Polymer-bubbling for one-step synthesis of three-dimensional cobalt/carbon foams against electromagnetic pollution
TL;DR: In this article, a nitrate-assisted polymer-bubbling strategy is reported for the synthesis of Co/carbon foams, which is simply accomplished by direct pyrolyzing the mixture of polyvinylpyrrolidone (PVP) and cobalt nitrate hexahydrate (Co(NO3)2∙6H2O).
About: This article is published in Journal of Materials Science & Technology.The article was published on 2021-12-10. It has received 36 citations till now. The article focuses on the topics: Microstructure & Reflection loss.
Citations
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TL;DR: In this article, a review comprehensively introduces recent advancements on electromagnetic absorption enhancement in MOFs-derived magnetic carbon-based composites and some available strategies therein, and some challenges and prospects are also proposed to indicate the pending issues on performance breakthrough and mechanism exploration.
Abstract: Magnetic carbon-based composites are the most attractive candidates for electromagnetic (EM) absorption because they can terminate the propagation of surplus EM waves in space by interacting with both electric and magnetic branches. Metal-organic frameworks (MOFs) have demonstrated their great potential as sacrificing precursors of magnetic metals/carbon composites, because they provide a good platform to achieve high dispersion of magnetic nanoparticles in carbon matrix. Nevertheless, the chemical composition and microstructure of these composites are always highly dependent on their precursors and cannot promise an optimal EM state favorable for EM absorption, which more or less discount the superiority of MOFs-derived strategy. It is hence of great importance to develop some accompanied methods that can regulate EM properties of MOFs-derived magnetic carbon-based composites effectively. This review comprehensively introduces recent advancements on EM absorption enhancement in MOFs-derived magnetic carbon-based composites and some available strategies therein. In addition, some challenges and prospects are also proposed to indicate the pending issues on performance breakthrough and mechanism exploration in the related field.
89 citations
TL;DR: In this paper , a controllable seeding of nitrogen-doped carbon nanotubes (NCNTs) on the surface of Co/C foams through in-situ growth is demonstrated.
48 citations
TL;DR: In this paper , a corrosion-resistant graphene-based carbon-coated iron (Fe@C) magnetic composite foam is fabricated via self-assembly of iron phthalocyanine/Fe3O4 (FePc hybrid) on the graphene skeletons under solvothermal conditions and then annealing at high temperature.
Abstract: Designing and fabricating high-performance microwave absorption materials with efficient electromagnetic absorption and corrosion resistance becomes a serious and urgent concern. Herein, novel corrosion-resistant graphene-based carbon-coated iron (Fe@C) magnetic composite foam is fabricated via self-assembly of iron phthalocyanine/Fe3O4 (FePc hybrid) on the graphene skeletons under solvothermal conditions and then annealing at high temperature. As a result, the rational construction of a hierarchical impedance gradient between graphene skeletons and Fe@C particles can facilitate the optimization in impedance matching and attenuation characteristic of the foam, realizing the efficient dissipation for incident electromagnetic waves. Additionally, the performance of electromagnetic absorption can be controllably regulated by optimizing annealing temperature and/or time. More importantly, the formation of a carbon-coated iron structure substantially improves the corrosion resistance of magnetic particles, endowing the composite foam with excellent stability and durability in microwave absorption performance.
43 citations
TL;DR: In this paper , a 1D@2D@1D hierarchical structure integrated with multi-hetero-interfaces via self-assembly and an autocatalytic pyrolysis is designed to fully unlock the microwave attenuation potential of materials, realizing ultra-efficient MA performance.
Abstract: Developing microwave absorption (MA) materials with ultrahigh efficiency and facile preparation method remains a challenge. Herein, a superior 1D@2D@1D hierarchical structure integrated with multi-heterointerfaces via self-assembly and an autocatalytic pyrolysis is designed to fully unlock the microwave attenuation potential of materials, realizing ultra-efficient MA performance. By precisely regulating the morphology of the metal organic framework precursor toward improved impedance matching and intelligently integrating multi-heterointerfaces to boosted dielectric polarization, the specific return loss value of composites can be effectively tuned and optimized to -1002 dB at a very thin thickness of 1.8 mm. These encouraging achievements shed fresh insights into the precise design of ultra-efficient MA materials.
39 citations
TL;DR: In this article , a series of carbon nanotubes (CNTs)@Ni/C foams (CNCFs-2) through two-step pyrolysis processes were successfully fabricated for high-performance carbon-based microwave absorption materials.
35 citations
References
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TL;DR: In this paper, a model and theoretical understanding of the Raman spectra in disordered and amorphous carbon is given, and the nature of the G and D vibration modes in graphite is analyzed in terms of the resonant excitation of \ensuremath{\pi} states and the long-range polarizability of the long range bonding.
Abstract: The model and theoretical understanding of the Raman spectra in disordered and amorphous carbon are given. The nature of the G and D vibration modes in graphite is analyzed in terms of the resonant excitation of \ensuremath{\pi} states and the long-range polarizability of \ensuremath{\pi} bonding. Visible Raman data on disordered, amorphous, and diamondlike carbon are classified in a three-stage model to show the factors that control the position, intensity, and widths of the G and D peaks. It is shown that the visible Raman spectra depend formally on the configuration of the ${\mathrm{sp}}^{2}$ sites in ${\mathrm{sp}}^{2}$-bonded clusters. In cases where the ${\mathrm{sp}}^{2}$ clustering is controlled by the ${\mathrm{sp}}^{3}$ fraction, such as in as-deposited tetrahedral amorphous carbon (ta-C) or hydrogenated amorphous carbon (a-C:H) films, the visible Raman parameters can be used to derive the ${\mathrm{sp}}^{3}$ fraction.
12,593 citations
TL;DR: The mechanical flexibility and easy coating capability offered by MXenes and their composites enable them to shield surfaces of any shape while providing high EMI shielding efficiency.
Abstract: Materials with good flexibility and high conductivity that can provide electromagnetic interference (EMI) shielding with minimal thickness are highly desirable, especially if they can be easily processed into films. Two-dimensional metal carbides and nitrides, known as MXenes, combine metallic conductivity and hydrophilic surfaces. Here, we demonstrate the potential of several MXenes and their polymer composites for EMI shielding. A 45-micrometer-thick Ti3C2Tx film exhibited EMI shielding effectiveness of 92 decibels (>50 decibels for a 2.5-micrometer film), which is the highest among synthetic materials of comparable thickness produced to date. This performance originates from the excellent electrical conductivity of Ti3C2Tx films (4600 Siemens per centimeter) and multiple internal reflections from Ti3C2Tx flakes in free-standing films. The mechanical flexibility and easy coating capability offered by MXenes and their composites enable them to shield surfaces of any shape while providing high EMI shielding efficiency.
3,251 citations
TL;DR: The broadband and tunable high-performance microwave absorption properties of an ultralight and highly compressible graphene foam (GF) are investigated and it is shown that via physical compression, the microwave absorption performance can be tuned.
Abstract: The broadband and tunable high-performance microwave absorption properties of an ultralight and highly compressible graphene foam (GF) are investigated. Simply via physical compression, the microwave absorption performance can be tuned. The qualified bandwidth coverage of 93.8% (60.5 GHz/64.5 GHz) is achieved for the GF under 90% compressive strain (1.0 mm thickness). This mainly because of the 3D conductive network.
1,533 citations
TL;DR: In this paper, a classification of nanostructure morphology according to the mechanism responsible for the magnetic properties is presented, followed by a brief discussion of some promising experimental techniques in synthesis and measurements.
Abstract: Understanding the correlation between magnetic properties and nanostructure involves collaborative efforts between chemists, physicists, and materials scientists to study both fundamental properties and potential applications. This article introduces a classification of nanostructure morphology according to the mechanism responsible for the magnetic properties. The fundamental magnetic properties of interest and the theoretical frameworks developed to model these properties are summarized. Common chemical and physical techniques for the fabrication of magnetic nanostructures are surveyed, followed by some examples of recent investigations of magnetic systems with structure on the nanometer scale. The article concludes with a brief discussion of some promising experimental techniques in synthesis and measurements.
1,522 citations
TL;DR: Owing to the magnetic-dielectric synergistic effect, the obtained CoNi@SiO2 @TiO2 microspheres exhibit outstanding microwave absorption performance with a maximum reflection loss of -58.2 dB and wide bandwidth of 8.1 GHz.
Abstract: The synthesis of CoNi@SiO2 @TiO2 core-shell and CoNi@Air@TiO2 yolk-shell microspheres is reported for the first time. Owing to the magnetic-dielectric synergistic effect, the obtained CoNi@SiO2 @TiO2 microspheres exhibit outstanding microwave absorption performance with a maximum reflection loss of -58.2 dB and wide bandwidth of 8.1 GHz (8.0-16.1 GHz, < -10 dB).
1,409 citations