In this paper,the structure evolution of cerium cobaltohexanoate(Ce[Co(CN)6],Ce-Co Prussian blue analog(PBA))has been realized by solvent catalysis at room temperature.The hexagonal bipyramidal microcrystals of Ce-Co ...In this paper,the structure evolution of cerium cobaltohexanoate(Ce[Co(CN)6],Ce-Co Prussian blue analog(PBA))has been realized by solvent catalysis at room temperature.The hexagonal bipyramidal microcrystals of Ce-Co PBA can be gradually transformed into dendrites by different proportions of ethanol(EtOH)and water.At the same time,the porous dendrites CeO_(2)/Co@carbon nanotub(CNT)with oxygen-rich vacancies(OVs)can be obtained by annealing Ce-Co PBA at 700℃.The microstructure study shows that carbon nanotubes will be catalyzed after annealing at high temperature,and the cobalt metal particles encapsulated in carbon nanotubes will be anchored in the matrix,regulating the impedance matching and multi-polarization suppression of the material,and its unique structure,vacancies,and strong interface effect make the material exhibit excellent electromagnetic wave(EMW)absorption performance.When the matching thickness is 2.5 mm,the minimum reflection loss(RLmin)of the composite is-51.68 dB,and the effective absorption bandwidth(RL<-10 dB)is 7.76 GHz.These results show that the prepared CeO_(2)/Co@CNT composite has excellent EMW absorption properties.It is expected to be a candidate material for EMW absorption.展开更多
In this work,two-dimensional NiCeOx nanosheet-modified carbon nanotubes(CNTs)composites were prepared by a hydrothermal method.NiCeOx with different morphologies can be formed by adjusting the addition ratio of nickel...In this work,two-dimensional NiCeOx nanosheet-modified carbon nanotubes(CNTs)composites were prepared by a hydrothermal method.NiCeOx with different morphologies can be formed by adjusting the addition ratio of nickel salt and cerium salt,and the introduction of CNTs in the subsequent synthesis process can effectively prevent the aggregation of NiCeOx nanosheets.Microstructural studies show that hexagonal NiCeOx nanosheets with a size of 100 nm are uniformly intertwined with CNTs.When applied to the attenuation of electromagnetic waves,NiCeOx/CNTs composites exhibit better electromagnetic wave(EMW)absorption performance than pure CNTs and NiCeOx nanosheets due to improved impedance matching and multiple polarization relaxation.At the matching thickness of 1.9 mm,the composite exhibits a minimum reflection loss(RL_(min))of–53.2 dB and an effective absorption bandwidth(RL<–10 dB)of 5.04 GHz with a thickness of 2.3 mm.These results indicate that the as-prepared NiCeOx/CNTs composites have excellent EMW absorption performance and are expected to be a candidate material for EMW absorption.展开更多
Metal-organic framework-derived composites have been widely used in electromagnetic wave(EMW)absorption,but the traditional synthetic strategy greatly limits the structure and species of MOFs.This research provided a ...Metal-organic framework-derived composites have been widely used in electromagnetic wave(EMW)absorption,but the traditional synthetic strategy greatly limits the structure and species of MOFs.This research provided a solvent-free method to synthesize Co-MOF and its derivatives.Using CoSnO_(3)as the precursor,the preparation of Co-MOF is achieved by bridging the cobalt(II)ion of CoSnO_(3)and the 2-methylimidazole skeleton.The CoSn/N-doped carbon(CoSn/NC)composites derived from CoSnO_(3)-MOF(Co-MOF with CoSnO_(3)as Co source)retain the original morphology of CoSnO_(3).Besides,the polarization effect produced by the N-doped carbon layers also benefits the excellent EMW absorption performance of the CoSn/NC composites.It is reflected in the minimum reflection loss(RL)of-48.2 dB at 2.2 mm and the effective bandwidth(EBA)of 5.84 GHz.This work provides a new channel to the construction of Co-MOFs,which could be extended to other Co-based oxides and vastly expand the species of MOFs based on metallic Co.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52377026 and 52301192)the Natural Science Foundation of Shandong Province(Nos.ZR2019YQ24 and ZR2020QF084)+2 种基金the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)the Special Financial of Shandong Province(Structural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams).
文摘In this paper,the structure evolution of cerium cobaltohexanoate(Ce[Co(CN)6],Ce-Co Prussian blue analog(PBA))has been realized by solvent catalysis at room temperature.The hexagonal bipyramidal microcrystals of Ce-Co PBA can be gradually transformed into dendrites by different proportions of ethanol(EtOH)and water.At the same time,the porous dendrites CeO_(2)/Co@carbon nanotub(CNT)with oxygen-rich vacancies(OVs)can be obtained by annealing Ce-Co PBA at 700℃.The microstructure study shows that carbon nanotubes will be catalyzed after annealing at high temperature,and the cobalt metal particles encapsulated in carbon nanotubes will be anchored in the matrix,regulating the impedance matching and multi-polarization suppression of the material,and its unique structure,vacancies,and strong interface effect make the material exhibit excellent electromagnetic wave(EMW)absorption performance.When the matching thickness is 2.5 mm,the minimum reflection loss(RLmin)of the composite is-51.68 dB,and the effective absorption bandwidth(RL<-10 dB)is 7.76 GHz.These results show that the prepared CeO_(2)/Co@CNT composite has excellent EMW absorption properties.It is expected to be a candidate material for EMW absorption.
基金supported by the Natural Science Foundation of Shandong Province(no.ZR2019YQ24)the Tais han Scholars and Young Experts Program of Shandong Province(no.tsqn202103057)+1 种基金the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)the Special Financial of Shandong Province(Structural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams).
文摘In this work,two-dimensional NiCeOx nanosheet-modified carbon nanotubes(CNTs)composites were prepared by a hydrothermal method.NiCeOx with different morphologies can be formed by adjusting the addition ratio of nickel salt and cerium salt,and the introduction of CNTs in the subsequent synthesis process can effectively prevent the aggregation of NiCeOx nanosheets.Microstructural studies show that hexagonal NiCeOx nanosheets with a size of 100 nm are uniformly intertwined with CNTs.When applied to the attenuation of electromagnetic waves,NiCeOx/CNTs composites exhibit better electromagnetic wave(EMW)absorption performance than pure CNTs and NiCeOx nanosheets due to improved impedance matching and multiple polarization relaxation.At the matching thickness of 1.9 mm,the composite exhibits a minimum reflection loss(RL_(min))of–53.2 dB and an effective absorption bandwidth(RL<–10 dB)of 5.04 GHz with a thickness of 2.3 mm.These results indicate that the as-prepared NiCeOx/CNTs composites have excellent EMW absorption performance and are expected to be a candidate material for EMW absorption.
基金financially supported by the National Natural Science Foundation of China(No.51407134)Natural Science Foundation of Shandong Province(No.ZR2019YQ24)+4 种基金Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)China Postdoctoral Science Foundation(No.2016M590619)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)the support from The Thousand Talents Plan,The World-Class University and Discipline,The Taishan Scholar’s Advantageous and Distinctive Discipline Program of Shandong ProvinceThe World-Class Discipline Program of Shandong Province。
文摘Metal-organic framework-derived composites have been widely used in electromagnetic wave(EMW)absorption,but the traditional synthetic strategy greatly limits the structure and species of MOFs.This research provided a solvent-free method to synthesize Co-MOF and its derivatives.Using CoSnO_(3)as the precursor,the preparation of Co-MOF is achieved by bridging the cobalt(II)ion of CoSnO_(3)and the 2-methylimidazole skeleton.The CoSn/N-doped carbon(CoSn/NC)composites derived from CoSnO_(3)-MOF(Co-MOF with CoSnO_(3)as Co source)retain the original morphology of CoSnO_(3).Besides,the polarization effect produced by the N-doped carbon layers also benefits the excellent EMW absorption performance of the CoSn/NC composites.It is reflected in the minimum reflection loss(RL)of-48.2 dB at 2.2 mm and the effective bandwidth(EBA)of 5.84 GHz.This work provides a new channel to the construction of Co-MOFs,which could be extended to other Co-based oxides and vastly expand the species of MOFs based on metallic Co.