Graphene Oxide Aerogels\nwith Oriented Microstructures\nas Bilayer Materials for Enhanced Broadband Microwave Absorption

Advancements in communication technologies have led to\nincreased\nconcern regarding broadband electromagnetic pollution, creating an\nurgent demand for broadband microwave absorbing materials. However,\nbroadband microwave absorption is still a big challenge. This work\nfocuses on graphene aerogels with oriented microstructures, trying\nto obtain microwave absorbing materials with broadband in a view different\nfrom previous exploration. The graphene oxide (GO) aerogels demonstrated\nanisotropic characteristics in their structure and electromagnetic\nparameters. By assembling GO aerogels with different concentrations\nand structures, bilayer GO aerogels with broadband microwave absorption\ncould be obtained. The surface of the GO aerogels exhibited lower\npermittivity, which suppressed the initial reflection. On the contrary,\nthe high internal permittivity enhanced internal absorption, leading\nto broadband absorption capabilities. The reflection loss (RL) of\nthe GO aerogels less than −10 dB was in 3.95–18 GHz\nrange, a minimum RL (RL<sub>min</sub>) of −32.99 dB at 7.50\nGHz. This broadband absorption performance coupled with lightweight\nproperties suggest that the inhomogeneous reduced GO bilayer aerogel\ncould effectively mitigate broadband electromagnetic wave energy,\nwhich is suitable for national defense application such as in aircraft\nand warship.