Electromagnetic wave(EMW)absorbers with anti-corrosion property are highly desired to enhance the durability of military targets in harsh condition.Herein,cross-link NiAl-layered double hydroxide(NiAl-LDH)nanosheets o...Electromagnetic wave(EMW)absorbers with anti-corrosion property are highly desired to enhance the durability of military targets in harsh condition.Herein,cross-link NiAl-layered double hydroxide(NiAl-LDH)nanosheets on the inner/outer surfaces of carbon microtubes(CMTs)are ingeniously constructed through the combination of atomic layer deposition technique and a hydrothermal method.The obtained NiAl-LDH/CMT composite exhibits excellent EMW absorption and corrosion resistance performance.The large internal cavity of CMT significantly enhances impedance matching.The uniform distribution of NiAl-LDH nanosheets on both the inner and outer surfaces of CMT generates numerous heterogeneous inter-faces that induce substantial polarization loss.Consequently,at a filler rate of only 5 wt.%,the NiAl-LDH/CMT composite exhibits a minimum reflection loss of−60.2 dB and a maximum effective absorp-tion bandwidth of 5.9 GHz.In addition,the combined high impermeability of CMT and the effective Cl^(-)-trapping ability of NiAl-LDH endows NiAl-LDH/CMT composite with outstanding corrosion protection property in simulated seawater environment.Furthermore,the PO_(4)^(3-)anions are effectively incorporated into the NiAl-LDH interlayer via anion exchange,which can further enhance corrosion protection capac-ity through surface inactivation from slow-release PO_(4)^(3-)anions without reducing their EMW absorption performance.In summary,this work can give guidance for the development of efficient anti-corrosion EMW absorption materials.展开更多
The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-perform...The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-performance MAMs,little attention was paid to their absorption frequency regulation to respond to variable input frequencies and their stability and durability to cope with complex environments.Here,a highly compressible polyimide-packaging carbon nanocoils/carbon foam(PI@CNCs/CF)fabricated by a facile vacuum impregnation method is reported to be used as a dynamically frequency-tunable and environmentally stable microwave absorber.PI@CNCs/CF exhibits good structural stability and mechanical properties,which allows precise absorption frequency tuning by simply changing its compression ratio.For the first time,the tunable effective absorption bandwidth can cover the whole test frequency band(2−18 GHz)with the broadest effective absorption bandwidth of 10.8 GHz and the minimum reflection loss of−60.5 dB.Moreover,PI@CNCs/CF possesses excellent heat insulation,infrared stealth,self-cleaning,flame retardant,and acid-alkali corrosion resistance,which endows it high reliability even under various harsh environments and repeated compression testing.The frequency-tunable mechanism is elucidated by combining experiment and simulation results,possibly guiding in designing dynamically frequency-tunable MAMs with good environmental stability in the future.展开更多
For harsh real-world service settings,it is essential to build corrosion-resistant,diverse,and effective microwave absorbers.Herein,we successfully prepared a 3D NiAl-layered double hydroxide/carbon nanofibers(NiAl-LD...For harsh real-world service settings,it is essential to build corrosion-resistant,diverse,and effective microwave absorbers.Herein,we successfully prepared a 3D NiAl-layered double hydroxide/carbon nanofibers(NiAl-LDH/CNFs)composite material as an anticorrosive microwave absorber assisted by an atomic layer deposition(ALD)method.The size,coating thickness,and content of NiAl-LDH can be readily adjusted by changing the ALD cycling numbers.The optimized NiAl-LDH/CNFs demonstrates prominent microwave absorbing properties including the strongest reflection loss of–55.65 dB and the widest effective absorption bandwidth of 4.80 GHz with only 15 wt%loading.The reasons for performance improvement are the cooperative effect of interfacial polarization loss,conduction loss,and three-dimensional porous structure.Moreover,due to the synergistic effects between the excellent impermeability of CNFs and the trapping ability of NiAl-LDH for chloride ions,NiAl-LDH/CNFs exhibits strong corrosion resistances under acidic,neutral,and alkaline conditions.NiAl-LDH/CNFs should be a potential candidate to simultaneously use for microwave absorption and corrosion resistance,and this work provides a certain guiding significance for designing microwave absorbers that satisfy the corrosion resistance.展开更多
Two key limitations affecting the commercial application of carbon foams for fast clean-up of varied oils are the complex synthesis process and poor mechanical stability.In this work,an effective method is reported to...Two key limitations affecting the commercial application of carbon foams for fast clean-up of varied oils are the complex synthesis process and poor mechanical stability.In this work,an effective method is reported to fabricate the efficient oil-absorbing materials(CSF@MCF)of carbon spiral fibers(CSFs)anchored on melamine carbon foam(MCF)with superior mechanical properties and excellent photothermal con-version.The interwoven CSFs can not only provide extra rigidity but also reduce the stress concentration of the carbon skeleton,which greatly improves the mechanical properties with 6.3 times maximum compression stress and 4.5 times ultimate tensile strength than MCF.In addition,the pure carbon component can reduce the interface resistance and excite the free electrons more easily,thus realizing high-efficiency photothermal conversion in a wide range of wavelengths.Under light irradiation,the CSF@MCF can be quickly heated up to 70℃and achieve ultra-high absorption of crude oil,up to 62 g g_(-1),due to its low density and large absorption volume.Meanwhile,the CSF@MCF exhibits impressive absorption stability with persistent superhydrophobicity and a high recovery efficiency of over 85%.Superadding its simple preparation process,low production cost,and excellent acid-alkali resistance,the CSF@MCF shows great commercial potential for effectively absorbing varied oils.展开更多
Microwave absorption(MA)materials possessing multifunctional capabilities are increasingly imperative to meet the demanding requirements of complex service environments,particularly those prone to biofouling.Conventio...Microwave absorption(MA)materials possessing multifunctional capabilities are increasingly imperative to meet the demanding requirements of complex service environments,particularly those prone to biofouling.Conventional MA materials,however,have predominantly focused on achieving high absorption performance while largely overlooking the essential aspect of anti-biofouling properties.Herein,we rationally construct core-shell Cu/ZnO arrays(Cu/ZnO_(ars))hybrid nanostructures on carbon foam(CF)to achieve enhanced MA performance and antibiofouling property.The unique porous architecture of CF is conducive to its absorption of the energy carried by electromagnetic waves through multiple reflections and scattering.Additionally,Cu/ZnO_(ars) with abundant voids and high aspect ratios are uniformly distributed on the CF skeleton surface,forming numerous hetero-interfaces that significantly strengthen interfacial polarization.The resulting Cu/ZnO_(ars)/CF composite exhibits exceptional electromagnetic wave attenuation capacity,achieving a minimum reflection loss of−50.6 dB and a broad effective absorption bandwidth of 8.64 GHz at a low fill loading of only 3 wt.%.Furthermore,the composite demonstrates effective antibacterial and anti-algal capabilities.This study presents an effective strategy for designing carbon-based materials to simultaneously enhance MA performance and anti-biofouling property.展开更多
Combining magnetic materials with high dielectric MXene has been proven to be an effective method to construct superb electromagnetic protective materials as they can introduce interface polarization and collaborate d...Combining magnetic materials with high dielectric MXene has been proven to be an effective method to construct superb electromagnetic protective materials as they can introduce interface polarization and collaborate dielectric-magnetic loss mechanism.However,the application of such hybrid structure is constrained by the obvious instability of MXene at acidic,basic,and high-temperature environments.Herein,inspired by the great advantage of unique“hard shell and soft core”protective structure of natural coconuts,polydopamine(PDA)@Co_(3)O_(4)/Ti_(3)C_(2)T_(x)(M)/polytetrafluoroethylene(PTFE)composite was fabricated for durable electromagnetic protective application.In this structure,the antioxidant PDA and chemically inert PTFE serve as a robust protective layer analogous to a“coconut shell”,effectively encapsulating the Co_(3)O_(4)/Ti_(3)C_(2)T_(x)core,which functions as the primary additive for electromagnetic wave attenuation.The PDA@Co_(3)O_(4)/M/PTFE composite demonstrates a reflection loss(RL)value of−59.12 dB and an effective absorption bandwidth(EAB)of 6.72 GHz.It also exhibits electromagnetic shielding effectiveness of up to 27.67 dB and an absorption efficiency of 94.12%.Furthermore,the composite shows excellent environmental stability under acidic,basic,and sunlight exposure conditions,along with outstanding hydrophobic and flame-retardant properties.In conclusion,the PDA@Co_(3)O_(4)/M/PTFE has significant potential to satisfy electromagnetic protective need of electronic systems,aerospace,and defense industries under harsh conditions.展开更多
Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve ...Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve the superior electrochemical properties of CIBs,the structure design of electrode materials is essential.Herein,2D NiAl-layered double hydroxide(NiAl-LDH)nanoarrays derived from Al2O3 are in-situ grafted to graphene(G)by atomic layer deposition(ALD)and hydrothermal method.The achieved NiAl-LDH@G hybrids with 2D NiAl-LDH arrays grown perpendicularly on graphene surface,can efficiently prevent the stacking of LDHs and enlarge specific surface area to provide more active sites.The NiAl-LDH@G cathode exhibits a maximum discharge capacity of 223.3 mA h g^(-1)and an excellent reversible capacity of 107 mA h g^(-1)over 500 cycles at 100 mA g^(-1)with a high coulombic efficiency around 96%,whereas pure NiAl-LDH has a discharge capacity of only 48.8 mA h g^(-1)and a coulombic efficiency(CE)of about 78%.More importantly,the NiAl-LDH@G electrode has a stable voltage at 1.9 V and an outstanding discharge capacity of higher than 72 mA h g^(-1)after 120 days.Additionally,XRD,XPS,and EDS have been employed to unveil the electrochemical reaction and Cl-storage mechanism of the NiAlLDH@G cathode in CIBs.This work opens a facile and reasonable way for improving electrochemical performance at anion-type rechargeable batteries in terms of cathode material design and mechanism interpretation.展开更多
An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The...An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.展开更多
With the increasingly severe electromagnetic interference issue and the huge heat dissipation demand caused by the miniaturized and integrated electronic devices,exploring the heat-conduction microwave absorption(MA)m...With the increasingly severe electromagnetic interference issue and the huge heat dissipation demand caused by the miniaturized and integrated electronic devices,exploring the heat-conduction microwave absorption(MA)materials is highly desired and remains a great challenge.Herein,we reported the fabrication of ZnO/amorphous carbon(ZnO/AC)hybrid films covered on the surface of graphene(ZnO/AC/Graphene)to simultaneously apply as the MA and thermal management materials.The ZnO/AC coatings synthesized with the auxiliary of an atomic layer deposition(ALD)method are highly uniform and controllable,which can significantly improve the MA performance and thermal conduction properties of graphene.The reflection loss(RL)of−55.4 dB and the effective absorption bandwidth of 5.3 GHz were achieved with thickness of 2.0 mm for ZnO/AC/Graphene at a low loading content(3 wt.%).The minimum RL of−57.9 dB can be obtained in the ZnO/AC/Graphene composites at a low frequency(7.8 GHz).Moreover,the absorption frequency can be regulated by changing the ZnO/AC which can be readily implemented by adjusting the ALD cycles of ZnO.The thermal conductivity of ZnO/AC/Graphene is up to 257.8 mW·m^(−1)·K^(−1),increased by 53.2%compared with natural rubber.The enhancement mechanisms of microwave loss and heat conduction are systematically studied in detail.This work not only develops an excellent candidate,but also provides a novel strategy to design functional materials for heat-conduction MA application.展开更多
Electromagnetic pollution and heat dissipation problems are becoming increasingly worthy of attention due to the rapid development of electronic devices,which puts forward an urgent demand for microwave absorbers with...Electromagnetic pollution and heat dissipation problems are becoming increasingly worthy of attention due to the rapid development of electronic devices,which puts forward an urgent demand for microwave absorbers with excellent thermal management performance.Herein,high-performance Co/carbon nanofiber(Co/CNF)microwave absorbers with high thermal conductivity were fabricated by facile step-by-step method.The microwave absorption properties can be readily tuned by adjusting the content and size of Co nanoparticles through concentration gradient adsorption.Benefiting from the formation of dielectric and magnetic coupling network,Co/CNF composites possess intensive dipole polarization,interface polarization,and magnetic loss.The optimal Co/CNF composites exhibit outstanding microwave absorption performance with a minimum reflection loss(RL)of−53.0 dB at 11.44 GHz,and a maximum effective absorption bandwidth(EAB)of 5.5 GHz.In addition,the thermal conductivities of the Co/CNF-natural rubber(Co/CNF-NR)composites are significantly improved.This work may inspire the exploration of high-efficiency heat-conduction microwave absorbers based on CNF.展开更多
To tackle the increasing electromagnetic pollution,new and efficient electromagnetic wave absorption(EWA)and shielding(EWS)materials are urgently needed.Multi-component synergism and complex microstructure design are ...To tackle the increasing electromagnetic pollution,new and efficient electromagnetic wave absorption(EWA)and shielding(EWS)materials are urgently needed.Multi-component synergism and complex microstructure design are effective measures to improve the EWA and EWS properties.However,how to implement the above designs still faces huge challenges.Herein,multi-interface carbon-coated FeCoNi nanoneedles grown on carbon cloth(FeCoNi@C/CC)were synthesized by a combination of hydrothermal process and chemical vapor deposition(CVD)technology with the concept of“green synthesis”.Using acetylene as the carbon source and atmosphere,the FeCoNi ternary hydroxide can be transformed into a multiple magnetic component(Fe3O4,Ni,and Co metals)by simple annealing.Simultaneously,a uniform carbon layer is formed on the surface,resulting in a composite system with a variety of heterogeneous interfaces and loss mechanisms.Additionally,the dielectric and magnetic loss capacities can be effectively adjusted by changing the temperature of CVD.The optimized FeCoNi@C/CC as filler exhibits remarkable EWA performance with a minimum reflection loss of69.3 dB at a thickness of 1.82 mm and a maximum effective absorption bandwidth of 6.80 GHz.Moreover,the composites as an integrated component also show a fascinating electromagnetic interference shielding efficiency of 42.2 dB.This work provides a guide for the structural design of high-performance electromagnetic protection materials with multiheterogeneous interfaces.展开更多
基金financially supported by the National Natu-ral Science Foundation of China(Nos.U24A20204,22168016,and 22278101)the Innovation Project for Scientific and Technological Talents in Hainan Province(No.KJRC2023C08)the Innovation Research Team in Hainan Province(No.525CXTD607).
文摘Electromagnetic wave(EMW)absorbers with anti-corrosion property are highly desired to enhance the durability of military targets in harsh condition.Herein,cross-link NiAl-layered double hydroxide(NiAl-LDH)nanosheets on the inner/outer surfaces of carbon microtubes(CMTs)are ingeniously constructed through the combination of atomic layer deposition technique and a hydrothermal method.The obtained NiAl-LDH/CMT composite exhibits excellent EMW absorption and corrosion resistance performance.The large internal cavity of CMT significantly enhances impedance matching.The uniform distribution of NiAl-LDH nanosheets on both the inner and outer surfaces of CMT generates numerous heterogeneous inter-faces that induce substantial polarization loss.Consequently,at a filler rate of only 5 wt.%,the NiAl-LDH/CMT composite exhibits a minimum reflection loss of−60.2 dB and a maximum effective absorp-tion bandwidth of 5.9 GHz.In addition,the combined high impermeability of CMT and the effective Cl^(-)-trapping ability of NiAl-LDH endows NiAl-LDH/CMT composite with outstanding corrosion protection property in simulated seawater environment.Furthermore,the PO_(4)^(3-)anions are effectively incorporated into the NiAl-LDH interlayer via anion exchange,which can further enhance corrosion protection capac-ity through surface inactivation from slow-release PO_(4)^(3-)anions without reducing their EMW absorption performance.In summary,this work can give guidance for the development of efficient anti-corrosion EMW absorption materials.
基金supported by the National Natural Science Foundation of China(grants 22278101,22068010,and 52365044)the Natural Science Foundation of Hainan Province(grants 120RC454 and 519QN176)the Innovation Project for Scientific and Technological Talents in Hainan Province(grant KJRC2023C08)。
文摘The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-performance MAMs,little attention was paid to their absorption frequency regulation to respond to variable input frequencies and their stability and durability to cope with complex environments.Here,a highly compressible polyimide-packaging carbon nanocoils/carbon foam(PI@CNCs/CF)fabricated by a facile vacuum impregnation method is reported to be used as a dynamically frequency-tunable and environmentally stable microwave absorber.PI@CNCs/CF exhibits good structural stability and mechanical properties,which allows precise absorption frequency tuning by simply changing its compression ratio.For the first time,the tunable effective absorption bandwidth can cover the whole test frequency band(2−18 GHz)with the broadest effective absorption bandwidth of 10.8 GHz and the minimum reflection loss of−60.5 dB.Moreover,PI@CNCs/CF possesses excellent heat insulation,infrared stealth,self-cleaning,flame retardant,and acid-alkali corrosion resistance,which endows it high reliability even under various harsh environments and repeated compression testing.The frequency-tunable mechanism is elucidated by combining experiment and simulation results,possibly guiding in designing dynamically frequency-tunable MAMs with good environmental stability in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.22068010,22278101,and 22168016)the Finance Science and Technology Project of Hainan Province(Grant Nos.ZDYF2020009)the Natural Science Foundation of Hainan Province(Grant Nos.2019RC142 and 519QN176).
文摘For harsh real-world service settings,it is essential to build corrosion-resistant,diverse,and effective microwave absorbers.Herein,we successfully prepared a 3D NiAl-layered double hydroxide/carbon nanofibers(NiAl-LDH/CNFs)composite material as an anticorrosive microwave absorber assisted by an atomic layer deposition(ALD)method.The size,coating thickness,and content of NiAl-LDH can be readily adjusted by changing the ALD cycling numbers.The optimized NiAl-LDH/CNFs demonstrates prominent microwave absorbing properties including the strongest reflection loss of–55.65 dB and the widest effective absorption bandwidth of 4.80 GHz with only 15 wt%loading.The reasons for performance improvement are the cooperative effect of interfacial polarization loss,conduction loss,and three-dimensional porous structure.Moreover,due to the synergistic effects between the excellent impermeability of CNFs and the trapping ability of NiAl-LDH for chloride ions,NiAl-LDH/CNFs exhibits strong corrosion resistances under acidic,neutral,and alkaline conditions.NiAl-LDH/CNFs should be a potential candidate to simultaneously use for microwave absorption and corrosion resistance,and this work provides a certain guiding significance for designing microwave absorbers that satisfy the corrosion resistance.
基金supported by the National Natural Sci-ence Foundation of China (NSFC,Grant Nos.22168016,22068010,51875318,11564011,and 51362010)Shandong Provincial Key Research and Development Program (Major Scientific and Technological Innovation Project) (Grant No.2019JZZY020205)+1 种基金the Qilu Outstanding Scholar Program of Shandong University.The Natural Science Foundation of Hainan Province (Grant Nos.2019RC142,120RC454,and 519QN176)the State Key Labo-ratory of Advanced Power Transmission Technology (Grant No.SGGR0000DWJS1800561).
文摘Two key limitations affecting the commercial application of carbon foams for fast clean-up of varied oils are the complex synthesis process and poor mechanical stability.In this work,an effective method is reported to fabricate the efficient oil-absorbing materials(CSF@MCF)of carbon spiral fibers(CSFs)anchored on melamine carbon foam(MCF)with superior mechanical properties and excellent photothermal con-version.The interwoven CSFs can not only provide extra rigidity but also reduce the stress concentration of the carbon skeleton,which greatly improves the mechanical properties with 6.3 times maximum compression stress and 4.5 times ultimate tensile strength than MCF.In addition,the pure carbon component can reduce the interface resistance and excite the free electrons more easily,thus realizing high-efficiency photothermal conversion in a wide range of wavelengths.Under light irradiation,the CSF@MCF can be quickly heated up to 70℃and achieve ultra-high absorption of crude oil,up to 62 g g_(-1),due to its low density and large absorption volume.Meanwhile,the CSF@MCF exhibits impressive absorption stability with persistent superhydrophobicity and a high recovery efficiency of over 85%.Superadding its simple preparation process,low production cost,and excellent acid-alkali resistance,the CSF@MCF shows great commercial potential for effectively absorbing varied oils.
基金supported by the National Natural Science Foundation of China(Nos.U24A20204,22168016,52502092,and 22278101)the Innovation Project for Scientific and Technological Talents in Hainan Province(No.KJRC2023C08)the Innovation Research Team in Hainan Province(No.525CXTD607).
文摘Microwave absorption(MA)materials possessing multifunctional capabilities are increasingly imperative to meet the demanding requirements of complex service environments,particularly those prone to biofouling.Conventional MA materials,however,have predominantly focused on achieving high absorption performance while largely overlooking the essential aspect of anti-biofouling properties.Herein,we rationally construct core-shell Cu/ZnO arrays(Cu/ZnO_(ars))hybrid nanostructures on carbon foam(CF)to achieve enhanced MA performance and antibiofouling property.The unique porous architecture of CF is conducive to its absorption of the energy carried by electromagnetic waves through multiple reflections and scattering.Additionally,Cu/ZnO_(ars) with abundant voids and high aspect ratios are uniformly distributed on the CF skeleton surface,forming numerous hetero-interfaces that significantly strengthen interfacial polarization.The resulting Cu/ZnO_(ars)/CF composite exhibits exceptional electromagnetic wave attenuation capacity,achieving a minimum reflection loss of−50.6 dB and a broad effective absorption bandwidth of 8.64 GHz at a low fill loading of only 3 wt.%.Furthermore,the composite demonstrates effective antibacterial and anti-algal capabilities.This study presents an effective strategy for designing carbon-based materials to simultaneously enhance MA performance and anti-biofouling property.
基金supported by the National Natural Science Foundation of China(Grant Nos.22168016,22278101,and U24A20204)the Innovation Project for Scientific and Technological Talents in Hainan Province(Grant No.KJRC2023C08)+2 种基金the Innovation Team Project of Natural Science Foundation in Hainan Province(Grant No.525CXTD607)the Finance Science and Technology Project of Hainan Province(Grant No.ZDYF2020009)the Innovative Research Project for Graduate Students of Hainan Province(Grant No.Qhyb2024-51).
文摘Combining magnetic materials with high dielectric MXene has been proven to be an effective method to construct superb electromagnetic protective materials as they can introduce interface polarization and collaborate dielectric-magnetic loss mechanism.However,the application of such hybrid structure is constrained by the obvious instability of MXene at acidic,basic,and high-temperature environments.Herein,inspired by the great advantage of unique“hard shell and soft core”protective structure of natural coconuts,polydopamine(PDA)@Co_(3)O_(4)/Ti_(3)C_(2)T_(x)(M)/polytetrafluoroethylene(PTFE)composite was fabricated for durable electromagnetic protective application.In this structure,the antioxidant PDA and chemically inert PTFE serve as a robust protective layer analogous to a“coconut shell”,effectively encapsulating the Co_(3)O_(4)/Ti_(3)C_(2)T_(x)core,which functions as the primary additive for electromagnetic wave attenuation.The PDA@Co_(3)O_(4)/M/PTFE composite demonstrates a reflection loss(RL)value of−59.12 dB and an effective absorption bandwidth(EAB)of 6.72 GHz.It also exhibits electromagnetic shielding effectiveness of up to 27.67 dB and an absorption efficiency of 94.12%.Furthermore,the composite shows excellent environmental stability under acidic,basic,and sunlight exposure conditions,along with outstanding hydrophobic and flame-retardant properties.In conclusion,the PDA@Co_(3)O_(4)/M/PTFE has significant potential to satisfy electromagnetic protective need of electronic systems,aerospace,and defense industries under harsh conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.22278101,22068010,22168016,and 52365044)the Natural Science Foundation of Hainan Province(Grant Nos.2019RC142 and 519QN176)the Finance Science and Technology Project of Hainan Province(Grant No.ZDYF2020009).
文摘Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve the superior electrochemical properties of CIBs,the structure design of electrode materials is essential.Herein,2D NiAl-layered double hydroxide(NiAl-LDH)nanoarrays derived from Al2O3 are in-situ grafted to graphene(G)by atomic layer deposition(ALD)and hydrothermal method.The achieved NiAl-LDH@G hybrids with 2D NiAl-LDH arrays grown perpendicularly on graphene surface,can efficiently prevent the stacking of LDHs and enlarge specific surface area to provide more active sites.The NiAl-LDH@G cathode exhibits a maximum discharge capacity of 223.3 mA h g^(-1)and an excellent reversible capacity of 107 mA h g^(-1)over 500 cycles at 100 mA g^(-1)with a high coulombic efficiency around 96%,whereas pure NiAl-LDH has a discharge capacity of only 48.8 mA h g^(-1)and a coulombic efficiency(CE)of about 78%.More importantly,the NiAl-LDH@G electrode has a stable voltage at 1.9 V and an outstanding discharge capacity of higher than 72 mA h g^(-1)after 120 days.Additionally,XRD,XPS,and EDS have been employed to unveil the electrochemical reaction and Cl-storage mechanism of the NiAlLDH@G cathode in CIBs.This work opens a facile and reasonable way for improving electrochemical performance at anion-type rechargeable batteries in terms of cathode material design and mechanism interpretation.
文摘An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.
基金the National Natural Science Foundation of China(Nos.22068010 and 22168016)the Natural Science Foundation of Hainan Province(No.519QN176)the Finance Science and technology project of Hainan Province(No.ZDYF2020009).
文摘With the increasingly severe electromagnetic interference issue and the huge heat dissipation demand caused by the miniaturized and integrated electronic devices,exploring the heat-conduction microwave absorption(MA)materials is highly desired and remains a great challenge.Herein,we reported the fabrication of ZnO/amorphous carbon(ZnO/AC)hybrid films covered on the surface of graphene(ZnO/AC/Graphene)to simultaneously apply as the MA and thermal management materials.The ZnO/AC coatings synthesized with the auxiliary of an atomic layer deposition(ALD)method are highly uniform and controllable,which can significantly improve the MA performance and thermal conduction properties of graphene.The reflection loss(RL)of−55.4 dB and the effective absorption bandwidth of 5.3 GHz were achieved with thickness of 2.0 mm for ZnO/AC/Graphene at a low loading content(3 wt.%).The minimum RL of−57.9 dB can be obtained in the ZnO/AC/Graphene composites at a low frequency(7.8 GHz).Moreover,the absorption frequency can be regulated by changing the ZnO/AC which can be readily implemented by adjusting the ALD cycles of ZnO.The thermal conductivity of ZnO/AC/Graphene is up to 257.8 mW·m^(−1)·K^(−1),increased by 53.2%compared with natural rubber.The enhancement mechanisms of microwave loss and heat conduction are systematically studied in detail.This work not only develops an excellent candidate,but also provides a novel strategy to design functional materials for heat-conduction MA application.
基金supported by the National Natural Science Foundation of China(Grant Nos.22068010,22168016,51875318,52175341)the Natural Science Foundation of Hainan Province(Grant Nos.2019RC142,120RC454,519QN176)the Finance Science and technology project of Hainan Province(Grant No.ZDYF2020009).
文摘Electromagnetic pollution and heat dissipation problems are becoming increasingly worthy of attention due to the rapid development of electronic devices,which puts forward an urgent demand for microwave absorbers with excellent thermal management performance.Herein,high-performance Co/carbon nanofiber(Co/CNF)microwave absorbers with high thermal conductivity were fabricated by facile step-by-step method.The microwave absorption properties can be readily tuned by adjusting the content and size of Co nanoparticles through concentration gradient adsorption.Benefiting from the formation of dielectric and magnetic coupling network,Co/CNF composites possess intensive dipole polarization,interface polarization,and magnetic loss.The optimal Co/CNF composites exhibit outstanding microwave absorption performance with a minimum reflection loss(RL)of−53.0 dB at 11.44 GHz,and a maximum effective absorption bandwidth(EAB)of 5.5 GHz.In addition,the thermal conductivities of the Co/CNF-natural rubber(Co/CNF-NR)composites are significantly improved.This work may inspire the exploration of high-efficiency heat-conduction microwave absorbers based on CNF.
基金supported by the National Natural Science Foundation of China(Grant Nos.22168016,22278101,and 22068010)the Natural Science Foundation of Hainan Province(Grant Nos.120RC454 and 519QN176)the Innovation Project for Scientific and Technological Talents in Hainan Province(Grant No.KJRC2023C08).
文摘To tackle the increasing electromagnetic pollution,new and efficient electromagnetic wave absorption(EWA)and shielding(EWS)materials are urgently needed.Multi-component synergism and complex microstructure design are effective measures to improve the EWA and EWS properties.However,how to implement the above designs still faces huge challenges.Herein,multi-interface carbon-coated FeCoNi nanoneedles grown on carbon cloth(FeCoNi@C/CC)were synthesized by a combination of hydrothermal process and chemical vapor deposition(CVD)technology with the concept of“green synthesis”.Using acetylene as the carbon source and atmosphere,the FeCoNi ternary hydroxide can be transformed into a multiple magnetic component(Fe3O4,Ni,and Co metals)by simple annealing.Simultaneously,a uniform carbon layer is formed on the surface,resulting in a composite system with a variety of heterogeneous interfaces and loss mechanisms.Additionally,the dielectric and magnetic loss capacities can be effectively adjusted by changing the temperature of CVD.The optimized FeCoNi@C/CC as filler exhibits remarkable EWA performance with a minimum reflection loss of69.3 dB at a thickness of 1.82 mm and a maximum effective absorption bandwidth of 6.80 GHz.Moreover,the composites as an integrated component also show a fascinating electromagnetic interference shielding efficiency of 42.2 dB.This work provides a guide for the structural design of high-performance electromagnetic protection materials with multiheterogeneous interfaces.
