The growing complexity of electromagnetic(EM)interference has driven significant demand for next-generation absorbers that combine lightweight,flexibility,and good electromagnetic attenuation capability.The low-dimens...The growing complexity of electromagnetic(EM)interference has driven significant demand for next-generation absorbers that combine lightweight,flexibility,and good electromagnetic attenuation capability.The low-dimensional ternary Co_(3)ZnC/Co/CNT composites with hollow structures have been synthesized through in-situ polymerization and high-temperature carbonization.The unique integration of low-dimensional nanostructures and multicomponent heterointerfaces confers exceptional EM absorption properties,achieving a reflection loss of−70.0 dB and significantly reducing radar cross section(RCS)scattering signals.It is particularly meaningful that the numerical simulation of Co_(3)ZnC/Co/CNT metama-terial reveals ultrawideband absorption performance,achieving 10.7 GHz(7.3-18.0 GHz)at a thickness of 4.5 mm and extending to 15 GHz(3.0-18.0 GHz)with a 10.5 mm.Moreover,the Co_(3)ZnC/Co/CNT composites retain meritorious EM absorption properties after flexible film formation,broadening their usability and application scope.These investigations will provide seminal insights encompassing theoretical validation,experimental synthesis,and practical application for the next generation of absorbers.展开更多
Manipulation of electromagnetic waves is essential to various microwave applications,and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials(RAM)can bring new solutions to broa...Manipulation of electromagnetic waves is essential to various microwave applications,and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials(RAM)can bring new solutions to broadband electromagnetic stealth.The microwave transmission method is used to measure the physical parameters of the plasma unit.The designed structure exhibits superior absorption performance and radar cross-section(RCS)reduction capability in the 2–18 GHz band,with unique absorption advantage in the S and C frequency bands.It is found that the combination of the plasma and the RAM can significantly broaden the absorption frequency band and improve the absorption performance with excellent synergistic stealth capability.Experimental and simulation results present that broadband,wide-angle,tunable electromagnetic wave absorption and RCS reduction can be achieved by adjusting the spatial layout of the combined plasma layer and the type of RAMs,which creates opportunities for microwave transmission and selective stealth of equipment.Therefore,the wave manipulation by combined plasma array and RAM provides a valuable reference for developing numerous applications,including radar antenna stealth,spatial filter,and high power microwave shielding.展开更多
Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination environment.Nonetheless,the synthesis of an atomically precise low-coordination single-atom...Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination environment.Nonetheless,the synthesis of an atomically precise low-coordination single-atom catalyst remains a grand challenge.Herein,we report a coordinately unsaturated Ni-N_(3)single-atom electrocatalyst using a metal-organic framework(MOF)derived N-C support with abundant exposed N for excellent electrochemical CO_(2)reduction.The obtained Ni-N_(3)/NC active site exhibited highly efficient CO_(2)-to-CO conversion with a Faradaic efficiency of 94.6%at the current density of 100 mA/cm^(2).In situ X-ray absorption spectroscopy(XAS)measurement suggested that the Ni atomic center with unsaturated coordination had the lower initial chemical state and higher charge transfer ability.In situ Fourier transform infrared(FT-IR)and theoretical calculation results revealed that the unsaturated catalytically active center could facilitate activation of CO_(2)and thus heighten CO_(2)electroreduction activity.These findings provided insights into the rational design of definitive coordination structure of SACs for boosting activity and selectivity.展开更多
基金supported by the National University of Defense Technology Independent Innovation Science Fund(Nos.24-ZZCXJDZ-42 and XJJC2024088)Hefei Municipal Natural Science Foundation(No.K130936103)The authors extend their gratitude to Ms.Zhang from Scientific Compass(www.shiyanjia.com)for providing invaluable assistance.
文摘The growing complexity of electromagnetic(EM)interference has driven significant demand for next-generation absorbers that combine lightweight,flexibility,and good electromagnetic attenuation capability.The low-dimensional ternary Co_(3)ZnC/Co/CNT composites with hollow structures have been synthesized through in-situ polymerization and high-temperature carbonization.The unique integration of low-dimensional nanostructures and multicomponent heterointerfaces confers exceptional EM absorption properties,achieving a reflection loss of−70.0 dB and significantly reducing radar cross section(RCS)scattering signals.It is particularly meaningful that the numerical simulation of Co_(3)ZnC/Co/CNT metama-terial reveals ultrawideband absorption performance,achieving 10.7 GHz(7.3-18.0 GHz)at a thickness of 4.5 mm and extending to 15 GHz(3.0-18.0 GHz)with a 10.5 mm.Moreover,the Co_(3)ZnC/Co/CNT composites retain meritorious EM absorption properties after flexible film formation,broadening their usability and application scope.These investigations will provide seminal insights encompassing theoretical validation,experimental synthesis,and practical application for the next generation of absorbers.
基金supported by National Natural Science Foundation of China(No.51907198)Natural Science Research Foundation of Anhui Province(No.1908085MF205)+1 种基金Director Fund of State Key Laboratory of Pulsed Power Laser Technology(Nos.SKL2021ZR07,SKL2021ZR06)China Postdoctoral Science Foundation(No.2021MD703944).
文摘Manipulation of electromagnetic waves is essential to various microwave applications,and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials(RAM)can bring new solutions to broadband electromagnetic stealth.The microwave transmission method is used to measure the physical parameters of the plasma unit.The designed structure exhibits superior absorption performance and radar cross-section(RCS)reduction capability in the 2–18 GHz band,with unique absorption advantage in the S and C frequency bands.It is found that the combination of the plasma and the RAM can significantly broaden the absorption frequency band and improve the absorption performance with excellent synergistic stealth capability.Experimental and simulation results present that broadband,wide-angle,tunable electromagnetic wave absorption and RCS reduction can be achieved by adjusting the spatial layout of the combined plasma layer and the type of RAMs,which creates opportunities for microwave transmission and selective stealth of equipment.Therefore,the wave manipulation by combined plasma array and RAM provides a valuable reference for developing numerous applications,including radar antenna stealth,spatial filter,and high power microwave shielding.
基金supported by Guangdong Basic and Applied Basic Research Foundation(No.2022A1515011828)Natural Science Foundation of Guangdong Province(No.2022A1515012661)+4 种基金the National Key R&D Program of China(Nos.2021YFA1600800 and 2020YFA0710203)the National Natural Science Foundation of China(Nos.12025505,22179125,22002147,22106126,and 12205304)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0450200)the Youth Innovation Promotion Association CAS(Nos.2015366 and 2022458)the Collaborative Innovation Program of Hefei Science Center,CAS(No.2021HSC-CIP006).
文摘Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination environment.Nonetheless,the synthesis of an atomically precise low-coordination single-atom catalyst remains a grand challenge.Herein,we report a coordinately unsaturated Ni-N_(3)single-atom electrocatalyst using a metal-organic framework(MOF)derived N-C support with abundant exposed N for excellent electrochemical CO_(2)reduction.The obtained Ni-N_(3)/NC active site exhibited highly efficient CO_(2)-to-CO conversion with a Faradaic efficiency of 94.6%at the current density of 100 mA/cm^(2).In situ X-ray absorption spectroscopy(XAS)measurement suggested that the Ni atomic center with unsaturated coordination had the lower initial chemical state and higher charge transfer ability.In situ Fourier transform infrared(FT-IR)and theoretical calculation results revealed that the unsaturated catalytically active center could facilitate activation of CO_(2)and thus heighten CO_(2)electroreduction activity.These findings provided insights into the rational design of definitive coordination structure of SACs for boosting activity and selectivity.
