Controlled Pyrolysis\nof MIL-88A Derived Varied-Phase\nFe<sub>2</sub>O<sub>3</sub>@C Nanocomposites with Adjustably Electromagnetic\nWave Absorption Properties

Diverse phases of Fe<sub>2</sub>O<sub>3</sub> manifest\ndistinct\nphysical and chemical attributes. Herein, Fe<sub>2</sub>O<sub>3</sub> and Fe<sub>2</sub>O<sub>3</sub>@C dodecahedrons with the yolk-shell\nstructure were prepared by controllable pyrolysis of MIL-88 MOFs with\ndifferent processes. The corresponding pyrolytic stages in air were\nproposed, followed closely via a similar self-oxidation/reduction\nprocedure in the N<sub>2</sub> atmosphere. In terms of microwave absorption\nperformance, the hollow α-Fe<sub>2</sub>O<sub>3</sub>@C nanocomposites\nwith the yolk-shell structure could facilitate the dielectric loss,\nand the interfaces between α-Fe<sub>2</sub>O<sub>3</sub> and\nC promote the dissipation of an electromagnetic wave, which improve\nelectromagnetic attenuation capability and enrich the loss mechanism\nof Fe<sub>2</sub>O<sub>3</sub> collaboratively. Due to its carbon-coated\nhollow structure, αγ-Fe<sub>2</sub>O<sub>3</sub>@C nanocomposites\ncalcinated at 400 °C exhibit the best ability for electromagnetic\nenergy conversion. The device has a matching thickness of 2.25 mm,\nan effective absorption bandwidth of 11.2 to 15.64 GHz, and a total\nwidth of 4.44 GHz. Its highest reflection loss (RL) is −52\ndB at 8.6 GHz (X band). In the range of −80 < θ <\n80, the maximum radar cross section (RCS) reduction of α-Fe<sub>2</sub>O<sub>3</sub>@C is greater than 20 dB m<sup>2</sup>. A great\ndeal of attention has been paid to theoretical simulations of RCS\nbecause of its reasonable composition and low-cost features. This\nwork breaks ground for fabricating a MIL-88-derived electromagnetic\nwave absorber via the enlightenment of RCS simulations.