Diverse Structural Design Strategies of MXene‑Based Macrostructure for High‑Performance Electromagnetic Interference Shielding

There is an urgent demand for flexible,lightweight,mechanically robust,excellent electromagnetic interference(EMI)shielding materials.Two-dimensional(2D)transition metal carbides/nitrides(MXenes)have been potential candidates for the construction of excellent EMI shielding materials due to their great electrical electroconductibility,favorable mechanical nature such as flexibility,large aspect ratios,and simple processability in aqueous media.The applicability of MXenes for EMI shielding has been intensively explored;thus,reviewing the relevant research is beneficial for advancing the design of high-performance MXene-based EMI shields.Herein,recent progress in MXene-based macrostructure development is reviewed,including the associated EMI shielding mechanisms.In particular,various structural design strategies for MXene-based EMI shielding materials are highlighted and explored.In the end,the difficulties and views for the future growth of MXene-based EMI shields are proposed.This review aims to drive the growth of high-performance MXene-based EMI shielding macrostructures on basis of rational structural design and the future high-efficiency utilization of MXene.

Printable Aligned Single-Walled Carbon Nanotube Film with Outstanding Thermal Conductivity and Electromagnetic Interference Shielding Performance

Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.

Research on Electromagnetic Wave Absorption Based on Electrospinning Technology

At present,in order to overcome electromagnetic interference and prevent electromagnetic harm,the research of new and efficient electromagnetic wave absorbing materials has become the research focus in the field of materials science.The one-dimensional structure can promote the impedance matching and attenuation characteristics of the absorbing materials.Electrospinning,as an effective method to prepare nanofibers with high length-diameter ratio,has been widely concerned because it is suitable for struc-tural design of various materials.In this paper,the research progress and absorption properties of nano-fiber materials prepared by electrospinning combined with different processes are introduced.

Ultralight aerogel sphere composed of nanocellulose-derived carbon nanofiber and graphene for excellent electromagnetic wave absorption

A novel type of three-dimensional ultralight aerogel sphere,consisting of one-dimensional nanocellulose-derived carbon fibers and two-dimensional graphene layers,was prepared based on a developed drop-freeze-drying followed by carbonization approach.The nanofibrous carbon efficiently prevents the agglomeration of the graphene layers,which,in turn,reduces the shrinkage and maintains the structural stability of the hybrid carbon aerogel spheres.Consequently,the aerogel spheres showing an ultralow-density of 2.8 mg/cm^(3) and a porosity of 99.98%accomplish the tunable dielectric property and electromagnetic wave(EMW)absorption performance.The high-efficiency utilization of biomass-derived fibrous nanocarbon,graphene,the porous structure of the hybrid aerogel spheres leads to the excellent EMW absorption performance.The aerogel spheres display an effective absorption bandwidth of 6.16 GHz and a minimum reflection loss of−70.44 dB even at a filler loading of merely 3 wt.%,significantly outperforming that of other biomass-derived carbon-based EMW absorbing materials.This work offers a feasible,facile,scalable approach for fabricating high-performance and sustainable biomass-based aerogels,suggesting a tremendous application potential in EMW absorption and aerospace.

A temperature-activated nanocomposite metamaterial absorber with a wide tunability

Novel thin and flexible broadband electromagnetic microwave absorbers are realized with nanocomposites and achieve a wide frequency tunability （from 10 to 17.2 GHz） by actively adjusting the resistance. The proposed absorbers are fabricated by scalable screen printing of optimized nanoparticle ink onto the flexible dielectric composite substrates. Based on the shape memory effects of the substrate and piezoresistive effect of the nanocomposite frequency selective surface, a controllable sheet resistance, and thereby tunable wave absorption performance, can be realized in a temperature-activated and dynamically stable manner. The results provide new dimensions for the design of active electromagnetic devices by utilizing previously underestimated intrinsic properties of the artificial materials and the smart behavior of polymer-based nanocomposites.

三维多孔碳基吸波材料的研究进展

随着电磁波(EMW)污染的日益严重,开发高性能电磁波吸收材料(EWAMs)已成为研究热点.碳基EWAMs具有优异的物理、化学稳定性和高导电性带来的强介电损耗.特别是三维(3D)多孔碳基EWAMs在EMW吸收研究领域长盛不衰.3D多孔结构大大降低了材料的密度,有利于EMW的多次反射和散射,优化了阻抗匹配,因此有望实现“低密度、薄厚度、宽吸收带宽、强吸收”的目标.在此,我们首先阐明了相关的理论基础和评价方法.之后,我们以材料来源为主线索,总结了3D多孔碳基EWAMs的最新研究进展,并突出了其中一些独特而新颖的观点.最后,提出了3D多孔碳基EWAMs的挑战和前景,这将有助于高性能EWAMs的进一步发展.

Nanocellulose-assisted preparation of electromagnetic interference shielding materials with diversified microstructure

Sustainable and renewable nanocellulose attracts more and more attention in various fields due to its high strength-to-weight ratio,small diameter,large aspect ratio,and abundant functional groups.The excellent properties and structural characteristics enabled a great potential of nanocellulose for efficient interactions with functional nanomaterials such as carbon nanotube,graphene,transition metal carbides/nitrides(MXenes),and metal nanoparticles,which is beneficial for preparing high-performance electromagnetic interference(EMI)shields.We review the advances in the nanocelluloseassisted preparation of composite films and aerogels for EMI shielding application.The nanocellulose-based composites are evaluated in terms of their EMI shielding performance and the shielding mechanisms,including conduction,polarization,and multiple reflections are summarized.In addition to the constituent structure and contents,we highlight the significance of the microstructure design in enhancing the EMI shielding performance of the nanocellulose-based EMI shields.Finally,the current challenges and outlook for these fascinating nanocellulose-based EMI shielding composites are discussed.

Bioinspired cellulose-integrated MXene-based hydrogels for multifunctional sensing and electromagnetic interference shielding

Bioinspired hydrogels are complex materials with distinctive properties comparable to biological tissues.Their exceptional sensitivity to various external stimuli leads to substantial application potential in wearable smart devices.However,these multifaceted hydrogels are often challenging to be combined with pattern customization,stimulus responsiveness,self-healing,and biocompatibility.Herein,inspired by mussel secretions,a printable,self-healing,and biocompatible MXene-based composite hydrogel was designed and prepared by incorporating Ti3C2Tx MXene nanosheets into the hydrogel framework through the chelation of calcium ions(Ca2+)with polyacrylic acid and cellulose nanofibers at alkaline conditions.The biocompatible conductive hydrogel exhibited sensitivity(gauge factor of 2.16),self-healing(within 1 s),recognition,and adhesion,distinguishing it as an ideal candidate for wearable multifunctional sensors toward strain sensing,vocal sensing,signature detection,and Morse code transmission.Additionally,the multifunctional hydrogel manifested efficient electromagnetic interference shielding properties(reaching more than 30 dB at a thickness of 2.0 mm),protecting electronics and humans from electromagnetic radiation and pollution.Therefore,the presented work represents a versatile strategy for developing environmentally friendly conductive hydrogels,demonstrating the perspectives of intelligent hydrogels for multifunctional applications.