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
Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high co...Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high conductivity and spontaneous aggregation of MXene suffer from limited EMW response.Inspired by dielectric–magnetic synergy effect,the strategy of decorating MXene with magnetic elements is expected to solve this challenge.In this work,zigzag-like Mo_(2)TiC_(2)–MXene nanofibers(Mo-based MXene(Mo–MXene)NFs)with cross-linked networks are fabricated by hydrofluoric acid(HF)etching and potassium hydroxide(KOH)shearing processes.Subsequently,Co-metal–organic framework(MOF)and derived CoNi layered double hydroxide(LDH)ultrathin nanosheets are grown inside Mo–MXene NFs,and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo–MXene NFs network.Benefiting from synergistic effect of highly dispersed small CoNi alloy nanoparticles,a three-dimensional(3D)conductive network assembled by zigzag-like Mo–MXene NFs,numerous N-doped hollow carbon vesicles,and abundant dual heterogeneous interface,the designed Mo–MXene/CoNi–NC heterostructure provides robust EMW absorption ability with a reflection loss(RL)value of−68.45 dB at the thickness(d)of 4.38 mm.The robust EMW absorption performance can be attributed to excellent dielectric loss,magnetic loss,impedance matching(Z),and multiple scattering and reflection triggered by the unique 3D network structure.This work puts up great potential in developing advanced MXene-based EMW absorption devices.展开更多
Two-dimensional(2D)transition metal carbide MXene-based materials hold great potentials applied for new electromagnetic wave(EMW)absorbers.However,the application of MXenes in the field of electromagnetic wave absorpt...Two-dimensional(2D)transition metal carbide MXene-based materials hold great potentials applied for new electromagnetic wave(EMW)absorbers.However,the application of MXenes in the field of electromagnetic wave absorption(EMA)is limited by the disadvantages of poor impedance matching,single loss mechanism,and easy oxidation.In this work,MoO_(3)/TiO_(2)/Mo_(2)TiC_(2)T_(x)hybrids were prepared by the annealing-treated Mo_(2)TiC_(2)T_(x)MXene and uniform MoO_(3)and TiO_(2)oxides in-situ grew on Mo_(2)TiC_(2)T_(x)layers.At the annealing temperature of 300℃,the minimum reflection loss(RLmin)value of MoO_(3)/TiO_(2)/Mo_(2)TiC_(2)T_(x)reaches-30.76 dB(2.3 mm)at 10.18 GHz with a significantly broadening effective absorption bandwidth(EAB)of 8.6 GHz(1.8 mm).The in-situ generated oxides creating numerous defects and heterogeneous interfaces enhance dipolar and interfacial polarizations and optimize the impedance matching of Mo_(2)TiC_(2)T_(x).Considering the excellent overall performance,the MoO_(3)/TiO_(2)/Mo_(2)TiC_(2)T_(x)hybrids can be a promising candidate for EMA.展开更多
Semiconductor-noble metal composite has become a research focus due to its superior performance compared with its respective component.Although various methods have been developed to synthesize semiconductor-noble met...Semiconductor-noble metal composite has become a research focus due to its superior performance compared with its respective component.Although various methods have been developed to synthesize semiconductor-noble metal heterostructures,most of them are relatively complex multistep and use toxic reactants of high cost and risk.In this work,a series of Cu_(2)O/Ag heterojunctions were quickly prepared in one step via simple microwave-assisted green route.XRD,SEM,TEM,EDS,XPS,etc.were used to characterize obtained products,and the results indicate a Cu_(2)O/Ag metal-semiconductor heterojunction in micro-nano size was fabricated successfully.In addition,antibacterial behavior of Cu_(2)O/Ag heterojunctions against E.coli and S.aureus were investigated.Owing to the synergistic effect of Cu_(2)O and Ag,the heterojunction exhibits much better antibacterial performance than the pristine Cu_(2)O does.This work provides new insights into the green design and fabrication of surface-modified Cu_(2)O hybrid multifunctional materials for antibacterial applications.展开更多
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This work was supported by the National Natural Science Foundation of China(No.22269010)the Jiangxi Provincial Natural Science Foundation(No.20224BAB214021)+3 种基金the Training Program for Academic and Technical Leaders of Major Disciplines in Jiangxi Province(No.20212BCJ23020)the Science and Technology Project of Jiangxi Provincial Department of Education(No.GJJ211305)the National Natural Science Foundation of China(No.U2004177)the Outstanding Youth Fund of Henan Province(No.212300410081).
文摘Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high conductivity and spontaneous aggregation of MXene suffer from limited EMW response.Inspired by dielectric–magnetic synergy effect,the strategy of decorating MXene with magnetic elements is expected to solve this challenge.In this work,zigzag-like Mo_(2)TiC_(2)–MXene nanofibers(Mo-based MXene(Mo–MXene)NFs)with cross-linked networks are fabricated by hydrofluoric acid(HF)etching and potassium hydroxide(KOH)shearing processes.Subsequently,Co-metal–organic framework(MOF)and derived CoNi layered double hydroxide(LDH)ultrathin nanosheets are grown inside Mo–MXene NFs,and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo–MXene NFs network.Benefiting from synergistic effect of highly dispersed small CoNi alloy nanoparticles,a three-dimensional(3D)conductive network assembled by zigzag-like Mo–MXene NFs,numerous N-doped hollow carbon vesicles,and abundant dual heterogeneous interface,the designed Mo–MXene/CoNi–NC heterostructure provides robust EMW absorption ability with a reflection loss(RL)value of−68.45 dB at the thickness(d)of 4.38 mm.The robust EMW absorption performance can be attributed to excellent dielectric loss,magnetic loss,impedance matching(Z),and multiple scattering and reflection triggered by the unique 3D network structure.This work puts up great potential in developing advanced MXene-based EMW absorption devices.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U2004177 and U21A2064)Outstanding Youth Fund of Henan Province(No.212300410081)Support Plan for Scientific and Technological Innovation Talents in Colleges and Universities of Henan Province(No.22HASTIT001)。
文摘Two-dimensional(2D)transition metal carbide MXene-based materials hold great potentials applied for new electromagnetic wave(EMW)absorbers.However,the application of MXenes in the field of electromagnetic wave absorption(EMA)is limited by the disadvantages of poor impedance matching,single loss mechanism,and easy oxidation.In this work,MoO_(3)/TiO_(2)/Mo_(2)TiC_(2)T_(x)hybrids were prepared by the annealing-treated Mo_(2)TiC_(2)T_(x)MXene and uniform MoO_(3)and TiO_(2)oxides in-situ grew on Mo_(2)TiC_(2)T_(x)layers.At the annealing temperature of 300℃,the minimum reflection loss(RLmin)value of MoO_(3)/TiO_(2)/Mo_(2)TiC_(2)T_(x)reaches-30.76 dB(2.3 mm)at 10.18 GHz with a significantly broadening effective absorption bandwidth(EAB)of 8.6 GHz(1.8 mm).The in-situ generated oxides creating numerous defects and heterogeneous interfaces enhance dipolar and interfacial polarizations and optimize the impedance matching of Mo_(2)TiC_(2)T_(x).Considering the excellent overall performance,the MoO_(3)/TiO_(2)/Mo_(2)TiC_(2)T_(x)hybrids can be a promising candidate for EMA.
基金financially supported by the National Natural Science Foundation of China(Nos.U2004177 and 21504082)Zhongyuan Thousand Talents Plan Project,Outstanding Youth Fund of Henan Province(No.212300410081)Natural Science Research Project of Henan Educational Committee(No.20A43001)。
文摘Semiconductor-noble metal composite has become a research focus due to its superior performance compared with its respective component.Although various methods have been developed to synthesize semiconductor-noble metal heterostructures,most of them are relatively complex multistep and use toxic reactants of high cost and risk.In this work,a series of Cu_(2)O/Ag heterojunctions were quickly prepared in one step via simple microwave-assisted green route.XRD,SEM,TEM,EDS,XPS,etc.were used to characterize obtained products,and the results indicate a Cu_(2)O/Ag metal-semiconductor heterojunction in micro-nano size was fabricated successfully.In addition,antibacterial behavior of Cu_(2)O/Ag heterojunctions against E.coli and S.aureus were investigated.Owing to the synergistic effect of Cu_(2)O and Ag,the heterojunction exhibits much better antibacterial performance than the pristine Cu_(2)O does.This work provides new insights into the green design and fabrication of surface-modified Cu_(2)O hybrid multifunctional materials for antibacterial applications.