Construction of iron manganese metal-organic frameworks derived manganese ferrite/carbon modified graphene composites toward broadband and efficient electromagnetic dissipation

The preparation of carbon-based electromagnetic wave (EMW) absorbers with thin matching thickness, wide absorption bandwidth, strong absorption intensity and low filling ratio remains a huge challenge. Metal-organic frameworks (MOFs) are widely considered to be ideal self-sacrificing templates for the construction of carbon-based EMW absorbers. In this work, bimetallic FeMn-MOFs derived MnFe2O4/C/Graphene composites were fabricated by a two-step route of solvothermal reaction and subsequent pyrolysis treatment. The results showed that the microscopic morphology of carbon skeletons evolved from loofah-like to octahedral, and then to polyhedron and pomegranate by adjusting the molar ratio of Fe3+ to Mn2+. Furthermore, when the molar ratio of Fe3+ to Mn2+ was 2:1, the obtained MnFe2O4/C/Graphene composite exhibited the best EMW absorption capacity. Specifically, the minimum reflection loss of -72.7 dB and the maximum effective absorption bandwidth of 5.1 GHz were achieved at a low filling ratio of only 10 wt%. In addition, the possible EMW absorption mechanism of MnFe2O4/C/Graphene composites was proposed. Therefore, the research results of this work would contribute to the construction of broadband and efficient carbon-based EMW absorbers derived from MOFs.