Achieving superior electromagnetic wave absorbers through the novel metal-organic frameworks derived magnetic porous carbon nanorods

Renewable porous biochar and 2D MXene have attracted significant attention in high-end electromagnetic interference (EMI) shielding fields, due to unique orderly structures and excellent electrical conductivity (σ) value. In this work, the wood-derived porous carbon (WPC) skeleton from natural wood was performed as a template. And excellent conductive and ultra-light 3D MXene aerogel was then constructed to prepare the MXene aerogel/WPC composites, based on highly ordered honeycomb cells inner WPC as a microreactor. Higher carbonization temperature is more conducive to the graphitization degree of natural wood. MXene aerogel/WPC composites achieve the optimal EMI SE value of up to 71.3 dB at density as low as 0.197 g/cm3. Such wall-like “mortar-brick” structures (WPC skeleton as “mortar” and MXene aerogel as “brick”) not only effectively solve the unstable structure problem of MXene aerogel networks, but also greatly prolong the transmission paths of the electromagnetic waves and dissipate the incident electromagnetic waves in the form of heat and electric energy, thereby exhibiting the superior EMI shielding performance. In addition, MXene aerogel/WPC composites also exhibit good anisotropic compressive strength, excellent thermal insulation and flame retardant properties. Such ultra-light, green and efficient multi-functional bio-carbon-based composites have great application potential in the high-end EMI shielding fields of aerospace and national defence industry, etc.

Ultra-light MXene aerogel/wood-derived porous carbon composites with wall-like “mortar/brick” structures for electromagnetic interference shielding

Carbon-based composites have gained extensive attention as microwave absorbing materials due to the lighter weight compared with other materials. In this work, Co/C nanocomposites with Co nanoparticles uniformly distributed in amorphous carbon sheets are prepared by a freezing dry and carbothermic reduction process. Hierarchical porous microstructures (micropores, mesopores, macropores) are achieved by ice template and huge amounts of gas during carbothermal reduction. Excellent absorption performance is achieved at a very low Co/C content (10% and 15%), which is a great success to design ultralight absorbers. At 10% content level, the effective absorption bandwidth is 5.0 GHz with a thin thickness of 1.8 mm, while the absorption bandwidth is 4.7 GHz with a thin thickness of 1.5 mm at 15% Co/C content level. The excellent absorption performance is attributed to excellent impedance matching resulting from synergy of cobalt and carbon and strong interfacial polarization induced by the hierarchical porous microstructures. This work provides a new pathway of designing ultralight absorbers with the advantage of thin thickness and wide bandwidth. Excellent absorption performance is achieved at only 10% Co/C content level, a success to design ultralight absorbers.

Hierarchically porous Co/C nanocomposites for ultralight high-performance microwave absorption

With the booming development of electronic information technology, the problems caused by electromagnetic (EMs) waves have gradually become serious, and EM wave absorption materials are playing an essential role in daily life. Carbon nanostructures stand out for their unique structures and properties compared with the other absorption materials. Graphene, carbon nanotubes, and other special carbon nanostructures have become especially significant as EM wave absorption materials in the high-frequency range. Moreover, various nanocomposites based on carbon nanostructures and other lossy materials can be modified as high-performance absorption materials. Here, the EM wave absorption theories of carbon nanostructures are introduced and recent advances of carbon nanostructures for high-frequency EM wave absorption are summarized. Meanwhile, the shortcomings, challenges, and prospects of carbon nanostructures for high-frequency EM wave absorption are presented. Carbon nanostructures are typical EM wave absorption materials being lightweight and having broadband properties. Carbon nanostructures and related nanocomposites represent the developing orientation of high-performance EM wave absorption materials.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201801057

Toward the Application of High Frequency Electromagnetic Wave Absorption by Carbon Nanostructures

Magnetite (Fe3O4)/carbon (C) composite flowers with an average size of 4–6 μm were prepared through a facile route including a solvothermal approach and a carbon reduction process. The resultant Fe3O4/C composites are porous and exhibit a three-dimensional (3D) flower-like morphology with the core–shell Fe3O4@C nanoparticles hybridized by amorphous carbon sheets. The epoxy resin composites containing 50 wt % 3D porous Fe3O4/C composite flowers display an optimal reflection loss (RL) value of −54.6 dB at 5.7 GHz at a thin thickness of 4.27 mm and the effective bandwidth with RL < −10 dB reaches 6.0 GHz at a thickness of 2.1 mm. These enhanced EM wave absorption performances are attributed to the synergistic effects of Fe3O4 and carbon as well as the structural advantages, e.g., three-dimensional structure with large surface area, porous and core–shell structures of Fe3O4/C flowers. These results suggest the 3D porous Fe3O4/C composite flowers designed here can serve as ideal candidates for high-performance...

Enhanced Electromagnetic Wave Absorption of Three-Dimensional Porous Fe3O4/C Composite Flowers

Design and synthesis of TiO2/Co/carbon nanofibers with tunable and efficient electromagnetic absorption

To tackle the aggravating electromagnetic wave (EMW) pollution issues, high-efficiency EMW absorption materials are urgently explored. Metal–organic framework (MOF) derivatives have been intensively investigated for EMW absorption due to the distinctive components and structures, which is expected to satisfy diverse application requirements. The extensive developments on MOF derivatives demonstrate its significantly important role in this research area. Particularly, MOF derivatives deliver huge performance superiorities in light weight, broad bandwidth, and robust loss capacity, which are attributed to the outstanding impedance matching, multiple attenuation mechanisms, and destructive interference effect. Herein, we summarized the relevant theories and evaluation methods, and categorized the state-of-the-art research progresses on MOF derivatives in EMW absorption field. In spite of lots of challenges to face, MOF derivatives have illuminated infinite potentials for further development as EMW absorption materials.
Highlights:
1 In terms of components and structures, this review summarizes progresses and highlights strategies of MOF derivatives for efficient electromagnetic wave absorption.2 We also systematically delineate relevant theories and points out the prospects and current challenges.

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Carbon-Based MOF Derivatives: Emerging Efficient Electromagnetic Wave Absorption Agents

Broadband absorbers derived from metal–organic frameworks are highly desirable in the electromagnetic (EM) wave absorption field. Herein, a strategy for cobalt-decorated porous ZrO2/C hybrid octahe...

High-Efficiency Electromagnetic Wave Absorption of Cobalt-Decorated NH2-UIO-66-Derived Porous ZrO2/C.

Modern communication technologies put forward higher requirements for electromagnetic wave (EMW) absorption materials. Metal–organic framework (MOF) derivatives have been widely concerned with its diverse advantages. To break the mindset of magnetic-derivative design, and make up the shortage of monometallic non-magnetic derivatives, we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption. The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415 (TiZr-MOFs) are qualified with a minimum reflection loss of − 67.8 dB (2.16 mm, 13.0 GHz), and a maximum effective absorption bandwidth of 5.9 GHz (2.70 mm). Through in-depth discussions, the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed. Therefore, this work confirms the huge potentials of non-magnetic bimetallic MOFs derivatives in EMW absorption applications.

/pdf/non-magnetic-bimetallic-mof-derived-porous-carbon-wrapped-19ie9fz9mn.pdf

Jing Qiao

Papers

Design and synthesis of TiO2/Co/carbon nanofibers with tunable and efficient electromagnetic absorption

Carbon-Based MOF Derivatives: Emerging Efficient Electromagnetic Wave Absorption Agents

High-Efficiency Electromagnetic Wave Absorption of Cobalt-Decorated NH2-UIO-66-Derived Porous ZrO2/C.

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption.

CuNi alloy/ carbon foam nanohybrids as high-performance electromagnetic wave absorbers