Preparation of Thin Porous Carbon Membranes from Polyacrylonitrile by Phase Separation and Heat Treatment

Lee, Hwa Su; Baek, Ga Young; Jeong, Se Young; Shin, Kwanwoo; Jung, Chan-Hee; Choi, Jae‐Hak

doi:10.1166/jnn.2017.14135

Cited by 9 publications

(4 citation statements)

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“…FeCo@C-PCF-3 sample exhibit a higher complex permittivity values with high electrical conductivity and more polarization effect. Besides, electrical conductivity (Figure c) calculated by the equation of σ AC = ε 0 ε″ w = ε 0 ε″2π f , , prove strong connection between ε″ value and conductivity that is also consistent with analysis of Figure b. Furthermore, we could deduce that with enhanced ε″ values, electrical conductivity gradually added.…”

Section: Resultssupporting

confidence: 85%

Nano Bimetallic@Carbon Layer on Porous Carbon Nanofibers with Multiple Interfaces for Microwave Absorption Applications

Liang

Quan

Chen

et al. 2018

ACS Appl. Nano Mater.

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Porous carbon fibers (FeCo@C-PCFs) hybrids are fabricated by a two-step process involving the electrospinning followed by heat treatment, in which several steps are involved including the reduction of polyvalent metal ions, the produced alloy nanoparticles are encapsulated into porous carbon substrate, yielding the FeCo-polyacrylonitrile networks (FeCo-PAN) that are formed in situ and function as the building blocks. After altering feeding proportion of Co 2+ and Fe 3+ , the formation of FeCo@ C-PCF compounds could be controlled. More importantly, FeCo alloys seem to have higher chemical stability. With different graphitization degrees, FeCo@C-PCF compounds were proven to be outstanding microwave (MW) absorbent including thickness, effective bandwidth, and reflection loss (RL). The maximum RL values reached −56 dB at 1.85 mm and broadest bandwidth was 8.3 GHz.

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Section: Resultssupporting

confidence: 85%

Nano Bimetallic@Carbon Layer on Porous Carbon Nanofibers with Multiple Interfaces for Microwave Absorption Applications

Liang

Quan

Chen

et al. 2018

ACS Appl. Nano Mater.

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“…The polarization loss of the absorbers mainly includes several mechanisms such as ion polarization, dipole polarization, electron polarization, and interfacial polarization. 44 However, in general, the ion polarization process has not kept up with the change of the frequency of the 10 5 Hz EM field, 45 and the electron polarization is only present in the band 10 13 to 10 16 Hz. 46 Therefore, the polarization loss of the composites synthesized in this paper may have dipole polarization and interfacial polarization.…”

Section: Resultsmentioning

confidence: 99%

Light-weight Gadolinium Hydroxide@polypyrrole Rare-Earth Nanocomposites with Tunable and Broadband Electromagnetic Wave Absorption

Wei¹,

Liu²,

Lu³

et al. 2019

ACS Appl. Mater. Interfaces

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Light-weight and highly efficient nanocomposite absorbing materials are gaining tremendous interest in recent years. Because of the unique electronic structure characteristics, nanoscale rare-earth materials are of great significance in the development of advanced functional materials. Herein, gadolinium hydroxide/polypyrrole (Gd(OH)3@PPy) nanocomposites were synthesized by a facial chemical solution route. The composites could achieve an absorbing performance of −51.4 dB at 16.2 GHz with a bandwidth of 4.8 GHz, covering the entire Ku band at a thickness of only 2.2 mm. Furthermore, the absorption intensity and bandwidth can be effectively tuned by adjusting the concentration of Gd(OH)3 in the composite. Because of the improvement of impedance matching, dual-loss mechanism, and the synergistic effect of rare-earth hydroxides and conductive polymers, light-weight gadolinium hydroxide@polypyrrole composites are considered as promising candidates for strong and broadband electromagnetic wave absorption.

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“…Importantly, 1D nanofiber can build conductive network, which brings about better electrical conductivity (higher σ value). Lee et al successfully achieved thin porous graphitic carbon membranes and these membranes showed a high electrical conductivity . Therefore, nanofibers are of higher ε″ values, which means higher dissipation of electric energy.…”

Section: Resultsmentioning

confidence: 99%

“…Lee et al successfully achieved thin porous graphitic carbon membranes and these membranes showed a high electrical conductivity. 37 Therefore, nanofibers are of higher ε″ values, which means higher dissipation of electric energy. Thus, the ε″ values of CNF-3 sample are higher than that of C1 sample in the rage of 2−18 GHz.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Structural and Carbonized Design of 1D FeNi/C Nanofibers with Conductive Network to Optimize Electromagnetic Parameters and Absorption Abilities

Liang

et al. 2018

ACS Sustainable Chem. Eng.

170

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The optimized electromagnetic (EM) parameters are highly indispensable for outstanding microwave absorbers. Generally speaking, it is very necessary to suitably improve permittivity and permeability of the materials. The combination of magnetic/dielectric materials is a good choice. Herein, the irregular shaped FeNi/C composites were synthesized in N 2 atmosphere with unsatisfied EM parameters. To further optimize EM parameters and enhance microwave absorption abilities, constructing one-dimensional (1D) structure is also an excellent scheme. 1D FeNi/C nanofibers were successfully obtained by electrospinning technology combined with heat treatment. Enhanced microwave absorption abilities can be fulfilled by conductive network structure, better dielectric loss, and stronger interface polarization intensity. Moreover, carbonized time toward nanofibers plays a key role in microwave absorption, which could influence complex permittivity and dielectric loss of materials. It is found that FeNi/C nanofibers with highly carbonized degree display better microwave absorbing properties. The reflection loss (RL) values less than −10 dB can be observed in 12.8−17.2 GHz (a broad bandwidth of 4.4 GHz) with an absorber thickness of only 1.8 mm. The absorber with a thickness of 2.7 mm has the minimum RL value of −24.8 dB at 9.4 GHz. In this regard, these nanofibers are very likely to be used as EM-wave absorbers in practical application. Furthermore, this work provides a useful strategy to optimize electromagnetic parameters and absorption abilities of metal/carbon absorbers. It may promote the development of 1D metal/carbon composites in microwave absorption field.

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Preparation of Thin Porous Carbon Membranes from Polyacrylonitrile by Phase Separation and Heat Treatment

Cited by 9 publications

References 0 publications

Nano Bimetallic@Carbon Layer on Porous Carbon Nanofibers with Multiple Interfaces for Microwave Absorption Applications

Nano Bimetallic@Carbon Layer on Porous Carbon Nanofibers with Multiple Interfaces for Microwave Absorption Applications

Light-weight Gadolinium Hydroxide@polypyrrole Rare-Earth Nanocomposites with Tunable and Broadband Electromagnetic Wave Absorption

Structural and Carbonized Design of 1D FeNi/C Nanofibers with Conductive Network to Optimize Electromagnetic Parameters and Absorption Abilities

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