Preparation of graphene-manganese cobaltate composites by solid-state roasting-ball milling and its electromagnetic wave absorption property

Electromagnetic pollution does great harm to human health, production, and national security. Electromagnetic wave (EMW) absorption materials are the most promising way to solve electromagnetic pollution. Cobalt oxidebased absorbers have been widely studied because of their rich dissipation and excellent absorption performance. Herein, we prepared MnCo2O4 absorber by a solid-state roasting method, and the surface of MnCo2O4 was coated with flake-like graphene by ball milling, then the MnCo2O4@Graphene composites with heterogeneous interface was successfully synthesized. The results of XRD, SEM and TEM show that the spinel MnCo2O4 with high crystallinity, and the crystal lattice structure and surface morphology of MnCo2O4 can be improved by ball milling process, the EMW absorption capacity can be significantly enhanced. The synergy of MnCo2O4 and graphene in composites had better incidence and impedance matching, the reflection loss(RL) value is -40.2 dB at 5.8 GHz when the thickness is 4.0 mm.