Abstract
Graphene-based powder absorbers have been used to attain excellent microwave absorption. However, it is not clear if inferior microwave absorption by pure graphene materials can be attributed to impedance mismatching or inadequate attenuation capability. In this comparative study, we focus on these aspects. Graphene nanoplatelets (GNPs) multi-component composites (GNPs@NixSy@MoS2) were prepared by hydrothermal reaction with different S and Mo molar ratios. The morphologies, phase crystals, elemental composition, and magnetic properties of the composites were also analyzed. In addition, microwave absorption of the as-prepared samples was investigated and it revealed that the impedance mismatching could be responsible for inferior microwave absorption; higher conductivity can lead to skin effect that inhibits the further incidence of microwaves into the absorbers. Furthermore, the optimum reflection loss (RL) of GNPs@NixSy@MoS2-2 can reach −43.3 dB at a thickness of 2.2 mm and the corresponding bandwidth with effective attenuation (RL < −10 dB) of up to 3.6 GHz (from 7.0 to 10.6 GHz). Compared with the GNPs, the enhanced microwave absorption can be assigned to the synergistic effects of conductive and dielectric losses.
Highlights
Electromagnetic (EM) pollution by the modern industry has become inevitable because EM radiation harms health, military devices performance, and information transmission
This is attributed to their sheet-like morphology, which can generate larger interfacial polarization and high dielectric loss
Considering nano-structural engineering and impedance matching [30,31,32,33,34,35,36], we present novel and high-efficiency absorbing metal sulfides on graphene nanoplatelets (GNPs@NixSy@MoS2) with hierarchical structures
Summary
Electromagnetic (EM) pollution by the modern industry has become inevitable because EM radiation harms health, military devices performance, and information transmission. Heterostructure MoS2 hybrids such as MoS2/Ni nanoparticles [22], MoS2/carbon nanotubes [23], core-shell NiS2@MoS2 nanosphere [24], and self-assembled carbon sphere coated by MoS2 nanosheets (CS/MoS2) [13] are facile candidates for fabricating absorbers to reduce EM pollution This is attributed to their sheet-like morphology, which can generate larger interfacial polarization and high dielectric loss. Impedance matching is presumably another key factor for materials’ MAP; this explains why semiconductor materials are preferred over insulators for high MAP absorbers Metal sulfides and their composites are associated with excellent EM absorption due to their higher dielectric loss than metal oxides [25,26]. Studies on morphologies and EM absorption properties suggest that the as-prepared GNPs@NixSy@MoS2 with hierarchical nanostructures have optimized morphology and impedance matching, strong dielectric loss, and interface polarization, resulting in excellent MAP
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