Metal organic frameworks-derived Fe-Co nanoporous carbon/graphene composite as a high-performance electromagnetic wave absorber

Based on the EM wave absorption principle, superior absorbers should have the characteristics of strong attenuation constant and suitable impedance matching. In this work, a novel hierarchical composite consisting of Fe-Co nanoparticles embedded in porous carbon decorated with graphene (Fe-Co/NPC/RGO) was synthesized by a simple hydrothermal route using a Co metal organic framework (MOF) followed by calcination process. The microstructure, composition, magnetic properties and microwave absorption performances of as-synthesized samples were characterized and discussed. Compared with Fe-Co/NPC, the Fe-Co/NPC/RGO composite possessed high attenuation constant, excellent impedance matching and synergistic effect, which resulted in significant improvement in its microwave absorption properties. The optimal reflection loss (RL) was −52.9 dB at 10.1 GHz for a thickness of 2.5 mm, and the corresponding absorption bandwidth (RL < −10 dB) was almost 3.1 GHz (8.6–11.7 GHz). When the thickness was adjusted from 1.5 to 4 mm, the efficient absorption bandwidth (RL < −10 dB, 90% absorption) was as high as 13.2 GHz (over frequency range of 4.8–18 GHz). The excellent absorption performance of Fe-Co/NPC/RGO derived from MOF provides a new route for the preparation of light-weight microwave absorbers with strong absorption and wide bandwidth.