Ultrathin MoS₂ Nanosheets Encapsulated in Hollow Carbon Spheres: A Case of a Dielectric Absorber with Optimized Impedance for Efficient Microwave Absorption

Abstract

A dielectric loss-type electromagnetic wave (EMW) absorber, especially over a broad frequency range, is important yet challenging. As the most typical dielectric attenuation absorber, carbon-based nanostructures were highly pursued and studied. However, their poor impedance-matching issues still exist. Here, to further optimize dielectric properties and enhance reflection loss, ultrathin MoS2 nanosheets encapsulated in hollow carbon spheres (MoS2@HCS) were prepared via a facile template method. The diameter and shell thickness of the as-prepared HCSs were ∼250 and ∼20 nm. The encapsulated MoS2 nanosheets presented high dispersity and crystallinity. Compared to a pure HCS or MoS2 absorber, MoS2@HCS exhibited an optimized impedance characteristic, which can be attributed to the synergistic effects between HCSs (ensuring rapid electron transmission and compensating the low conductivity of MoS2) and MoS2 nanosheets (exposing sufficient numbers of active sites for polarizations and multi-reflection). Consequently, the MoS2@HCS was endowed with −65 dB EMW attenuation ability under 2 mm and the effective attenuation bandwidth under −20 dB was ∼3.3 GHz over the K-band under 1.2 mm and ∼3.4 GHz over the Ka-band under merely 0.7 mm. These results suggested that the MoS2@HCS is a promising dielectric absorber for practical applications. Meanwhile, this work introduces a facile and versatile strategy, which could in principle be extended to other transition metal sulfide@HCS for designing novel EMW absorbers.

MoS2-Decorated/Integrated Carbon Fiber: Phase Engineering Well-Regulated Microwave Absorber

“…Moreover, the miniaturization and integration of electronic circuits and components put forward the request of flexible portable microwave absorption electronic devices [5,6]. Two-dimension (2D) materials, such as reduced graphene oxide (RGO) [7][8][9][10], MoS 2 [11][12][13][14][15], and new member Mxene [16][17][18][19], are usually applied as microwave absorber owing to their high specific surface area and abundant functional groups as well as defects, which will enhance the propagation paths of incident electromagnetic wave (EMW) inside absorbers by scattering effect and increase the loss through polarization relaxation loss. As one of the 2D material, MoS 2 has adjustable electrical property and can change between insulators and semiconductor metals.…”

Defect Induced Polarization Loss in Multi‐Shelled Spinel Hollow Spheres for Electromagnetic Wave Absorption Application

“…Development of hollow structured materials has been regard as an attractive solution to solve high density issue of materials. [19][20][21] As an attractive micro/nanostructure, multi-shelled hollow spheres (MSHS) have aroused extensive attention due to its unique features such as lightweight, controllable shell numbers and thickness, shell porosity, and intershell spacing. [22][23][24][25][26][27] It can be foreseen that this peculiar structure is favorable for promoting the EM wave absorption performance by following aspects: 1) the multiple shells would lead to the multiple reflections when incident EM wave propagates in the cavities between two adjacent shells; 2) the abundant interfaces generated on the shell-air-shell could boost the interfacial polarization; 3) due to the existence of multiple cavities in this structure, its low density and lightweight features can precisely circumvent density issue of MCo 2 O 4 -based EM wave absorbers.…”

MoS2 nanoparticle/activated carbon composite as a dual-band material for absorbing microwaves

“…A high performance MW absorber apart from having strong absorption and wide effective absorption bandwidth (EAB) i.e. the frequency range having RL < -10 dB, should also have lightweight, good thermal stability and ability to tune MW absorption for desired frequency bands 1,2 .…”

“…A two-dimensional transition metal dichalcogenide, molybdenum disulphide (MoS 2 ), has emerged as a new class of microwave absorbing material in recent years due to its large specific surface area and high dielectric properties [1][2][3][4] . 2D MoS 2 nanosheets prepared by Ning et al 5 using top down exfoliation method reported maximum reflection loss (RL max ) = -38.42 dB.…”

“…In order to enhance the MW absorption properties of MoS 2 , there are generally two approaches: first, to combine a magnetic material with MoS 2 : like MoS 2 /FeS 2 7 , MoS 2 -iron oxide 3 , Porous coin-like Fe@MoS 2 8 , BaFe 12 O 19 @MoS 2 9 and second; to incorporate a nonmagnetic or pure dielectric material with MoS 2 . Generally, a pure dielectric absorber faces with the problem of poor impedance matching 2 , but in recent reported studies, various carbon-based materials has been combined with MoS 2 and showed that a dielectric absorber can also give enhanced MW absorbing performance. Like MoS 2 coated carbon fiber fabricated by Zhang et al 10 gave an excellent EAB of 10.85 GHz.…”