Apium-derived biochar loaded with MnFe₂O₄@C for excellent low frequency electromagnetic wave absorption

Given the rapid development of electrommunication and radar detection technologies, low frequency electromagnetic wave materials have received more and more attention. Herein, the Apium-derived biochar loaded with MnFe₂O₄@C has been successfully prepared by using co-solvothermal and calcination method. The cladding carbon layer on MnFe₂O₄ NPs is migrated from biochar via thermal diffusion, and the biochar is covered with the ferrite NPs as well. Thus, the combination of dielectric and magnetic loss endows the composite with excellent low frequency electromagnetic absorption ability i.e. the optimal microwave absorbing intensity is −48.92 dB at 0.78 GHz with an extended effective absorbing bandwidth of 0.38–1.78 GHz for only 2.5 mm thickness, being ascribed to nature resonance, multiple interfacial and surface polarization, strong electromagnetic attenuation ability and good impedance matching property in detail. This bio-based ferrite composites have great potential in preparation of MAMs due to the advantages of extraordinary performance, lightweight property, environmental protection and easy degradation.