The expansion of high-frequency 5G/6G wireless networks, automotive radar modules, satellite communications, and high-density integrated microelectronics has intensified electromagnetic congestion. High-frequency electromagnetic radiation induces Electromagnetic Interference (EMI), degrading signal integrity in sensitive integrated circuits, causing system malfunctions, and raising potential human exposure concerns. Traditional metallic shielding options (e.g., copper foils or aluminum plates) rely on surface reflection to block electromagnetic waves. However, this reflection mechanism traps radiation within device enclosures, triggering signal resonance and secondary electromagnetic pollution. Furthermore, dense metals are heavy, susceptible to chemical corrosion, and lack mechanical flexibility, limiting their suitability for aerospace, military stealth, wearable electronics, and lightweight consumer hardware requiring thin, absorption-dominated shielding solutions.

Three-dimensional porous aerogel composites—including carbon aerogels, reduced graphene oxide (rGO) aerogels, MXene aerogels, and magnetic metal/aerogel hybrids—provide a platform for addressing high-frequency electromagnetic noise and advancing radar cross-section (RCS) reduction technologies. Aerogels offer low bulk densities (down to a few $text{mg/cm}^3$), large specific surface areas, and interconnected conductive, dielectric, or magnetic three-dimensional networks. These characteristics allow engineers to satisfy impedance matching and electromagnetic attenuation parameters within a single material architecture.

The EMI shielding and microwave absorption mechanisms of functional aerogels depend on their porous microstructures. When incident high-frequency electromagnetic waves strike the aerogel interface, the high air fraction (>90% volume) matches the wave impedance of the composite to that of free space. This reduces surface reflections and allows electromagnetic waves to enter the internal matrix. Once inside the tortuous nanopores, continuous conductive pathways (provided by graphene or MXene nanosheets) generate micro-induced currents and dielectric loss, dissipating electromagnetic energy as localized heat. Concurrently, embedded magnetic nanoparticles (e.g., $text{Fe}_3text{O}_4$ or $text{CoNi}$ alloys) introduce magnetic hysteresis loss and natural resonance. Furthermore, the internal pore walls force incoming wave fronts to undergo multiple internal reflections and scattering events, trapping energy until completely dissipated.

These absorption-dominated aerogel EMI shielding systems achieve shielding efficiencies (SE) exceeding 60 dB to 100 dB (attenuating over 99.9999% of incident radiation energy) at reduced thickness, while minimizing secondary reflection pollution. In addition, these aerogels integrate low density, mechanical flexibility, and thermal insulation, making them suitable for stealth aircraft coatings, unmanned aerial vehicle (UAV) radomes, high-density microelectronic packaging, and electromagnetic protective apparel.