Carbon Composite Networks with Ultrathin Skin Layers of Graphene Film for Exceptional Electromagnetic Interference Shielding

Natural cotton was selected as a cheap and renewable carbon source to fabricate novel carbon networks with porous three-dimensional conductive frameworks composed of numerous unique hollow carbon fibers by pyrolysis, and outstanding electromagnetic interference (EMI) shielding effectiveness (SE) of ∼26.9–46.9 dB was observed for the samples (∼0.3 mm in thickness) with density of ∼0.14–0.06 g/cm3. Moreover, the combination of cotton-derived carbon networks with graphene through the construction of a sandwich configuration, where graphene sheets were dispersed inhomogeneously on both sides of carbon networks, was further developed and the resultant carbon composite networks with ultrathin skin layers of graphene film in thickness of only ∼2 μm possessed higher EMI SE of ∼48.5–87.0 dB than that (∼33.7–55.6 dB) of pure carbon networks in thickness of ∼0.3–0.7 mm, possibly due to the enhanced EM reflection and absorption of EM waves penetrating the material. The SE increment of ∼26–41% was also observed in the sandwiched samples in comparison with the counterparts with homogeneous graphene dispersion, demonstrating a very promising configuration for the significant SE enhancement.