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• Vacancies enriched WS 2 was constructed via simple cold plasma treatment. • The strong polarization attenuation effects were found to be attributed to the formation of S vacancies in WS 2 architecture. • A broadband effective absorption of 5 GHz (RL < −10 dB) at 2.19 mm thickness was achieved. Defect engineering could provide new ideas for the design of transition metal disulfide electromagnetic wave (EMW) absorbers with high performance. Since the effects of dipoles on impedance matching and EMW absorption are crucial for the development of novel absorbers, the polarization attenuation dependence on defect engineering should be understood at micro- and macro-scales. In this paper, it is found that the defect-rich WS 2 nanoflowers synthesized by the cold plasma method possess excellent EMW absorption properties. Cold plasma treatment of materials is easy to perform and maintains the original shape of the material to a high degree. The formation of defects results in abundant electrochemically active sites, increased multiple reflection losses, improved dielectric properties and impedance matching in the materials. The RL min of the defect-rich material with a thickness of 3.19 mm is as high as −54.36 dB at 8.16 GHz, and the effective absorption bandwidth is 4.72 GHz. The results reveal that the formation of defective vacancies enhances the effects of dipole polarization of the material on improving its EMW absorption properties. Thus, this work provides not only a facile preparation route for novel EMW-absorbing materials, but also a new strategy for tunning defects in transition metal disulfides. [Display omitted] [ABSTRACT FROM AUTHOR]

Although VB-Group transition metal disulfides (TMDs) VS2nanomaterials with specific electronic properties and multiphase microstructures have shown fascinating potential in the field of electromagnetic wave (EMW) absorption, the efficient utilization of VS2is limited by the technical bottleneck of its narrow effective absorption bandwidth (EAB) which is attributed to environmental instability and a deficient electromagnetic (EM) loss mechanism. In order to fully exploit the maximal utilization values of VS2nanomaterials for EMW absorption through mitigating the chemical instability and optimizing the EM parameters, biomass-based glucose derived carbon (GDC) like sugar-coating has been decorated on the surface of stacked VS2nanosheets viaa facile hydrothermal method, followed by high-temperature carbonization. As a result, the modulation of doping amount of glucose injection solution (Glucose) could effectively manipulate the encapsulation degree of GDC coating on VS2nanosheets, further implementing the EM response mechanisms of the VS2/GDC hybrids (coupling effect of conductive loss, interfacial polarization, relaxation, dipole polarization, defect engineering and multiple reflections and absorptions) through regulating the conductivity and constructing multi-interface heterostructures, as reflected by the enhanced EMW absorption performance to a great extent. The minimum reflection loss (Rmin) of VS2/GDC hybrids could reach −52.8 dB with a thickness of 2.7 mm at 12.2 GHz. Surprisingly, compared with pristine VS2, the EAB of the VS2/GDC hybrids increased from 2.0 to 5.7 GHz, while their environmental stability was effectively enhanced by virtue of GDC doping. Obviously, this work provides a promising candidate to realize frequency band tunability of EMW absorbers with exceptional performance and environmental stability.

High performance microwave absorption (MA) materials especially those with tunable frequency are highly desirable for telecommunication industries and military camouflage in the information era. Herein, we constructed hierarchical heterostructures based on VB-group laminated vanadium disulfide (VS 2) nanosheets embedded with cobalt tetroxide (Co 3 O 4) nanoparticles. The highly dispersed Co 3 O 4 nanoparticles generate strong electromagnetic coupling networks that could enhance the loss properties of MA materials. Moreover, the interconnected VS 2 layered network results in dipolar/interfacial polarization, multiple reflection and scattering favorable for the enhanced MA performance. Impressively, the maximum reflection loss of the VS 2 /Co 3 O 4 hybrids containing 10% Co 3 O 4 can reach 57.96 dB at a thin thickness of 1.57 mm, and the bandwidth with an RL value less than -10 dB is as large as 3.5 GHz. The effective MA band could be adjusted in a range of 15.1 GHz (2.9-18 GHz) from S to Ku bands by the increase in thickness from 1.2 mm to 5.5 mm. The results show that the synergistic effect of multiple loss mechanisms and good impedance matching could be the reasons for strong MA capability in nearly all frequency bands, and thus, the high-performance and lightweight MA materials could be developed by the VS 2 /Co 3 O 4 hybrids. [ABSTRACT FROM AUTHOR]

A systematic summary of current research trends in the development of transition metal disulfides (TMDs) electromagnetic wave (EMW) absorption materials.In-depth comparisons on the structures, preparation methods, application merits of VIB- and VB-group TMDs.Structure engineering modulation of TMDs in achieving superior EMW absorption is outlined from the viewpoints of heterostructures, defects, morphologies, and phases.Exclusive insights into the challenges, strategies, and opportunities in the design of EMW absorption materials with outstanding performance are provided.

Flexible and wearable electromagnetic interference (EMI) shielding material is one of the current research focuses in the field of EMI shielding. In this work, for the first time, WS2-carbon fiber (WS2-CF) composites are synthesized by implanting WS2, which has a multiphase structure and a large number of defects, onto the surface of carbon fiber (CF) by using a simple one-step hydrothermal method, and are applied to protect electronic devices from EMI. It is found that the EMI shielding performance of WS2-CF is significantly improved, especially for those at Sand C-bands. At 2 GHz, the EMI shielding efficiency could reach 36.0 dB at a typical thickness of 3.00 mm of the composite, which is much better than that of pure CF (25.5 dB). Besides paving a novel avenue to optimize the electromagnetic shielding performance of flexible and wearable CF-based EMI shielding materials, which have great potential in the practical application for EMI shielding, this work provides a new paradigm for the design and synthesis of EMI shielding materials which have a broad application prospect.

Graphic Abstract: The introduction of NiO into VB-group layered VS2leads to excellent microwave absorption performance with tunable frequency band.

The construction of structures with multiple interfaces and dielectric/magnetic heterostructures enables the design of materials with unique physical and chemical properties, which has aroused intensive interest in scientific and technological fields. Especially, for electromagnetic (EM) wave absorption, enhanced interface polarization and improved impedence match with high Snoek's limitation could be achieved by multiple interfaces and dielectric/magnetic heterostructures, respectively, which are benificial to high-efficiency electromagnetic wave absorption (EWA). However, by far, the principles in the design or construction of structures with multiple interfaces and dielectric/magnetic heterostructures, and the relationships between those structures or heterostructures and their EWA performance have not been fully summarized and reviewed. This article aims to provide a timely review on the research progresses of high-efficency EM wave absorbers with multiple interfaces and dielectric/magnetic heterostructures, focusing on various promising EWA materials. Particularly, EM attenuation mechanisms in those structures with multiple interfaces and dielectric/magnetic heterostructures are discussed and generalized. Furthermore, the changllenges and future developments of EM wave absorbers based on those structures are proposed.

Zinc-ion hybrid supercapacitors (ZHSCs) have been widely considered as promising candidates for flexible electrochemical energy storage devices. The key challenge is to develop hydrogel electrolytes with high hydrophilicity, anti-freezing, bending resistance, and stable interface with electrodes. This study reported a hydrogel electrolyte system that can meet the above functions, in which the zincophilic and negatively charged SO3−, migratable Na+, abundant hydrophilic functional groups, gum xanthan, and porous architecture could effectively promote the electrochemical performance of ZHSCs. ZHSCs with such hydrogel electrolytes not only exhibited good low-temperature performance but also showed excellent bending resistance ability. A high specific capacitance could be kept after a long air-working lifespan over 10,000 cycles under a wide operation voltage of 1.85 V at −10 °C. Furthermore, flexible ZHSCs could maintain the capacitance retention of 93.18% even after continuous 500 bends at an angle of 180°. The designed hydrogel electrolytes could be also used for other electrochemical energy storage devices with anti-freezing and bending resistance by changing electrolyte salt.

Graphical Abstract:

Detailed summary of current trends in the advancement of flexible EMI shielding materials.The theoretical shielding mechanisms and the latest concept of "green shielding" index (gs) are outlined.Functional applications of flexible EMI shielding materials are introduced from thermal conductivity, hydrophobicity to transparency, sensing even multiple functions.Exclusive insights in challenges and future design strategies opportunities for flexible EMI shielding materials are provided.

Abstract

Two-dimensional black phosphorus (2D BP) possesses huge potential in electrochemical energy storage field owing to its unique electronic structure, high charge carrier mobility, and large interlayer spacing.Comparison on the different preparation methods and processes, characteristics, and applications of few-layer BP is presented.The applications of 2D BP in electrochemical energy storage devices in these years are well reviewed.

WS2–rGO nanosheets with ultra-small thicknesses and ultra-lightweight, were successfully prepared by a facile hydrothermal method.The WS2–rGO isomorphic heterostructures exhibited remarkable microwave absorption properties.