Fabrication of NiCo₂-Anchored Graphene Nanosheets by Liquid-Phase Exfoliation for Excellent Microwave Absorbers

Abstract

Graphene nanosheets (GNSs) were prepared by an efficient liquid-phase exfoliation method, and then the NiCo/GNS nanohybrids were fabricated using the single-mode microwave-assisted hydrothermal technique. The NiCo/GNS composites with different GNS proportions were investigated as microwave absorbers. Morphology investigation suggested that NiCo nanocrystals were uniformly anchored on the GNS without aggregation. The electromagnetic parameters of NiCo/GNS nanohybrids could be artificially adjusted by changing the GNS proportion, which led to an exceptional microwave-absorbing performance. A reflection loss (RL) exceeding -20 dB was obtained in the frequency range of 5.3-16.4 GHz for the absorber thicknesses of 1.2-3.2 mm, while an optimal RL of -30 dB was achieved at 11.7 GHz for a thickness of 1.6 mm. The enhanced microwave-absorbing performance indicated that the NiCo/10 wt % GNS composite has great potential for use as an excellent microwave absorber.

Synthesis and Microwave Absorbing Properties of Porous One-Dimensional Nickel Sulfide Nanostructures

“…However, when the proportion of fillers is increased to 40 wt%, both the ε ′ and ε ″ dramatically decrease, which is possibly due to the fact that the higher concentration of Ni x S y in this nanohybrid may result in severe agglomeration. Similar phenomena could be observed in dielectric loss tangent (tan δ e = ε ″/ ε ′) which is universally applied to evaluate the dielectric loss capacity of the microwave absorber (Yang et al, 2017 ), shown in Figure 4C . It can be seen that the dielectric loss tangent increases with the Ni x S y proportion first, getting a maximum value of 0.35 with 30 wt% Ni x S y , and then decreases to a value of 0.1.…”

Lightweight and Flexible Cotton Aerogel Composites for Electromagnetic Absorption and Shielding Applications

“…The optimal reflection loss (RL) of −30 dB was achieved for NiCo 2 /GNS composite with GNS mass ratio of 10%, which should be attributed to the mild dielectric loss ability resulting from proper loading ratio of conductive GNS. [11] Although the microwave absorber and shielding have been developed well in the past decades, the combination of these two functions in one material is still rarely performed. Based on our previous description, the concept of tuning conductivity can associate absorption with shielding.…”

Electromagnetic wave absorbing properties of glucose‐derived carbon‐rich SiOC ceramics annealed at different temperatures

“…[1][2][3] Over the past few decades, microwave absorption materials with the advantage of flexible, lightweight, thermally, thin in thickness, and strong in absorption over a broad absorption frequency range are highly enjoyed for aircraft and electronics. [4][5][6] Therefore, numerous studies have focused on developing the absorbents with special microstructures including porous structure, core-shelled structure and heterostructure, which can greatly enhance electromagnetic wave absorption properties due to interfacial polarization, multiple reflection, and synergistic effects. 1,2,[7][8][9] Of all the critical electromagnetic wave absorption materials, polymer-derived ceramics (PDC), including SiOC, SiBCN, SiCN, and Si 3 N 4 , have captured growing attention due to their controllable microstructure, lightweight, excellent thermomechanical properties, and a wide absorption frequency.…”