Flexible ultra-thin Fe3O4/MnO2 core-shell decorated CNT composite with enhanced electromagnetic wave absorption performance
Introduction
High-performance electromagnetic (EM) wave absorption materials are in high demand in the past few decades [[1], [2], [3], [4]]. To date, more and more attentions have been paid to design of promising electromagnetic wave absorbents with strong absorption [[5], [6], [7]]. In addition to EM wave absorbing capability, low density and thin thickness absorbents are desirable in the fields of aerospace, automobile and electronic devices [[8], [9], [10]]. In spite of their good absorbing performance, conventional solid particles, such as ferrites, metallic magnets, ceramics, and their hybrids have drawbacks of high density, poor stability, and large loading content, which hindered their practical applications [4,11]. Recently, nano carbon-based materials, especially graphene and carbon nanotube, have received much attention for EM wave absorption, due to their low density, high specific surface area, large aspect ratios, and chemical stability [8,12]. However, individual graphene sheet or carbon nanotube (CNT) powder suffers from poor dispersion in a matrix material [13,14]. The fabrication of ultrathin, optically homogeneous, electrically conducting films of CNTs offers a wide-variety of applications [[15], [16], [17], [18]]. Here, CNT films with controllable web-like networks of CNTs in a stable and flexible form can be used as the basic building block for preparing EM wave absorption composites [19]. The CNT film fabricated by floating catalyst chemical vapor deposition method and used in the present research has an ultra-thin thickness of 2 μm and density of 807 mg/cm2, which overcomes the shortcomings of self-assembled three-dimensional graphene oxide foam in large thickness and poor flexibility [1,12,20].
Furthermore, among the many varieties of magnetic particles, Fe3O4 is unique in its large constant magnetic moment and negligible conductivity, which give rise to both magnetic loss and dielectric loss [21]. However, in order to overcome the shortcomings of high density and susceptibility to oxidation, the fabrication of innovative Fe3O4-based nanocomposite is necessary. Wang etc. fabricated graphene-Fe3O4 nanohybrids, and the maximum reflection loss (RL) was up to −40.36 dB with a thickness of 5.0 mm [22]. Liu etc. synthesized multifunctional composite microspheres with spinel Fe3O4 cores and anatase TiO2 shells as absorbents [23]. A facile and efficient strategy for the synthesis of yolk-shell microspheres with magnetic Fe3O4 cores and copper silicate shells has been developed by Liu etc. [24]. Furthermore, the development of hierarchical structure for enhanced absorption capability has also attracted much interest. For example, Wang etc. fabricated novel hierarchical graphene@Fe3O4 nanocluster@carbon@MnO2 nanosheet array composites, and the maximum reflection loss was 38.8 dB at 15 GHz [25]. Ren etc. fabricated a three-dimensional SiO2@Fe3O4 core/shell nanorod array/graphene architecture with a minimal RL value of −27.3 dB [26]. Yang etc. fabricated a novel hierarchical architecture of NiO nanorings on SiC by a facile two-step method, and the reflection loss exceeded −40 dB [27]. Also, MnO2, as an important transition-metal oxide, has attracted considerable attention because of its low cost, good thermal stability, various structural morphologies, etc. The large surface areas, abundance of cavities of MnO2 also enabled its application as EM wave absorbing material [28,29]. Consequently, Fe3O4 nanoparticles and MnO2 nanosheets were chosen to decorate the CNT film surface.
In this paper, we synthesised an ultra-thin MnO2/Fe3O4/CNT film with Fe3O4 core-MnO2 shell structure on the surface of the CNT film, the EM wave absorbing properties of the ultra-thin composite film was measured and the mechanism of the enhanced EM wave absorption capability was investigated.
Section snippets
Materials
Macroscopic CNT film was fabricated by floating catalyst chemical vapor deposition (FCCVD) method [30,31]. In this process, ethanol, ferrocene, and thiophene were used as carbon source, catalyst precursor, and promotor, respectively. The macroscopic CNT film with randomly oriented CNT bundles has a density of 807 mg/cm3. The conductivity of the CNT film is 377 S/cm. Polydimethylsiloxane (PDMS) have a specific gravity of 1.07g/cc and viscosity of 3000 cps (Smooth-on, Inc., USA). Ferric
Morphology and structure analysis
The hierarchical microstructure of the MnO2/Fe3O4/CNT film is shown schematically in Fig. 1a. Here, the Fe3O4 nanoparticles were uniformly deposited on the CNT bundles, then MnO2 nanosheets were deposited on the mamoparticles. Fig. 1b shows the vector network analyzer for characterizing the typical electromagnetic parameters. The ultra-thin specimens possess high flexibility as demonstrated in Fig. 1c.
Fig. 2a shows that Fe3O4 particles with irregular sizes of 80–100 nm are dispersed on the CNT.
Conclusions
In conclusion, the MnO2/Fe3O4/CNT film fabricated in this study greatly improves the EM wave absorption capability in terms of reduction in reflection loss and enhancement in absorption bandwidth. The MnO2/Fe3O4/CNT film-PDMS composite with 10% weight ratio of MnO2 achieved the highest wave-absorbing capability; its minimum reflection loss and bandwidth (<-10 dB) were −42.2 dB and 7.1 GHz, respectively. The CNT film, MnO2 nanosheets and the interfacial polarization of the hierarchical structure
Acknowledgements
Y.Q.S. acknowledges the financial support from the China Scholarship Council (CSC). W.B.L. would like to acknowledge the support by the National Key Research and Development Program of China (No. 2016YFA0203301).
References (35)
- et al.
Three-dimensional reduced graphene oxide foam modified with ZnO nanowires for enhanced microwave absorption properties
Carbon
(2017) - et al.
In-situ synthesis of hierarchically porous and polycrystalline carbon nanowires with excellent microwave absorption performance
Carbon
(2016) - et al.
Lightweight hollow carbon nanospheres with tunable sizes towards enhancement in microwave absorption
Carbon
(2016) - et al.
The role of microwave absorption on formation of graphene from graphite oxide
Carbon
(2012) - et al.(2017)
- et al.
The revolutionary creation of new advanced materials—carbon nanotube composites
Compos B Eng
(2002) - et al.
Characterization of enhanced interfacial bonding between epoxy and plasma functionalized carbon nanotube films
Compos Sci Technol
(2017) - et al.
A three-dimensional absorber hybrid with polar oxygen functional groups of MWNTs/graphene with enhanced microwave absorbing properties
Compos B Eng
(2017) - et al.(2014)
- et al.
Dependency of tunable microwave absorption performance on morphology-controlled hierarchical shells for core-shell Fe 3 O 4@ MnO 2 composite microspheres
Chem Eng J
(2016)
Multilayered graphene-carbon nanotube-iron oxide three-dimensional heterostructure for flexible electromagnetic interference shielding film
Carbon
Broadband and tunable high-performance microwave absorption of an ultralight and highly compressible graphene foam
Adv Mater
Metamaterial electromagnetic wave absorbers
Adv Mater
Microwave absorption enhancement and complex permittivity and permeability of Fe encapsulated within carbon nanotubes
Adv Mater
In situ growth of core-sheath heterostructural SiC nanowire arrays on carbon fibers and enhanced electromagnetic wave absorption performance
ACS Appl Mater Interfaces
Engineering nanostructured polymer blends with controlled nanoparticle location for excellent microwave absorption: a compartmentalized approach
Nanoscale
Enhanced microwave absorption property of reduced graphene oxide (RGO)-MnFe2O4 nanocomposites and polyvinylidene fluoride
ACS Appl Mater Interfaces
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