Dumbbell-Like Fe₃O₄@N-Doped Carbon@2H/1T-MoS₂ with Tailored Magnetic and Dielectric Loss for Efficient Microwave Absorbing

Ferroferric oxide (Fe3O4)/C composites have received much attention as a result of converting electromagnetic waves to heat for harvesting efficient electromagnetic wave (EMW) absorbing performance. However, the practical EMW absorbing of these absorbers is still greatly hindered by the unmatched impedance properties and limited EMW absorbing ability. Tuning the morphologies at nanoscale and assembling the nanoarchitecture construction are essential to address this issue. Herein, dumbbell-like Fe3O4@N-doped carbon (NC)@2H/1T-MoS2 yolk–shell nanostructures are rationally designed and fabricated via a facile etching and wet chemical synthesis strategy. By manipulating the etching time toward the magnetic Fe3O4 component, the dielectric and magnetic loss of absorbers could be well-tuned, thus achieving the optimized impedance characteristics. As a result, the maximum refection losses (RLmaxs) of Fe3O4@NC-9h and Fe3O4@NC-15h are −19.8 dB@7.9 GHz and −39.5 dB@8.3 GHz, respectively. Moreover, the MoS2 nanosheets with a mixed 2H/1T phase anchored on Fe3O4@NC-15h (Fe3O4@NC-15h@MoS2) further boost the RLmax to −68.9 dB@5.8 GHz with an effective absorbing bandwidth of ∼5.25 GHz. The tailored synergistic effect between dielectric and magnetic loss and the introduced interfacial polarization (Fe3O4@NC/MoS2) are discussed to explain the drastically enhanced microwave absorbing ability. This work opens up new possibilities for effective manipulation of electromagnetic wave attenuation performance in magnetic–dielectric-type nanostructures.