Graphene Oxide Aerogels with Oriented Microstructures as Bilayer Materials for Enhanced Broadband Microwave Absorption

Advancements in communication technologies have led to increased concern regarding broadband electromagnetic pollution, creating an urgent demand for broadband microwave absorbing materials. However, broadband microwave absorption is still a big challenge. This work focuses on graphene aerogels with oriented microstructures, trying to obtain microwave absorbing materials with broadband in a view different from previous exploration. The graphene oxide (GO) aerogels demonstrated anisotropic characteristics in their structure and electromagnetic parameters. By assembling GO aerogels with different concentrations and structures, bilayer GO aerogels with broadband microwave absorption could be obtained. The surface of the GO aerogels exhibited lower permittivity, which suppressed the initial reflection. On the contrary, the high internal permittivity enhanced internal absorption, leading to broadband absorption capabilities. The reflection loss (RL) of the GO aerogels less than −10 dB was in 3.95–18 GHz range, a minimum RL (RLmin) of −32.99 dB at 7.50 GHz. This broadband absorption performance coupled with lightweight properties suggest that the inhomogeneous reduced GO bilayer aerogel could effectively mitigate broadband electromagnetic wave energy, which is suitable for national defense application such as in aircraft and warship.