carbon aerogels (Co/C-CA). The resulting Co/C-CA composites contain ZIF-67-derived nanoscale Co/C nanoparticles anchored within a hierarchical porous carbon aerogel network, which helps preserve the three-dimensional skeleton and creates magnetic-dielectric interfaces. The optimized Co/C-CA-700 composite exhibited a minimum reflection loss (RL min ) of −60.9 dB and a maximum effective absorption bandwidth (EAB) of 6.34 GHz. The improved absorption is attributed to balanced impedance matching, interfacial polarization, dipole relaxation, magnetic resonance, and conductive loss regulated by carbonization temperature, together with cross-scale coupling between nanoscale Co/C units and the carbon aerogel framework. This work provides a structure-oriented strategy for lightweight and broadband EMW absorption.