Composition and structure control of ultralight graphene foam for high-performance microwave absorption
Introduction
With the rapid arising of information technology, microwave absorption materials are playing an increasingly significant role in electronic reliability, healthcare, and national defense security [1], [2], [3], [4]. For example, the microwave absorption (MA) materials applied in the emerging high-speed communication apparatus like satellites could improve the receiver’s signal quality by suppressing the noise [5]. Besides, MA materials in the radar station and the relay station could protect inside workers from overdose exposure to high-power microwave [6]. Most importantly, with the gradual maturation of novel advanced anti-stealth radars such as ultra wide band radar, phased array radar, multi-static radar and passive radar, high-performance counter-detection MA materials serve as a very efficient route in increasing the survivability of military units via reducing their radar cross-section [7]. The ideal MA materials are primarily required to establish an excellent double-win relationship between intense absorption ability and broad absorption bandwidth. In addition, MA materials with ultralight weight and thin thickness will be advantageous in the fields of aerospace, aviation, ground vehicles and fast-growing next-generation green miniature electronics [1], [8], [9].
The interfacial impedance gap and radiation energy loss characteristics are considered as the two core principles that determine the MA performance of a material [10], [11], [12], [13]. The microwave propagation for a typical homogenous material’s MA process depends on several factors, including dielectric permittivity ε, magnetic permeability μ and electrical conductivity δ, which are a comprehensive reflection of significant component and structural characteristics [4], [14], [15], [16].
For decades, researchers have made considerable efforts towards designing and fabricating various MA materials by adjusting the electrical conductivity, dielectric constant and magnetic permeability in the pursuit of low interfacial impedance gap as well as high loss ratio of incident microwave [10], [11], [13], [17], [18]. In most cases, separate solid particle absorbents, such as ferrites [19], [20], metal powders [20], [21], ceramics [22], carbon nano/micromaterials [23], [24] and their hybrids [2], [15], [25], [26], are extensively adopted as fillers into microwave-transparent organic or inorganic adhesives to fabricate MA composites. Besides mediocre MA performance, most of them have also been kept far from practical application for some shortcomings, such as high density, poor stability and large loading content [1], [12], [27]. It has been demonstrated, for instance, 70 wt% or more magnetic iron particles with a very high density of 8 g/cm3 are required in typical MA composites [17], [20].
Three-dimensional (3D) macroscopic porous lossy materials have been expected to be the most promising candidate for lightweight high-performance broadband MA application [28], [29], [30], [31], [32]. Compared with conventional uniform solid MA materials, the MA foam, with so many homogenously-dispersed internal pores, not only shows lower bulk density but also gives much smaller effective permittivity, which makes it less resistive to the detective incident microwave in a wide frequency range [16], [33]. Until now, considerable attentions have been paid to synthesis and application of porous bulk materials for microwave suppression, such as conductive polymer foam [28], [34], [35], silicon carbide foam [36], [37], carbon foam [7], [29], [38], [39] and carbon nanotube sponge [40]. However, for most MA foams reported previously, their MA behaviors could not be compared with those of traditional solid MA materials [7], [35], [36]. Furthermore, it is still a big challenge to reveal the composition & structure–performance relationship of MA foams due to their complicated irregular structures and preparation techniques, which severely hinders their practical application.
Recently, significant progress toward 3D macroscopic interconnected graphene networks has opened up a new route for the exploitation of porous bulk material for lightweight and broadband high-performance MA application [38], [41], [42], [43], [44], [45], [46], [47], [48], [49]. In the previous communication, we preliminarily proved the outstanding microwave absorbing performance of macroscopic GFs, which showed that GFs may have great potential in MA application [32]. However, there remains much uncertainty in the GF’s MA property dependence on its morphology and composition. Therefore, it is very significant to develop a facile and controllable method to prepare additive-free large-sized GFs and establish the relationship between the MA property and the GF’s intrinsic structure and component, which is essential in an in-depth understanding of its MA mechanism and more importantly developing a universal strategy to effectively enhance the MA property of bulk porous materials.
Herein, we demonstrate design and fabrication of various GFs with different internal morphologies and compositions and investigate their MA performance in 2–18 GHz, which is intensively occupied for satellite communications, remote sensing, radar detections and weapons guidance and tracking. The MA performance of the GF foam is found to be strongly correlated to the C/O ratio, sp2 carbon domain size and graphene framework microstructure. A maximum absorbing value of −34.0 dB as well as 14.3 GHz qualified bandwidth can be obtained for the GF with an ultralow density of 1.6 mg/cm3, which is close to the density of ambient air (1.2 mg/cm3) and much lower than those of the carbon foam (166 mg/cm3) [29] and the SiC foam (∼256 mg/cm3) [37]. More importantly, the GF presents the best average absorption intensity compared with other typical MA materials in 2–18 GHz.The specific MA efficiency is nearly two orders of magnitude higher than those of the best available MA materials ever reported. The mechanism for the MA performance dependence on the composition and structure of the GF is revealed. The well-matched interfacial impedance combined with high loss ability gives rise to the enhanced MA performance.
Section snippets
Synthesis of GF
The raw material, single-layer graphene oxide (GO), was prepared using a modified Hummers method as described elsewhere and has the lateral size mainly above 10 μm [42]. The initial concentrated GO ethanol solution was diluted into three GO ethanol reaction solutions with concentrations of 0.3, 0.6 and 0.9 mg/mL, respectively. After solvothermal reaction, solvent exchange and freeze drying, three original GFs with different graphene volume fractions were obtained. The GFs made from 0.3 to
The dependence of MA performance on the GF’s chemical composition
The macroscopic additive-free GF for MA tests was prepared mainly through a solvothermal reaction, followed by solvent removal and thermal reduction. By varying annealing temperatures in the thermal reduction from room temperature to 800 °C, five types of pie-shaped GFs starting from the same GO concentration of 0.6 mg/mL were obtained to study the MA performance dependence on the chemical composition. For convenience, the unannealed GF is labeled as T0 and the other annealed products were
Conclusion
In summary, we have prepared series of GFs with various chemical compositions and physical structures by controlling the GO concentration of the initial solution and thermal-reduction temperature. The analyses of the GFs’ compositions, structures and electromagnetic properties suggest that the MA performance of the GF is strongly correlated with the C/O ratio, conjugated carbon content and the graphene skeleton microstructure. A maximum absorption value of −34.0 dB as well as 14.3 GHz qualified
Acknowledgments
The authors gratefully acknowledge financial support from the MOST (Grants 2012CB933401), NSFC (Grants 21374050, 91433101, 51472124 and 51273093), MOE (B12015), PCSIRT (IRT1257) and NSF of Tianjin City (Grant 15JCYBJC17700).
References (57)
- et al.
Reflection and absorption contributions to the electromagnetic interference shielding of single-walled carbon nanotube/polyurethane composites
Carbon
(2007) - et al.
Bioeffects of microwave – a brief review
Bioresour. Technol.
(2003) - et al.
Microwave characteristics of sandwich composites with mesophase pitch carbon foams as core
Carbon
(2004) - et al.
Epoxy-silicone filled with multi-walled carbon nanotubes and carbonyl iron particles as a microwave absorber
Carbon
(2010) - et al.
Microwave absorbing properties of a thermally reduced graphene oxide/nitrile butadiene rubber composite
Carbon
(2012) - et al.
Electromagnetic and microwave absorbing properties of multi-walled carbon nanotubes/polymer composites
Mater. Sci. Eng. B
(2006) - et al.
Synthesis and microwave absorption properties of Fe–C nanofibers by electrospinning with disperse Fe nanoparticles parceled by carbon
Carbon
(2014) - et al.
Electromagnetic shielding performance of carbon foams
Carbon
(2012) - et al.
Investigation of carbon foams as microwave absorber: numerical prediction and experimental validation
Carbon
(2006) - et al.
Computation of radar absorbing silicon carbide foams and their silica matrix composites
Comput. Mater. Sci.
(2007)
Carbon foam: preparation and application
Carbon
Ultrathin carbon foams for effective electromagnetic interference shielding
Carbon
Electromagnetic wave absorption properties of graphene modified with carbon nanotube/poly(dimethyl siloxane) composites
Carbon
Enhanced microwave absorption property of reduced graphene oxide (RGO)-MnFe2O4 nanocomposites and polyvinylidene fluoride
ACS Appl. Mater. Interfaces
Gamma-Fe2O3-MWNT/poly(p-phenylenebenzobisoxazole) composites with excellent microwave absorption performance and thermal stability
Nanoscale
A covalent route for efficient surface modification of ordered mesoporous carbon as high performance microwave absorbers
Nanoscale
Synthesis of an electromagnetic wave absorber for high-speed wireless communication
J. Am. Chem. Soc.
Microwave absorption of single-walled carbon nanotubes/soluble cross-linked polyurethane composites
J. Phys. Chem. C
One-pot synthesis of CoFe2O4/graphene oxide hybrids and their conversion into FeCo/graphene hybrids for lightweight and highly efficient microwave absorber
J. Mater. Chem. A
Synthesis and microwave absorption enhancement of graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures
Nanoscale
Enhanced Dielectric Properties and Excellent Microwave Absorption of SiC Powders Driven with NiO Nanorings
Adv. Opt. Mater.
Controllable synthesis of porous Fe3O4@ZnO sphere decorated graphene for extraordinary electromagnetic wave absorption
Nanoscale
Microporous Co@CoO nanoparticles with superior microwave absorption properties
Nanoscale
Highly aligned graphene/polymer nanocomposites with excellent dielectric properties for high-performance electromagnetic interference shielding
Adv. Mater.
Microwave absorption enhancement and complex permittivity and permeability of Fe encapsulated within carbon nanotubes
Adv. Mater.
Numerical predictions for radar absorbing silicon carbide foams using a finite integration technique with a perfect boundary approximation
Smart Mater. Struct.
Microwave absorption enhancement of multifunctional composite microspheres with spinel Fe3O4 Cores and Anatase TiO2 shells
Small
Shape anisotropy, exchange-coupling interaction and microwave absorption of hard/soft nanocomposite ferrite microfibers
J. Am. Ceram. Soc.
Cited by (408)
A radar-infrared compatible stealth metamaterial with bird's nest morphology
2024, Journal of Alloys and CompoundsEffects of lattice configuration on multifunctionality of C-sandwich radome
2024, International Journal of Mechanical SciencesWatermelon pulp biochar decorated with Co<inf>3</inf>Fe<inf>7</inf> for high-efficiency electromagnetic wave absorption
2024, Journal of Magnetism and Magnetic Materials