Ultralight, highly compressible and fire-retardant graphene aerogel with self-adjustable electromagnetic wave absorption

Macroscopic three-dimensional (3D) free-standing porous all-graphene aerogel with ultralight density and high compressibility is successfully fabricated through a mild in-situ self-assembly and thermal annealing processes. The formed interconnected 3D porous graphene network, high thermal stable all-graphene composition and large porosity of aerogels made it possible to remove heat quickly during combustion, exhibiting a conspicuous fire-retardancy. Meanwhile, excellent recoverable compressibility with high strain levels of up to 75% endowed the aerogel with high sensitive strain-responsive characteristic in volume electrical conductivity, thereby opening a new way for realizing the adjustment of internal free space and electrical conductivity of 3D architecture. Based on the results, the microwave absorption performance of the graphene aerogel was effectively self-adjusted via a simple mechanical compression. The optimal absorbing value was up to 61.09 dB with a broad qualified bandwidth of 6.30 GHz at the thickness of 4.81 mm when the compression strain ratio of the sample was controlled to be 30%.