In this work,porous carbon particles were prepared from wheat flour by pyrolysis and activation.Through the subsequent coprecipitation and electroless plating,the surface and pores of carbon particles were modified by...In this work,porous carbon particles were prepared from wheat flour by pyrolysis and activation.Through the subsequent coprecipitation and electroless plating,the surface and pores of carbon particles were modified by nickel-rich particles with different morphologies.Several loss mechanisms,including dielectric loss,magnetic loss,multiple reflection and scattering loss,were used to assess the attenuation ability to incident electromagnetic waves of these composite particles.The result shows that the chain-shaped morphology of nickel can provide the highest dielectric loss.Under the filler loading of 20 wt.%,the minimum reflection loss(RL min)reached-38.42 dB at 13.2 GHz,and the_(max)imum effective absorption bandwidth(EAB_(max))was 5.2 GHz with a matching thickness of 2 mm.The excellent performance of the composite particles is attributed to the synergistic effect of outstanding impedance matching and supe-rior electromagnetic loss ability caused by the chain structure.The result shows that the morphology of modifiers in carbon-based composites is important to improve microwave absorption performance,and this work provides inspiration for the design of high-performance porous carbon-based composites.展开更多
In this study,flower-like MoS2 constructed by nanosheets was synthesized by a simple hydrothermal method.The hydrothermal process was optimized and the effects of hydrothermal condition,including reaction temperature,...In this study,flower-like MoS2 constructed by nanosheets was synthesized by a simple hydrothermal method.The hydrothermal process was optimized and the effects of hydrothermal condition,including reaction temperature,reaction time and the ratio of Mo source to S source(Mo:S)in precursor,on microwave absorption performances and dielectric properties were investigated.Our results showed that when the reaction temperature was 180℃,the reaction time was 18 h,and the Mo:S was 1:3.5,the synthesized MoS2 had the best performance:Its minimum reflection loss could reach-55.78 dB,and the corresponding matching thickness was 2.30 mm with a wide effective bandwidth of 5.17 GHz.Further researches on the microwave absorption mechanism revealed that in addition to the destructive interference of electromagnetic waves,various polarization phenomena such as defect dipole polarization were the main reasons for microwave loss.We believe that MoS2 is a candidate for a practical microwave absorbent.展开更多
基金This work was financially supported by the Shenyang Major Achievements Transformation Project(No.20-203-5-18).
文摘In this work,porous carbon particles were prepared from wheat flour by pyrolysis and activation.Through the subsequent coprecipitation and electroless plating,the surface and pores of carbon particles were modified by nickel-rich particles with different morphologies.Several loss mechanisms,including dielectric loss,magnetic loss,multiple reflection and scattering loss,were used to assess the attenuation ability to incident electromagnetic waves of these composite particles.The result shows that the chain-shaped morphology of nickel can provide the highest dielectric loss.Under the filler loading of 20 wt.%,the minimum reflection loss(RL min)reached-38.42 dB at 13.2 GHz,and the_(max)imum effective absorption bandwidth(EAB_(max))was 5.2 GHz with a matching thickness of 2 mm.The excellent performance of the composite particles is attributed to the synergistic effect of outstanding impedance matching and supe-rior electromagnetic loss ability caused by the chain structure.The result shows that the morphology of modifiers in carbon-based composites is important to improve microwave absorption performance,and this work provides inspiration for the design of high-performance porous carbon-based composites.
基金financially supported by the National Natural Science Foundation of China(No.21403298)。
文摘In this study,flower-like MoS2 constructed by nanosheets was synthesized by a simple hydrothermal method.The hydrothermal process was optimized and the effects of hydrothermal condition,including reaction temperature,reaction time and the ratio of Mo source to S source(Mo:S)in precursor,on microwave absorption performances and dielectric properties were investigated.Our results showed that when the reaction temperature was 180℃,the reaction time was 18 h,and the Mo:S was 1:3.5,the synthesized MoS2 had the best performance:Its minimum reflection loss could reach-55.78 dB,and the corresponding matching thickness was 2.30 mm with a wide effective bandwidth of 5.17 GHz.Further researches on the microwave absorption mechanism revealed that in addition to the destructive interference of electromagnetic waves,various polarization phenomena such as defect dipole polarization were the main reasons for microwave loss.We believe that MoS2 is a candidate for a practical microwave absorbent.
