From VIB‑to VB‑Group Transition Metal Disulfides:Structure Engineering Modulation for Superior Electromagnetic Wave Absorption

The laminated transition metal disulfides(TMDs),which are well known as typical two-dimensional(2D)semiconductive materials,possess a unique layered structure,leading to their wide-spread applications in various fields,such as catalysis,energy storage,sensing,etc.In recent years,a lot of research work on TMDs based functional materials in the fields of electromagnetic wave absorption(EMA)has been carried out.Therefore,it is of great significance to elaborate the influence of TMDs on EMA in time to speed up the application.In this review,recent advances in the development of electromagnetic wave(EMW)absorbers based on TMDs,ranging from the VIB group to the VB group are summarized.Their compositions,microstructures,electronic properties,and synthesis methods are presented in detail.Particularly,the modulation of structure engineering from the aspects of heterostructures,defects,morphologies and phases are systematically summarized,focusing on optimizing impedance matching and increasing dielectric and magnetic losses in the EMA materials with tunable EMW absorption performance.Milestones as well as the challenges are also identified to guide the design of new TMDs based dielectric EMA materials with high performance.

Spontaneous Orientation Polarization of Anisotropic Equivalent Dipoles Harnessed by Entropy Engineering for Ultra‑Thin Electromagnetic Wave Absorber

The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engineering of conductive/dielectric genes.Electron migration modes within HEAs as manipulated by the electronegativity,valence electron configurations and molar proportions of constituent elements determine the steady state and efficiency of equivalent dipoles.Herein,enlightened by skin-like effect,a reformative carbothermal shock method using carbonized cellulose paper(CCP)as carbon supporter is used to preserve the oxygencontaining functional groups(O·)of carbonized cellulose fibers(CCF).Nucleation of HEAs and construction of emblematic shell-core CCF/HEAs heterointerfaces are inextricably linked to carbon metabolism induced by O·.Meanwhile,the electron migration mode of switchable electronrich sites promotes the orientation polarization of anisotropic equivalent dipoles.By virtue of the reinforcement strategy,CCP/HEAs composite prepared by 35%molar ratio of Mn element(CCP/HEAs-Mn_(2.15))achieves efficient electromagnetic wave(EMW)absorption of−51.35 dB at an ultra-thin thickness of 1.03 mm.The mechanisms of the resulting dielectric properties of HEAs-based EMW absorbing materials are elucidated by combining theoretical calculations with experimental characterizations,which provide theoretical bases and feasible strategies for the simulation and practical application of electromagnetic functional devices(e.g.,ultra-wideband bandpass filter).

Low-frequency and dual-band microwave absorption properties of novel VB-group disulphides(3R–TaS_(2))nanosheets

As electromagnetic technology advances and demand for electronic devices grows,concerns about electromagnetic pollution intensify.This has spurred focused research on innovative electromagnetic absorbers,particularly chalcogenides,noted for their superior absorption capabilities.In this study,we successfully synthesize 3R–TaS_(2)nanosheets using a straightforward calcination method for the first time.These nanosheets exhibit significant absorption capabilities in both the C-band(4–8 GHz)and Ku-band(12–18 GHz)frequency ranges.By optimizing the calcination process,the complex permittivity of TaS_(2)is enhanced,specifically for those synthesized at 1000℃for 24 h.The nanosheets possess dual-band absorption properties,with a notable minimum reflection loss(RLmin)of41.4 dB in the C-band,and an average absorption intensity exceeding 10 dB in C-and Ku-bands,in the absorbers with a thickness of 5.6 mm.Additionally,the 3R–TaS_(2)nanosheets are demonstrated to have an effective absorption bandwidth of 5.04 GHz(3.84–8.88 GHz)in the absorbers with thicknesses of 3.5–5.5 mm.The results highlight the multiple reflection effects in 3R–TaS_(2)as caused by their stacked structures,which could be promising low-frequency absorbers.

Recent Advances in Design Strategies and Multifunctionality of Flexible Electromagnetic Interference Shielding Materials

With rapid development of 5G communication technologies,electromagnetic interference(EMI)shielding for electronic devices has become an urgent demand in recent years,where the development of corresponding EMI shielding materials against detrimental electromagnetic radiation plays an essential role.Meanwhile,the EMI shielding materials with high flexibility and functional integrity are highly demanded for emerging shielding applications.Hitherto,a variety of flexible EMI shielding materials with lightweight and multifunctionalities have been developed.In this review,we not only introduce the recent development of flexible EMI shielding materials,but also elaborate the EMI shielding mechanisms and the index for"green EMI shielding"performance.In addition,the construction strategies for sophisticated multifunctionalities of flexible shielding materials are summarized.Finally,we propose several possible research directions for flexible EMI shielding materials in near future,which could be inspirational to the fast-growing next-generation flexible electronic devices with reliable and multipurpose protections as offered by EMI shielding materials.

Lightweight and High-Performance Microwave Absorber Based on 2D WS2-RGO Heterostructures

Two-dimensional(2D)nanomaterials are categorized as a new class of microwave absorption(MA)materials owing to their high specific surface area and peculiar electronic properties.In this study,2D WS2-reduced graphene oxide(WS2-rGO)heterostructure nanosheets were synthesized via a facile hydrothermal process;moreover,their dielectric and MA properties were reported for the first time.Remarkably,the maximum reflection loss(RL)of the sample-wax composites containing 40 wt% WS2-rGO was-41.5 dB at a thickness of 2.7 mm;furthermore,the bandwidth where RL<-10 dB can reach up to 13.62 GHz(4.38-18 GHz).Synergistic mechanisms derived from the interfacial dielectric coupling and multiple-interface scattering after hybridization of WS2 with rGO were discussed to explain the drastically enhanced microwave absorption performance.The results indicate these lightweight WS2-rGO nanosheets to be potential materials for practical electromagnetic wave-absorbing applications.

Two‑Dimensional Black Phosphorus Nanomaterials:Emerging Advances in Electrochemical Energy Storage Science

Two-dimensional black phosphorus(2D BP),well known as phosphorene,has triggered tremendous attention since the first discovery in 2014.The unique puckered monolayer structure endows 2D BP intriguing properties,which facilitate its potential applications in various fields,such as catalyst,energy storage,sensor,etc.Owing to the large surface area,good electric conductivity,and high theoretical specific capacity,2D BP has been widely studied as electrode materials and significantly enhanced the performance of energy storage devices.With the rapid development of energy storage devices based on 2D BP,a timely review on this topic is in demand to further extend the application of 2D BP in energy storage.In this review,recent advances in experimental and theoretical development of 2D BP are presented along with its structures,properties,and synthetic methods.Particularly,their emerging applications in electrochemical energy storage,including Li−/K−/Mg−/Na-ion,Li–S batteries,and supercapacitors,are systematically summarized with milestones as well as the challenges.Benefited from the fast-growing dynamic investigation of 2D BP,some possible improvements and constructive perspectives are provided to guide the design of 2D BP-based energy storage devices with high performance.

Hydrophilic polyanionic hydrogel electrolyte for anti-freezing and bending resistant zinc-ion hybrid supercapacitors

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 SO_(3)^(−),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℃.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.

Titanium-containing high entropy oxide(Ti-HEO):A redox expediting electrocatalyst towards lithium polysulfides for high performance Li-S batteries

Since lithium sulfur(Li-S)energy storage devices are anticipated to power portable gadgets and electric vehicles owing to their high energy density(2600 Wh·kg^(-1));nevertheless,their usefulness is constrained by sluggish sulfur reaction kinetics and soluble lithium polysulfide(LPS)shuttling effects.High electrically conductive bifunctional electrocatalysts are urgently needed for Li-S batteries,and high-entropy oxide(HEO)is one of the most promising electrocatalysts.In this work,we synthesize titanium-containing high entropy oxide(Ti-HEO)(TiFeNiCoMg)O with enhanced electrical conductivity through calcining metal-organic frameworks(MOF)templates at modest temperatures.The resulting single-phase Ti-HEO with high conductivity could facilitate chemical immobilization and rapid bidirectional conversion of LPS.As a result,the Ti-HEO/S/KB cathode(with 70 wt.%of sulfur)achieves an initial discharge capacity as high as~1375 mAh·g^(-1)at 0.1 C,and a low-capacity fade rate of 0.056%per cycle over 1000 cycles at 0.5 C.With increased sulfur loading(~5.0 mg·cm^(-2)),the typical Li-S cell delivered a high initial discharge capacity of~607 mAh·g^(-1)at 0.2 C and showcased good cycling stability.This work provides better insight into the synthesis of catalytic Ti-containing HEOs with enhanced electrical conductivity,which are effective in simultaneously enhancing the LPS-conversion kinetics and reducing the LPS shuttling effect.

Building the conformal protection of VB-group VS_(2)laminated heterostructure based on biomass-derived carbon for excellent broadband electromagnetic waves absorption

Although VB-Group transition metal disulfides(TMDs)VS_(2)nanomaterials with specific electronic properties and multiphase microstructures have shown fascinating potential in the field of electro-magnetic wave(EMW)absorption,the efficient utilization of VS_(2)is 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 VS_(2)nanomaterials 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 VS_(2)nanosheets via a 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 VS_(2)nanosheets,further imple-menting the EM response mechanisms of the VS_(2)/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 VS_(2)/GDC hybrids could reach52.8 dB with a thickness of 2.7 mm at 12.2 GHz.Surprisingly,compared with pristine VS_(2),the EAB of the VS_(2)/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 perfor-mance and environmental stability.

Synergetic dielectric loss and magnetic loss towards superior microwave absorption through hybridization of few-layer WS2 nanosheets with NiO nanoparticles

WS2 nanomaterials have attracted great attention in the field of electromagnetic wave absorption due to their high specific surface area,layered structure,and peculiar electronic properties.However,further improvements on their limited electromagnetic absorbing(EMA)capacity and bandwidth are urgently required for their practical application as EMA absorbents.In this work,WS2/NiO hybrids with heterostructures are prepared by a hydrothermal method and developed into EMA absorbents.The maximum reflection loss of the hybrids with 20%NiO loading could reach-53.31 dB at a thickness of 4.30 mm;the bandwidth with a reflection loss value of less than-10 dB is determined to be13.46 GHz(4.54–18 GHz)when the thickness of the absorbent is between 3.5 and 5.5 mm.It is found that the enhanced EMA performance of WS2/NiO hybrids is caused by the addition of magnetic NiO,which could result in the interfaces between WS2 and NiO being responsible for the synergetic magnetic loss and dielectric loss in the hybrids.This work provides a new approach for the design of excellent EMA materials for practical applications.

High-performance microwave absorption enabled by Co_(3)O_(4) modified VB-group laminated VS_(2) with frequency modulation from S-band to Ku-band

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.

Construction of multiple interfaces and dielectric/magnetic heterostructures in electromagnetic wave absorbers with enhanced absorption performance:A review

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.

Engineering flexible and green electromagnetic interference shielding materials with high performance through modulating WS_(2) nanosheets on carbon fibers

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,WS_(2)-carbon fiber(WS_(2)-CF)composites are synthesized by implanting WS_(2),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 WS_(2)-CF is significantly improved,especially for those at Se and 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.

Nickel-metal-organic framework nanobelt based composite membranes for efficient Sr^(2+) removal from aqueous solution

The sorption removal of radionuclides Sr^(2+) using a freestanding functional membrane is an interesting and significant research area in the remediation of radioactive wastes.Herein,a novel self-assembled membrane consisting of metaleorganic framework(MOF)nanobelts and graphene oxides(GOs)are synthesized through a simple and facile filtration method.The membrane possesses a unique interwove morphology as evidenced from SEM images.Batch experiments suggest that the GO/Ni-MOF composite membrane could remove Sr^(2+) ions from aqueous solutions and the Sr^(2+) adsorption capacity and efficiency of the GO/Ni-MOF composite membrane is relevant to the MOF content in the composite.Thus,the dominant interaction mechanism was interface or surface complexation,electrostatic interaction as well as ion substitution.The maximum effective sorption of Sr^(2+) over GO/Ni-MOF membrane is 32.99% with 2 mg composite membrane containing a high content of Ni-MOF at 299 K in 100 mg/L Sr^(2+) aqueous solution.The FT-IR and XPS results suggest that the synergistic effect between GO and Ni-MOF is determinant in the sorption Sr^(2+) process.The GO/Ni-MOF composite membrane is demonstrated to have the advantages of efficient removal of Sr^(2+),low cost and simple synthesis route,which is promising in the elimination of radionuclide contamination.