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a Schematic illustration of the preparation process of carbon fiber decorated with magnetic metal–encapsulated CNTs with double-sided high-efficiency EMI shielding and electrocatalytic oxygen properties. b XRD patterns, c electrical conductivity, and d magnetic hysteresis loops of carbon fibers decorated by magnetic metal–encapsulated CNTs
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Although carbon fibers have been broadly used as electromagnetic shields, it is still a challenge to achieve high-efficiency shielding performances with tunable reflection/absorption mechanism. Herein, magnetic metal–encapsulated carbon nanotubes (CNTs) grown on carbon fibers are fabricated via a modified chemical vapor deposition procedure, whose...
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In electrocatalytic processes, traditional powder/film electrodes inevitably suffer from damage or deactivation, reducing their catalytic performance and stability. In contrast, self-healing electrocatalysts, through special structural design or composition methods, can automatically repair at the damaged sites, restoring their electrocatalytic act...
Citations
... At the microscopic level, CNTs may be viewed as seamless cylinders (with single or multiple concentric shells) formed by rolling up a honeycomb lattice of carbon hexagons [36]. Due to their outstanding electrical, thermal, and mechanical properties, various multifunctional polymer composites have been developed using CNTs [37]. Conductive polymer nanocomposites are already being used in electromagnetic interference shielding [38], anti-static coatings [39], flexible electronics [40], and strain sensors [41]. ...
A photocurable resin/carbon nanotube (CNT) nanocomposite was fabricated from aligned CNTs in an acrylic matrix. The conductivity of the nanocomposite increased rapidly and then stabilized when the CNT content was increased up to and beyond the percolation threshold. Various structures were created using a digital light processing (DLP) 3D printer. Various polymeric dispersants (SMA-amide) were designed and synthesized to improve the CNT dispersion and prevent aggregation. The benzene rings and lone electron pairs on the dispersant interacted with aromatic groups on the CNTs, causing the former to wrap around the latter. This created steric hindrance, thereby stabilizing and dispersing the CNTs in the solvent. CNT/polymer nanocomposites were created by combining the dispersant, CNTs, and a photocurable resin. The CNT content of the nanocomposite and the 3D printing parameters were tuned to optimize the conductivity and printing quality. A touch-based human interface device (HID) that utilizes the intrinsic conductivity of the nanocomposite and reliably detects touch signals was fabricated, enabling the free design of sensors of various styles and shapes using a low-cost 3D printer. The production of sensors without complex circuitry was achieved, enabling novel innovations.
... With the synergistic effect of one-dimensional AgNWs and two-dimensional Ti 3 C 2 T x , the AgNWs/Ti 3 C 2 T x /MF sponges had an EMI SE of up to 52.6 dB at a density of only 49.5 mg cm 3 . The oxides of iron [61][62][63], cobalt [64][65][66], and manganese [67,68] have excellent magnetic properties as wave absorbents. When combined with MXene, it can adjust the electromagnetic characteristics of MXene and introduce magnetic losses to improve EMI SE. ...
With the rapid development of the 5th-generation (5G) mobile communication technology, the applications of high-frequency and high-power electronic equipment are becoming increasingly broadened, which seriously affects the operation of electronic components and human health. Therefore, the research on high-performance electromagnetic interference (EMI) shielding materials is of great significance for the development and upgrading of 5G electronic equipment. In recent years, the transition metal carbides, nitrides, and carbonitrides (MXenes) have gradually received extensive attention from scholars due to ultra-high electrical conductivity, large specific surface area, and excellent hydrophilicity. This review introduces the preparation methods of MXenes and the latest research progress of MXene-based nanomaterials in the field of EMI shielding. In this review, the EMI shielding mechanism and the preparation methods of MXenes are briefly introduced first. Next, the research progress of MXene-based EMI shielding materials in recent years is reviewed, and various kinds of MXene-based EMI shielding materials are introduced in detail, especially the preparation of MXene/polymer EMI shielding composites with various structures. The key scientific and technical problems in the field of MXene-based EMI shielding materials are put forward, and the future development trend is prospected.
... It is well known that lightweight carbon materials are often applied as an effective absorption component due to their readily accessible dielectric properties, such as polarization relaxation and conduction loss, which facilitate the dissipation of incident microwaves within the gigahertz range. 7,8 According to the available research reports, multi-walled carbon nanotubes (MWCNT)s, 9,10 carbon fibers (CFs), 11,12 graphene, 13,14 reduced graphene oxide (rGO) 15,16 and even biochar [17][18][19] are very popular in the preparation of related MAMs owing to their special properties or structural effects. However, the performance of single-carbon materials for microwave absorption is very limited, due to multiple factors including the relatively simple dielectric mechanism and poor impedance adaptation between MAMs and free air. ...
The design of wide-band microwave absorption materials is currently an effective strategy to eliminate excessive microwave radiation contamination. Herein, a facile method of polymerization, magnetic doping and calcination was employed to prepare Fe3C-decorated N-doped carbon nanoparticles from polyacrylonitrile. The research demonstrates the high defect state of the amorphous carbon within the composites, and the increase in temperature induced enhancement of the Fe2+/Fe3+ ratio, reducing the performance after absorption saturation. The composite obtained under 650°C treatment has the best microwave absorption ability, with a maximal reflection loss (RL) of 39.32 dB at 3.44 GHz and the broadest efficient absorption bandwidth of 6.19 GHz at only 2.3 mm for a low filling rate of 10 wt.%. The combined effect of conduction loss, dipole and interface polarizations, exchange and natural resonances, and eddy-current loss under matched impedance promotes this excellent absorption performance, which confirms the practicability of this absorber for shielding of electromagnetic radiation pollution.
... Polymer reinforced with carbon fibers (CFs) [1] gradually replaces traditional materials in defense/aerospace [2], automotive [3], transportation, electronics [4][5][6][7], and new energy vehicle fields [8,9] because of high specific strength and modulus [10,11]. However, weak fiber-polymer interfacial adhesion will be detrimental to stress transfer and influence the final applications of these nanocomposites [12][13][14]. ...
Through electrophoretic deposition (EPD), hybrid graphene oxide-polyethyleneimine–coated carbon fibers (named as ACF/GO-PEI) were prepared to improve the interfacial performances between carbon fibers and epoxy matrix. These rigid GO sheets and flexible PEI polymer could work together, resulting in the improvement of mechanical performances. In this strategy, rigid GO sheets make mechanical interlocking in the interface of composites, and flexible PEI bridges all three parts, i.e., fiber, GO, and epoxy, by covalent bond and electrovalent bond. Moreover, homogenized distribution of the GO-PEI sheets covered on carbon fiber owing to the electrostatic interactions of the positively charged ions and steric effect, effectively increasing the surface roughness and surface energy. The interfacial shear strength (IFSS) of ACF/GO-PEI reinforced epoxy composite could reach 79.2 MPa. In comparison with untreated one, the value was enhanced 69.2%. This study provides new ideas for expanding the application of nanocomponents in traditional composite materials.
... Therefore, the materials reconstructed by decomposition and recombination after pyrolysis modify the electronic structure of M-N-C [17]. Moreover, the metal phthalocyanine has been found to show a significantly optimized electronic structure when further combined with carbon materials, which can be attributed to the high specific surface area, excellent electrical conductivity, chemical stability, and easily adjustable surface chemistry of carbon materials [18,[41][42][43][44][45][46][47][48][49]. Furthermore, the decorated heteroatoms with lower (B, P, S, and transition metals) or higher (N) electronegativities distinct from that of carbon can polarize adjacent carbon atoms and change the electronic properties of the carbon skeletons [50,51], which will modify the related electrocatalytic performance [52]. ...
In recent years, transition metal-nitrogen-carbon (M–N-C) composites are expected to be an alternative to platinum group metal (PGM) among various non-precious metal catalysts investigated. However, the major challenge comes from insufficient electrocatalytic performance and durability for oxygen reduction reaction (ORR). In addition to the selection of suitable central metal active sites, the electrocatalytic activity and stability of the M–N-C catalysts can be enhanced by adjusting the electronic structure of the catalysts. In this work, M–N-C/F composites were synthesized by loading transition metal phthalocyanine complexes onto pre-fluorinated carbon nanotubes through a simple pyrolysis method. Pyrroline-N (PN) and graphite-N (GN) formed after thermal treatment can act as electron acceptors to modulate their charge distribution on the M-N4 sites, and the use of pre-fluorinated nanotubes also allows for a more controlled introduction of fluoride ions that are well coordinated to transition metals, both of which can modulate and modify the electronic structure of M–N-C catalysts. The obtained manganese phthalocyanine/fluorinated carbon nanotubes at 800 °C (MnPc/FCNT800) exhibit a competitive electrocatalytic ORR performance with the half-wave potential (E1/2) of 0.9 V and only 12.1% decay after 20-h long-term chronoamperometry (CA) test in 1.0 M KOH electrolyte, outperforming the commercial Pt/C. Overall, this work paves the way of the electronic structure modification and design of such M–N-C composites for sustainable energy applications.
Graphical Abstract
... With the widespread application of modern electronic technology in areas such as communication, navigation, and detection [1][2][3][4], a range of electromagnetic (EM) defense technologies have been developed to defend against the harmful effects of EM radiation, interference, and detection [5][6][7][8]. ...
The inability of existing electromagnetic wave absorbing materials (EAMs) to manipulate electromagnetic waves in multiple dimensions leads to the failure to satisfy the demands placed on electromagnetic (EM) defense technology by the current complex EM environment. To break this dilemma, this study focuses on the impedance properties of EAMs, conferring additional ability to disperse and deflect reflected waves by encoding EAMs with opposite phase responses in different impedance mismatch modes. Due to the synergy of both absorption and scattering mechanisms, the developed scattering metasurface absorber exhibits excellent anti-reflection performance, with reflectivity below 0.1 in the 7.8-16.7 GHz at 2 mm thickness. Furthermore, a genetic algorithm is employed to tailor the desired scattering field to meet the stealth requirements of specific environments, allowing for the directional transmission of EM energy in the one-dimensional or homogeneous distribution in the three-dimensional. The proposed scattering metasurface absorber constructed by coded EAMs exhibited excellent anti-reflection properties and environmental stealth adaptability, opening up new possibilities for the development of advanced EM defense technology.
... Hongtao Guo et al. established that adding conductive fillers enhances not only the dielectric properties of EMI shielding materials in order to improve total EMI shielding due to dielectric loss, but also the mechanical properties of the entire composite fibres [21]. Normally carbonaceous compounds anchored with Fe ingredients [22,23] are one of the best choices for EMI shielding applications because of their double attenuation mechanism followed by enhanced dielectric and magnetic loss characteristics [24]. Although the limited mechanical flexibility of the carbonaceous compounds can be overcome by anchoring a wide variety of polymers, the composite films demonstrated significantly high reflectivity instead of a high absorption process. ...
In this communication, the electromagnetic interference shielding (EMI) performance and dielectric properties of the high temperature sustainable α-MnO2 semiconductor quantum dots (SQDs) have been modulated by incorporating cobalt ions into its crystal structure by employing a modified chemical synthesis technique as well as post-calcination treatment. The phase and structural investigation confirm the Co atoms are present inside the (2×2) tunnel of α-MnO2 hollandite type network and with the increasing sintering temperature the crystallite size of the samples has been found to be increasing. The theoretical bandgap energy of the samples using generalized gradient approximation with Hubbard U correction term (GGA + U) is found to be in good agreement with the experimental findings. From PL spectra it has been found that the peak locations are shifted because of the variation of the inherent bandgap energy which confirms the particles are quantum dots (QDs) in nature. Gigantic dielectric constant has been observed for the sample CM450 at low frequency (∼0.7 M at 40 Hz) with moderate tangent loss. This enhances the shielding performance (∼48 dB at 17.5 GHz) of the unwanted electromagnetic signals emitted from the daily using electronic gadgets at X-band and Ku-band. Such valuable shielding performance can be ascribed to the dual effect of dipolar as well as Maxwell Wagner Sillars (MWS) interfacial polarization effect. Considering all the performance it can be clearly concluded that the presence of a foreign element like Co creates a remarkable footprint to enhance all the electrical performance of the α-MnO2 SQDs and makes the material highly suitable for high dielectric separator as well as an efficient material for EMI pollution shielding application in electronic industry.
... Moreover, the metal phthalocyanine is found to show signi cantly optimized electronic structure when further combined with carbon materials, which can be attributed to the high speci c surface area, excellent electrical conductivity, chemical stability, and easily adjustable surface chemistry of carbon materials [9,[26][27][28][29][30][31][32][33]. Furthermore, the decorated heteroatoms with lower (B, P, S, and transition metals) or higher (N) electronegativities distinct from that of carbon can polarize adjacent carbon atoms and change the electronic properties of the carbon skeletons [34,35], which will modify the related electrocatalytic performance [36]. ...
In recent years, transition metal-nitrogen-carbon (M-N-C) composites are expected to be an alternative to platinum group metal (PGM) among various nonprecious metal catalysts investigated. However, the major challenge comes from insufficient electrocatalytic performance and durability for oxygen reduction reaction (ORR). In addition to the selection of suitable central metal active sites, the electrocatalytic activity and stability of the M-N-C catalysts can be enhanced by adjusting the electronic structure of the catalysts. In this work, M-N-C/F composites were synthesized by loading transition metal phthalocyanine complexes onto pre-fluorinated carbon nanotubes through a simple pyrolysis method. Pyrroline-N(PN) and graphite-N(GN) formed after thermal treatment can act as electron acceptors to modulate their charge distribution on the M-N 4 sites, and the use of pre-fluorinated nanotubes also allows for a more controlled introduction of fluoride ions that are well coordinated to transition metals, both of which can modulate and modify the electronic structure of M-N-C catalysts. The obtained manganese phthalocyanine/fluorinated carbon nanotubes at 800°C (MnPc/FCNT800) exhibits a competitive electrocatalytic ORR performance with the half-wave potential ( E 1/2 ) of 0.9 V and only 12.1% decay after 20 h long-term chronoamperometry (CA) test in 1.0 M KOH electrolyte, outperforming the commercial Pt/C. Overall, this work paves the way of the electronic structure modification and design of such M-N-C composites for sustainable energy applications.
... As attractive alternatives to precious metal-based materials, transition metal compounds (TMCs) have attracted tremendous interest [14][15][16][17][18], and have been considered as catalysts for electrochemical oxygen evolution owing to their active sites of metal-O (M-O), M-S, and M-P bonds [19][20][21][22]. For example, iron-encapsulated CNTs on carbon fiber showed boosted oxygen evolution reaction performances [23]. However, OER over TMCs suffers from inferior electrochemical performances and poor stability, attributed to unstable structure and inactive intrinsic activity. ...
The implementation of low-cost and efficient electrocatalysts for water oxidation is crucial for the development of industrial water electrolysis; however, they often suffer from inferior activity or poor stability. Herein, we demonstrated 0.7-nm iridium clusters embedded onto Ni–Mo–P (Ir-NMP) that exhibited an ultralow overpotential of 290 mV vs reversible hydrogen electrode (RHE) to reach the current density of 50 mA cm⁻² in 1 M KOH, together with low Tafel slope of 63.9 mV dec⁻¹, high mass activity of 2604 A gIr⁻¹, and excellent catalytic stability with almost complete retention of activity within more than 30 h. According to characterizations and analyses, the interlaced crystalline and amorphous structure of Ni − Mo − P made homogeneous embedment of ultrathin Ir clusters onto NMP substrate, and the introduction of Ir clusters enabled the optimization of electronic structure for Ni and Mo species in NMP, which were available to the highly efficient and durable Ir-NMP electrocatalyst for OER.
... Microwave absorbing materials can be divided into three categories according to the attenuation mechanism of electromagnetic waves, each of which has its own advantages and disadvantages [28]. The first is conductive materials based on carbon, typically including graphene [29][30][31][32], carbon nanotubes (CNTs) [33,34] and carbon nanofibers [35][36][37]. The advantages of them are low density, high stability and conductivity. ...
