Abstract
AbstarctGraphene has sparked extensive research interest for its excellent physical properties and its unique potential for application in absorption of electromagnetic waves. However, the processing of stable large-scale graphene and magnetic particles on a micrometer-thick conductive support is a formidable challenge for achieving high reflection loss and impedance matching between the absorber and free space. Herein, a novel and simple approach for the processing of a CNT film-Fe3O4-large scale graphene composite is studied. The Fe3O4 particles with size in the range of 20–200 nm are uniformly aligned along the axial direction of the CNTs. The composite exhibits exceptionally high wave absorption capacity even at a very low thickness. Minimum reflection loss of −44.7 dB and absorbing bandwidth of 4.7 GHz at −10 dB are achieved in composites with one-layer graphene in six-layer CNT film-Fe3O4 prepared from 0.04 M FeCl3. Microstructural and theoretical studies of the wave-absorbing mechanism reveal a unique Debye dipolar relaxation with an Eddy current effect in the absorbing bandwidth.
Highlights
The rapid development of modern electronic equipment and wireless devices has resulted in severe electromagnetic (EM) radiation pollution, which has implications in human health and the normal functioning of electronics
To enhance the ability of EM wave absorption, highly conductive films with randomly oriented Carbon nanotubes (CNTs) coated by Fe3O4 nanoparticles were used as absorbing layers, the single chemical vapor deposition graphene were laid on the surface of CNT-Fe3O4 film as blocking layer (Supplementary Fig. S1), and the CNT film-Fe3O4 with epoxy resin (EPONTM Resin 862) was impedance matching layer
For the CNT film-Fe3O4 composite prepared from 0.01 M FeCl3, Fe3O4 nanocrystals cover the CNT surface and form a few spherical particles with diameters ranging from 10–20 nm (Fig. 1a)
Summary
The rapid development of modern electronic equipment and wireless devices has resulted in severe electromagnetic (EM) radiation pollution, which has implications in human health and the normal functioning of electronics. The anticipated improvement in EM wave absorption performance has often been hindered by the poor dispersion of CNTs and their impedance mismatch with free space[10]. Large-scale multilayer graphene/methyl methacrylate for EM wave absorption has been suggested theoretically and realized in numerical simulations[18,19,20], large-scale graphene absorption has never been demonstrated experimentally This is due to the fact that large-scale graphene suffers from statistical fluctuations in strength and toughness as well as impedance mismatch with free space due to the high permittivity and negligible permeability[21]. In order to enhance impedance matching and absorption of both electric and magnetic fields in graphene, the improved decoration and blend of magnetic metal or metal oxide particles have become effective approaches for researchers. The design and processing of high-performance EM-absorbing materials based on CNT and graphene remain a formidable challenge
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