Abstract
Graphene has been regarded as a promising candidate in microwave absorption field but still faces some major challenges, including the limitation of mass production and poor impedance matching. Here, we demonstrate a simple approach to fabricate multilayer graphene in a kilo-mass/hour (≥2.5 kg/h) scale through an oxidation-thermal expansion-air convection shearing process. The subsequent incorporation of hexagonal boron nitride nanoparticles (h-BNNPs) can effectively tailor the dielectric and magnetic properties of the as-obtained multilayer graphene, which can significantly boost its microwave absorption performance. The as-obtained multilayer graphene/h-BNNP hybrid with 40 wt.% of h-BNNPs, exhibits extremely low reflection loss value of −67.35 dB at 8.04 GHz when the absorber thickness is 3.29 mm, ranking it as one of the most attractive absorbers reported to date. Moreover, the multilayer graphene/h-BNNP hybrids possess low densities less than 0.45 g/cm3, making them very attractive for practical microwave absorption application.
Highlights
Severe electromagnetic microwave pollution induced by the rapid development of electronic information technologies including wireless data communications, satellite communications, radar detections, self-concealing, as well as microwave heating,[1,2,3] has aroused global concerns
The MG/hexagonal boron nitride nanoparticles (h-BNNPs) hybrids were fabricated via a facile ball milling (QM-QX-2, MITR, China) process with the as-obtained multilayer graphene and commercial Hexagonal boron nitride (h-BN) powders as precursors (Fig. 2a–d)
For the MG/h-BNNP-40% based absorber, the minimum reflection loss (RL) values of the absorber below −20 dB can be, respectively, discovered in the frequency range of 3.3 to 10.5 GHz and 14.0 to 18.0 GHz with the absorber thickness of 1.0–6.0 mm (Fig. S16f). These results indicate that the MG/h-BNNP hybrids have an excellent capability to efficiently absorb electromagnetic microwaves in a wide frequency range
Summary
Severe electromagnetic microwave pollution induced by the rapid development of electronic information technologies including wireless data communications, satellite communications, radar detections, self-concealing, as well as microwave heating,[1,2,3] has aroused global concerns. To eliminate the detriment of this electromagnetic microwave pollution on human beings and wildlife, highly efficient microwave absorption materials are required. Searching for ideal microwave absorption materials is challengeable, because of the critical indispensable requirement, such as good mechanical strength, light weight, low loading rate, decent chemical corrosion resistance and high thermal stability.[4,5] Recently, graphene-based nanocomposites have attracted great interest in exploring efficient microwave absorption materials due to their exceptional chemical and physical properties such as low density, good chemical inertness, and excellent mechanical properties.[6,7,8,9] two major issues still need to be solved for their practical application, including the limitation of large-scale fabrication and poor impedance matching that resulted from the high dielectric constant and nonmagnetic property of graphene
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