Expanded graphite and thermally reduced graphene oxide filled with NiCo2O4 for improve microwave absorption

Three-dimensional porous carbon materials provide an effective way for electromagnetic wave absorbers that are lightweight and effective. We explore the effects of different three-dimensional porous expanded graphite (EG) and thermally reduced graphene oxide (TERGO) on wave absorption performance in this study. NiCo2O4-EG and NiCo2O4-TERGO three-dimensional wave-absorbing materials were prepared by an in situ self-assembly hydrothermal process. To address the problem of impedance mismatch and improve the attenuation capability, the microstructure of EG and TERGO were designed to control the conductivity loss and polarization loss. After heat treatment at 800 °C to form a regular honeycomb pore distribution, TERGO composites have moderate conductivity and conductive losses, as well as multiple polarization loss mechanisms. Consequently, the NiCo2O4-TERGO800 composite with a lower filling ratio displayed excellent microwave absorption, with the bandwidth of reflection loss ≤−10 dB coved 4.05 GHz. These findings provide valuable insights for fabrication and research of three-dimensional porous carbon material microwave absorbers.