Constructing Heterostructures via In Situ Thermal Reduction of rGO/Fe3O4 for High-Efficiency Microwave Absorption

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As communication technology rapidly develops, electronic devices increasingly enhance human convenience, and the electromagnetic waves they emit not only cause environmental pollution but also negatively impact the human nervous system. Therefore, the development of electromagnetic wave-absorbing materials has garnered widespread attention in the scientific community. In this study, an rGO/Fe3O4 composite material with a heterogeneous structure was successfully prepared using a hydrothermal method, followed by annealing under an argon atmosphere. SEM and TEM analyses revealed a uniform composite structure when the annealing temperature reached 1000 °C. XRD results indicated that as the annealing temperature increased, Fe3O4 partially transformed into Fe2O3 and was eventually reduced to α-Fe at 1000 °C. This phase and microstructural transformation effectively modulate the impedance matching and electromagnetic loss. The rGO/Fe3O4-1000 composite achieved a minimum reflection loss of −55.02 dB at 1.76 mm, and the effective absorption bandwidth is 5.36 GHz.