LightweightHierarchical Carbon Nanocomposites with Highly Efficient and TunableElectromagnetic Interference Shielding Properties

摘要

High-performance electromagnetic interference shielding is becoming vital for the next generation of telecommunication and sensor devices among which portable and wearable applications require highly flexible and lightweight materials having efficient absorption-dominant shielding. Herein, we report on lightweight carbon foam–carbon nanotube/carbon nanofiber nanocomposites that are synthesized in a two-step robust process including a simple carbonization of open-pore structure melamine foams and subsequent growth of carbon nanotubesanofibers by chemical vapor deposition. The microstructure of the nanocomposites resembles a 3-dimensional hierarchical network of carbonaceous skeleton surrounded with a tangled web of bamboo-shaped carbon nanotubes and layered graphitic carbon nanofibers. The microstructure of the porous composite enables absorption-dominant (absorbance ∼0.9) electromagnetic interference shielding with an effectiveness of ∼20–30 dB and with an equivalent mass density normalized shielding effectiveness of ∼800–1700 dB cm³ g^–1 at the K-band frequency (18–26.5GHz). Moreover, the hydrophobic nature of the materials grants water-repellencyand stability in humid conditions important for reliable operationin outdoor use, whereas the mechanical flexibility and durabilitywith excellent piezoresistive behavior enable strain-responsive tuningof electrical conductivity and electromagnetic interference shielding,adding on further functionalities. The demonstrated nanocompositesare versatile and will contribute to the development of reliable devicesnot only in telecommunication but also in wearable electronics, aerospaceengineering, and robotics among others.