Hierarchically dielectric-magnetic hybrid aerogels with plentiful heterointerfaces for high-efficiency electromagnetic wave absorption and thermal insulation

Multifunctional electromagnetic wave (EMW) absorption materials with brilliant thermal insulation capability are highly desired for electromagnetic protection in extreme environments, which could withstand severe temperature fluctuation. The simultaneous realization of these exceptional qualities poses a huge challenge. The hierarchical microarchitecture engineering strategy is regarded as a powerful approach for tailoring the structural attributes of materials at various levels, enabling the achievement of multiple functions. Herein, a range of novel EMW absorption aerogels with heterogeneous interfaces and multi-dimensional encapsulated structures are fabricated through facile hydrothermal and subsequent directional freeze-drying strategy. The presence of multi-arch lamellar structure and parallel venations within the aerogel tremendously improves the impedance matching and facilitates EMW reflection and scattering. The interconnected conductive network constructed by overlapped MXene and rGO as well as defects within themselves serve as vital factors for conduction and polarization losses, significantly enhancing EMW attenuation. Moreover, the incorporation of CoFe₂O₄ nanoparticles induces the generation of magnetic loss, enriching the dissipation mechanisms. The systematic components and structure enable the resultant aerogels to achieve brilliant EMW absorption performance. The ultralight MXene/rGO/CoFe₂O₄ aerogel (13.81 mg/cm³) realizes a minimum reflection loss (RL_min) of −71.0 dB at 10.73 GHz under the thickness of 3.32 mm and a wide effective absorption bandwidth (EAB) of 7.3 GHz (8.8–16.1 GHz) almost covered the whole X and Ku band. The real EMW attenuation capacity of the aerogels used in practice is intuitively verified by the radar cross section simulation. The density functional theory calculation was employed to clarify the contribution of multiscale structural engineering to enhanced EMW absorption. Furthermore, the complex and intertwined three-dimensional continuous network adequately inhibits the heat transfer and prevents the localized areas from being prone to water absorption, endowing the obtained aerogels with outstanding thermal insulation and hydrophobic behavior. The integration of multifunctionalities powerfully guarantees the resultant aerogels as advanced EMW absorption materials in complex environment. This work offers valuable guidance and inspiration for effectively tackling the growing challenges associated with complex electromagnetic surroundings.