Construction of Graphene/Fe3O4@Hollow Glass Microsphere Composite Foam with Excellent Electromagnetic Interference Shielding, Joule Heating, and Flame-Retardant Properties.

The development of lightweight multifunctional materials integrating electromagnetic interference (EMI) shielding, Joule heating and flame retardancy is highly demanded for advanced electronics and aerospace systems. Herein, we fabricate graphene/Fe3O4@hollow glass microsphere (G/Fe3O4@HGM) composite foam with an ultralow density of 0.36 g/cm-3. The porous structure synergizes graphene's conductivity, Fe3O4's magnetism and HGM's low thermal conductivity to optimize impedance matching. The foam delivers absorption-dominated EMI shielding with a maximum X-band shielding effectiveness (SE) of 60.1 dB and an average absorption coefficient of 0.56, which effectively suppresses secondary electromagnetic reflection pollution. The composite exhibits stable voltage-controllable Joule heating: the 25 wt% Fe3O4@HGM sample reaches 91.3 °C at 16 V, enabling rapid de-icing within 200 s and stable thermal maintenance at -20 °C. Flame tests confirm no combustion or structural collapse under open flame. This work provides a simple fabrication strategy for lightweight multifunctional materials applicable to aerospace stealth, electronic thermal management and anti-icing systems.