Porous metal microsphere M@C-rGO (metal = Mn, Fe, Co, Ni, Cu) aerogels with high low-frequency microwave absorption, strong thermal insulation and superior anticorrosion performance

Nowadays, the development of multifunctional electromagnetic wave absorbers to improve the survivability of military equipment in complex environments is becoming a significant and unavoidable challenge. Here, three-dimensional porous metal microsphere@chitosan reduced graphene oxide (M@C-rGO, M = Mn, Fe, Co, Ni, Cu) aerogels are constructed via a simple ice template method and subsequent pyrolysis. The embedding of different metal microspheres realizes the modulation of the electromagnetic parameters of the synthesized aerogel, achieving a balance between attenuation capability and impedance matching. As expected, the synthesized Cu@C-rGO aerogel exhibits strong microwave absorption in the C-band with a minimum reflection loss (RL_min) of −59.28 dB, which also features an effective absorption bandwidth (EAB) of 6.32 GHz in the high-frequency band. Furthermore, the synthesized aerogels have superior radar stealth, thermal insulation and anticorrosion properties. Typically, the thermal conductivity of Cu@C-rGO is 0.0339 W m⁻¹ K⁻¹, and the charge transfer resistance (R_ct) is 1.421 × 10⁵ Ω cm². Impressively, more than 90% of the EAB could be retained after 7 days of corrosion in NaCl solution. Consequently, this work provides valuable guidance and insight into the development of multifunctional electromagnetic wave absorbers.