Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significan...Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.展开更多
With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electro...With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electronic instruments.Therefore,the design and preparation of electromagnetic absorbing composites represent an efficient approach to mitigate the current hazards of electromagnetic radiation.However,traditional electromagnetic absorbers are difficult to satisfy the demands of actual utilization in the face of new challenges,and emerging absorbents have garnered increasing attention due to their structure and performance-based advantages.In this review,several emerging composites of Mxene-based,biochar-based,chiral,and heat-resisting are discussed in detail,including their synthetic strategy,structural superiority and regulation method,and final optimization of electromagnetic absorption ca-pacity.These insights provide a comprehensive reference for the future development of new-generation electromagnetic-wave absorption composites.Moreover,the potential development directions of these emerging absorbers have been proposed as well.展开更多
Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption,but still remain the formidable challenges in decreasing filler loadings.Herein,sandwich NC@Co/NC@MnO_(2)c...Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption,but still remain the formidable challenges in decreasing filler loadings.Herein,sandwich NC@Co/NC@MnO_(2)composites with hollow cavity,multiple hetero-interfaces,and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrothermal reaction.In the sandwich composites,middle magnetic components(Co/NC)are wrapped by inner N-doped carbon(NC)matrix and outer hierarchical MnO_(2)nanosheets.Importantly,hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorption bandwidth without sacrificing the absorption intensity.The maximum reflection loss of sandwich NC@Co/NC@MnO_(2)composites reaches-44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm.These results provide us a new insight into preparing efficient electromagnetic wave absorbers by interface engineering and hollow construction.展开更多
Precisely reducing the size of metal-organic frameworks(MOFs)derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation;however,the underlying relationship between the...Precisely reducing the size of metal-organic frameworks(MOFs)derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation;however,the underlying relationship between the size of derivatives and phase engineering has not been clarified so far.Herein,a spatial confined growth strategy is proposed to encapsulate small-size MOFs derivatives into hollow carbon nanocages.It realizes that the hollow cavity shows a significant spatial confinement effect on the size of confined MOFs crystals and subsequently affects the dielectric polarization due to the phase hybridization with tunable coherent interfaces and heterojunctions owing to size-dependent oxidation motion,yielding to satisfied microwave attenuation with an optimal reflection loss of-50.6 d B and effective bandwidth of 6.6 GHz.Meanwhile,the effect of phase hybridization on dielectric polarization is deeply visualized,and the simulated calculation and electron holograms demonstrate that dielectric polarization is shown to be dominant dissipation mechanism in determining microwave absorption.This spatial confined growth strategy provides a versatile methodology for manipulating the size of MOFs derivatives and the understanding of size-dependent oxidation-induced phase hybridization offers a precise inspiration in optimizing dielectric polarization and microwave attenuation in theory.展开更多
Lightweight and high-performance are two determining factors for metal-organic-frameworks(MOFs)derived microwave absorbers.However,most of the reported MOFs derived absorbers usually possess high filler loading.Herein...Lightweight and high-performance are two determining factors for metal-organic-frameworks(MOFs)derived microwave absorbers.However,most of the reported MOFs derived absorbers usually possess high filler loading.Herein,a series of MOFs derived magnetic porous carbon microspheres with tunable diameter and high specific surface area have been synthesized via a pyrolysis process.The synthesized magnetic porous carbon microspheres,constructed by uniformly distributed core-shell Ni@C,exhibit high-performance microwave absorption with a low filler loading of 10 wt%.Considering the mciro-mesoporous structures,matched impedance,strong conductive loss,enhanced dipolar/interfacial polarization as well as strong magnetic coupling network,a minimum reflection loss of-60 dB and an absorption bandwidth of 7.0 GHz can be achieved at 2.6 mm.Moreover,the bandwidth reaches as wide as 10.2 GHz when the thickness is 4 mm.In addition,compared with other MOFs derived absorbers,this work provides us a simple strategy for the synthesis of porous carbon microspheres with lightweight and high-performance microwave absorption for practical applications.展开更多
High-performance electromagnetic(EM)wave absorbers,covalently bonded reduced graphene oxideFe_(3)O_(4) nanocomposites(rGO-Fe_(3)O_(4)),are synthesized via hydrothermal reaction,amidation reaction and reduction process...High-performance electromagnetic(EM)wave absorbers,covalently bonded reduced graphene oxideFe_(3)O_(4) nanocomposites(rGO-Fe_(3)O_(4)),are synthesized via hydrothermal reaction,amidation reaction and reduction process.The microstructure,surface element composition and morphology of rGO-Fe_(3)O_(4) nanocomposites are characterized and corresponding EM wave absorption properties are analyzed in great detail.It demonstrates that Fe_(3)O_(4) nanoparticles are successfully covalently grafted onto graphene by amide bonds.When the mass ratio of rGO and Fe_(3)O_(4) is 2:1(sample S2),the absorber exhibits the excellent EM wave absorption performance that the maximum reflection loss(RL)reaches up to-48.6 dB at 14.4 GHz,while the effective absorption bandwidth(RL<-10 dB)is 6.32 GHz(11.68-18.0 GHz)with a matching thickness of 2.1 mm.Furthermore,radar cross section(RCS)simulation calculation is also adopted to evaluate the ability of absorbers to scatter EM waves,which proves again that the absorption performance of absorber S2 is optimal.The outstanding EM wave absorption performance is attributed to the synergistic effect between dielectric and magnetic loss,good attenuation ability and excellent impedance matching.Moreover,covalent bonds considered to be carrier channels can facilitate electron migration,adjust EM parameters and then enhance EM wave absorption perfo rmance.This work provides a possible method for preparing efficient EM wave absorbers.展开更多
Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of di...Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of different phases on the EMW absorbing performance,such as 1T and 2H phase,is still not studied.In this work,micro-1T/2H MoS_(2) is achieved via a facile one-step hydrother-mal route,in which the 1T phase is induced by the intercalation of vip molecules and ions.The EMW absorption mechanism of single MoS_(2) is revealed by presenting a comparative study between 1T/2H MoS_(2) and 2H MoS_(2).As a result,1T/2H MoS_(2) with the matrix loading of 15%exhibits excellent microwave absorption property than 2H MoS_(2).Furthermore,taking the advantage of 1T/2H MoS_(2),a flexible EMW absorbers that ultrathin 1T/2H MoS_(2)grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%.This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.展开更多
Graphene sheets(GNs) have high conductivity, but they exhibit weak electromagnetic(EM) wave absorption performance. Here, poly(3,4-ethylenedioxythiophene)(PEDOT) nanofibers were decorated on the surface of GNs in whic...Graphene sheets(GNs) have high conductivity, but they exhibit weak electromagnetic(EM) wave absorption performance. Here, poly(3,4-ethylenedioxythiophene)(PEDOT) nanofibers were decorated on the surface of GNs in which the residual defects and groups act as the active sites and therefore are beneficial for the deposition of PEDOT nanofibers.The SEM images display that PEDOT nanofibers are successfully decorated on the surface of GNs through in situ polymerization. The diameter of the PEDOT nanofibers were ranged from 15 to 50 nm with hundreds of nanometers in length. The EM wave absorption properties of graphene, PEDOT, and GNs-PEDOT were also investigated. Compared to pure graphene and PEDOT, the EM wave absorption properties of GNs-PEDOT improved significantly. The maximum value of RLwas up to-48.1 d B at 10.5 GHz with a thickness of only 2 mm. Meanwhile, the absorption bandwidth of RL values below-10 d B was 9.4 GHz(5.8–12.3, 12.9–15.8 GHz) in the thickness of 1.5–3 mm. The enhancement is attributed to the modification of PEDOT and the unique structure of nanofibers. On one hand, the deposition of PEDOT nanofibers on the surface of GNs decreases the conductivity of graphene, and makes impedance match better. On the other hand, the unique structure of PEDOT nanofibers results in relatively large specific surfaces areas, providing more active sites for reflection and scattering of EM waves. Therefore, our findings demonstrate that the deposition of conducting polymers on GNs by non-covalent bond is an efficient way to fabricate strong EM wave absorbers.展开更多
Solid-state lithium batteries(SSLBs) have attracted great interest from researchers due to their inherent high energy density and high safety performance.In order to develop SSLBs,the following two key problems should...Solid-state lithium batteries(SSLBs) have attracted great interest from researchers due to their inherent high energy density and high safety performance.In order to develop SSLBs,the following two key problems should be solved:(1) Improving the lithium ion conductivity of solid electrolyte at room temperature;and(2) improving the interface between the electrode and the electrolyte.Herein,we propose a new multifunctional filler for reinforcing polymer electrolytes.The composite solid electrolytes(CSEs)mainly contain a MOF-derived Co-doped hollow porous carbon nanocage,which absorbs Li~+ containing ionic liquid(Li-ILs@HPCN),polyethylene oxide(PEO) and lithium bis(trifluoromethanesulfonyl)imide.By optimizing the composition of the CSEs,the CSEs membrane with high ionic conductivity(1.91×10^(-4) S cm^(-1) at 30℃),wide electrochemical stability(5.2 V) and high mobility of lithium ion(0.5) was obtained.Even at a current density of 0.2 mA cm^(-2),the PILH electrolyte possesses excellent interfacial stability against Li metal in Li symmetrical batteries exceeds 1600 h.Finally,the SSLBs(LFP/PILH/Li) showed excellent cycle stability,and the capacity was maintained at 152.9 and140.0 mA h g^(-1) after 150 cycles at a current density of 0.2 C and 0.5 C.This work proposes a completely new strategy for building high-performance SSLBs.展开更多
The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by ...The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by one-step carbonization method using high-yield and low-cost biomass silkworm excrement as a precursor.As an anode for SIB,HHPC-1100 exhibits a capacity of 331.7 mA h g^(-1) at 20 mA g^(-1),while it also reveals remarkable rate performance and stable long cycle capability due to its abundant pore structure and proper amount of hetero atom doping.Moreover,the synergistic effect of O,N,S,P co-doping in carbon materials on sodium ion adsorption is verified by the first-principles study,which provide a theoretical basis for the prominent electrochemical performance of the material.展开更多
Starch has a wide range of sources and can be used as a high-quality precursor for sodium-ion battery anode materials.However,the carbonization yield and specific capacity of carbon materials obtained by directly pyro...Starch has a wide range of sources and can be used as a high-quality precursor for sodium-ion battery anode materials.However,the carbonization yield and specific capacity of carbon materials obtained by directly pyrolyzing starch are low.Herein,starch is used as the carbon source,and ammonium polyphosphate(APP)is used as the cross-linking agent and dopant to prepare a nitrogen and phosphorus co-doped porous carbon(NPPC).As the anode for sodium-ion batteries,NPPC-2 exhibits a high reversible capacity of 385.8 mAhg^(-1)at 50 mAg^(-1).Even after 1000 cycles at a large current density of 5 Ag^(-1),the reversible capacity can still be maintained at 126.9 mAhg^(-1).Based on detailed data and first-principles calculations,the excellent performance of NPPC is due to the effective doping of nitrogen and phosphorus elements,which distorts the graphite sheet,introduces defects,and increases the graphite layer spacing,thereby enhancing the adsorption capacity of the carbon material for sodium ions,reducing the diffusion barrier of sodium ions.This work provides a new idea for heteroatom doping and carbon material modification.展开更多
Dielectric-magnetic integrated absorbers have attracted arousing attention in microwave absorption,however,it still remains a great challenge to simultaneously achieve superior dielectric polarization and strong magne...Dielectric-magnetic integrated absorbers have attracted arousing attention in microwave absorption,however,it still remains a great challenge to simultaneously achieve superior dielectric polarization and strong magnetic loss.Herein,we propose a multi-scale structure optimization strategy to anchor CoNiMOFs derived OD CoNi alloy onto 1 D core-shell Ni@C surface.By decorating with the poly-dopamine layer,the connection between 1 D NiO and CoNi-MOFs precursors was greatly improved via the electrostatic interaction.Benefiting from the overlapping conductive networks,enhanced interfacial polarization among the multi-dimensional heterogeneous interfaces and strong magnetic interaction,the fabricated multi-dimensional Ni@C-CoNi composites exhibit outstanding microwave absorption.Typically,the optimal reflection loss is as high as-51.4 dB at 1.9 mm,and the effective absorption bandwidth achieves 4.6 GHz with a thickness of only 1.3 mm.This multi-scale structure optimization strategy inspires us with an efficient method to fabricate ideal microwave absorbers and the obtained multi-dimensional composites can be used as promising candidates in electromagnetic radiation protection.展开更多
Subtle microstructure design and an appropriate multicomponent strategy are essential for advanced electromagnetic absorbing(EMA)materials with a wide effective absorption bandwidth(EAB)and intense absorption.However,...Subtle microstructure design and an appropriate multicomponent strategy are essential for advanced electromagnetic absorbing(EMA)materials with a wide effective absorption bandwidth(EAB)and intense absorption.However,sophisticated environments restrict the range of applications for EMA materials.Herein,three hollow spherical bifunctional CoSx/MnS/C nanocomposites with different crystal structures were constructed via cation exchange and subsequent vulcanization.The manganese sulfide and carbon generated during vulcanization exhibit a narrow band gap and enhanced conductivity,thereby facilitating conductive loss.The presence of cobalt sulfide facilitates the improvement of magnetic loss.More importantly,there is a potential difference between different phases at the heterogeneous interface,resulting in a region of space charge,which is conducive to interfacial polarization.The 3D hollow structure and heterogeneous dielectric/magnetic interfaces benefit the predominant EMA performance by forming perfect impedance matching,interface polarization,conduction loss,and magnetic loss effects.Specifically,an optimal reflection loss(RL)of-51.31 dB at 10.72 GHz and an effective EAB of 5.92 GHz at 2.1 mm can be achieved for Co_(1-x) S/MnS/C nanocomposite.Moreover,the nanocomposites maintained promising self-anticorrosion properties in simulated seawater environments.Transition metal sulfides with superior self-anticorrosion properties provide a pathway to efficient wave-absorbing materials in complicated environments.展开更多
Metal-organic-frameworks(MOFs)derived carbon-based composites with balanced impedance matching and synergistic dielectric/magnetic loss are considered as promising microwave absorbers.With the aim to promote interfaci...Metal-organic-frameworks(MOFs)derived carbon-based composites with balanced impedance matching and synergistic dielectric/magnetic loss are considered as promising microwave absorbers.With the aim to promote interfacial polarization,herein,heterogeneous junctions composed of magnetic Ni core and binary dielectric shells(C and PEDOT)are synthesized by annealing Ni-MOFs precursors and an in-situ polymerization strategy,forming Ni@C@PEDOT spheres with multilayer heterogeneous interfaces.The results indicate that the final absorption attenuation is sensitive to the thickness of the dielectric PEDOT layer,when the thickness of the PEDOT layer is 224 nm,an optimal reflection loss of-72.4 d B is achieved at 2 mm and the effective absorption bandwidth reaches 6.4 GHz with a thickness of only 1.85 mm,the excellent absorption attenuation is accredited to the promoted impedance matching,enhanced conduction loss as well as the synergistic interfacial polarization induced by magnetic core and binary dielectric shells.Meanwhile,this work offers a simple and significant strategy in preparation for ideal microwave absorbers by rational design of multilayer heterogeneous interfaces.展开更多
Electromagnetic synergy and porous characteristics are two dominant factors in realizing light-weight and high-efficient microwave absorption performance.In this paper,a formaldehydeassisted metal-ligand crosslinking ...Electromagnetic synergy and porous characteristics are two dominant factors in realizing light-weight and high-efficient microwave absorption performance.In this paper,a formaldehydeassisted metal-ligand crosslinking strategy and a subsequent pyrolysis process are employed to synthesize magnetic porous carbon spheres with the electromagnetic synergy and porous characteristics,in which metal ions are tightly anchored in poly-(tannin acid)spheres because of the strong chelation coordination between them.The chemical composition of magnetic particles and the microwave absorption performance of the derived magnetic porous carbon spheres can be manipulated by adjusting the metal ions.Benefiting from the cooperative effects of porous structure,matched impedance,the electromagnetic synergistic enhancement between magnetic particles and carbon matrix,as well as the improved interfacial polarization caused by the large number of hetero-interfaces,both the microwave absorption intensity and the effective absorption bandwidths are significantly enhanced for magnetic porous carbon spheres,such as Co-PCSs and CoNi-PCSs,compared with PCSs.With 15 wt.%filler loading,the maximum reflection loss of CoNi-PCSs is -51 dB at 2.2 mm and the effective bandwidth is 7.2 GHz at 2.9 mm.Furthermore,this study provides the theoretical theory for the design and development of light-weight and highly efficient microwave absorption materials.展开更多
Hollow engineering is considered to be an essential subfield in promoting electromagnetic(EM)wave absorption intensity and realizing lightweight characteristics.However,the enhancement of the effective absorption band...Hollow engineering is considered to be an essential subfield in promoting electromagnetic(EM)wave absorption intensity and realizing lightweight characteristics.However,the enhancement of the effective absorption bandwidth(EAB)still faces considerable challenges.Herein,hollow carbon nanocages with CoFe_(2)Se_(4)quantum dots(HCNs@CoFe_(2)Se_(4)-QDs)with superior EM wave absorption intensity and ultra broadband EAB are produced by using tightly arranged SiO_(2)spheres as hard-template materials.Specifically,the removal of SiO_(2)templates inevitably results in the formation of a hollow cavity,which is favorable for optimizing impedance matching and increasing the absorption intensity.In addition,the incorporation of selenium powder effectively increases the number of heterogeneous interfaces by forming CoFe_(2)Se_(4)quantum dots(QDs)during the pyrolysis process,leading to strengthened interfacial polarization and ultra broadband EAB.As a result,superior EM wave attenuation with a minimum reflection loss(RL)of−67.6 dB and an EAB of 11.4 GHz is achieved with only a 20 wt%filler ratio.This design concept of hollow engineering with magnetic QDs provides inspiration for optimizing the EM wave absorption intensity and simultaneously promoting the absorption bandwidth.展开更多
With the increasing seriousness of electromagnetic pollution in civil applications and national defense,current radar absorbing structures(RASs)with narrow absorption performance and high density are inadequate to mee...With the increasing seriousness of electromagnetic pollution in civil applications and national defense,current radar absorbing structures(RASs)with narrow absorption performance and high density are inadequate to meet the demands for excellent electromagnetic absorption performance.Therefore,achieving broadband absorption capabilities in RASs across the frequency range of 2 to 40 GHz is a pressing issue and a topic of significant interest.This review article summarizes the multi-dimensional design of broadband RASs by integrating materials,structures,and manufacturing processes,promoting the application of novel materials in three-dimensional structures through advanced manufacturing processes in the future.Meanwhile,the multi-scale absorption mechanism,including the micro-scale absorption attenuation mechanism and macro-scale absorption resonance,has been relatively new frontier has been discussed,highlighting their potential for diverse applications across multiple fields.展开更多
Carbon nanofibers(CNFs)have emerged as promising candidates for realizing lightweight and high-performance electromagnetic(EM)wave absorbing materials owing to their obvious merits,such as long-range conductive networ...Carbon nanofibers(CNFs)have emerged as promising candidates for realizing lightweight and high-performance electromagnetic(EM)wave absorbing materials owing to their obvious merits,such as long-range conductive networks,tunable dielectric properties,and atomic-scale composition regulation.The existing challenges are how to optimize surface impedance matching through structural design and realize multifrequency response characteristics by EM synergistic effects.In this study,we propose a confined-coordination growth strategy to anchor small-sized Co nanoparticles and simultaneously introduce structural defects on the surface of CNFs to realize lightweight and superior EM wave absorption.Interestingly,these post-coordinated metal–organic framework(MOF)-derived small Co nanoparticles can balance surface impedance,strengthen interfacial polarization,and promote interfacial electric field polarization,and the sublimation of Zn species introduces structural defects to regulate the dielectric constant and trigger defect polarization.Benefiting from the combined advantages of matched impedance,long-range conductive networks,abundant dielectric‒magnetic heterointerfaces,and structural defects,the minimum reflection loss(RL)of the CNFs reached as high as-51.0 dB,and the effective absorption bandwidth(EAB)covered the entire Ku band with a broad bandwidth of 7.33 GHz.This strategy provides integrated insight into optimizing the impedance characteristics of CNFs and manipulating the EM wave absorbing performance.展开更多
Microwave absorbing materials(MAMs)has been intensively investigated in order to meet the requirement of electromagnetic radiation control,especially in S and C band.In this work,FeCo-based magnetic MAMs are hydrother...Microwave absorbing materials(MAMs)has been intensively investigated in order to meet the requirement of electromagnetic radiation control,especially in S and C band.In this work,FeCo-based magnetic MAMs are hydrothermally synthesized via a magnetic-field-induced process.The composition and morphology of the MAMs are capable of being adjusted simultaneously by the atomic ratio of Fe2+to Co2+in the precursor.The hierarchical magnetic microchain,which has a core–shell structure of twodimensional FexCo1−xOOH nanosheets anchored vertically on the surface of a one-dimensional(1D)Co microchain,shows significantly enhanced microwave absorption in C band,resulting in a reflection loss(RL)of lower than−20 dB at frequencies ranging from 4.4 to 8.0 GHz under a suitable matching thickness.The magnetic coupling of Co microcrystals and the double-loss mechanisms out of the core-shell structure are considered to promote the microwave attenuation capability.The hierarchical design of 1D magnetic MAMs provides a feasible strategy to solve the electromagnetic pollution in C band.展开更多
Carbon nanotubes(CNTs)incorporated polymeric composites have been extensively investigated for microwave absorption at target frequencies to meet the requirement of radar cross-section reduction.In this work,a strateg...Carbon nanotubes(CNTs)incorporated polymeric composites have been extensively investigated for microwave absorption at target frequencies to meet the requirement of radar cross-section reduction.In this work,a strategy of efficient utilization of CNT in producing CNT incorporated aramid papers is demonstrated.The layer-by-layer self-assembly technique is used to coat the surfaces of meta-aramid fibers and fibrils with CNT,providing novel raw materials available for the large-scale papermaking.The hierarchical construction of CNT networks resolves the dilemma of increasing CNT content and avoiding the agglomeration of CNT,which is a frequent challenge for CNT incorporated polymeric composites.The composite paper,which contains abundant heterogeneous interfaces and long-range conductive networks,is capable of reaching a high permittivity and dielectric loss tangent at a low CNT loading,its complex permittivity is,so far,adjustable in the range of(1.20−j0.05)to(25.17−j18.89)at 10 GHz.Some papers with optimal matching thicknesses achieve a high-efficiency microwave absorption with a reflection loss lower than−10 dB in the entire X-band.展开更多
基金financially supported by the National Natural Science Foundation of China(52373271)Science,Technology and Innovation Commission of Shenzhen Municipality under Grant(KCXFZ20201221173004012)+1 种基金National Key Research and Development Program of Shaanxi Province(No.2023-YBNY-271)Open Testing Foundation of the Analytical&Testing Center of Northwestern Polytechnical University(2023T019).
文摘Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.
基金supported by the Surface Project of Local De-velopment in Science and Technology Guided by Central Govern-ment(No.2021ZYD0041)the National Natural Science Founda-tion of China(Nos.52377026 and 52301192)+3 种基金the Natural Science Foundation of Shandong Province(No.ZR2019YQ24)the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Special Financial of Shandong Province(Struc-tural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Tal-ent Teams)the“Sanqin Scholars”Innovation Teams Project of Shaanxi Province(Clean Energy Materials and High-Performance Devices Innovation Team of Shaanxi Dongling Smelting Co.,Ltd.).
文摘With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electronic instruments.Therefore,the design and preparation of electromagnetic absorbing composites represent an efficient approach to mitigate the current hazards of electromagnetic radiation.However,traditional electromagnetic absorbers are difficult to satisfy the demands of actual utilization in the face of new challenges,and emerging absorbents have garnered increasing attention due to their structure and performance-based advantages.In this review,several emerging composites of Mxene-based,biochar-based,chiral,and heat-resisting are discussed in detail,including their synthetic strategy,structural superiority and regulation method,and final optimization of electromagnetic absorption ca-pacity.These insights provide a comprehensive reference for the future development of new-generation electromagnetic-wave absorption composites.Moreover,the potential development directions of these emerging absorbers have been proposed as well.
基金support from the National Natural Science Foundation of China(No.U21A2093)Natural Science Foundation of Shaanxi Province(No.2022JM-260)Fundamental Research Funds for the Central Universities(No.G2022KY05109).This work is also financially supported by the Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.We would like to thank Zhang San from Shiyanjia Lab(www.shiyanjia.com)for the VSM analysis.
文摘Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption,but still remain the formidable challenges in decreasing filler loadings.Herein,sandwich NC@Co/NC@MnO_(2)composites with hollow cavity,multiple hetero-interfaces,and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrothermal reaction.In the sandwich composites,middle magnetic components(Co/NC)are wrapped by inner N-doped carbon(NC)matrix and outer hierarchical MnO_(2)nanosheets.Importantly,hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorption bandwidth without sacrificing the absorption intensity.The maximum reflection loss of sandwich NC@Co/NC@MnO_(2)composites reaches-44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm.These results provide us a new insight into preparing efficient electromagnetic wave absorbers by interface engineering and hollow construction.
基金This work was financially supported by the National Natural Science Foundation of China(U21A2093 and 52102370)the Natural Science Foundation of Shaanxi Province(2022JM-260)+2 种基金the Shanghai Key Laboratory of R&D for Metallic Functional Materials(2021-01)and Open Fund of Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province(JBGS014)Open access funding provided by Shanghai Jiao Tong University
文摘Precisely reducing the size of metal-organic frameworks(MOFs)derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation;however,the underlying relationship between the size of derivatives and phase engineering has not been clarified so far.Herein,a spatial confined growth strategy is proposed to encapsulate small-size MOFs derivatives into hollow carbon nanocages.It realizes that the hollow cavity shows a significant spatial confinement effect on the size of confined MOFs crystals and subsequently affects the dielectric polarization due to the phase hybridization with tunable coherent interfaces and heterojunctions owing to size-dependent oxidation motion,yielding to satisfied microwave attenuation with an optimal reflection loss of-50.6 d B and effective bandwidth of 6.6 GHz.Meanwhile,the effect of phase hybridization on dielectric polarization is deeply visualized,and the simulated calculation and electron holograms demonstrate that dielectric polarization is shown to be dominant dissipation mechanism in determining microwave absorption.This spatial confined growth strategy provides a versatile methodology for manipulating the size of MOFs derivatives and the understanding of size-dependent oxidation-induced phase hybridization offers a precise inspiration in optimizing dielectric polarization and microwave attenuation in theory.
基金financially supported by the Fundamental Research Funds for the Central Universities(310201911cx037)the Shanghai Key Laboratory of R&D for Metallic Functional Materials(2021-01)the seed Foundation of Innovation and Creation for Graduate Students in Northwestern Polytechnical University(CX2020210)。
文摘Lightweight and high-performance are two determining factors for metal-organic-frameworks(MOFs)derived microwave absorbers.However,most of the reported MOFs derived absorbers usually possess high filler loading.Herein,a series of MOFs derived magnetic porous carbon microspheres with tunable diameter and high specific surface area have been synthesized via a pyrolysis process.The synthesized magnetic porous carbon microspheres,constructed by uniformly distributed core-shell Ni@C,exhibit high-performance microwave absorption with a low filler loading of 10 wt%.Considering the mciro-mesoporous structures,matched impedance,strong conductive loss,enhanced dipolar/interfacial polarization as well as strong magnetic coupling network,a minimum reflection loss of-60 dB and an absorption bandwidth of 7.0 GHz can be achieved at 2.6 mm.Moreover,the bandwidth reaches as wide as 10.2 GHz when the thickness is 4 mm.In addition,compared with other MOFs derived absorbers,this work provides us a simple strategy for the synthesis of porous carbon microspheres with lightweight and high-performance microwave absorption for practical applications.
基金financially supported by the National Natural Science Foundation of China(No.51672222)the Joint Fund Project-Enterprise-Shaanxi Coal Joint Fund Project(No.2019JLM-32)the Spaceflight Foundation of China(No.2014-HT-XGD)。
文摘High-performance electromagnetic(EM)wave absorbers,covalently bonded reduced graphene oxideFe_(3)O_(4) nanocomposites(rGO-Fe_(3)O_(4)),are synthesized via hydrothermal reaction,amidation reaction and reduction process.The microstructure,surface element composition and morphology of rGO-Fe_(3)O_(4) nanocomposites are characterized and corresponding EM wave absorption properties are analyzed in great detail.It demonstrates that Fe_(3)O_(4) nanoparticles are successfully covalently grafted onto graphene by amide bonds.When the mass ratio of rGO and Fe_(3)O_(4) is 2:1(sample S2),the absorber exhibits the excellent EM wave absorption performance that the maximum reflection loss(RL)reaches up to-48.6 dB at 14.4 GHz,while the effective absorption bandwidth(RL<-10 dB)is 6.32 GHz(11.68-18.0 GHz)with a matching thickness of 2.1 mm.Furthermore,radar cross section(RCS)simulation calculation is also adopted to evaluate the ability of absorbers to scatter EM waves,which proves again that the absorption performance of absorber S2 is optimal.The outstanding EM wave absorption performance is attributed to the synergistic effect between dielectric and magnetic loss,good attenuation ability and excellent impedance matching.Moreover,covalent bonds considered to be carrier channels can facilitate electron migration,adjust EM parameters and then enhance EM wave absorption perfo rmance.This work provides a possible method for preparing efficient EM wave absorbers.
基金the National Natural Science Foundation of China(No.51672222)Joint Fund Project-Enterprise-Shaanxi Coal Joint Fund Project(2019JLM-32)+2 种基金Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202054)the Graduate innovation team of Northwestern Polytechnical Universitythe Analysis and Testing Center of Northwestern Polytechnical University for their technical assistance in SEM(Verios G4).
文摘Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of different phases on the EMW absorbing performance,such as 1T and 2H phase,is still not studied.In this work,micro-1T/2H MoS_(2) is achieved via a facile one-step hydrother-mal route,in which the 1T phase is induced by the intercalation of vip molecules and ions.The EMW absorption mechanism of single MoS_(2) is revealed by presenting a comparative study between 1T/2H MoS_(2) and 2H MoS_(2).As a result,1T/2H MoS_(2) with the matrix loading of 15%exhibits excellent microwave absorption property than 2H MoS_(2).Furthermore,taking the advantage of 1T/2H MoS_(2),a flexible EMW absorbers that ultrathin 1T/2H MoS_(2)grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%.This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.
文摘Graphene sheets(GNs) have high conductivity, but they exhibit weak electromagnetic(EM) wave absorption performance. Here, poly(3,4-ethylenedioxythiophene)(PEDOT) nanofibers were decorated on the surface of GNs in which the residual defects and groups act as the active sites and therefore are beneficial for the deposition of PEDOT nanofibers.The SEM images display that PEDOT nanofibers are successfully decorated on the surface of GNs through in situ polymerization. The diameter of the PEDOT nanofibers were ranged from 15 to 50 nm with hundreds of nanometers in length. The EM wave absorption properties of graphene, PEDOT, and GNs-PEDOT were also investigated. Compared to pure graphene and PEDOT, the EM wave absorption properties of GNs-PEDOT improved significantly. The maximum value of RLwas up to-48.1 d B at 10.5 GHz with a thickness of only 2 mm. Meanwhile, the absorption bandwidth of RL values below-10 d B was 9.4 GHz(5.8–12.3, 12.9–15.8 GHz) in the thickness of 1.5–3 mm. The enhancement is attributed to the modification of PEDOT and the unique structure of nanofibers. On one hand, the deposition of PEDOT nanofibers on the surface of GNs decreases the conductivity of graphene, and makes impedance match better. On the other hand, the unique structure of PEDOT nanofibers results in relatively large specific surfaces areas, providing more active sites for reflection and scattering of EM waves. Therefore, our findings demonstrate that the deposition of conducting polymers on GNs by non-covalent bond is an efficient way to fabricate strong EM wave absorbers.
基金supported by the Joint Fund Project-EnterpriseShaanxi Coal Joint Fund Project (2019JLM-32)。
文摘Solid-state lithium batteries(SSLBs) have attracted great interest from researchers due to their inherent high energy density and high safety performance.In order to develop SSLBs,the following two key problems should be solved:(1) Improving the lithium ion conductivity of solid electrolyte at room temperature;and(2) improving the interface between the electrode and the electrolyte.Herein,we propose a new multifunctional filler for reinforcing polymer electrolytes.The composite solid electrolytes(CSEs)mainly contain a MOF-derived Co-doped hollow porous carbon nanocage,which absorbs Li~+ containing ionic liquid(Li-ILs@HPCN),polyethylene oxide(PEO) and lithium bis(trifluoromethanesulfonyl)imide.By optimizing the composition of the CSEs,the CSEs membrane with high ionic conductivity(1.91×10^(-4) S cm^(-1) at 30℃),wide electrochemical stability(5.2 V) and high mobility of lithium ion(0.5) was obtained.Even at a current density of 0.2 mA cm^(-2),the PILH electrolyte possesses excellent interfacial stability against Li metal in Li symmetrical batteries exceeds 1600 h.Finally,the SSLBs(LFP/PILH/Li) showed excellent cycle stability,and the capacity was maintained at 152.9 and140.0 mA h g^(-1) after 150 cycles at a current density of 0.2 C and 0.5 C.This work proposes a completely new strategy for building high-performance SSLBs.
基金supported by the National Natural Science Foundation of China(Grant No.51872236)the Joint Fund ProjectEnterprise-Shaanxi Coal Joint Fund Project(2019JLM-32)。
文摘The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by one-step carbonization method using high-yield and low-cost biomass silkworm excrement as a precursor.As an anode for SIB,HHPC-1100 exhibits a capacity of 331.7 mA h g^(-1) at 20 mA g^(-1),while it also reveals remarkable rate performance and stable long cycle capability due to its abundant pore structure and proper amount of hetero atom doping.Moreover,the synergistic effect of O,N,S,P co-doping in carbon materials on sodium ion adsorption is verified by the first-principles study,which provide a theoretical basis for the prominent electrochemical performance of the material.
基金the National Natural Science Foundation of China(No.51872236)the Joint Fund Project-Enterprise-Shaanxi Coal Joint Fund Project(No.2019JLM32)。
文摘Starch has a wide range of sources and can be used as a high-quality precursor for sodium-ion battery anode materials.However,the carbonization yield and specific capacity of carbon materials obtained by directly pyrolyzing starch are low.Herein,starch is used as the carbon source,and ammonium polyphosphate(APP)is used as the cross-linking agent and dopant to prepare a nitrogen and phosphorus co-doped porous carbon(NPPC).As the anode for sodium-ion batteries,NPPC-2 exhibits a high reversible capacity of 385.8 mAhg^(-1)at 50 mAg^(-1).Even after 1000 cycles at a large current density of 5 Ag^(-1),the reversible capacity can still be maintained at 126.9 mAhg^(-1).Based on detailed data and first-principles calculations,the excellent performance of NPPC is due to the effective doping of nitrogen and phosphorus elements,which distorts the graphite sheet,introduces defects,and increases the graphite layer spacing,thereby enhancing the adsorption capacity of the carbon material for sodium ions,reducing the diffusion barrier of sodium ions.This work provides a new idea for heteroatom doping and carbon material modification.
基金financially supported by the National Natural Science Foundation of China (Nos.52173254,11975124)the Natural Science Foundation of Jiangsu Province (BK20211200)+4 种基金the Natural Science Foundation of Shaanxi Province (No.2022JM-260)the China Postdoctoral Science Foundation (No.2020M681601)the Fundamental Research Funds for the Central Universities (Nos.30920041103,30920021107)the Shanghai Key Laboratory of R&D for Metallic Functional Materials (2021-01)the Open Fund from Henan University of Science and Technology。
文摘Dielectric-magnetic integrated absorbers have attracted arousing attention in microwave absorption,however,it still remains a great challenge to simultaneously achieve superior dielectric polarization and strong magnetic loss.Herein,we propose a multi-scale structure optimization strategy to anchor CoNiMOFs derived OD CoNi alloy onto 1 D core-shell Ni@C surface.By decorating with the poly-dopamine layer,the connection between 1 D NiO and CoNi-MOFs precursors was greatly improved via the electrostatic interaction.Benefiting from the overlapping conductive networks,enhanced interfacial polarization among the multi-dimensional heterogeneous interfaces and strong magnetic interaction,the fabricated multi-dimensional Ni@C-CoNi composites exhibit outstanding microwave absorption.Typically,the optimal reflection loss is as high as-51.4 dB at 1.9 mm,and the effective absorption bandwidth achieves 4.6 GHz with a thickness of only 1.3 mm.This multi-scale structure optimization strategy inspires us with an efficient method to fabricate ideal microwave absorbers and the obtained multi-dimensional composites can be used as promising candidates in electromagnetic radiation protection.
基金financially supported by the National Natu-ral Science Foundation of China(Nos.52377026 and 52301192)the Natural Science Foundation of Shandong Province(No.ZR2019YQ24)+3 种基金the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Re-search and Innovation Team of Structural-Functional Polymer Com-posites)the Special Financial of Shandong Province(Structural De-sign of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams)the“Sanqin Scholars”Innovation Teams Project of Shaanxi Province(Clean Energy Materials and High-Performance Devices Innovation Team of Shaanxi Dongling Smelting Co.,Ltd.).
文摘Subtle microstructure design and an appropriate multicomponent strategy are essential for advanced electromagnetic absorbing(EMA)materials with a wide effective absorption bandwidth(EAB)and intense absorption.However,sophisticated environments restrict the range of applications for EMA materials.Herein,three hollow spherical bifunctional CoSx/MnS/C nanocomposites with different crystal structures were constructed via cation exchange and subsequent vulcanization.The manganese sulfide and carbon generated during vulcanization exhibit a narrow band gap and enhanced conductivity,thereby facilitating conductive loss.The presence of cobalt sulfide facilitates the improvement of magnetic loss.More importantly,there is a potential difference between different phases at the heterogeneous interface,resulting in a region of space charge,which is conducive to interfacial polarization.The 3D hollow structure and heterogeneous dielectric/magnetic interfaces benefit the predominant EMA performance by forming perfect impedance matching,interface polarization,conduction loss,and magnetic loss effects.Specifically,an optimal reflection loss(RL)of-51.31 dB at 10.72 GHz and an effective EAB of 5.92 GHz at 2.1 mm can be achieved for Co_(1-x) S/MnS/C nanocomposite.Moreover,the nanocomposites maintained promising self-anticorrosion properties in simulated seawater environments.Transition metal sulfides with superior self-anticorrosion properties provide a pathway to efficient wave-absorbing materials in complicated environments.
基金the Shanghai Key Laboratory of R&D for Metallic Functional Materials(2021-01)。
文摘Metal-organic-frameworks(MOFs)derived carbon-based composites with balanced impedance matching and synergistic dielectric/magnetic loss are considered as promising microwave absorbers.With the aim to promote interfacial polarization,herein,heterogeneous junctions composed of magnetic Ni core and binary dielectric shells(C and PEDOT)are synthesized by annealing Ni-MOFs precursors and an in-situ polymerization strategy,forming Ni@C@PEDOT spheres with multilayer heterogeneous interfaces.The results indicate that the final absorption attenuation is sensitive to the thickness of the dielectric PEDOT layer,when the thickness of the PEDOT layer is 224 nm,an optimal reflection loss of-72.4 d B is achieved at 2 mm and the effective absorption bandwidth reaches 6.4 GHz with a thickness of only 1.85 mm,the excellent absorption attenuation is accredited to the promoted impedance matching,enhanced conduction loss as well as the synergistic interfacial polarization induced by magnetic core and binary dielectric shells.Meanwhile,this work offers a simple and significant strategy in preparation for ideal microwave absorbers by rational design of multilayer heterogeneous interfaces.
基金financially supported by the National Natural Science Foundation of China(No.52373271).
文摘Electromagnetic synergy and porous characteristics are two dominant factors in realizing light-weight and high-efficient microwave absorption performance.In this paper,a formaldehydeassisted metal-ligand crosslinking strategy and a subsequent pyrolysis process are employed to synthesize magnetic porous carbon spheres with the electromagnetic synergy and porous characteristics,in which metal ions are tightly anchored in poly-(tannin acid)spheres because of the strong chelation coordination between them.The chemical composition of magnetic particles and the microwave absorption performance of the derived magnetic porous carbon spheres can be manipulated by adjusting the metal ions.Benefiting from the cooperative effects of porous structure,matched impedance,the electromagnetic synergistic enhancement between magnetic particles and carbon matrix,as well as the improved interfacial polarization caused by the large number of hetero-interfaces,both the microwave absorption intensity and the effective absorption bandwidths are significantly enhanced for magnetic porous carbon spheres,such as Co-PCSs and CoNi-PCSs,compared with PCSs.With 15 wt.%filler loading,the maximum reflection loss of CoNi-PCSs is -51 dB at 2.2 mm and the effective bandwidth is 7.2 GHz at 2.9 mm.Furthermore,this study provides the theoretical theory for the design and development of light-weight and highly efficient microwave absorption materials.
基金supported by the National Natural Science Foundation of China(No.52373271)the Open Foundation of the Key Laboratory of Multispectral Absorbing Materials and Structures,Ministry of Education(No.KPKFJJ20250011-2).
文摘Hollow engineering is considered to be an essential subfield in promoting electromagnetic(EM)wave absorption intensity and realizing lightweight characteristics.However,the enhancement of the effective absorption bandwidth(EAB)still faces considerable challenges.Herein,hollow carbon nanocages with CoFe_(2)Se_(4)quantum dots(HCNs@CoFe_(2)Se_(4)-QDs)with superior EM wave absorption intensity and ultra broadband EAB are produced by using tightly arranged SiO_(2)spheres as hard-template materials.Specifically,the removal of SiO_(2)templates inevitably results in the formation of a hollow cavity,which is favorable for optimizing impedance matching and increasing the absorption intensity.In addition,the incorporation of selenium powder effectively increases the number of heterogeneous interfaces by forming CoFe_(2)Se_(4)quantum dots(QDs)during the pyrolysis process,leading to strengthened interfacial polarization and ultra broadband EAB.As a result,superior EM wave attenuation with a minimum reflection loss(RL)of−67.6 dB and an EAB of 11.4 GHz is achieved with only a 20 wt%filler ratio.This design concept of hollow engineering with magnetic QDs provides inspiration for optimizing the EM wave absorption intensity and simultaneously promoting the absorption bandwidth.
基金supported by the National Natural Science Foundation of China(Nos.12402173,52373271)the National Key R&D Program of China(Nos.2023YFB3709602,2023YFB3709603)the Key R&D Program of Shaanxi Province(No.2024CY-GJHX-33).
文摘With the increasing seriousness of electromagnetic pollution in civil applications and national defense,current radar absorbing structures(RASs)with narrow absorption performance and high density are inadequate to meet the demands for excellent electromagnetic absorption performance.Therefore,achieving broadband absorption capabilities in RASs across the frequency range of 2 to 40 GHz is a pressing issue and a topic of significant interest.This review article summarizes the multi-dimensional design of broadband RASs by integrating materials,structures,and manufacturing processes,promoting the application of novel materials in three-dimensional structures through advanced manufacturing processes in the future.Meanwhile,the multi-scale absorption mechanism,including the micro-scale absorption attenuation mechanism and macro-scale absorption resonance,has been relatively new frontier has been discussed,highlighting their potential for diverse applications across multiple fields.
基金financially supported by the National Natural Science Foundation of China(No.52373271)the Key Research and Development Project of Shaanxi Province(No.2025CY-YBXM-150)。
文摘Carbon nanofibers(CNFs)have emerged as promising candidates for realizing lightweight and high-performance electromagnetic(EM)wave absorbing materials owing to their obvious merits,such as long-range conductive networks,tunable dielectric properties,and atomic-scale composition regulation.The existing challenges are how to optimize surface impedance matching through structural design and realize multifrequency response characteristics by EM synergistic effects.In this study,we propose a confined-coordination growth strategy to anchor small-sized Co nanoparticles and simultaneously introduce structural defects on the surface of CNFs to realize lightweight and superior EM wave absorption.Interestingly,these post-coordinated metal–organic framework(MOF)-derived small Co nanoparticles can balance surface impedance,strengthen interfacial polarization,and promote interfacial electric field polarization,and the sublimation of Zn species introduces structural defects to regulate the dielectric constant and trigger defect polarization.Benefiting from the combined advantages of matched impedance,long-range conductive networks,abundant dielectric‒magnetic heterointerfaces,and structural defects,the minimum reflection loss(RL)of the CNFs reached as high as-51.0 dB,and the effective absorption bandwidth(EAB)covered the entire Ku band with a broad bandwidth of 7.33 GHz.This strategy provides integrated insight into optimizing the impedance characteristics of CNFs and manipulating the EM wave absorbing performance.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(No.U21A2093)This work was also financially supported by the Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘Microwave absorbing materials(MAMs)has been intensively investigated in order to meet the requirement of electromagnetic radiation control,especially in S and C band.In this work,FeCo-based magnetic MAMs are hydrothermally synthesized via a magnetic-field-induced process.The composition and morphology of the MAMs are capable of being adjusted simultaneously by the atomic ratio of Fe2+to Co2+in the precursor.The hierarchical magnetic microchain,which has a core–shell structure of twodimensional FexCo1−xOOH nanosheets anchored vertically on the surface of a one-dimensional(1D)Co microchain,shows significantly enhanced microwave absorption in C band,resulting in a reflection loss(RL)of lower than−20 dB at frequencies ranging from 4.4 to 8.0 GHz under a suitable matching thickness.The magnetic coupling of Co microcrystals and the double-loss mechanisms out of the core-shell structure are considered to promote the microwave attenuation capability.The hierarchical design of 1D magnetic MAMs provides a feasible strategy to solve the electromagnetic pollution in C band.
基金the National Natural Science Foundation of China(No.U21A2093).
文摘Carbon nanotubes(CNTs)incorporated polymeric composites have been extensively investigated for microwave absorption at target frequencies to meet the requirement of radar cross-section reduction.In this work,a strategy of efficient utilization of CNT in producing CNT incorporated aramid papers is demonstrated.The layer-by-layer self-assembly technique is used to coat the surfaces of meta-aramid fibers and fibrils with CNT,providing novel raw materials available for the large-scale papermaking.The hierarchical construction of CNT networks resolves the dilemma of increasing CNT content and avoiding the agglomeration of CNT,which is a frequent challenge for CNT incorporated polymeric composites.The composite paper,which contains abundant heterogeneous interfaces and long-range conductive networks,is capable of reaching a high permittivity and dielectric loss tangent at a low CNT loading,its complex permittivity is,so far,adjustable in the range of(1.20−j0.05)to(25.17−j18.89)at 10 GHz.Some papers with optimal matching thicknesses achieve a high-efficiency microwave absorption with a reflection loss lower than−10 dB in the entire X-band.
