Transverse size effect on electromagnetic wave absorption performance of exfoliated thin-layered flake graphite

Exploration of effective electromagnetic wave absorption (EWA) materials is still urgent in terms of the electromagnetic wave pollution and radiation. Herein, the thin-layered flake graphite prepared by shear-assisted supercritical CO2 exfoliation possesses excellent absorption property over the frequency range of 2–18 GHz, with broad effective absorption peaks at 4–8 GHz and 10–18 GHz where the value of reflection loss (RL) is below −30 dB and the RLmin of −49 dB at a thickness of 1.49 mm with only 20 wt% loading. The thin-layered flake graphite with large size (average 179.9 μm) possesses high conductivity, contributing to a large number of electronics migrating. However, the graphite with small size distribution is favorable to dipole polarization and interfacial polarization. As the small size graphite sheets (25 wt%) were distributed among the gaps between the large flake graphite sheets (75 wt%), the enhanced electronics migrating bridge effect between the large flake graphite sheets would be available for the enhanced dielectric loss. Our study paves an effective way for scalable and green production of high efficient EWA materials. The thin-layered flake graphite with suitable transverse size distribution was exfoliated by shear-assisted supercritical CO2 fluid, which has excellent microwave absorption performance. [Display omitted]