Growing electromagnetic pollution has plagued researchers in the field of electromagnetic(EM)energy dissipation for many years;it is increasingly important to solve this problem efficiently.Metal-organic frameworks(MO...Growing electromagnetic pollution has plagued researchers in the field of electromagnetic(EM)energy dissipation for many years;it is increasingly important to solve this problem efficiently.Metal-organic frameworks(MOFs),a shining star of functional materials,have attracted great attention for their advantages,which include highly tunable porosity,structure,and versatility.MOF-derived electromagnetic wave(EMW)absorbers,with advantages such as light weight,thin matching thickness,strong capacity,and wide effective bandwidth,are widely reported.However,current studies lack a systematic summary of the ternary synergistic effects of the precursor component-structure-EMW absorption behavior of MOF derivatives.Here we describe in detail the electromagnetic(EM)energy dissipation mechanism and strategy for preparing MOF-derived EMW absorbers.On the basis of this description,the following means are suggested for adjusting the EM parameters of MOF derivatives,achieving excellent EM energy dissipation:(1)changing the metal and ligands to regulate the chemical composition and morphology of the precursor,(2)controlling pyrolysis parameters(including temperature,heating rate,and gas atmosphere)to manipulate the structure and components of derivatives,and(3)compounding with enhancement phases,including carbon nanomaterials,metals,or other MOFs.展开更多
This work aimed to help the bamboo industry develop methodology for producing imperfection-free bamboo boards that can serve either decorative or structural benefit to consumers seeking to engage with the bioeconomy.S...This work aimed to help the bamboo industry develop methodology for producing imperfection-free bamboo boards that can serve either decorative or structural benefit to consumers seeking to engage with the bioeconomy.Specifically,softened and slotted bamboo tubes were handled by a roller device with nails to render crack-free flattened bamboo board.Softening temperature and time were optimized herein according to findings regarding chemical composition and board mechanical properties.The optimal softening parameters for saturated steam heat treatment is proved to be 160°C for 8 min.The flattened bamboo board possesses an increased bending strength of 101.5 MPa and a decreased bending modulus of 7.7 GPa,being compared with only-softened bamboo.The corresponding changing mechanism is determined in-depth by the micro-morphological and mechanical results based on in-situ SEM and AFM technologies.Under the action of nails and rolling processes,the bamboo texture becomes compact with crushed and fragmented conduit walls.The resulting cell cavity then becomes stretched and compressed,taking on a morphology which allows for the mechanical penalties associated with flattening to be avoided.According to the micro-mechanical results obtained by AFM,compared with unflatten bamboo,the Young’s modulus of the cell membrane in transverse direction(YT)decreases to 1.00 GPa while the corresponding Young’s modulus in radial direction(YR)increases to 7.29 GPa.展开更多
Although advances in wireless technologies such as miniature and wearable electronics have improved the quality of our lives,the ubiquitous use of electronics comes at the expense of increased exposure to electromagne...Although advances in wireless technologies such as miniature and wearable electronics have improved the quality of our lives,the ubiquitous use of electronics comes at the expense of increased exposure to electromagnetic(EM)radiation.Up to date,extensive efforts have been made to develop high-performance EM absorbers based on synthetic materials.However,the design of an EM absorber with both exceptional EM dissipation ability and good environmental adaptability remains a substantial challenge.Here,we report the design of a class of carbon heterostructures via hierarchical assembly of graphitized lignocellulose derived from bamboo.Specifically,the assemblies of nanofibers and nanosheets behave as a nanometer-sized antenna,which results in an enhancement of the conductive loss.In addition,we show that the composition of cellulose and lignin in the precursor significantly influences the shape of the assembly and the formation of covalent bonds,which affect the dielectric response-ability and the surface hydrophobicity(the apparent contact angle of water can reach 135°).Finally,we demonstrate that the obtained carbon heterostructure maintains its wideband EM absorption with an effective absorption frequency ranging from 12.5 to 16.7 GHz under conditions that simulate the real-world environment,including exposure to rainwater with slightly acidic/alkaline pH values.Overall,the advances reported in this work provide new design principles for the synthesis of high-performance EM absorbers that can find practical applications in real-world environments.展开更多
With the aim of utilizing reconstituted bamboo as a carbon cycle oriented material,the improvement of physical and mechanical properties has been actively studied to solve using problems The saturated steam heat treat...With the aim of utilizing reconstituted bamboo as a carbon cycle oriented material,the improvement of physical and mechanical properties has been actively studied to solve using problems The saturated steam heat treatment process has been widely used in worldwide.With the development and exploration of this technology,two step satu-rated steam heat treatment process appears in some practical production,that is,affer a period of saturated steam heat treatment at a lower temperature,the bamboo bundles are taken out and seasoned for a period of time,and then put back into the heat tank again,and heated at a higher temperature for another period of time.During the two-step saturated steam heat treatment,the physical and mechanical properties of bamboo changed.However,the mechanism of two step saturated steam heat treatment has not been thoroughly discussed.For purpose that this paper all discuss and find out the mechanism of two step saturated steam heat treatment on the change of physical and mechanical properties of reconstituted bamboo.In this work,the one and two step saturated steam heat treat-ments were carried out according to the actual production parameters,and the physical and mechanical properties of the reconstituted bamboo board made of treated bamboo bundles were analyzed,including the color change,the thickness swelling(TS),modulus of elasticity(MOE),modulus of rupture(MOR)and shear strength.The results indicate that two-step saturated steam heat treatment is better than one step.Based on the detailed study of the chemical composition,crytalinity and micro morphologial characteristics of the heated bamboo bundles,it is further revealed that during two-step saturated steam heat treatment,oxygen air is added to the reaction system between the two heat treatment processes to further catalyze the oxidation of hemicellulose and enhance the crystal-linity of cellulose,so as to improve the properties of the final products.Our work has optimized the saturated steam heat treatment process which is widely used in industry,pointing out a new idea in the experimental and theoretical basis for the development of recombinant bamboo manufacturing industry.展开更多
A novel magnetic adsorbent was synthesized by magnetizing bentonite by APTES-Fe_3O_4 via a functional groupbridged interaction. The characterization of APTES-Fe_3O_4/bentonite was conducted via transmission electron m...A novel magnetic adsorbent was synthesized by magnetizing bentonite by APTES-Fe_3O_4 via a functional groupbridged interaction. The characterization of APTES-Fe_3O_4/bentonite was conducted via transmission electron microscope(TEM), X-ray diffraction(XRD), Fourier transform infrared spectrophotometer(FT-IR), thermal gravimetric analysis(TGA), vibrating sample magnetometer(VSM), zeta potential analysis and Brunner–Emmet–Teller(BET). The APTES-Fe_3O_4/bentonite was assessed as adsorbents for methylene blue(MB) with a high adsorption capacity(91.83 mg·g^(-1)). Factors affecting the adsorption of MB(such as p H, equilibrium time, temperature and initial concentration) were investigated. The adsorption process completely reaches equilibrium after 120 min and the maximum sorption is achieved at p H 8.0. The adsorption trend follows the pseudosecond order kinetics model. The adsorption data gives good fits with Langmuir isotherm model. The parameter factor RLfalls between 0 and 1, indicating the adsorption of MB is favorable. The adsorption process is endothermic with positive ΔH^0 values. The positive values of ΔG^0 confirm the affinity of the adsorbent towards MB, and suggest an increased randomness at the solid–liquid interface during the adsorption process. Regeneration of the saturated adsorbent was easily carried out via gamma-irradiation.展开更多
Biomass-derived residue carbonization has been an important issue for"carbon fixation"and"zero emission",and the carbonized products have multiple application potentials.However,there have been no ...Biomass-derived residue carbonization has been an important issue for"carbon fixation"and"zero emission",and the carbonized products have multiple application potentials.However,there have been no specific research to study the differences in macro-and micro-morphology,electrical properties and many other aspects of the products obtained from carbonization of pure cellulose,pure lignin or their complex,lignocellulose.In this work,lignocellulose with cellulose to lignin mass ratio of 10:1 is obtained using p-toluenesulfonic acid hydrolysis followed by homogenization process at a controlled condition.Then,carbon heterostructure with fibers and sheets(CH-10)are obtained by pyrolysis at 1500℃.Detailed results imply that the fiber-like carbon structure possesses high crystallinity and low defect density,coming from carbonization of the cellulose content in lignocellulose(LC)nanofibers.Correspondingly,the graphite-like carbon sheet with high defect density and low crystallinity comes from carbonization of the lignin content in LCs.Further investigation indicates CH-10 possesses enhanced polarization and moderate impedance matching which makes it an ideal candidate for electromagnetic wave(EMW)absorption.CH-10 exhibits an excellent EMW absorption performance with a minimum RL value of-50.05 dB and a broadest absorption bandwidth of 4.16 GHz at a coating thickness as thin as 1.3 mm.展开更多
Materials that can absorb electromagnetic(EM)wave have garnered increased attention in recent years due to their potential to mitigate the ever increasing environmental pollution by EM waves.Thanks to recent advances ...Materials that can absorb electromagnetic(EM)wave have garnered increased attention in recent years due to their potential to mitigate the ever increasing environmental pollution by EM waves.Thanks to recent advances in micro/nanofabrication,a variety of magnetic metal-based EM absorbers have been reported.The design and synthesis of EM absorbers that exhibit efficient and wide-band absorption at small thicknesses,however,remains elusive.Here we report the design of fibrous nanostructures consisting of magnetic iron(Fe)nanoparticles and carbon nanotubes(CNTs),which exhibits a wide-band EM absorption(3.8 GHz)while maintain the thickness at 1.2 mm.In our work,we created a novel core-shell structure by immersing the highly fibrous CNT-Fe structure into solid-state silicon(SiO)matrix.Finally,the SiO-coated CNT-Fe structures exhibit good stability against air-induced oxidation and acid corrosion while maintaining high EM absorption.Overall,the results reported in this study present new avenues to absorb EM from ambient air.We believe that our work elevates the utility of EM absorbers to real-world applications such as anti-acid and oxidation ability.展开更多
Electromagnetic(EM)wave absorbers with wideband absorption capability are proposed as a strategy to mitigate environmental pollution by EM waves.However,designing an EM absorber with its performance capacity independe...Electromagnetic(EM)wave absorbers with wideband absorption capability are proposed as a strategy to mitigate environmental pollution by EM waves.However,designing an EM absorber with its performance capacity independent of the EM wave incident angle remains elusive to date.Resolving this challenge requires development of EM absorbers whose EM absorption performance is insensitive to the EM wave incident angle.Herein,we synthesized EM absorbers with a variety of structures with different symme-tries(including micro-/nanospheres,nanoflakes and nanotubes)to study the effect of the EM absorbers’structure and the EM wave incident angle on the EM absorption performance.Our analysis reveals that non-magnetic EM absorbers with spatially symmetric nanostructures exhibit excellent EM wave incident angle-insensitivity.Finally,we demonstrate that a class of non-magnetic EM absorbers made from bam-boo derived-carbon nanospheres exhibit EM incident angle-insensitivity and wideband EM absorption performance with an effective absorption band up to 3.5 GHz when the thickness is 1.4 mm,a signif-icant improvement from prior studies which used thicknesses as high as 3-4 mm for comparable EM absorption performance.展开更多
With the increasing usage of varied electronic devices,the induced electromagnetic interference(EMI)irradiation pollution has become a novel environmental pollution besides of water and air pollutions,drawing a great ...With the increasing usage of varied electronic devices,the induced electromagnetic interference(EMI)irradiation pollution has become a novel environmental pollution besides of water and air pollutions,drawing a great of interests from the scientists to address EMW radiation problem via designing various electromagnetic wave(EMW)absorbers,which is supposed to be with lightweight,thin thickness,wide effective absorbing bandwidth and strong absorbing capacity.One kind of the most attractive absorbers is magnetic carbon composites.Here,we successfully synthesized porous structural C/Fe composites by in-situ carbonization of pre-prepared Fe_(3)O_(4)/wood fibers at 1000℃.The EMW absorption property of C/Fe composites is excellent with a minimum RL value of-32.67 dB at 9.86 GHz,a matching thickness of 2.2 mm and a wide response bandwidth of 14.5 GHz.This excellent absorption performance is proved to be due to the continuous network of Fe_(3)O_(4)/Fe/Fe_(3)C hybrids,permitting optimal impedance matching,the strongest dielectric loss and the optimal magnetic loss.Moreover,the interface polarizations of Fe-Fe_(3)C and Fe_(3)O_(4)-Fe interfaces,are positive to improve the microwave absorption performance.展开更多
基金financially supported by the Natural Science Foundation of Jiangsu Province(No.BK20221336)the Jiangsu Agricultural Science and Technology Independent Innovation Fund(No.CX(20)3041)+2 种基金the National Natural Science Foundation of China(No.31971740)the Research Project of the Jiangxi Forestry Bureau(No.202134)the Nanping Science and Technology Planning Project(No.2020Z001)。
文摘Growing electromagnetic pollution has plagued researchers in the field of electromagnetic(EM)energy dissipation for many years;it is increasingly important to solve this problem efficiently.Metal-organic frameworks(MOFs),a shining star of functional materials,have attracted great attention for their advantages,which include highly tunable porosity,structure,and versatility.MOF-derived electromagnetic wave(EMW)absorbers,with advantages such as light weight,thin matching thickness,strong capacity,and wide effective bandwidth,are widely reported.However,current studies lack a systematic summary of the ternary synergistic effects of the precursor component-structure-EMW absorption behavior of MOF derivatives.Here we describe in detail the electromagnetic(EM)energy dissipation mechanism and strategy for preparing MOF-derived EMW absorbers.On the basis of this description,the following means are suggested for adjusting the EM parameters of MOF derivatives,achieving excellent EM energy dissipation:(1)changing the metal and ligands to regulate the chemical composition and morphology of the precursor,(2)controlling pyrolysis parameters(including temperature,heating rate,and gas atmosphere)to manipulate the structure and components of derivatives,and(3)compounding with enhancement phases,including carbon nanomaterials,metals,or other MOFs.
基金This research was funded by Financial support from the National Natural Science Foundation of China(Nos.61601227,31971740)China Postdoctoral Science Foundation(2017M621598)+4 种基金Nature Science Foundation of Jiangsu Province(BK20160939)Key University Science Research Project of Jiangsu Province(17KJA220004)Jiangsu Agricultural Science and Technology Independent Innovation Project(CX(18)3033)Science and Technology Program of Fujian Province(2019N3014)Open Fund of Key Laboratory of National Forestry and Grassland Administration/Beijing for Bamboo&Rattan Science and Technology(ICBR-2020-08).
文摘This work aimed to help the bamboo industry develop methodology for producing imperfection-free bamboo boards that can serve either decorative or structural benefit to consumers seeking to engage with the bioeconomy.Specifically,softened and slotted bamboo tubes were handled by a roller device with nails to render crack-free flattened bamboo board.Softening temperature and time were optimized herein according to findings regarding chemical composition and board mechanical properties.The optimal softening parameters for saturated steam heat treatment is proved to be 160°C for 8 min.The flattened bamboo board possesses an increased bending strength of 101.5 MPa and a decreased bending modulus of 7.7 GPa,being compared with only-softened bamboo.The corresponding changing mechanism is determined in-depth by the micro-morphological and mechanical results based on in-situ SEM and AFM technologies.Under the action of nails and rolling processes,the bamboo texture becomes compact with crushed and fragmented conduit walls.The resulting cell cavity then becomes stretched and compressed,taking on a morphology which allows for the mechanical penalties associated with flattening to be avoided.According to the micro-mechanical results obtained by AFM,compared with unflatten bamboo,the Young’s modulus of the cell membrane in transverse direction(YT)decreases to 1.00 GPa while the corresponding Young’s modulus in radial direction(YR)increases to 7.29 GPa.
基金the startup fund of the Ohio State University(OSU)OSU Sustainability Institute Seed Grant+2 种基金OSU Institute for Materials Research Kickstart Facility Grantthe National Natural Science Foundation of China(No.31971740)the Science and technology project of Jiangsu Province(BE2018391).
文摘Although advances in wireless technologies such as miniature and wearable electronics have improved the quality of our lives,the ubiquitous use of electronics comes at the expense of increased exposure to electromagnetic(EM)radiation.Up to date,extensive efforts have been made to develop high-performance EM absorbers based on synthetic materials.However,the design of an EM absorber with both exceptional EM dissipation ability and good environmental adaptability remains a substantial challenge.Here,we report the design of a class of carbon heterostructures via hierarchical assembly of graphitized lignocellulose derived from bamboo.Specifically,the assemblies of nanofibers and nanosheets behave as a nanometer-sized antenna,which results in an enhancement of the conductive loss.In addition,we show that the composition of cellulose and lignin in the precursor significantly influences the shape of the assembly and the formation of covalent bonds,which affect the dielectric response-ability and the surface hydrophobicity(the apparent contact angle of water can reach 135°).Finally,we demonstrate that the obtained carbon heterostructure maintains its wideband EM absorption with an effective absorption frequency ranging from 12.5 to 16.7 GHz under conditions that simulate the real-world environment,including exposure to rainwater with slightly acidic/alkaline pH values.Overall,the advances reported in this work provide new design principles for the synthesis of high-performance EM absorbers that can find practical applications in real-world environments.
基金This research was funded by Financial support fom the National Natural Science Foundation of China(No.31971740)Key University Science Research Project of Jiangsu Province(17KJA220004)+2 种基金Jiangsu Agricultural Science and Technology Independent Innovation Fund(CX(20)3041)Science and Technology Program of Fujian Province(2019N3014)Open Fund of Key Laboratory of National Forestry and Grassland Admini stration/Beijing for Bamboo&Rattan Science and Technology(ICBR-2020-08).
文摘With the aim of utilizing reconstituted bamboo as a carbon cycle oriented material,the improvement of physical and mechanical properties has been actively studied to solve using problems The saturated steam heat treatment process has been widely used in worldwide.With the development and exploration of this technology,two step satu-rated steam heat treatment process appears in some practical production,that is,affer a period of saturated steam heat treatment at a lower temperature,the bamboo bundles are taken out and seasoned for a period of time,and then put back into the heat tank again,and heated at a higher temperature for another period of time.During the two-step saturated steam heat treatment,the physical and mechanical properties of bamboo changed.However,the mechanism of two step saturated steam heat treatment has not been thoroughly discussed.For purpose that this paper all discuss and find out the mechanism of two step saturated steam heat treatment on the change of physical and mechanical properties of reconstituted bamboo.In this work,the one and two step saturated steam heat treat-ments were carried out according to the actual production parameters,and the physical and mechanical properties of the reconstituted bamboo board made of treated bamboo bundles were analyzed,including the color change,the thickness swelling(TS),modulus of elasticity(MOE),modulus of rupture(MOR)and shear strength.The results indicate that two-step saturated steam heat treatment is better than one step.Based on the detailed study of the chemical composition,crytalinity and micro morphologial characteristics of the heated bamboo bundles,it is further revealed that during two-step saturated steam heat treatment,oxygen air is added to the reaction system between the two heat treatment processes to further catalyze the oxidation of hemicellulose and enhance the crystal-linity of cellulose,so as to improve the properties of the final products.Our work has optimized the saturated steam heat treatment process which is widely used in industry,pointing out a new idea in the experimental and theoretical basis for the development of recombinant bamboo manufacturing industry.
基金Supported by the National Natural Science Foundation of China(61601227)the Natural Science Foundation of Jiangsu Province(BK20160939)+1 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(16KJB180010)the Qing Lan Project and Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A novel magnetic adsorbent was synthesized by magnetizing bentonite by APTES-Fe_3O_4 via a functional groupbridged interaction. The characterization of APTES-Fe_3O_4/bentonite was conducted via transmission electron microscope(TEM), X-ray diffraction(XRD), Fourier transform infrared spectrophotometer(FT-IR), thermal gravimetric analysis(TGA), vibrating sample magnetometer(VSM), zeta potential analysis and Brunner–Emmet–Teller(BET). The APTES-Fe_3O_4/bentonite was assessed as adsorbents for methylene blue(MB) with a high adsorption capacity(91.83 mg·g^(-1)). Factors affecting the adsorption of MB(such as p H, equilibrium time, temperature and initial concentration) were investigated. The adsorption process completely reaches equilibrium after 120 min and the maximum sorption is achieved at p H 8.0. The adsorption trend follows the pseudosecond order kinetics model. The adsorption data gives good fits with Langmuir isotherm model. The parameter factor RLfalls between 0 and 1, indicating the adsorption of MB is favorable. The adsorption process is endothermic with positive ΔH^0 values. The positive values of ΔG^0 confirm the affinity of the adsorbent towards MB, and suggest an increased randomness at the solid–liquid interface during the adsorption process. Regeneration of the saturated adsorbent was easily carried out via gamma-irradiation.
基金supported by funding from the National Natural Science Foundation of China(31770609,31570552)Jiangsu Agricultural Science and Technology Independent Innovation Fund(CX(20)3041)。
文摘Biomass-derived residue carbonization has been an important issue for"carbon fixation"and"zero emission",and the carbonized products have multiple application potentials.However,there have been no specific research to study the differences in macro-and micro-morphology,electrical properties and many other aspects of the products obtained from carbonization of pure cellulose,pure lignin or their complex,lignocellulose.In this work,lignocellulose with cellulose to lignin mass ratio of 10:1 is obtained using p-toluenesulfonic acid hydrolysis followed by homogenization process at a controlled condition.Then,carbon heterostructure with fibers and sheets(CH-10)are obtained by pyrolysis at 1500℃.Detailed results imply that the fiber-like carbon structure possesses high crystallinity and low defect density,coming from carbonization of the cellulose content in lignocellulose(LC)nanofibers.Correspondingly,the graphite-like carbon sheet with high defect density and low crystallinity comes from carbonization of the lignin content in LCs.Further investigation indicates CH-10 possesses enhanced polarization and moderate impedance matching which makes it an ideal candidate for electromagnetic wave(EMW)absorption.CH-10 exhibits an excellent EMW absorption performance with a minimum RL value of-50.05 dB and a broadest absorption bandwidth of 4.16 GHz at a coating thickness as thin as 1.3 mm.
基金the funding support from the startup fund of the Ohio State University(OSU),OSU Sustainability Institute Seed Grant,and OSU Institute for Materials Research Kickstart Facility Grantthe National Natural Science Foundation of China(No.31971740)+1 种基金Science and technology project of Jiangsu Province(BE2018391)the Open Fund from Henan University of Science and technology。
文摘Materials that can absorb electromagnetic(EM)wave have garnered increased attention in recent years due to their potential to mitigate the ever increasing environmental pollution by EM waves.Thanks to recent advances in micro/nanofabrication,a variety of magnetic metal-based EM absorbers have been reported.The design and synthesis of EM absorbers that exhibit efficient and wide-band absorption at small thicknesses,however,remains elusive.Here we report the design of fibrous nanostructures consisting of magnetic iron(Fe)nanoparticles and carbon nanotubes(CNTs),which exhibits a wide-band EM absorption(3.8 GHz)while maintain the thickness at 1.2 mm.In our work,we created a novel core-shell structure by immersing the highly fibrous CNT-Fe structure into solid-state silicon(SiO)matrix.Finally,the SiO-coated CNT-Fe structures exhibit good stability against air-induced oxidation and acid corrosion while maintaining high EM absorption.Overall,the results reported in this study present new avenues to absorb EM from ambient air.We believe that our work elevates the utility of EM absorbers to real-world applications such as anti-acid and oxidation ability.
基金financial support from the startup fund of the Ohio State University (OSU)OSU Sustainability Institute Seed Grant+5 种基金OSU Institute for Materials Research Kickstart Facility Grantthe National Natural Science Foundation of China (No. 31971740)support from the National Natural Science Foundation of China (No. 31901007)Science and technology project of Jiangsu Province (BE2018391)State Key Laboratory Special Fund(No. 2060204)fund from Henan University of Science and Technology (2020-RSC02)
文摘Electromagnetic(EM)wave absorbers with wideband absorption capability are proposed as a strategy to mitigate environmental pollution by EM waves.However,designing an EM absorber with its performance capacity independent of the EM wave incident angle remains elusive to date.Resolving this challenge requires development of EM absorbers whose EM absorption performance is insensitive to the EM wave incident angle.Herein,we synthesized EM absorbers with a variety of structures with different symme-tries(including micro-/nanospheres,nanoflakes and nanotubes)to study the effect of the EM absorbers’structure and the EM wave incident angle on the EM absorption performance.Our analysis reveals that non-magnetic EM absorbers with spatially symmetric nanostructures exhibit excellent EM wave incident angle-insensitivity.Finally,we demonstrate that a class of non-magnetic EM absorbers made from bam-boo derived-carbon nanospheres exhibit EM incident angle-insensitivity and wideband EM absorption performance with an effective absorption band up to 3.5 GHz when the thickness is 1.4 mm,a signif-icant improvement from prior studies which used thicknesses as high as 3-4 mm for comparable EM absorption performance.
基金the National Natural Science Foundation of China(No.61601227,31570552)China Postdoctoral Science Foundation(No.2017M621598)+4 种基金Nature Science Foundation of Jiangsu Province(No.BK20160939)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.16KJB180010)Key University Science Research Project of Jiangsu Province(No.17KJA220004)Student Practice Innovation and Training Program of Jiangsu Province(No.201710298017Z)Student Practice Innovation and Training Program of Nanjing Forestry University(No.2017NFUSPITP105,2017NFUSPITP092).
文摘With the increasing usage of varied electronic devices,the induced electromagnetic interference(EMI)irradiation pollution has become a novel environmental pollution besides of water and air pollutions,drawing a great of interests from the scientists to address EMW radiation problem via designing various electromagnetic wave(EMW)absorbers,which is supposed to be with lightweight,thin thickness,wide effective absorbing bandwidth and strong absorbing capacity.One kind of the most attractive absorbers is magnetic carbon composites.Here,we successfully synthesized porous structural C/Fe composites by in-situ carbonization of pre-prepared Fe_(3)O_(4)/wood fibers at 1000℃.The EMW absorption property of C/Fe composites is excellent with a minimum RL value of-32.67 dB at 9.86 GHz,a matching thickness of 2.2 mm and a wide response bandwidth of 14.5 GHz.This excellent absorption performance is proved to be due to the continuous network of Fe_(3)O_(4)/Fe/Fe_(3)C hybrids,permitting optimal impedance matching,the strongest dielectric loss and the optimal magnetic loss.Moreover,the interface polarizations of Fe-Fe_(3)C and Fe_(3)O_(4)-Fe interfaces,are positive to improve the microwave absorption performance.
