Lightweight\nHierarchical Carbon Nanocomposites with Highly Efficient and Tunable\nElectromagnetic Interference Shielding Properties

Abstract

High-performance\nelectromagnetic interference shielding is becoming vital for the next\ngeneration of telecommunication and sensor devices among which portable\nand wearable applications require highly flexible and lightweight\nmaterials having efficient absorption-dominant shielding. Herein,\nwe report on lightweight carbon foam–carbon nanotube/carbon\nnanofiber nanocomposites that are synthesized in a two-step robust\nprocess including a simple carbonization of open-pore structure melamine\nfoams and subsequent growth of carbon nanotubes/nanofibers by chemical\nvapor deposition. The microstructure of the nanocomposites resembles\na 3-dimensional hierarchical network of carbonaceous skeleton surrounded\nwith a tangled web of bamboo-shaped carbon nanotubes and layered graphitic\ncarbon nanofibers. The microstructure of the porous composite enables\nabsorption-dominant (absorbance ∼0.9) electromagnetic interference\nshielding with an effectiveness of ∼20–30 dB and with\nan equivalent mass density normalized shielding effectiveness of ∼800–1700\ndB cm³ g^–1 at the K-band frequency (18–26.5\nGHz). Moreover, the hydrophobic nature of the materials grants water-repellency\nand stability in humid conditions important for reliable operation\nin outdoor use, whereas the mechanical flexibility and durability\nwith excellent piezoresistive behavior enable strain-responsive tuning\nof electrical conductivity and electromagnetic interference shielding,\nadding on further functionalities. The demonstrated nanocomposites\nare versatile and will contribute to the development of reliable devices\nnot only in telecommunication but also in wearable electronics, aerospace\nengineering, and robotics among others.