Atomic Valence Reversal-Induced Polarization Resonance Spurs Highly Efficient Electromagnetic Wave Absorption in α-FeO@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-FeO 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-FeO 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-FeO 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.