The escalating demand for electromagnetic protection against increasingly severe electromagnetic pollution is making the development of advanced electromagnetic wave absorbing material systems imperative.MXene-based e...The escalating demand for electromagnetic protection against increasingly severe electromagnetic pollution is making the development of advanced electromagnetic wave absorbing material systems imperative.MXene-based electromagnetic wave absorbing fillers demonstrate advantages of lightweight and high efficiency.However,their microscale dimensions hinder the formation of interconnected networks within matrices,resulting in limited electromagnetic(EM)loss mechanisms and narrow effective absorption bandwidths.Herein,we employ wet spinning combined with molten salt-assisted in-situ synthesis to fabricate MAX@rGO(rGMAX_(n))fibrous absorbers featuring a hierarchical structure of“columnar cactus covered with MAX spheres”.Precise regulation of MAX phase content enables controlled tuning of the electromagnetic properties of rGMAX_(n) fibers.Moreover,subsequent in-situ etching further enhances their EM performance,yielding MXene@rGO(rGMX_(n))fibers with a hierarchical structure of“columnar cactus decorated with MXene nanosheet clusters”.Freeze-drying is utilized to modulate fiber filling content,and fibrous felts with conductive networks are obtained,which exhibit excellent electromagnetic wave absorption performance.Among them,the as-prepared rGMX_(10) fibrous felt exhibits good electromagnetic wave absorption performance at a low filling content(10 wt.%)with the RL_(max) of 54.4 dB and an effective absorption bandwidth of 5.31 GHz.This enhancement originates from improved impedance matching characteristics through fiber-interconnected networks and multiple electromagnetic loss mechanisms enabled by the hierarchical structure.The strategy of in-situ growing hierarchical MXene@rGO fibers establishes a novel approach for developing MXene-based fibrous absorbing materials.展开更多
Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-ins...Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.展开更多
Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the...Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.展开更多
The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbi...The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbide nanowires using lignite and waste silicon powder as raw materials through carbothermal reduction.The staggered structure of nanowires promotes the creation of interfacial polarization,impedance matching,and multiple loss mechanisms,leading to enhanced electromagnetic absorption performance.The silicon carbide nanowires demonstrate outstanding electromagnetic absorption capabilities with the minimum reflection loss of-48.09 d B at10.08 GHz and an effective absorption bandwidth(the reflection loss less than-10 d B)ranging from 8.54 to 16.68 GHz with a thickness of 2.17 mm.This research presents an innovative approach for utilizing solid waste in an environmentally friendly manner to produce broadband silicon carbide composite absorbers.展开更多
Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usu...Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usually involves complex procedures and extremely depends on unidirectional freezing technique.Herein,we propose a groundbreaking approach that leverages the assemblies of salting-out protein induced by ammonium metatungstate(AM)as the precursor,and then acquire directional three-dimensional carbon-based foams through simple pyrolysis.The electrostatic interaction between AM and protein ensures well dispersion of WC_(1−x)nanoparticles on carbon frameworks.The content of WC_(1−x)nanoparticles can be rationally regulated by AM dosage,and it also affects the electromagnetic(EM)properties of final carbon-based foams.The optimized foam exhibits exceptional EM absorption performance,achieving a remarkable minimum reflection loss of−72.0 dB and an effective absorption bandwidth of 6.3 GHz when EM wave propagates parallel to the directional pores.Such performance benefits from the synergistic effects of macroporous architecture and compositional design.Although there is a directional dependence of EM absorption,radar stealth simulation demonstrates that these foams can still promise considerable reduction in radar cross section with the change of incident angle.Moreover,COMSOL simulation further identifies their good performance in preventing EM interference among different electronic components.展开更多
Designing materials with both structural load-bearing capacity and broadband electromagnetic(EM)wave absorption properties remains a significant challenge.In this work,SiOC/SiC/SiO_(2)composite with gyroid structures ...Designing materials with both structural load-bearing capacity and broadband electromagnetic(EM)wave absorption properties remains a significant challenge.In this work,SiOC/SiC/SiO_(2)composite with gyroid structures were prepared through digital light processing(DLP)3D printing,polymer-derived ceramics(PDCs),chemical vapor infiltration(CVI),and oxidation technologies.The incorporation of the CVISiC phase effectively increases the dissipation capability,while the synergistic interaction between the gyroid structure and SiO_(2)phase significantly improves impedance matching performance.The SiOC/SiC/SiO_(2)composite achieved a minimum reflection loss(RL min)of-62.2 d B at 4.3 mm,and the effective absorption bandwidth(EAB)covered the X-band,with a thickness range of 4.1 mm-4.65 mm.The CST simulation results explain the broadband and low-frequency absorption characteristics,with an EAB of 8.4 GHz(9.6-18 GHz)and an RL min of-21.5 dB at 5 GHz.The excellent EM wave attenuation performance is associated primarily with polarization loss,conduction loss,the gyroid structure's enhancement of multiple reflections and scattering of EM waves,and the resonance effect between the structural units.The SiOC/SiC/SiO_(2)composite also demonstrated strong mechanical properties,with a maximum compressive failure strength of 31.6 MPa in the height direction.This work opens novel prospects for the development of multifunctional structural wave-absorbing materials suitable for broadband microwave absorption and load-bearing properties.展开更多
The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-...The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.展开更多
Metal foams are a fascinating group of materials that possess distinct physicochEMIcal properties and interconnected strut features with high surface area-to-volume ratios, high specific strength and lightweight natur...Metal foams are a fascinating group of materials that possess distinct physicochEMIcal properties and interconnected strut features with high surface area-to-volume ratios, high specific strength and lightweight nature. These characteristics make them ideal for applications in vibration damping, heat insulation and weight reduction. In recent years, there has been increasing interest in the application of interfering energy conversion such as electromagnetic wave (EMW) and sound, where the metal foams could emerge as a solution. This paper will present a comprehensive review of the preparation methods as well as the interference energy converting mechanisms for metal foams. Typically, the progress and prospective aspects of metal foams for EMW absorption, electromagnetic interference (EMI) shielding and sound absorption have been emphasized. Through this review, we aspire to offer valuable insights for the development of multifunctional applications with metal foam materials.展开更多
The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly ...The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly favorable due to its retrofit viability.This review analyzes advancements in chemical absorption technologies specific to shipborne applications,focusing on absorbent development,absorption tower optimization,and system integration.This article begins with an overview of OCC principles and advantages,followed by a discussion of technological progress,including feasibility studies and project outcomes.It explores various chemical absorbents,assessing performance,degradation,and emissions.The structural configurations of absorption towers and their modeling techniques are examined,alongside challenges such as limited vessel space,energy constraints,and gas-liquid distribution inefficiencies.Future directions emphasize the need for innovative absorbent designs,advanced simulation for tower optimization,and enhanced integration with ship energy systems,including renewable energy and waste heat recovery.The potential for intelligent technologies to enable real-time monitoring and automated management of carbon capture systems is highlighted.Finally,further investigations into fundamental interfaces and reaction kinetics are essential for advancing shipborne carbon capture technologies,providing a crucial reference for researchers and practitioners in the field.展开更多
As electromagnetic pollution escalates and protection demands diversify,there is an urgent requirement for versatile carbon foam materials capable of absorbing electromagnetic waves(EMWs).Furthermore,the concern about...As electromagnetic pollution escalates and protection demands diversify,there is an urgent requirement for versatile carbon foam materials capable of absorbing electromagnetic waves(EMWs).Furthermore,the concern about global warming and the depletion of petrochemical resources calls for facile and eco-friendly methods for the large-scale production of multi-functional and biodegradable carbon foams.Herein,cornstraw-derived carbon foams(CCFs)integrating EMW absorption,sound absorption,and heat insulation were prepared by a facile dual-template strategy.Benefiting from the dual-template effect of air bubbles and ice crystals,the obtained foam manifests an ultra-low density of 31 mg/cm^(3),large poros-ity of 0.85 and also super-broad absorption with an effective absorption bandwidth(EAB)of 7.18 GHz at 3.6 mm,even beyond most carbon-based composite foams.Moreover,abundant pores also endow the foam with good thermal insulation performance(as low as 0.041 W/(m K))and high sound absorp-tion coefficient(0.8 at 1250-6000 Hz),which are equivalent to commercial foams.The excellent EMW absorption performance originates from conduction loss produced by the three-dimensional(3D)inter-connected network structure and also interfacial polarization and multiple scattering induced by porous structure.Additionally,the abundant closed pores in foam prevent thermal convection and thus provide good thermal-insulation performance,yet the opening pores proffer excellent sound absorption through resonance and friction absorption.This study provides new insights into the green synthesis of multi-functional microwave absorbing foam and also supplies a new thermal-insulation material for exterior walls of buildings exposed to electromagnetic environment.展开更多
The advancement of rail transportation necessitates energy absorption structures that not only ensure safety but also optimize space utilization,a critical yet often overlooked aspect in existing designs.This study pr...The advancement of rail transportation necessitates energy absorption structures that not only ensure safety but also optimize space utilization,a critical yet often overlooked aspect in existing designs.This study presents a compact energy absorption structure(CE)that integrates the advantages of cutting rings and thin-walled tube modules,offering a solution with the high space utilization and the superior crashworthiness.Through theoretical modeling and experimental validation using a drop-weight test system,we analyzed the dynamic response and energy absorption characteristics of the CE.Comparative analysis with existing structures,namely the cutting shear rings(CSR)energy absorption structure and thin-walled tube structure(TW),revealed that the CE significantly improves specific energy absorption(SEA)by 102.76%and 61.54%,respectively,and optimizes crush force efficiency(CFE)by increasing 8.23%and 5.49%compared to CSR and TW.The innovative design of the CE,featuring deformation gradient and delay response strategies,showcases its potential for practical application in engineering,advancing the field of crashworthiness engineering.展开更多
A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modifie...A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.展开更多
Carbon dioxide(CO_(2))is the predominant greenhouse gas in the Earth’s atmosphere and plays a crucial role in global warming.Given the inherent limitations of monoethanolamine absorbents in current commercial large-s...Carbon dioxide(CO_(2))is the predominant greenhouse gas in the Earth’s atmosphere and plays a crucial role in global warming.Given the inherent limitations of monoethanolamine absorbents in current commercial large-scale CO_(2)capture applications,amino acid ionic liquids(AAILs)have garnered extensive interest in this field due to their adjustable structure,low volatility,high thermal stability,and significant absorption capacity.However,the number of comprehensive reviews recently published on the CO_(2)absorption by AAILs remains limited.In addition,researchers have differing opinions on the AAILs/CO_(2)reaction mechanisms.Therefore,this review provides a thorough overview of the reaction mechanisms and structure-activity relationships associated with AAILs for CO_(2)capture.Moreover,it outlines the research advancements in pure AAILs and their mixtures,including aqueous AAILs and AAIL-organic solvent mixtures.The effects of varying ionic structures and additives on the absorption properties of AAILs are examined in detail.In conclusion,although AAILs exhibit high CO_(2)absorption loading and possess numerous appealing characteristics,further research is essential to comprehensively evaluate their viability for large-scale CO_(2)capture from flue gas.展开更多
Carbon fiber(CF)has shown excellent performance in the application of absorbing materials,with characteristics such as high dielectric loss,strong flexibility,and lightweight are considered to be the support for furth...Carbon fiber(CF)has shown excellent performance in the application of absorbing materials,with characteristics such as high dielectric loss,strong flexibility,and lightweight are considered to be the support for further development of CF based microwave absorbing materials.However,its single component,unstable structure,monotonous absorption mechanism,and impedance mismatch limit its ability to become a thin,light,wide,and strong absorbing material.In this study,we first proposed porous carbon fiber(PC)composite magnetic nanoparticles and a multi-layer core-shell fiber membrane coated with transition metal sulfides,demonstrating outstanding microwave absorption performance with a remarkable reflection loss of-65 dB.The excellent electromagnetic wave absorption performance mainly comes from the processes of electrical relaxation and magnetic relaxation.The electrical relaxation is attributed to the high graphitization of N-doped carbon fibers,while the magnetic relaxation is attributed to the hysteresis loss caused by the Fe_(3)O_(4)core.Considering the influence of the structure of the absorbent on absorption performance,we also constructed porous and heterogeneous layer coating structures to increase multiple reflections.Provided valuable solutions for addressing issues such as electromagnetic interference,electromagnetic radiation protection,signal isolation,and improving equipment electromagnetic compatibility.展开更多
Currently,carbon materials derived from biomass are widely sought after as electromagnetic absorbing(EMWA)materials owing to the unique structure,as well as the wide range of natural acquisition pathways,economic viab...Currently,carbon materials derived from biomass are widely sought after as electromagnetic absorbing(EMWA)materials owing to the unique structure,as well as the wide range of natural acquisition pathways,economic viability,and simple processing.However,due to the high dielectric properties,mismatched impedance and single attenuation mechanism,they cannot achieve efficient EMWA performance.Herein,the biomass carbon/Co/porous carbon magnetic composites with a layered gradient structure were fabricated by in-situ deposition of ZIF-67 on the lotus leaf base and then pyrolysis at high temperature.By adjusting the pyrolysis temperature,the sample obtained at 650℃ achieved a minimum reflection value(RLmin)of-34.2dB at a matching thickness of 2.6mm,and a maximum effective absorption bandwidth(EAB)of 7.12GHz.The results indicate that this magnetic composite with a multi-sized layered gradient porous structure has a good electron transport network,a large number of heterogeneous interfaces,and dipole polarization centers,which are conducive to multiple reflection and scattering of microwaves,conduction loss,interface loss,magnetic loss,and impedance matching of materials.Therefore,this work provided a reference for optimizing the EMWA performance of carbon materials and designing a layered gradient porous magnetic composite with multi-sized structure.展开更多
We present a theoretical investigation of the electromagnetically induced absorption(EIA)due to transfer of population(TOP)in the double two-level system(TLS).It shows that one TLS is responsible for the sub-natural a...We present a theoretical investigation of the electromagnetically induced absorption(EIA)due to transfer of population(TOP)in the double two-level system(TLS).It shows that one TLS is responsible for the sub-natural absorption part of EIA,and the other TLS is responsible for the natural absorption part of EIA.We propose a scheme in which the sub-natural absorption part of EIA is governed by the effect of coherent hole burning(CHB)and achieves an enhancement of at least two orders of magnitude with the detuned coupling field,while the natural absorption part is dominated by the effect of Mollow absorption(MA)and does not change with the detuned coupling field.Due to the effects of CHB and MA,the magnitude of four-wave mixing(FWM)achieves a significant increase for double TLS.We show in detail the evolution of the magnitude of the FWM signal with coupling detuning and Rabi frequency.It is demonstrated that strong resonances occur in the FWM profile at frequencies symmetrically displaced from the frequency of the coupling field by coupling detuning.展开更多
Three sets of MXene(Ti_(3)C_(2)T_(x))@nano-Fe_(1)Co_(0.8)Ni_(1)composites with 15,45,and 90 mg MXene were prepared by in-situ liquid-phase deposition to effectively investigate the impact of the relationship between M...Three sets of MXene(Ti_(3)C_(2)T_(x))@nano-Fe_(1)Co_(0.8)Ni_(1)composites with 15,45,and 90 mg MXene were prepared by in-situ liquid-phase deposition to effectively investigate the impact of the relationship between MXene(Ti_(3)C_(2)T_(x))and nano-Fe_(1)Co_(0.8)Ni_(1)magnetic particles on the electromagnetic absorption properties of the composites.The microstructure,static magnetic properties,and electromag-netic absorption performance of these composites were studied.Results indicate that the MXene@nano-Fe_(1)Co_(0.8)Ni_(1)composites were primarily composed of face-centered cubic crystal structure particles and MXene,with spherical Fe_(1)Co_(0.8)Ni_(1)particles uniformly distrib-uted on the surface of the multilayered MXene.The alloy particles had an average particle size of approximately 100 nm and exhibited good dispersion without noticeable particle aggregation.With the increase in MXene content,the specific saturation magnetic and coer-civity of the composite initially decreased and then increased,displaying typical soft magnetic properties.Compared with those of the Fe_(1)Co_(0.8)Ni_(1)magnetic alloy particles alone,MXene addition caused an increasing trend in the real and imaginary parts of the dielectric constant of the composite.Meanwhile,the real and imaginary parts of the magnetic permeability exhibit decreasing trend.With the in-crease in MXene addition,the material attenuation constant increased and the impedance matching decreased.The minimum reflection loss increased,and the maximum effective absorption bandwidth decreased.When the MXene addition was 90 mg,the composite exhib-ited a minimum reflection loss of-46.9 dB with a sample thickness of 1.1 mm and a maximum effective absorption bandwidth of 3.60 GHz with a sample thickness of 1.0 mm.The effective absorption bandwidth of the composites and their corresponding thicknesses showed a decreasing trend with the increase in MXene addition,reducing by 50%from 1.5 mm without MXene addition to 1 mm with 90 mg of MXene addition.展开更多
Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,how...Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.展开更多
Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR clo...Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR cloaking mechanisms and functional integration limitations.Here,we propose a multiscale hierarchical structure design,integrating wrinkled MXene IR shielding layer and flexible Fe_(3)O_(4)@C/PDMS microwave absorption layer.The top wrinkled MXene layer induces the intensive diffuse reflection effect,shielding IR radiation signals while allowing microwave to pass through.Meanwhile,the permeable microwaves are assimilated into the bottom Fe_(3)O_(4)@C/PDMS layer via strong magneto-electric synergy.Through theoretical and experimental optimization,the assembled stealth devices realize a near-perfect stealth capability in both X-band(8–12 GHz)and long-wave infrared(8–14μm)wavelength ranges.Specifically,it delivers a radar cross-section reduction of−20 dB m^(2),a large apparent temperature modulation range(ΔT=70℃),and a low average IR emissivity of 0.35.Additionally,the optimal device demonstrates exceptional curved surface conformability,self-cleaning capability(contact angle≈129°),and abrasion resistance(recovery time≈5 s).This design strategy promotes the development of multispectral stealth technology and reinforces its applicability and durability in complex and hostile environments.展开更多
基金granted by the National Key R&D Program of China(No.2024YFB3409900).
文摘The escalating demand for electromagnetic protection against increasingly severe electromagnetic pollution is making the development of advanced electromagnetic wave absorbing material systems imperative.MXene-based electromagnetic wave absorbing fillers demonstrate advantages of lightweight and high efficiency.However,their microscale dimensions hinder the formation of interconnected networks within matrices,resulting in limited electromagnetic(EM)loss mechanisms and narrow effective absorption bandwidths.Herein,we employ wet spinning combined with molten salt-assisted in-situ synthesis to fabricate MAX@rGO(rGMAX_(n))fibrous absorbers featuring a hierarchical structure of“columnar cactus covered with MAX spheres”.Precise regulation of MAX phase content enables controlled tuning of the electromagnetic properties of rGMAX_(n) fibers.Moreover,subsequent in-situ etching further enhances their EM performance,yielding MXene@rGO(rGMX_(n))fibers with a hierarchical structure of“columnar cactus decorated with MXene nanosheet clusters”.Freeze-drying is utilized to modulate fiber filling content,and fibrous felts with conductive networks are obtained,which exhibit excellent electromagnetic wave absorption performance.Among them,the as-prepared rGMX_(10) fibrous felt exhibits good electromagnetic wave absorption performance at a low filling content(10 wt.%)with the RL_(max) of 54.4 dB and an effective absorption bandwidth of 5.31 GHz.This enhancement originates from improved impedance matching characteristics through fiber-interconnected networks and multiple electromagnetic loss mechanisms enabled by the hierarchical structure.The strategy of in-situ growing hierarchical MXene@rGO fibers establishes a novel approach for developing MXene-based fibrous absorbing materials.
基金supported by the Khalifa University of Science and Technology internal grants(Nos.2021-CIRA-109,2020-CIRA-007,and 2020-CIRA-024).
文摘Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.
基金support provided by the Center for Fabrication and Application of Electronic Materials at Dokuz Eylül University,Türkiye。
文摘Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.
基金supported by the National Natural Science Foundation of China(No.52436008)the Inner Mongolia Science and Technology Projects,China(Nos.JMRHZX20210003 and 2023YFCY0009)+3 种基金the Huaneng Group Co Ltd.,China(No.HNKJ23-H50)the National Natural Science Foundation of China(No.22408044)the China Postdoctoral Science Foundation(No.2024M761877)the National Key R&D Program of China(No.SQ2024YFD2200039)。
文摘The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbide nanowires using lignite and waste silicon powder as raw materials through carbothermal reduction.The staggered structure of nanowires promotes the creation of interfacial polarization,impedance matching,and multiple loss mechanisms,leading to enhanced electromagnetic absorption performance.The silicon carbide nanowires demonstrate outstanding electromagnetic absorption capabilities with the minimum reflection loss of-48.09 d B at10.08 GHz and an effective absorption bandwidth(the reflection loss less than-10 d B)ranging from 8.54 to 16.68 GHz with a thickness of 2.17 mm.This research presents an innovative approach for utilizing solid waste in an environmentally friendly manner to produce broadband silicon carbide composite absorbers.
基金financially supported by the National Natural Science Foundation of China(Nos.22475057 and No.52373262).
文摘Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usually involves complex procedures and extremely depends on unidirectional freezing technique.Herein,we propose a groundbreaking approach that leverages the assemblies of salting-out protein induced by ammonium metatungstate(AM)as the precursor,and then acquire directional three-dimensional carbon-based foams through simple pyrolysis.The electrostatic interaction between AM and protein ensures well dispersion of WC_(1−x)nanoparticles on carbon frameworks.The content of WC_(1−x)nanoparticles can be rationally regulated by AM dosage,and it also affects the electromagnetic(EM)properties of final carbon-based foams.The optimized foam exhibits exceptional EM absorption performance,achieving a remarkable minimum reflection loss of−72.0 dB and an effective absorption bandwidth of 6.3 GHz when EM wave propagates parallel to the directional pores.Such performance benefits from the synergistic effects of macroporous architecture and compositional design.Although there is a directional dependence of EM absorption,radar stealth simulation demonstrates that these foams can still promise considerable reduction in radar cross section with the change of incident angle.Moreover,COMSOL simulation further identifies their good performance in preventing EM interference among different electronic components.
基金financially supported by National Natural Science Foundation of China(Grant Nos.12141203,52202083,W2421013)the Natural Science Foundation Project of Shaanxi Province(Grant No.2024JC-YBMS-450)+1 种基金the Sichuan Science and Technology Program(Grant No.2024YFHZ0265)the Open Project of High-end Equipment Advanced Materials and Manufacturing Technology Laboratory(Grant No.2023KFKT0005)。
文摘Designing materials with both structural load-bearing capacity and broadband electromagnetic(EM)wave absorption properties remains a significant challenge.In this work,SiOC/SiC/SiO_(2)composite with gyroid structures were prepared through digital light processing(DLP)3D printing,polymer-derived ceramics(PDCs),chemical vapor infiltration(CVI),and oxidation technologies.The incorporation of the CVISiC phase effectively increases the dissipation capability,while the synergistic interaction between the gyroid structure and SiO_(2)phase significantly improves impedance matching performance.The SiOC/SiC/SiO_(2)composite achieved a minimum reflection loss(RL min)of-62.2 d B at 4.3 mm,and the effective absorption bandwidth(EAB)covered the X-band,with a thickness range of 4.1 mm-4.65 mm.The CST simulation results explain the broadband and low-frequency absorption characteristics,with an EAB of 8.4 GHz(9.6-18 GHz)and an RL min of-21.5 dB at 5 GHz.The excellent EM wave attenuation performance is associated primarily with polarization loss,conduction loss,the gyroid structure's enhancement of multiple reflections and scattering of EM waves,and the resonance effect between the structural units.The SiOC/SiC/SiO_(2)composite also demonstrated strong mechanical properties,with a maximum compressive failure strength of 31.6 MPa in the height direction.This work opens novel prospects for the development of multifunctional structural wave-absorbing materials suitable for broadband microwave absorption and load-bearing properties.
基金National Natural Science Foundation of China(No.51705545)。
文摘The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.
基金supported by the National Natural Science Foundation of China(No.52271180)the Leading Goose R&D Program of Zhejiang Province(2022C01110).
文摘Metal foams are a fascinating group of materials that possess distinct physicochEMIcal properties and interconnected strut features with high surface area-to-volume ratios, high specific strength and lightweight nature. These characteristics make them ideal for applications in vibration damping, heat insulation and weight reduction. In recent years, there has been increasing interest in the application of interfering energy conversion such as electromagnetic wave (EMW) and sound, where the metal foams could emerge as a solution. This paper will present a comprehensive review of the preparation methods as well as the interference energy converting mechanisms for metal foams. Typically, the progress and prospective aspects of metal foams for EMW absorption, electromagnetic interference (EMI) shielding and sound absorption have been emphasized. Through this review, we aspire to offer valuable insights for the development of multifunctional applications with metal foam materials.
基金supported by the National Natural Science Foundation of China(51876118)。
文摘The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly favorable due to its retrofit viability.This review analyzes advancements in chemical absorption technologies specific to shipborne applications,focusing on absorbent development,absorption tower optimization,and system integration.This article begins with an overview of OCC principles and advantages,followed by a discussion of technological progress,including feasibility studies and project outcomes.It explores various chemical absorbents,assessing performance,degradation,and emissions.The structural configurations of absorption towers and their modeling techniques are examined,alongside challenges such as limited vessel space,energy constraints,and gas-liquid distribution inefficiencies.Future directions emphasize the need for innovative absorbent designs,advanced simulation for tower optimization,and enhanced integration with ship energy systems,including renewable energy and waste heat recovery.The potential for intelligent technologies to enable real-time monitoring and automated management of carbon capture systems is highlighted.Finally,further investigations into fundamental interfaces and reaction kinetics are essential for advancing shipborne carbon capture technologies,providing a crucial reference for researchers and practitioners in the field.
基金financially supported by the National Science Foundation of China(Nos.52362024,22004106,51872238 and 21806129)the Fundamental Research Funds for the Central Universities(Nos.3102018zy045 and 3102019AX11)+1 种基金the Shaanxi Excellent Young Talents Support Program for Universities(No.202120006)the Key Laboratory of Icing and Anti/Deicing of CARDC(IADL20220401).
文摘As electromagnetic pollution escalates and protection demands diversify,there is an urgent requirement for versatile carbon foam materials capable of absorbing electromagnetic waves(EMWs).Furthermore,the concern about global warming and the depletion of petrochemical resources calls for facile and eco-friendly methods for the large-scale production of multi-functional and biodegradable carbon foams.Herein,cornstraw-derived carbon foams(CCFs)integrating EMW absorption,sound absorption,and heat insulation were prepared by a facile dual-template strategy.Benefiting from the dual-template effect of air bubbles and ice crystals,the obtained foam manifests an ultra-low density of 31 mg/cm^(3),large poros-ity of 0.85 and also super-broad absorption with an effective absorption bandwidth(EAB)of 7.18 GHz at 3.6 mm,even beyond most carbon-based composite foams.Moreover,abundant pores also endow the foam with good thermal insulation performance(as low as 0.041 W/(m K))and high sound absorp-tion coefficient(0.8 at 1250-6000 Hz),which are equivalent to commercial foams.The excellent EMW absorption performance originates from conduction loss produced by the three-dimensional(3D)inter-connected network structure and also interfacial polarization and multiple scattering induced by porous structure.Additionally,the abundant closed pores in foam prevent thermal convection and thus provide good thermal-insulation performance,yet the opening pores proffer excellent sound absorption through resonance and friction absorption.This study provides new insights into the green synthesis of multi-functional microwave absorbing foam and also supplies a new thermal-insulation material for exterior walls of buildings exposed to electromagnetic environment.
基金Project(12272414)supported by the National Natural Science Foundation of ChinaProject(2023RC3045)supported by the Science and Technology Innovation Plan of Hunan Province,China。
文摘The advancement of rail transportation necessitates energy absorption structures that not only ensure safety but also optimize space utilization,a critical yet often overlooked aspect in existing designs.This study presents a compact energy absorption structure(CE)that integrates the advantages of cutting rings and thin-walled tube modules,offering a solution with the high space utilization and the superior crashworthiness.Through theoretical modeling and experimental validation using a drop-weight test system,we analyzed the dynamic response and energy absorption characteristics of the CE.Comparative analysis with existing structures,namely the cutting shear rings(CSR)energy absorption structure and thin-walled tube structure(TW),revealed that the CE significantly improves specific energy absorption(SEA)by 102.76%and 61.54%,respectively,and optimizes crush force efficiency(CFE)by increasing 8.23%and 5.49%compared to CSR and TW.The innovative design of the CE,featuring deformation gradient and delay response strategies,showcases its potential for practical application in engineering,advancing the field of crashworthiness engineering.
基金Science and Technology Plan Project of Xizang Autonomous Region,China under Grant No.XZ202501YD0007。
文摘A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.
基金supported by the Natural Science Foundation of Shanghai(Grant No.24ZR1426200)the support from the Key Program of the National Natural Science Foundation of China(Grant No.52236004)。
文摘Carbon dioxide(CO_(2))is the predominant greenhouse gas in the Earth’s atmosphere and plays a crucial role in global warming.Given the inherent limitations of monoethanolamine absorbents in current commercial large-scale CO_(2)capture applications,amino acid ionic liquids(AAILs)have garnered extensive interest in this field due to their adjustable structure,low volatility,high thermal stability,and significant absorption capacity.However,the number of comprehensive reviews recently published on the CO_(2)absorption by AAILs remains limited.In addition,researchers have differing opinions on the AAILs/CO_(2)reaction mechanisms.Therefore,this review provides a thorough overview of the reaction mechanisms and structure-activity relationships associated with AAILs for CO_(2)capture.Moreover,it outlines the research advancements in pure AAILs and their mixtures,including aqueous AAILs and AAIL-organic solvent mixtures.The effects of varying ionic structures and additives on the absorption properties of AAILs are examined in detail.In conclusion,although AAILs exhibit high CO_(2)absorption loading and possess numerous appealing characteristics,further research is essential to comprehensively evaluate their viability for large-scale CO_(2)capture from flue gas.
基金supported by the Natural Science Foundation of Shaanxi(2024JC-YBQN-0442)the Scientific Research Program Funded by Education Department of Shaanxi Provincial Government(24JR117)。
文摘Carbon fiber(CF)has shown excellent performance in the application of absorbing materials,with characteristics such as high dielectric loss,strong flexibility,and lightweight are considered to be the support for further development of CF based microwave absorbing materials.However,its single component,unstable structure,monotonous absorption mechanism,and impedance mismatch limit its ability to become a thin,light,wide,and strong absorbing material.In this study,we first proposed porous carbon fiber(PC)composite magnetic nanoparticles and a multi-layer core-shell fiber membrane coated with transition metal sulfides,demonstrating outstanding microwave absorption performance with a remarkable reflection loss of-65 dB.The excellent electromagnetic wave absorption performance mainly comes from the processes of electrical relaxation and magnetic relaxation.The electrical relaxation is attributed to the high graphitization of N-doped carbon fibers,while the magnetic relaxation is attributed to the hysteresis loss caused by the Fe_(3)O_(4)core.Considering the influence of the structure of the absorbent on absorption performance,we also constructed porous and heterogeneous layer coating structures to increase multiple reflections.Provided valuable solutions for addressing issues such as electromagnetic interference,electromagnetic radiation protection,signal isolation,and improving equipment electromagnetic compatibility.
基金supported by the National Natural Science Foundation of China(Nos.21667019,22066017,and 52173267)the Aviation Science Foundation of China(No.2017ZF56020).
文摘Currently,carbon materials derived from biomass are widely sought after as electromagnetic absorbing(EMWA)materials owing to the unique structure,as well as the wide range of natural acquisition pathways,economic viability,and simple processing.However,due to the high dielectric properties,mismatched impedance and single attenuation mechanism,they cannot achieve efficient EMWA performance.Herein,the biomass carbon/Co/porous carbon magnetic composites with a layered gradient structure were fabricated by in-situ deposition of ZIF-67 on the lotus leaf base and then pyrolysis at high temperature.By adjusting the pyrolysis temperature,the sample obtained at 650℃ achieved a minimum reflection value(RLmin)of-34.2dB at a matching thickness of 2.6mm,and a maximum effective absorption bandwidth(EAB)of 7.12GHz.The results indicate that this magnetic composite with a multi-sized layered gradient porous structure has a good electron transport network,a large number of heterogeneous interfaces,and dipole polarization centers,which are conducive to multiple reflection and scattering of microwaves,conduction loss,interface loss,magnetic loss,and impedance matching of materials.Therefore,this work provided a reference for optimizing the EMWA performance of carbon materials and designing a layered gradient porous magnetic composite with multi-sized structure.
基金supported by the Open Subject of the State Key Laboratory of Quantum Optics Technologies and Devices(Grant No.KF202209)。
文摘We present a theoretical investigation of the electromagnetically induced absorption(EIA)due to transfer of population(TOP)in the double two-level system(TLS).It shows that one TLS is responsible for the sub-natural absorption part of EIA,and the other TLS is responsible for the natural absorption part of EIA.We propose a scheme in which the sub-natural absorption part of EIA is governed by the effect of coherent hole burning(CHB)and achieves an enhancement of at least two orders of magnitude with the detuned coupling field,while the natural absorption part is dominated by the effect of Mollow absorption(MA)and does not change with the detuned coupling field.Due to the effects of CHB and MA,the magnitude of four-wave mixing(FWM)achieves a significant increase for double TLS.We show in detail the evolution of the magnitude of the FWM signal with coupling detuning and Rabi frequency.It is demonstrated that strong resonances occur in the FWM profile at frequencies symmetrically displaced from the frequency of the coupling field by coupling detuning.
文摘Three sets of MXene(Ti_(3)C_(2)T_(x))@nano-Fe_(1)Co_(0.8)Ni_(1)composites with 15,45,and 90 mg MXene were prepared by in-situ liquid-phase deposition to effectively investigate the impact of the relationship between MXene(Ti_(3)C_(2)T_(x))and nano-Fe_(1)Co_(0.8)Ni_(1)magnetic particles on the electromagnetic absorption properties of the composites.The microstructure,static magnetic properties,and electromag-netic absorption performance of these composites were studied.Results indicate that the MXene@nano-Fe_(1)Co_(0.8)Ni_(1)composites were primarily composed of face-centered cubic crystal structure particles and MXene,with spherical Fe_(1)Co_(0.8)Ni_(1)particles uniformly distrib-uted on the surface of the multilayered MXene.The alloy particles had an average particle size of approximately 100 nm and exhibited good dispersion without noticeable particle aggregation.With the increase in MXene content,the specific saturation magnetic and coer-civity of the composite initially decreased and then increased,displaying typical soft magnetic properties.Compared with those of the Fe_(1)Co_(0.8)Ni_(1)magnetic alloy particles alone,MXene addition caused an increasing trend in the real and imaginary parts of the dielectric constant of the composite.Meanwhile,the real and imaginary parts of the magnetic permeability exhibit decreasing trend.With the in-crease in MXene addition,the material attenuation constant increased and the impedance matching decreased.The minimum reflection loss increased,and the maximum effective absorption bandwidth decreased.When the MXene addition was 90 mg,the composite exhib-ited a minimum reflection loss of-46.9 dB with a sample thickness of 1.1 mm and a maximum effective absorption bandwidth of 3.60 GHz with a sample thickness of 1.0 mm.The effective absorption bandwidth of the composites and their corresponding thicknesses showed a decreasing trend with the increase in MXene addition,reducing by 50%from 1.5 mm without MXene addition to 1 mm with 90 mg of MXene addition.
基金financially supported by the National Natural Science Foundation of China(Grants nos.62201411,62371378,22205168,52302150 and 62304171)the China Postdoctoral Science Foundation(2022M722500)+1 种基金the Fundamental Research Funds for the Central Universities(Grants nos.ZYTS2308 and 20103237929)Startup Foundation of Xidian University(10251220001).
文摘Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.
基金financial support from the National Nature Science Foundation of China(No.52273247)the National Science and Technology Major Project of China(J2019-VI-0017-0132).
文摘Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR cloaking mechanisms and functional integration limitations.Here,we propose a multiscale hierarchical structure design,integrating wrinkled MXene IR shielding layer and flexible Fe_(3)O_(4)@C/PDMS microwave absorption layer.The top wrinkled MXene layer induces the intensive diffuse reflection effect,shielding IR radiation signals while allowing microwave to pass through.Meanwhile,the permeable microwaves are assimilated into the bottom Fe_(3)O_(4)@C/PDMS layer via strong magneto-electric synergy.Through theoretical and experimental optimization,the assembled stealth devices realize a near-perfect stealth capability in both X-band(8–12 GHz)and long-wave infrared(8–14μm)wavelength ranges.Specifically,it delivers a radar cross-section reduction of−20 dB m^(2),a large apparent temperature modulation range(ΔT=70℃),and a low average IR emissivity of 0.35.Additionally,the optimal device demonstrates exceptional curved surface conformability,self-cleaning capability(contact angle≈129°),and abrasion resistance(recovery time≈5 s).This design strategy promotes the development of multispectral stealth technology and reinforces its applicability and durability in complex and hostile environments.
