Aramid honeycomb composites filled with rGO/BC aerogel for broadband microwave absorption and multifunctional applications

To overcome the limitations of carbon-based microwave-absorbing aerogels in mechanical properties and application versatility, this work integrated reduced graphene oxide/bacterial cellulose (rGO/BC) aerogels into the hexagonal cavities of aramid honeycomb substrates (GCH) through a directional freeze-drying strategy. This architecture leverages the exceptional compressive strength of an aramid framework to prevent the structural collapse of aerogel, while the ultralight rGO/BC aerogel with different graphene oxide (GO) concentrations (bulk density <3 kg/m³) imparts multifunctional without mass increase obviously. BC induces oriented pore alignment in the rGO aerogel matrix, enhancing elastic recovery, mitigating structure failure and cyclic fatigue loss of compression stress during service. Electromagnetic characterization revealed broadband X-band absorption universality across GCH composites, with minimum reflection loss (RL_min) exceeding −70 dB for GCH-3/10/12. Especially, the GCH-7 tested by arch method achieved RL_min of −19 dB over 1–18 GHz and effective absorption bandwidth (EAB) of 12.1 GHz (fully covered Ku-band) with 10 mm thickness, and the actual RL curve obtained through the arch method is in high agreement with the fitting results of electromagnetic parameters. Simultaneously, the composite exhibited integrated functionalities including fatigue durability, thermal insulation, self-extinguishing behavior, and high-frequency sound absorption. This work provides a new paradigm for the design of aerogel-honeycomb composites with both load-bearing capacity and multi-scenario applications, and with potential for promote the large-scale application of wave-absorbing materials in the fields of aerospace and electromagnetic protection.