Heterojunction and morphology control assume a significant part in adjusting the intrinsic electromagnetic properties of absorbers to acquire outstanding microwave absorption(MA)performance,but this still faces huge c...Heterojunction and morphology control assume a significant part in adjusting the intrinsic electromagnetic properties of absorbers to acquire outstanding microwave absorption(MA)performance,but this still faces huge challenges.Herein,FeS_(2)/C/MoS_(2)composite with core–shell structure was successfully designed and prepared via a multi-interface engineering.MoS_(2)nanosheets with 1T and 2H phases are coated on the outside of FeS_(2)/C to form a porous interconnected structure that can optimize the impedance matching characteristics and strengthen the interfacial polarization loss capacity.Remarkably,as-fabricated FCM-3 harvests a broad effective absorption bandwidth(EAB)of 5.12 GHz and a minimum reflection loss(RL_(min))value of-45.1 d B.Meanwhile,FCM-3 can accomplish a greatest radar cross section(RCS)reduction value of 18.52 d B m^(2)when the detection angle is 0°.Thus,the convenient computer simulation technology(CST)simulations and encouraging accomplishments provide a novel avenue for the further development of efficient and lightweight MA materials.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
Two-dimensional transition metal carbides and nitrides(MXene)have emerged as promising candidates for microwave absorption(MA)materials.However,they also have some drawbacks,such as poor impedance matching,high self-s...Two-dimensional transition metal carbides and nitrides(MXene)have emerged as promising candidates for microwave absorption(MA)materials.However,they also have some drawbacks,such as poor impedance matching,high self-stacking tendency,and high density.To tackle these challenges,MXene nanosheets were incorporated into polyacrylonitrile(PAN)nanofibers and subsequently assembled into a three-dimensional(3D)network structure through PAN carbonization,yielding MXene/C aerogels.The 3D network effectively extends the path of microcurrent transmission,leading to enhanced conductive loss of electromagnetic(EM)waves.Moreover,the aerogel’s rich pore structure significantly improves the impedance matching while effectively reducing the density of the MXenebased absorbers.EM parameter analysis shows that the MXene/C aerogels exhibit a minimum reflection loss(RL_(min))value of−53.02 dB(f=4.44 GHz,t=3.8 mm),and an effective absorption bandwidth(EAB)of 5.3 GHz(t=2.4 mm,7.44–12.72 GHz).Radar cross-sectional(RCS)simulations were employed to assess the radar stealth effect of the aerogels,revealing that the maximum RCS reduction value of the perfect electric conductor covered by the MXene/C aerogel reaches 12.02 dB m^(2).In addition to the MA performance,the MXene/C aerogel also demonstrates good thermal insulation performance,and a 5-mm-thick aerogel can generate a temperature gradient of over 30℃ at 82℃.This study provides a feasible design approach for creating lightweight,efficient,and multifunctional MXene-based MA materials.展开更多
The development of multifunctional composites with desirable electromagnetic wave absorption and antibacterial performance for the medical field has aroused wide interest.In this work,SioC/Ag composites were successfu...The development of multifunctional composites with desirable electromagnetic wave absorption and antibacterial performance for the medical field has aroused wide interest.In this work,SioC/Ag composites were successfully fabricated via the liquid-phase method.When the filler content of SiOC/Ag-3 is 40wt%,SiOC/Ag-3exhibits excellent electromagnetic wave absorption performance,achieving a minimum reflection loss(RL_(min))value of-58.03 dB with a matching thickness of only 2.82 mm.The superior electromagnetic wave absorption performance is attributed to(i)multiple reflections,(ii)conductive loss,and(iii)interfacial polarization loss.In addition,the radar cross-section(RCS)simulation indicates that all RCS values of the perfect electric conductor(PEC)with the SioC/Ag-3 coating are below-20 dB-m^(2)across the incident angle range from-60°to 60,indicating strong radar stealth performance.Moreover,SiOC/Ag composites also achieve excellent antibacterial ability against E.coli and S.aureus through the generation of reactive oxygen species(ROS)under visible light irradiation.This work provides new insights into the design and development of bifunctional composites with electromagnetic wave absorption and antibacterial performancefor application in medical devices.展开更多
Developing low density and efficient dielectric loss materials has become a research hotspot,which can greatly meet the demands of modern radars and settle the problem of electromagnetic wave pollution.Herein,a series...Developing low density and efficient dielectric loss materials has become a research hotspot,which can greatly meet the demands of modern radars and settle the problem of electromagnetic wave pollution.Herein,a series of N-doped ordered mesoporous carbon(OMC)materials with different nitrogen content were prepared via a modified self-assembly method and defect engineering in subsequent calcination treatment.It was discovered that the content and type of nitrogen doping can be effectively modulated by the amount of precursor dicyandiamide,resulting in the changes in porous structure,carbon defects,electromagnetic properties,microwave absorption(MA)performance and radar cross section(RCS)reduction values.Remarkably,as-fabricated OMC/N2.5 displays ideal MA performance,whose minimum reflection loss(RL(min))value reaches−35.3 dB at 7.76 GHz(3.0 mm)and its effective absorption bandwidth reaches 3.52 GHz(10.64-14.16 GHz,2.0 mm).Furthermore,the optimal RCS reduction values can be obtained as 12.01 dB·m^(2) when the detection theta is 30°,which validly reduces the chances of being detected by radar.Thus,this work opens up a novel way for the development of lightweight and high-efficiency MA materials.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52402354,62174016 and 12374394)China Postdoctoral Science Foundation(Nos.2023M740471)the Natural Science Foundation of Jiangsu Higher Education Institutions(Nos.24KJB430002)。
文摘Heterojunction and morphology control assume a significant part in adjusting the intrinsic electromagnetic properties of absorbers to acquire outstanding microwave absorption(MA)performance,but this still faces huge challenges.Herein,FeS_(2)/C/MoS_(2)composite with core–shell structure was successfully designed and prepared via a multi-interface engineering.MoS_(2)nanosheets with 1T and 2H phases are coated on the outside of FeS_(2)/C to form a porous interconnected structure that can optimize the impedance matching characteristics and strengthen the interfacial polarization loss capacity.Remarkably,as-fabricated FCM-3 harvests a broad effective absorption bandwidth(EAB)of 5.12 GHz and a minimum reflection loss(RL_(min))value of-45.1 d B.Meanwhile,FCM-3 can accomplish a greatest radar cross section(RCS)reduction value of 18.52 d B m^(2)when the detection angle is 0°.Thus,the convenient computer simulation technology(CST)simulations and encouraging accomplishments provide a novel avenue for the further development of efficient and lightweight MA materials.
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supported by the National Natural Science Foundation of China(52171033)the Natural Science Foundation of Jiangsu Province(No.BK20201283).
文摘Two-dimensional transition metal carbides and nitrides(MXene)have emerged as promising candidates for microwave absorption(MA)materials.However,they also have some drawbacks,such as poor impedance matching,high self-stacking tendency,and high density.To tackle these challenges,MXene nanosheets were incorporated into polyacrylonitrile(PAN)nanofibers and subsequently assembled into a three-dimensional(3D)network structure through PAN carbonization,yielding MXene/C aerogels.The 3D network effectively extends the path of microcurrent transmission,leading to enhanced conductive loss of electromagnetic(EM)waves.Moreover,the aerogel’s rich pore structure significantly improves the impedance matching while effectively reducing the density of the MXenebased absorbers.EM parameter analysis shows that the MXene/C aerogels exhibit a minimum reflection loss(RL_(min))value of−53.02 dB(f=4.44 GHz,t=3.8 mm),and an effective absorption bandwidth(EAB)of 5.3 GHz(t=2.4 mm,7.44–12.72 GHz).Radar cross-sectional(RCS)simulations were employed to assess the radar stealth effect of the aerogels,revealing that the maximum RCS reduction value of the perfect electric conductor covered by the MXene/C aerogel reaches 12.02 dB m^(2).In addition to the MA performance,the MXene/C aerogel also demonstrates good thermal insulation performance,and a 5-mm-thick aerogel can generate a temperature gradient of over 30℃ at 82℃.This study provides a feasible design approach for creating lightweight,efficient,and multifunctional MXene-based MA materials.
基金supported by the Science Foundation of Jiangxi Provincial Department of Education(No.GJ2400915)the Early Career Youth Science and Technology Talent Training Project of Jiangxi Province(No.20244BCE52206)the National Natural Science Foundation of China(No.52360018).
文摘The development of multifunctional composites with desirable electromagnetic wave absorption and antibacterial performance for the medical field has aroused wide interest.In this work,SioC/Ag composites were successfully fabricated via the liquid-phase method.When the filler content of SiOC/Ag-3 is 40wt%,SiOC/Ag-3exhibits excellent electromagnetic wave absorption performance,achieving a minimum reflection loss(RL_(min))value of-58.03 dB with a matching thickness of only 2.82 mm.The superior electromagnetic wave absorption performance is attributed to(i)multiple reflections,(ii)conductive loss,and(iii)interfacial polarization loss.In addition,the radar cross-section(RCS)simulation indicates that all RCS values of the perfect electric conductor(PEC)with the SioC/Ag-3 coating are below-20 dB-m^(2)across the incident angle range from-60°to 60,indicating strong radar stealth performance.Moreover,SiOC/Ag composites also achieve excellent antibacterial ability against E.coli and S.aureus through the generation of reactive oxygen species(ROS)under visible light irradiation.This work provides new insights into the design and development of bifunctional composites with electromagnetic wave absorption and antibacterial performancefor application in medical devices.
基金support by National Natural Science Foundation of China(NSFC)(Grant Nos.62174016)Suzhou Science and Technology Project(Grant No.SZS2020313)Jiangsu Province International Science and Technology Cooperation Project(Grant Nos.BZ2021023)and Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Developing low density and efficient dielectric loss materials has become a research hotspot,which can greatly meet the demands of modern radars and settle the problem of electromagnetic wave pollution.Herein,a series of N-doped ordered mesoporous carbon(OMC)materials with different nitrogen content were prepared via a modified self-assembly method and defect engineering in subsequent calcination treatment.It was discovered that the content and type of nitrogen doping can be effectively modulated by the amount of precursor dicyandiamide,resulting in the changes in porous structure,carbon defects,electromagnetic properties,microwave absorption(MA)performance and radar cross section(RCS)reduction values.Remarkably,as-fabricated OMC/N2.5 displays ideal MA performance,whose minimum reflection loss(RL(min))value reaches−35.3 dB at 7.76 GHz(3.0 mm)and its effective absorption bandwidth reaches 3.52 GHz(10.64-14.16 GHz,2.0 mm).Furthermore,the optimal RCS reduction values can be obtained as 12.01 dB·m^(2) when the detection theta is 30°,which validly reduces the chances of being detected by radar.Thus,this work opens up a novel way for the development of lightweight and high-efficiency MA materials.
