MOF-derived flower-like CoFe@C composites for enhanced electromagnetic wave absorption

Metal-organic frameworks (MOFs) display immense potential for the advancement of novel materials that can absorb electromagnetic (EM) waves. This potential stems from their tailored structures, high porosity, and large specific surface areas. However, it is still a challenge to enhance the EM wave absorption performance of magnetic carbon-based absorbers obtained from MOFs by reasonably regulating the structure. Herein, CoFe-MOF-derived CoFe@C composites with flower-like structure are successfully obtained by solvothermal method and high temperature carbonization. The Co/Fe molar ratio can be adjusted to easily tune the microstructure and electromagnetic parameters of CoFe@C. Due to the synergistic effect between components and microstructure of CoFe@C, the best EM absorption characteristics can be obtained. Specifically, Co0.5Fe0.5@C displays the optimal reflection loss (RL) value of −54.0 dB at 1.8 mm when the Co/Fe molar ratio is 0.5:0.5. The EAB can reach 5.8 GHz at a matching thickness of 2.1 mm. The remarkable absorption performance of Co0.5Fe0.5@C is assigned to the synergistic effect of different loss mechanisms, such as interface polarization, conductive loss and magnetic loss, together with the strong attenuation capacity and good impedance matching. The study offers a reference for designing and fabricating flower-like structure magnetic carbon-based composites with remarkable EM wave absorption capabilities.