Multi-polarization design of silica-graphene for enhancing microwave absorption performance in X-band

Obtaining a broadband microwave absorption (MA) response for pure graphene is always a challenge relying solely on itself without complicated modification or assistance with magnetic materials to neutralize its poor impedance. In this work, defective graphene is in-situ grown on silica (SiO₂) nanospheres and abundant graphene/SiO₂ (SG) micro-interfaces are formulated simultaneously. To further improve the lossy capacity and impedance, double-layer SG with different preparation temperature (DL) are prepared with an additional macro-interface. Discussion is focused on the effect of multi-polarization processes. Compared with the single-interface SG, DL has a more obvious frequency-dispersion effect which is benefit to broadband absorb, and the electromagnetic wave (EMW) loss capability of DL is also improved due to the enhanced interface and dipole polarizations. When the thickness of DL is 2.5 mm, its effective absorption bandwidth reaches 4.2 GHz, covering the whole X-band. This work provides a useful strategy for the expansion of the MA bandwidth.