The effect of microstructure of graphene foam on microwave absorption properties

The graphene foam (GF) was prepared by reducing graphene oxide (GO) with l-ascorbic acid (l-AA), followed by freeze-drying. Through changing the initial concentration of GO solution, several GFs with different microstructure could be obtained. The higher the initial concentration of GO, the more obviously the layered stacking of graphene sheet. According to the study, GFs with honeycomb microstructure possessed excellent performance on microwave absorption (MA). When the concentration of GO was 2 mg/ml, the resulting sample GF2 showed the best MA properties. When the thickness of the sample GF2 was 2 mm and the mass content of GF2 in the sample was only 3 wt%, the absolute value of the maximum reflection loss (|RLmax|) of GF2 could reach 41.0 dB at 16.2 GHz. And 11 GHz bandwidth of RL less than −5 dB, covering the whole Ku, X and half the Xc band, was achieved by GF2 with the thickness of 3 mm.