Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT...Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.展开更多
Carbonbased aerogels derived from biomass chitosan are encountering a flourishing moment in electromagnetic protection on account of lightweight,controllable fabrication and versatility.Nevertheless,developing a facil...Carbonbased aerogels derived from biomass chitosan are encountering a flourishing moment in electromagnetic protection on account of lightweight,controllable fabrication and versatility.Nevertheless,developing a facile construction method of component design with carbon-based aerogels for high-efficiency electromagnetic wave absorption(EWA)materials with a broad effective absorption bandwidth(EAB)and strong absorption yet hits some snags.Herein,the nitrogen-doped magnetic-dielectric-carbon aerogel was obtained via ice template method followed by carbonization treatment,homogeneous and abundant nickel(Ni)and manganese oxide(MnO)particles in situ grew on the carbon aerogels.Thanks to the optimization of impedance matching of dielectric/magnetic components to carbon aerogels,the nitrogen-doped magnetic-dielectric-carbon aerogel(Ni/MnO-CA)suggests a praiseworthy EWA performance,with an ultra-wide EAB of 7.36 GHz and a minimum reflection loss(RLmin)of−64.09 dB,while achieving a specific reflection loss of−253.32 dB mm−1.Furthermore,the aerogel reveals excellent radar stealth,infrared stealth,and thermal management capabilities.Hence,the high-performance,easy fabricated and multifunctional nickel/manganese oxide/carbon aerogels have broad application aspects for electromagnetic protection,electronic devices and aerospace.展开更多
Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the...Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.展开更多
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 field...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.展开更多
At present,metal-organic framework(MOF)-derived nano-micro architectures are actively explored for electromagnetic(EM)wave absorption owing to their flexible composition and structural manipulation that enhance dielec...At present,metal-organic framework(MOF)-derived nano-micro architectures are actively explored for electromagnetic(EM)wave absorption owing to their flexible composition and structural manipulation that enhance dielectric and magnetic attenuations.However,the basic design principles in MOF-derived microwave absorption materials have not been summarized.This review is devoted to analyzing design principles in MOF-derived microwave absorption materials from the following perspectives:diverse monomers(ligands and ions of MOFs),topologies,chemical states,and physical properties.The derived essential information regarding the EM wave absorption mechanism and the structural-functional dependency is also comprehensively summarized.Finally,a clear insight into the challenges and perspectives of the industrial revolution upgrading in this promising field is proposed.展开更多
In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which c...In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which can effectively adjust the thermodynamic and kinetic reactions of iron ions during the solvothermal process.As a result,Fe nanoparticles can be gradually decreased from the inner side to the surface across the hollow carbon shell.The results reveal that it offers an outstanding reflection loss value in combination with broadband wave absorption and flexible adjustment ability,which is superior to other relative graded distribution structures and satisfied with the requirements of lightweight equipment.In addition,this work elucidates the intrinsic microwave regulation mechanism of the multiscale hybrid electromagnetic wave absorber.The excellent impedance matching and moderate dielectric parameters are exhibited to be the dominative factors for the promotion of microwave absorption performance of the optimized materials.This strategy to prepare gradient-distributed microwave absorbing materials initiates a new way for designing and fabricating wave absorber with excellent impedance matching property in practical applications.展开更多
In recent years,electromagnetic wave(EMW)absorption has been extensively investigated for solving EMW radiation and pollution.The metal-organic frameworks(MOFs)have attracted attention due to their low density and uni...In recent years,electromagnetic wave(EMW)absorption has been extensively investigated for solving EMW radiation and pollution.The metal-organic frameworks(MOFs)have attracted attention due to their low density and unique structure,which can meet the requirements of strong reflection loss(RL)and wide absorption bandwidth of EMW absorption materials.In this manuscript,indium nanoparticles/porous carbon(In/C)nanorods composites were prepared via the pyrolysis of nanorods-like In-MOFs at a low temperature of450°C.Indium nanoparticles are evenly attached and embedded on porous carbon.Low electrical conductivity of In/C nanorods is unfavorable to EMW absorption performance,which is due to the low temperature carbonization.Thus,graphene(Gr)nanosheets with high electrical conductivity are introduced to adjust electromagnetic parameters of In/C nanorods for enhancing EMW absorption.The minimum RL of the In/C-Gr-4 composite is up to-43.7 dB with a thin thickness of 1.30 mm.In addition,when the thickness is further reduced to 1.14 mm,the minimum RL of-39.3 dB at 16.1 GHz and effective absorption bandwidth of 3.7 GHz(from 14.3 to 18.0 GHz)can be achieved.This work indicates that In/C-Gr composites show excellent EMW absorption performance.展开更多
High-performance electromagnetic wave absorption and electromagnetic interference(EMI)shielding materials with multifunctional characters have attracted extensive scientific and technological interest,but they remain ...High-performance electromagnetic wave absorption and electromagnetic interference(EMI)shielding materials with multifunctional characters have attracted extensive scientific and technological interest,but they remain a huge challenge.Here,we reported an electrostatic assembly approach for fabricating 2D/1D/0D construction of Ti_(3)C_(2)Tx/carbon nanotubes/Co nanoparticles(Ti_(3)C_(2)Tx/CNTs/Co)nanocomposites with an excellent electromagnetic wave absorption,EMI shielding efficiency,flexibility,hydrophobicity,and photother-mal conversion performance.As expected,a strong reflection loss of-85.8 dB and an ultrathin thickness of 1.4 mm were achieved.Mean-while,the high EMI shielding efficiency reached 110.1 dB.The excel-lent electromagnetic wave absorption and shielding performances were originated from the charge carriers,electric/magnetic dipole polariza-tion,interfacial polarization,natural resonance,and multiple internal reflections.Moreover,a thin layer of polydimethylsiloxane rendered the hydrophilic hierarchical Ti_(3)C_(2)Tx/CNTs/Co hydrophobic,which can prevent the degradation/oxidation of the MXene in high humidity condition.Interestingly,the Ti_(3)C_(2)Tx/CNTs/Co film exhibited a remark-able photothermal conversion performance with high thermal cycle stability and tenability.Thus,the multifunctional Ti_(3)C_(2)Tx/CNTs/Co nanocomposites possessing a unique blend of outstanding electromagnetic wave absorption and EMI shielding,light-driven heating perfor-mance,and flexible water-resistant features were highly promising for the next-generation intelligent electromagnetic attenuation system.展开更多
Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To bre...Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To break the mindset of magneticderivative design,and make up the shortage of monometallic non-magnetic derivatives,we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption.The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415(TiZr-MOFs)are qualified with a minimum reflection loss of−67.8 dB(2.16 mm,13.0 GHz),and a maximum effective absorption bandwidth of 5.9 GHz(2.70 mm).Through in-depth discussions,the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed.Therefore,this work confirms the huge potentials of nonmagnetic bimetallic MOFs derivatives in EMW absorption applications.展开更多
Rational designing of one-dimensional(1D)magnetic alloy to facilitate electromagnetic(EM)wave attenuation capability in low-frequency(2-6 GHz)microwave absorption field is highly desired but remains a significant chal...Rational designing of one-dimensional(1D)magnetic alloy to facilitate electromagnetic(EM)wave attenuation capability in low-frequency(2-6 GHz)microwave absorption field is highly desired but remains a significant challenge.In this study,a composite EM wave absorber made of a FeCoNi medium-entropy alloy embedded in a 1D carbon matrix framework is rationally designed through an improved electrospinning method.The 1D-shaped FeCoNi alloy embedded composite demonstrates the high-density and continuous magnetic network using off-axis electronic holography technique,indicating the excellent magnetic loss ability under an external EM field.Then,the in-depth analysis shows that many factors,including 1D anisotropy and intrinsic physical features of the magnetic medium-entropy alloy,primarily contribute to the enhanced EM wave absorption performance.Therefore,the fabricated EM wave absorber shows an increasing effective absorption band of 1.3 GHz in the low-frequency electromagnetic field at an ultrathin thickness of 2 mm.Thus,this study opens up a new method for the design and preparation of high-performance 1D magnetic EM absorbers.展开更多
Traditional ceramic materials are generally brittle and not flexible with high production costs,which seriously hinders their practical applications.Multifunctional nanofiber ceramic aerogels are highly desirable for ...Traditional ceramic materials are generally brittle and not flexible with high production costs,which seriously hinders their practical applications.Multifunctional nanofiber ceramic aerogels are highly desirable for applications in extreme environments,however,the integration of multiple functions in their preparation is extremely challenging.To tackle these challenges,we fabricated a multifunctional SiC@SiO_(2) nanofiber aerogel(SiC@SiO_(2) NFA)with a threedimensional(3D)porous cross-linked structure through a simple chemical vapor deposition method and subsequent heat-treatment process.The as-prepared SiC@SiO_(2) NFA exhibits an ultralow density(~11 mg cm^(-3)),ultra-elastic,fatigue-resistant and refractory performance,high temperature thermal stability,thermal insulation properties,and significant strain-dependent piezoresistive sensing behavior.Furthermore,the SiC@SiO_(2) NFA shows a superior electromagnetic wave absorption performance with a minimum refection loss(RL_(min))value of-50.36 d B and a maximum effective absorption bandwidth(EAB_(max))of 8.6 GHz.The successful preparation of this multifunctional aerogel material provides a promising prospect for the design and fabrication of the cutting-edge ceramic materials.展开更多
Combining 3D printing with precursor-derived ceramic for fabricating electromagnetic(EM) wave-absorbing metamaterials has attracted great attention. This study presents a novel ultraviolet-curable polysiloxane precurs...Combining 3D printing with precursor-derived ceramic for fabricating electromagnetic(EM) wave-absorbing metamaterials has attracted great attention. This study presents a novel ultraviolet-curable polysiloxane precursor for digital light processing(DLP) 3D printing to fabricate ceramic parts with complex geometry, no cracks and linear shrinkage. Guiding with the principles of impedance matching, attenuation, and effective-medium theory, we design a crosshelix-array metamaterial model based on the complex permittivity constant of precursor-derived ceramics. The corresponding ceramic metamaterials can be successfully prepared by DLP printing and subsequent pyrolysis process, achieving a low reflection coefficient and a wide effective absorption bandwidth in the X-band even under high temperature. This is a general method that can be extended to other bands, which can be realized by merely adjusting the unit structure of meta-materials. This strategy provides a novel and effective avenue to achieve “target-design-fabricating” ceramic metamaterials, and it exposes the downstream applications of highly efficient and broad EM wave-absorbing materials and structures with great potential applications.展开更多
Cobalt ferrite has problems such as poor impedance matching and high density,which results in unsatisfactory electromagnetic wave(EMW)absorption performance.In this study,the CoFe_(2)O_(4)@C core-shell structure compo...Cobalt ferrite has problems such as poor impedance matching and high density,which results in unsatisfactory electromagnetic wave(EMW)absorption performance.In this study,the CoFe_(2)O_(4)@C core-shell structure composite was synthesized by a two-step hydrothermal method.X-ray diffraction,transmission electron microscopy,Fourier transform infrared spectroscopy,thermogravimetric analysis,and vector network analysis et al.were used to test the structure and EMW absorption properties of CoFe_(2)O_(4)@C composite.The results show that the reflection loss(RL)of the CoFe_(2)O_(4)@C composite reaches the maximum value of25.66 dB at 13.92 GHz,and the effective absorbing band(EAB)is 4.59 GHz(11.20-15.79 GHz)when the carbon mass content is 6.01%.The RL and EAB of CoFe_(2)O_(4)@C composite are increased by 219.55%and 4.59 GHz respectively,and the density is decreased by 20.78%compared with the cobalt ferrite.Such enhanced EMW absorption properties of CoFe_(2)O_(4)@C composite are attributed to the attenuation caused by the strong natural resonance of the cobalt ferrite,moreover,the carbon coating layer adjusts the impedance matching of the composite,and the introduced dipole polarization and interface polarization can cause multiple Debye relaxation processes.展开更多
Owing to the tunable compositions and versatile functionality,the development of eco-friendly metal–phenolic coordination crystals derivatives is highly anticipated for electromagnetic wave absorption.In this study,t...Owing to the tunable compositions and versatile functionality,the development of eco-friendly metal–phenolic coordination crystals derivatives is highly anticipated for electromagnetic wave absorption.In this study,three kinds of magnetic hollow carbon spheres(HCSs)with macro-meso-microporous characteristics,including Fe/HCS,Co/HCS,and CoNi/HCS,are successfully fabricated via the co-operative hard template and self-assembling process,in which magnetic particles are encapsulated in carbon shell matrix after the pyrolysis of metal–polyphenol coordination crystals and further subsequent template removal.On the one hand,hierarchical macro-meso-micropores effectively balance the impedance gap between absorbers and air and introduce structural defects or distortion,leading to matched impedance and enhanced dipolar/defect polarization.On the other hand,wrapped magnetic particles provide uncountable hetero-interfaces and induce ferromagnetic resonance,resulting in strengthened interfacial polarization and additional magnetic loss.In particular,enhanced minimum reflection loss(RL,min)and broadband effective absorption bandwidth(EAB)are achieved with only 10 wt.%filler loading.Specifically,the RL,min and EAB values are-57.5 dB and 7.2 GHz for Fe/HCS,-50.0 dB and 5.8 GHz for Co/HCS,and-52.1 dB and 6.7 GHz for CoNi/HCS,respectively.Moreover,this work provides us a modular-assembly strategy to regulate the hollow cavity of absorbers and simultaneously manipulates the chemical components of absorbers to regulate electromagnetic wave absorption performance.展开更多
The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave(EMW)absorption are still challenging.In this paper,MXene was used as the aeroge...The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave(EMW)absorption are still challenging.In this paper,MXene was used as the aerogel matrix,modified with sea urchin-like magnetic Co/N-doped carbon@polyaniline(Co-NC@PANI),gelatin was introduced as the reinforcement phase of the aerogel backbone,and a microwave absorber with high efficiency and excellent performance was successfully prepared.The sea urchin-like Co-NC@PANI not only adjusted the impedance matching of the MXene but also introduced a magnetic loss mode into the composite.The multicomponent interfacial polarization,heterostructure,three-dimensional(3D)lightweight porous structure,and electromagnetic synergy strategy enabled the MXene-based aerogel modified by Co-NC@PANI(MCoP)to exhibit surprising EMW absorption properties.The maximum reflection loss(RL_(max))of the aerogel composite reached-62.4 dB,and the effective absorption bandwidth(EAB)reached 6.56 GHz when the loading was only 12%.In addition,through electromagnetic simulation experiments,the change in the electromagnetic field before and after EMW passed through the materials and the distribution of the volume loss density of EMW by the coaxial ring were observed.The coordinated electromagnetic balance strategy in the 3D network provides inspiration for the construction of materials and expands the research direction of lightweight and outstanding microwave absorbers.展开更多
With the development of the miniaturization of electronic equipment and lightweight weapon equipment,there are new requirements for electromagnetic wave absorption material(EMWAM).EMWAM has outstanding electromagnetic...With the development of the miniaturization of electronic equipment and lightweight weapon equipment,there are new requirements for electromagnetic wave absorption material(EMWAM).EMWAM has outstanding electromagnetic wave absorption properties and lightweight characteristics become an important direction of research.In this study,graphene/g-C_(3)N_(4)(GGCN)EMWAM was first synthesized in situ by simple heat treatment,in which the g-C_(3)N_(4) had a porous structure and dispersed on the surface of graphene.The impedance matching of the GGCN was well adjusted by decreasing the dielectric constant and attenuation constant due to the g-C_(3)N_(4) semiconductor property and the graphite-like structure.The EMW loss mechanism of GGCN was also analyzed by simulating GGCN’s electric field mode distribution and resistance loss power density.The analysis result shows that the distribution of g-C_(3)N_(4) among GGCN sheets can produce more polarization effects and relaxation effects by increasing the lamellar spacing.Furthermore,the polarization loss of GGCN could be increased successfully by porous g-C_(3)N_(4).Ultimately,the EMW absorption property of GGCN is optimized significantly,and GGCN exhibits excellent EMW absorption performance.When the thickness is 2 mm,the effective absorption bandwidth(EAB)can reach 4.6 GHz,and when the thickness is 4.5 mm,the minimum reflection loss(RLmin)at 4.56 GHz can reach-34.69 dB.Moreover,the practical application of EMWAM was studied by radar cross-section(RCS)simulation,showing that GGCN has a good application prospect.展开更多
Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the sing...Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the single loss mechanism vastly restrict the application.Hence,it’s an effective strat-egy to solve these issues by introducing magnetic components.Notably,layer double hydroxide(LDH)is an appropriate template to obtain magnetic component materials.Considering that ferromagnetic met-als such as Fe,Co,Ni,and their corresponding metal oxides are usually treated as magnetic compo-nents which are promising candidates for EMW absorption materials.Therefore,in this work,a FeNi-layered double hydroxide-reduced graphene oxide(FeNi-LDH-rGO)aerogel was synthesized through a series of processes such as electrostatic self-assembly,hydrothermal,freeze-drying,and annealing.The magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell nanospheres were obtained from FeNi-LDH precursor,anchoring on rGO nanosheets after the annealing treatment.Furthermore,the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption prop-erty and impedance matching performance were explored.As a consequence,the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth(EAB)of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt%and a low density of 4.4 mg/cm^(3).In conclusion,the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell struc-ture nanospheres.展开更多
The escalating electromagnetic(EM)pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave(EMW)absorbing materials.I...The escalating electromagnetic(EM)pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave(EMW)absorbing materials.In this paper,the flower-like CuS/γ-Fe_(2)O_(3) van der Waals(vdW)heterostructures have been synthesized via a facile two-step solvothermal approach.The flower-like CuS skeleton increases the attenuation path of EMW while reducing the material density.Different contents ofγ-Fe_(2)O_(3) nanoparticles anchor between the flower-like CuS nanosheets to constitute a heterogeneous structure,which enables dielectric and magnetic loss synergistically to optimize impedance matching and remarkably improve the EMW absorption performance.The minimum reflection loss(RLmin)is-49.36 dB with a thickness of only 1.6 mm and the effective absorption bandwidth(EAB)reaches 4.64 GHz(13.36–18 GHz).By adjusting the thickness of the absorber,the EAB can cover 96%of the GHz band.Notably,the superior absorption of-61.53 dB at middle frequency band can be obtained by adjusting the amount of Fe_(2)O_(3) addition.In this study,the adjustment of EM parameters and the optimization of impedance matching have been achieved by constructing a novel vdW heterogeneous structure,which provides fresh ideas and references for the design of high-performance EMW absorbing materials.展开更多
Bioderived carbon materials have garnered considerable interest in the fields of microwave absorption and shielding due to their reproducibility and environmental friendliness.In this study,KOH was evenly distributed ...Bioderived carbon materials have garnered considerable interest in the fields of microwave absorption and shielding due to their reproducibility and environmental friendliness.In this study,KOH was evenly distributed on biomass Tremella using the swelling induction method,leading to the preparation of a three-dimensional network-structured hierarchical porous carbon(HPC)through carbonization.The achieved microwave absorption intensity is robust at-47.34 dB with a thin thickness of 2.1 mm.Notably,the widest effective absorption bandwidth,reaching 7.0 GHz(11–18 GHz),is attained at a matching thickness of 2.2 mm.The exceptional broadband and reflection loss performance are attributed to the 3D porous networks,interface effects,carbon network defects,and dipole relaxation.HPC has outstanding absorption characteristics due to its excellent impedance matching and high attenuation constant.The uniform pore structures considerably optimize the impedance-matching performance of the material,while the abundance of interfaces and defects enhances the dielectric loss,thereby improving the attenuation constant.Furthermore,the impact of carbonization temperature and swelling rate on microwave absorption performance was systematically investigated.This research presents a strategy for preparing absorbing materials using biomass-derived HPC,showcasing considerable potential in the field of electromagnetic wave absorption.展开更多
Ultra-thin electromagnetic wave(EMW)absorbers present challenging demands on EMW absorption performance.Drawing inspiration from heather leaf structures,this study introduces an innovative design strategy for EMW abso...Ultra-thin electromagnetic wave(EMW)absorbers present challenging demands on EMW absorption performance.Drawing inspiration from heather leaf structures,this study introduces an innovative design strategy for EMW absorbing material,proposing biomimetic leaf SnO_(2) structures(bio-SnO_(2))on carbon fabric(CF).By employing leaf-shaped SnS2 as precursors,biomimetic leaf SnO_(2) nanostructures are constructed on CF surface after a simple thermal treatment,resulting in bio-SnO_(2)@CF composite.Experimental results indicate that bio-SnO_(2)@CF exhibits an exceptional minimum reflection loss of-54.8 dB at an incredibly thin thickness of 1.2 mm.Radar cross section(RCS)simulations further validate the outstanding EMW attenuation ability of bio-SnO_(2)@CF,attaining a maximum RCS reduction value of 16.9 dBm^(2) at an incident wave angle ofθ=0°.This novel research showcases the biomimetic structural design strategy and its remarkable function in enhancing the EMW absorbing performance at ultra-thin absorber thickness.展开更多
基金the National Natural Science Foundation(No.52073187)NSAF Foundation(No.U2230202)for their financial support of this project+3 种基金National Natural Science Foundation(No.51721091)Programme of Introducing Talents of Discipline to Universities(No.B13040)State Key Laboratory of Polymer Materials Engineering(No.sklpme2022-2-03)support of China Scholarship Council
文摘Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.
基金the National Natural Science Foundation of China(No.21902085 and 52172213)Natural Science and Development Foundation of Shenzhen(JCYJ20190807093205660)Postdoctoral Innovation Project of Shandong Province(SDCX-ZG-202202015).
文摘Carbonbased aerogels derived from biomass chitosan are encountering a flourishing moment in electromagnetic protection on account of lightweight,controllable fabrication and versatility.Nevertheless,developing a facile construction method of component design with carbon-based aerogels for high-efficiency electromagnetic wave absorption(EWA)materials with a broad effective absorption bandwidth(EAB)and strong absorption yet hits some snags.Herein,the nitrogen-doped magnetic-dielectric-carbon aerogel was obtained via ice template method followed by carbonization treatment,homogeneous and abundant nickel(Ni)and manganese oxide(MnO)particles in situ grew on the carbon aerogels.Thanks to the optimization of impedance matching of dielectric/magnetic components to carbon aerogels,the nitrogen-doped magnetic-dielectric-carbon aerogel(Ni/MnO-CA)suggests a praiseworthy EWA performance,with an ultra-wide EAB of 7.36 GHz and a minimum reflection loss(RLmin)of−64.09 dB,while achieving a specific reflection loss of−253.32 dB mm−1.Furthermore,the aerogel reveals excellent radar stealth,infrared stealth,and thermal management capabilities.Hence,the high-performance,easy fabricated and multifunctional nickel/manganese oxide/carbon aerogels have broad application aspects for electromagnetic protection,electronic devices and aerospace.
基金supported by National Natural Science Foundation of China (NSFC 52372041, 52302087, 51772060, 51672059 and 51621091)Heilongjiang Touyan Team Program+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. HIT.OCEF.2021003)the Shanghai Aerospace Science and Technology Innovation Fund (SAST2022-60)。
文摘Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.
基金This work was supported by the National Natural Science Foundation of China(52372289,52102368,52072192 and 51977009)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020SA001515110905).
文摘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.
基金supported by the National Natural Science Foundation of China(Nos.51872238,21806129,and 52074227)Fundamental Research Funds for the Central Universities(Nos.3102018zy045 and3102019AX11)the Natural Science Basic Research Plan in Shaanxi Province of China(Nos.2020JM-118 and2017JQ5116)。
文摘At present,metal-organic framework(MOF)-derived nano-micro architectures are actively explored for electromagnetic(EM)wave absorption owing to their flexible composition and structural manipulation that enhance dielectric and magnetic attenuations.However,the basic design principles in MOF-derived microwave absorption materials have not been summarized.This review is devoted to analyzing design principles in MOF-derived microwave absorption materials from the following perspectives:diverse monomers(ligands and ions of MOFs),topologies,chemical states,and physical properties.The derived essential information regarding the EM wave absorption mechanism and the structural-functional dependency is also comprehensively summarized.Finally,a clear insight into the challenges and perspectives of the industrial revolution upgrading in this promising field is proposed.
基金the National Natural Science Foundation of China(52102372,52162007,52163032)China Postdoctoral Science Foundation(2022M712321)the Jiangsu Province Postdoctoral Research Funding Program(2021K473C).
文摘In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which can effectively adjust the thermodynamic and kinetic reactions of iron ions during the solvothermal process.As a result,Fe nanoparticles can be gradually decreased from the inner side to the surface across the hollow carbon shell.The results reveal that it offers an outstanding reflection loss value in combination with broadband wave absorption and flexible adjustment ability,which is superior to other relative graded distribution structures and satisfied with the requirements of lightweight equipment.In addition,this work elucidates the intrinsic microwave regulation mechanism of the multiscale hybrid electromagnetic wave absorber.The excellent impedance matching and moderate dielectric parameters are exhibited to be the dominative factors for the promotion of microwave absorption performance of the optimized materials.This strategy to prepare gradient-distributed microwave absorbing materials initiates a new way for designing and fabricating wave absorber with excellent impedance matching property in practical applications.
基金supported by the National Natural Science Foundation of China(No.52071280)the Natural Science Foundation of Hebei Province,China(No.E2020203151)+2 种基金the Research Program of the College Science&Technology of Hebei Province,China(No.ZD2020121)the Cultivation Project for Basic Research and Innovation of Yanshan University(No.2021LGZD016)the Innovation Capability Improvement Project of Hebei province(No.22567605H)。
文摘In recent years,electromagnetic wave(EMW)absorption has been extensively investigated for solving EMW radiation and pollution.The metal-organic frameworks(MOFs)have attracted attention due to their low density and unique structure,which can meet the requirements of strong reflection loss(RL)and wide absorption bandwidth of EMW absorption materials.In this manuscript,indium nanoparticles/porous carbon(In/C)nanorods composites were prepared via the pyrolysis of nanorods-like In-MOFs at a low temperature of450°C.Indium nanoparticles are evenly attached and embedded on porous carbon.Low electrical conductivity of In/C nanorods is unfavorable to EMW absorption performance,which is due to the low temperature carbonization.Thus,graphene(Gr)nanosheets with high electrical conductivity are introduced to adjust electromagnetic parameters of In/C nanorods for enhancing EMW absorption.The minimum RL of the In/C-Gr-4 composite is up to-43.7 dB with a thin thickness of 1.30 mm.In addition,when the thickness is further reduced to 1.14 mm,the minimum RL of-39.3 dB at 16.1 GHz and effective absorption bandwidth of 3.7 GHz(from 14.3 to 18.0 GHz)can be achieved.This work indicates that In/C-Gr composites show excellent EMW absorption performance.
基金supported by the China Postdoctoral Science Foundation(Grant No.2020M671208)National Key Research and Development Program of China(Grant No.2019YFE0122900)+1 种基金National Natural Science Foundation of China(Grant No.51971162,U1933112,51671146)the Program of Shanghai Technology Research Leader(Grant No.18XD1423800)。
文摘High-performance electromagnetic wave absorption and electromagnetic interference(EMI)shielding materials with multifunctional characters have attracted extensive scientific and technological interest,but they remain a huge challenge.Here,we reported an electrostatic assembly approach for fabricating 2D/1D/0D construction of Ti_(3)C_(2)Tx/carbon nanotubes/Co nanoparticles(Ti_(3)C_(2)Tx/CNTs/Co)nanocomposites with an excellent electromagnetic wave absorption,EMI shielding efficiency,flexibility,hydrophobicity,and photother-mal conversion performance.As expected,a strong reflection loss of-85.8 dB and an ultrathin thickness of 1.4 mm were achieved.Mean-while,the high EMI shielding efficiency reached 110.1 dB.The excel-lent electromagnetic wave absorption and shielding performances were originated from the charge carriers,electric/magnetic dipole polariza-tion,interfacial polarization,natural resonance,and multiple internal reflections.Moreover,a thin layer of polydimethylsiloxane rendered the hydrophilic hierarchical Ti_(3)C_(2)Tx/CNTs/Co hydrophobic,which can prevent the degradation/oxidation of the MXene in high humidity condition.Interestingly,the Ti_(3)C_(2)Tx/CNTs/Co film exhibited a remark-able photothermal conversion performance with high thermal cycle stability and tenability.Thus,the multifunctional Ti_(3)C_(2)Tx/CNTs/Co nanocomposites possessing a unique blend of outstanding electromagnetic wave absorption and EMI shielding,light-driven heating perfor-mance,and flexible water-resistant features were highly promising for the next-generation intelligent electromagnetic attenuation system.
基金The authors acknowledge funding from the National Natural Science Foundation of China(Nos.51572157,21902085,and 51702188)Natural Science Foundation of Shandong Province(No.ZR2019QF012)+1 种基金Fundamental Research Funds for the Central Universities(No.2018JC036 and No.2018JC046)Young Scholars Program of Shandong University(No.2018WLJH25).
文摘Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To break the mindset of magneticderivative design,and make up the shortage of monometallic non-magnetic derivatives,we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption.The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415(TiZr-MOFs)are qualified with a minimum reflection loss of−67.8 dB(2.16 mm,13.0 GHz),and a maximum effective absorption bandwidth of 5.9 GHz(2.70 mm).Through in-depth discussions,the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed.Therefore,this work confirms the huge potentials of nonmagnetic bimetallic MOFs derivatives in EMW absorption applications.
基金supported by the National Natural Science Foundation of China(Nos.51725101,11727807,51672050,61790581,22088101)the Ministry of Science and Technology of China(973 Project Nos.2018YFA0209102 and 2021YFA1200600)Infrastructure and Facility Construction Project of Zhejiang Laboratory.
文摘Rational designing of one-dimensional(1D)magnetic alloy to facilitate electromagnetic(EM)wave attenuation capability in low-frequency(2-6 GHz)microwave absorption field is highly desired but remains a significant challenge.In this study,a composite EM wave absorber made of a FeCoNi medium-entropy alloy embedded in a 1D carbon matrix framework is rationally designed through an improved electrospinning method.The 1D-shaped FeCoNi alloy embedded composite demonstrates the high-density and continuous magnetic network using off-axis electronic holography technique,indicating the excellent magnetic loss ability under an external EM field.Then,the in-depth analysis shows that many factors,including 1D anisotropy and intrinsic physical features of the magnetic medium-entropy alloy,primarily contribute to the enhanced EM wave absorption performance.Therefore,the fabricated EM wave absorber shows an increasing effective absorption band of 1.3 GHz in the low-frequency electromagnetic field at an ultrathin thickness of 2 mm.Thus,this study opens up a new method for the design and preparation of high-performance 1D magnetic EM absorbers.
基金financially supported by the National Natural Science Foundation of China(No.U2004177 and U21A2064)Outstanding Youth Fund of Henan Province(No.212300410081)+1 种基金Scientific and Technological Innovation Talents in Colleges and Universities in Henan Province(22HASTIT001)The Research and Entrepreneurship Start-up Projects for Overseas Returned Talents。
文摘Traditional ceramic materials are generally brittle and not flexible with high production costs,which seriously hinders their practical applications.Multifunctional nanofiber ceramic aerogels are highly desirable for applications in extreme environments,however,the integration of multiple functions in their preparation is extremely challenging.To tackle these challenges,we fabricated a multifunctional SiC@SiO_(2) nanofiber aerogel(SiC@SiO_(2) NFA)with a threedimensional(3D)porous cross-linked structure through a simple chemical vapor deposition method and subsequent heat-treatment process.The as-prepared SiC@SiO_(2) NFA exhibits an ultralow density(~11 mg cm^(-3)),ultra-elastic,fatigue-resistant and refractory performance,high temperature thermal stability,thermal insulation properties,and significant strain-dependent piezoresistive sensing behavior.Furthermore,the SiC@SiO_(2) NFA shows a superior electromagnetic wave absorption performance with a minimum refection loss(RL_(min))value of-50.36 d B and a maximum effective absorption bandwidth(EAB_(max))of 8.6 GHz.The successful preparation of this multifunctional aerogel material provides a promising prospect for the design and fabrication of the cutting-edge ceramic materials.
基金supported by the National Science Fund for Distinguished Young Scholars(52025034)National Natural Science Foundation of China(21975204)Innovation Team of Shaanxi Sanqin Scholars。
文摘Combining 3D printing with precursor-derived ceramic for fabricating electromagnetic(EM) wave-absorbing metamaterials has attracted great attention. This study presents a novel ultraviolet-curable polysiloxane precursor for digital light processing(DLP) 3D printing to fabricate ceramic parts with complex geometry, no cracks and linear shrinkage. Guiding with the principles of impedance matching, attenuation, and effective-medium theory, we design a crosshelix-array metamaterial model based on the complex permittivity constant of precursor-derived ceramics. The corresponding ceramic metamaterials can be successfully prepared by DLP printing and subsequent pyrolysis process, achieving a low reflection coefficient and a wide effective absorption bandwidth in the X-band even under high temperature. This is a general method that can be extended to other bands, which can be realized by merely adjusting the unit structure of meta-materials. This strategy provides a novel and effective avenue to achieve “target-design-fabricating” ceramic metamaterials, and it exposes the downstream applications of highly efficient and broad EM wave-absorbing materials and structures with great potential applications.
基金supported by the National Natural Science Foundation of China(51372108).
文摘Cobalt ferrite has problems such as poor impedance matching and high density,which results in unsatisfactory electromagnetic wave(EMW)absorption performance.In this study,the CoFe_(2)O_(4)@C core-shell structure composite was synthesized by a two-step hydrothermal method.X-ray diffraction,transmission electron microscopy,Fourier transform infrared spectroscopy,thermogravimetric analysis,and vector network analysis et al.were used to test the structure and EMW absorption properties of CoFe_(2)O_(4)@C composite.The results show that the reflection loss(RL)of the CoFe_(2)O_(4)@C composite reaches the maximum value of25.66 dB at 13.92 GHz,and the effective absorbing band(EAB)is 4.59 GHz(11.20-15.79 GHz)when the carbon mass content is 6.01%.The RL and EAB of CoFe_(2)O_(4)@C composite are increased by 219.55%and 4.59 GHz respectively,and the density is decreased by 20.78%compared with the cobalt ferrite.Such enhanced EMW absorption properties of CoFe_(2)O_(4)@C composite are attributed to the attenuation caused by the strong natural resonance of the cobalt ferrite,moreover,the carbon coating layer adjusts the impedance matching of the composite,and the introduced dipole polarization and interface polarization can cause multiple Debye relaxation processes.
基金supports from the Natural Science Foundation of Shaanxi Province(No.2022JM-260)the Fundamental Research Funds for the Central Universities(No.G2022KY05109).
文摘Owing to the tunable compositions and versatile functionality,the development of eco-friendly metal–phenolic coordination crystals derivatives is highly anticipated for electromagnetic wave absorption.In this study,three kinds of magnetic hollow carbon spheres(HCSs)with macro-meso-microporous characteristics,including Fe/HCS,Co/HCS,and CoNi/HCS,are successfully fabricated via the co-operative hard template and self-assembling process,in which magnetic particles are encapsulated in carbon shell matrix after the pyrolysis of metal–polyphenol coordination crystals and further subsequent template removal.On the one hand,hierarchical macro-meso-micropores effectively balance the impedance gap between absorbers and air and introduce structural defects or distortion,leading to matched impedance and enhanced dipolar/defect polarization.On the other hand,wrapped magnetic particles provide uncountable hetero-interfaces and induce ferromagnetic resonance,resulting in strengthened interfacial polarization and additional magnetic loss.In particular,enhanced minimum reflection loss(RL,min)and broadband effective absorption bandwidth(EAB)are achieved with only 10 wt.%filler loading.Specifically,the RL,min and EAB values are-57.5 dB and 7.2 GHz for Fe/HCS,-50.0 dB and 5.8 GHz for Co/HCS,and-52.1 dB and 6.7 GHz for CoNi/HCS,respectively.Moreover,this work provides us a modular-assembly strategy to regulate the hollow cavity of absorbers and simultaneously manipulates the chemical components of absorbers to regulate electromagnetic wave absorption performance.
文摘The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave(EMW)absorption are still challenging.In this paper,MXene was used as the aerogel matrix,modified with sea urchin-like magnetic Co/N-doped carbon@polyaniline(Co-NC@PANI),gelatin was introduced as the reinforcement phase of the aerogel backbone,and a microwave absorber with high efficiency and excellent performance was successfully prepared.The sea urchin-like Co-NC@PANI not only adjusted the impedance matching of the MXene but also introduced a magnetic loss mode into the composite.The multicomponent interfacial polarization,heterostructure,three-dimensional(3D)lightweight porous structure,and electromagnetic synergy strategy enabled the MXene-based aerogel modified by Co-NC@PANI(MCoP)to exhibit surprising EMW absorption properties.The maximum reflection loss(RL_(max))of the aerogel composite reached-62.4 dB,and the effective absorption bandwidth(EAB)reached 6.56 GHz when the loading was only 12%.In addition,through electromagnetic simulation experiments,the change in the electromagnetic field before and after EMW passed through the materials and the distribution of the volume loss density of EMW by the coaxial ring were observed.The coordinated electromagnetic balance strategy in the 3D network provides inspiration for the construction of materials and expands the research direction of lightweight and outstanding microwave absorbers.
基金supported by the National Natural Science Foundation of China(No.51872058)the Supporting Program for Innovation Team of Outstanding Youth in Colleges and Universities of Shandong Province(No.2020KJA005)the Natural Science Foundation of Shandong Province(No.ZR2022QB156).
文摘With the development of the miniaturization of electronic equipment and lightweight weapon equipment,there are new requirements for electromagnetic wave absorption material(EMWAM).EMWAM has outstanding electromagnetic wave absorption properties and lightweight characteristics become an important direction of research.In this study,graphene/g-C_(3)N_(4)(GGCN)EMWAM was first synthesized in situ by simple heat treatment,in which the g-C_(3)N_(4) had a porous structure and dispersed on the surface of graphene.The impedance matching of the GGCN was well adjusted by decreasing the dielectric constant and attenuation constant due to the g-C_(3)N_(4) semiconductor property and the graphite-like structure.The EMW loss mechanism of GGCN was also analyzed by simulating GGCN’s electric field mode distribution and resistance loss power density.The analysis result shows that the distribution of g-C_(3)N_(4) among GGCN sheets can produce more polarization effects and relaxation effects by increasing the lamellar spacing.Furthermore,the polarization loss of GGCN could be increased successfully by porous g-C_(3)N_(4).Ultimately,the EMW absorption property of GGCN is optimized significantly,and GGCN exhibits excellent EMW absorption performance.When the thickness is 2 mm,the effective absorption bandwidth(EAB)can reach 4.6 GHz,and when the thickness is 4.5 mm,the minimum reflection loss(RLmin)at 4.56 GHz can reach-34.69 dB.Moreover,the practical application of EMWAM was studied by radar cross-section(RCS)simulation,showing that GGCN has a good application prospect.
文摘Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the single loss mechanism vastly restrict the application.Hence,it’s an effective strat-egy to solve these issues by introducing magnetic components.Notably,layer double hydroxide(LDH)is an appropriate template to obtain magnetic component materials.Considering that ferromagnetic met-als such as Fe,Co,Ni,and their corresponding metal oxides are usually treated as magnetic compo-nents which are promising candidates for EMW absorption materials.Therefore,in this work,a FeNi-layered double hydroxide-reduced graphene oxide(FeNi-LDH-rGO)aerogel was synthesized through a series of processes such as electrostatic self-assembly,hydrothermal,freeze-drying,and annealing.The magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell nanospheres were obtained from FeNi-LDH precursor,anchoring on rGO nanosheets after the annealing treatment.Furthermore,the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption prop-erty and impedance matching performance were explored.As a consequence,the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth(EAB)of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt%and a low density of 4.4 mg/cm^(3).In conclusion,the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell struc-ture nanospheres.
基金supported by the National Natural Science Foundation of China(No.22271018).
文摘The escalating electromagnetic(EM)pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave(EMW)absorbing materials.In this paper,the flower-like CuS/γ-Fe_(2)O_(3) van der Waals(vdW)heterostructures have been synthesized via a facile two-step solvothermal approach.The flower-like CuS skeleton increases the attenuation path of EMW while reducing the material density.Different contents ofγ-Fe_(2)O_(3) nanoparticles anchor between the flower-like CuS nanosheets to constitute a heterogeneous structure,which enables dielectric and magnetic loss synergistically to optimize impedance matching and remarkably improve the EMW absorption performance.The minimum reflection loss(RLmin)is-49.36 dB with a thickness of only 1.6 mm and the effective absorption bandwidth(EAB)reaches 4.64 GHz(13.36–18 GHz).By adjusting the thickness of the absorber,the EAB can cover 96%of the GHz band.Notably,the superior absorption of-61.53 dB at middle frequency band can be obtained by adjusting the amount of Fe_(2)O_(3) addition.In this study,the adjustment of EM parameters and the optimization of impedance matching have been achieved by constructing a novel vdW heterogeneous structure,which provides fresh ideas and references for the design of high-performance EMW absorbing materials.
基金the National Natural Science Foundation of China(Nos.52102036 and52301192)the Sichuan Science and Technology Program,China(No.2021JDRC0099)+3 种基金Taishan Scholars and Young Experts Program of Shandong Province,China(No.tsqn202103057)the Qingchuang Talents Induction Program of Shandong Higher Education Institution,China(Research and Innovation Team of Structural-Functional Polymer Composites)Special Financial of Shandong Province,China(Structural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams)“Sanqin Scholars”Innovation Teams Project of Shaanxi Province,China(Clean Energy Materials and High-Performance Devices Innovation Team of Shaanxi Dongling Smelting Co.,Ltd.)。
文摘Bioderived carbon materials have garnered considerable interest in the fields of microwave absorption and shielding due to their reproducibility and environmental friendliness.In this study,KOH was evenly distributed on biomass Tremella using the swelling induction method,leading to the preparation of a three-dimensional network-structured hierarchical porous carbon(HPC)through carbonization.The achieved microwave absorption intensity is robust at-47.34 dB with a thin thickness of 2.1 mm.Notably,the widest effective absorption bandwidth,reaching 7.0 GHz(11–18 GHz),is attained at a matching thickness of 2.2 mm.The exceptional broadband and reflection loss performance are attributed to the 3D porous networks,interface effects,carbon network defects,and dipole relaxation.HPC has outstanding absorption characteristics due to its excellent impedance matching and high attenuation constant.The uniform pore structures considerably optimize the impedance-matching performance of the material,while the abundance of interfaces and defects enhances the dielectric loss,thereby improving the attenuation constant.Furthermore,the impact of carbonization temperature and swelling rate on microwave absorption performance was systematically investigated.This research presents a strategy for preparing absorbing materials using biomass-derived HPC,showcasing considerable potential in the field of electromagnetic wave absorption.
基金supported by Zhejiang Provincial Natural Science Foundation of China(Nos.LQ23F050006,LQ21E020005)the National Natural Science Foundation of China(No.52002365).
文摘Ultra-thin electromagnetic wave(EMW)absorbers present challenging demands on EMW absorption performance.Drawing inspiration from heather leaf structures,this study introduces an innovative design strategy for EMW absorbing material,proposing biomimetic leaf SnO_(2) structures(bio-SnO_(2))on carbon fabric(CF).By employing leaf-shaped SnS2 as precursors,biomimetic leaf SnO_(2) nanostructures are constructed on CF surface after a simple thermal treatment,resulting in bio-SnO_(2)@CF composite.Experimental results indicate that bio-SnO_(2)@CF exhibits an exceptional minimum reflection loss of-54.8 dB at an incredibly thin thickness of 1.2 mm.Radar cross section(RCS)simulations further validate the outstanding EMW attenuation ability of bio-SnO_(2)@CF,attaining a maximum RCS reduction value of 16.9 dBm^(2) at an incident wave angle ofθ=0°.This novel research showcases the biomimetic structural design strategy and its remarkable function in enhancing the EMW absorbing performance at ultra-thin absorber thickness.