Harnessing Interfacial Polarization in Ultralight Heterostructure Aerogels for High-Efficiency Electromagnetic Dissipation

The increasing severity of electromagnetic pollution in the environment poses a significant challenge to electromagnetic absorption technologies, while the precise control of material structures to achieve multifunctional coupling remains a major challenge. Here, we introduce a temperature-programmable phase transition engineering strategy aimed at overcoming this challenge and achieving multifunctional synergy. Using freeze-drying and gradient annealing processes, we prepare an ultra-light aerogel (3.2 mg/cm3) composed of hollow NiCo nanocubes and reduced graphene oxide (rGO). The continuous phase transition from metallic nitrides/carbides to Co/Ni alloys by controlling the annealing temperature can optimize the magnetic composition and the degree of graphitization of the rGO, thus constructing a three-dimensional heterostructure. At an extremely low loading of just 8 wt% and a matched thickness of 2.5 mm, the Co/Ni@rGO aerogel annealed at 600 °C demonstrated a minimum reflection loss of -75.7 dB and an ultra-broad effective absorption bandwidth (EAB) of 8.9 GHz. Additionally, the density functional theory and simulation results indicate that the extremely narrow metal bandgap and interfacial charge transfer significantly enhance polarization loss. In multifunctional testing, the material successfully integrated hydrophobicity, infrared stealth, and radar cross-section reduction (-8.7 dB∙m2) properties. Furthermore, through macrostructural design based on metamaterial simulations, the EAB was significantly broadened to 14.83 GHz, enabling dynamically tunable adaptive protection. This work demonstrates that temperature-programmed phase-change engineering, which can overcome the limitations of low filling, high absorption and wide bandwidth, establishing a potential pathway for intelligent stealth materials, from component design to system integration.