Atomic Valence Reversal-Induced Polarization Resonance Spurs Highly Efficient Electromagnetic Wave Absorption in α‑Fe₂O₃@Carbon Microtubes

Variegation and complexity of polarization relaxation loss in many heterostructured materials provide available mechanisms to seek a strong electromagnetic wave (EMW) absorption performance. Here we construct a unique heterostructured compound that bonds α-Fe₂O₃ nanosheets of the (110) plane on carbon microtubes (CMTs). Through effective alignment between the Fermi energy level of CMTs and the conduction band position of α-Fe₂O₃ nanosheets at the interface, we attain substantial polarization relaxation loss via novel atomic valence reversal between Fe­(III) ↔ Fe­(III^–) induced with periodic electron injection from conductive CMTs under EMW irradiation to give α-Fe₂O₃ nanosheets. Such heterostructured materials possess currently reported minimum reflection loss of −84.01 dB centered at 10.99 GHz at a thickness of 3.19 mm and an effective absorption bandwidth (reflection loss ≤ −10 dB) of 7.17 GHz (10.83–18 GHz) at 2.65 mm. This work provides an effective strategy for designing strong EMW absorbers by combining highly efficient electron injection and atomic valence reversal.