In Situ “Work‐Invaliding‐Awakened” of Reduced Graphene Oxide/SiO ₂ Bilayer Aerogels for Broadband Microwave Absorption Based on Thermally Reduced Reconstructed Carbon Networks

Abstract The advancement of next‐generation communication technologies imposes new requirements on microwave absorption (MA) materials in millimeter‐wave frequencies. Current Ka‐band absorbers face limitations including narrow bandwidth and excessive thickness, which fall short of practical requirements. The innovative fabrication process reduced graphene oxide composites SiO₂ nanofibers (RGO/SiO₂) aerogels with an intrinsic bilayer architecture are fabricated. By combining material engineering with this inherent bilayer configuration, synergistic optimization of impedance matching and multimodal loss mechanisms is achieved. This enables the absorber to exhibit full Ka‐band absorption (26.5–40 GHz) at a minimal thickness of 1.83 mm. Furthermore, multispectral characterization techniques revealed a unique invaliding‐awakened mechanism of MA under ambient conditions. The reversible absorption characteristics originate from synergistic interactions between oxygen‐containing functional groups and sp 3 /sp 2 hybridized carbon domains on graphene surfaces. Directionally freeze‐dried‐reduced RGO/SiO 2 aerogels (DRSA) have anisotropic mechanical properties. In the longitudinal direction, it can withstand objects more than 20 000 times heavier. The composite aerogel also repels water, insulates well, and absorbs visible light. These distinctive properties establish the RGO/SiO₂ aerogel with its intrinsic bilayer architecture as a scientifically significant prototype for developing adaptable electromagnetic protection materials suitable for complex operational environments.