Controlled Pyrolysis of MIL-88A Derived Varied-Phase Fe₂O₃@C Nanocomposites with Adjustably Electromagnetic Wave Absorption Properties

Diverse phases of Fe2O3 manifest distinct physical and chemical attributes. Herein, Fe2O3 and Fe2O3@C dodecahedrons with the yolk-shell structure were prepared by controllable pyrolysis of MIL-88 MOFs with different processes. The corresponding pyrolytic stages in air were proposed, followed closely via a similar self-oxidation/reduction procedure in the N2 atmosphere. In terms of microwave absorption performance, the hollow α-Fe2O3@C nanocomposites with the yolk-shell structure could facilitate the dielectric loss, and the interfaces between α-Fe2O3 and C promote the dissipation of an electromagnetic wave, which improve electromagnetic attenuation capability and enrich the loss mechanism of Fe2O3 collaboratively. Due to its carbon-coated hollow structure, αγ-Fe2O3@C nanocomposites calcinated at 400 °C exhibit the best ability for electromagnetic energy conversion. The device has a matching thickness of 2.25 mm, an effective absorption bandwidth of 11.2 to 15.64 GHz, and a total width of 4.44 GHz. Its highest reflection loss (RL) is −52 dB at 8.6 GHz (X band). In the range of −80 < θ < 80, the maximum radar cross section (RCS) reduction of α-Fe2O3@C is greater than 20 dB m2. A great deal of attention has been paid to theoretical simulations of RCS because of its reasonable composition and low-cost features. This work breaks ground for fabricating a MIL-88-derived electromagnetic wave absorber via the enlightenment of RCS simulations.