Reflection Loss Value Research Articles

Microwave-absorbed porous carbon was prepared from agricultural coconut shell waste by a simple one-step high temperature charring

Coconut shell was a resourceful and renewable biomass waste in our country, which can obtain a rich pore structure after simple charring treatment. In this paper, coconut shell porous carbon (CSPC) material with good wave-absorbing properties was successfully prepared by activating coconut shell powder with KOH and charring at high temperature. The material had a porous structure, honeycomb, with the charring temperature and the proportion of activator gradually increased, the degree of graphitization gradually increased. When the charring temperature was 600 ℃ and the activator ratio was 0.5:1, the minimum reflection loss (RL min) value was −37.23 dB when the sample thickness was 1.5 mm and the test frequency was 16.72 GHz. The coconut shell porous carbon prepared was a new type of electromagnetic wave-absorbing material made from agricultural waste, which can obtain a better microwave absorption effect after simple processing.

Room temperature deprotonation engineering for large-scale preparation of MIL-88B-like for efficient electromagnetic wave absorption

Metal-organic frameworks (MOFs)-derived electromagnetic functional materials are a hot research trend in the field of microwave absorption (MA). However, there is a lack of high-yield strategies to drive high-performance MOFs-derived MA absorbers out of the laboratory. Herein, we prepared MIL-88B-like using a simple room-temperature liquid-phase method with more than 75 times the yield of the solvothermal method. The obtained MOFs were pyrolyzed to form C/FeO/FeN0.0324/Fe quaternary composite materials. Under suitable graphitizing conditions, the moderate conductivity of derivative material of M1 precursor carbonized at 700 °C (M1-700) not only meets the requirement of impedance matching but also provides high conduction loss. Meanwhile, the multiple polarization loss mechanisms from defect-induced polarization, dipole polarization, heterogeneous interfaces, and magnetic loss mechanism synergize with each other, resulting in an effective absorption bandwidth (EAB) of 6.71 GHz and a reflection loss (RL) value of −62.57 dB at 22.5 wt% filler, which is a 6-fold increase in the RL compared with that of the conventional MIL-88B-derived wave absorber. In conclusion, this work provides a feasible solution for practical absorbers and an excellent reference value for high MA performance materials for applications.

Amorphous-Co@Nd(BO2)3/rGO magnetic nanocomposites as high-frequency, wide-bandwidth and light-weight microwave absorbing materials

It is necessary to broaden absorption bandwidth, regulate applied frequency, reduce the weight and maintain strong absorption for magnetic microwave absorbing materials by constructing suitable material structures to satisfy the requirements for wide applications in various electromagnetic devices. In this work, well-structured amorphous-Co@Nd(BO2)3/rGO nanocomposites have been fabricated using a selective chemical reduction in a mixed aqueous solution containing Co2+ and Nd3+ ions along with GO sheets reduced by NaBH4 as the reductant, in which only Co2+ and GO but no Nd3+ ions were reduced. Very low coercivity of 0.4 Oe is achieved in amorphous-Co@Nd(BO2)3/rGO nanocomposites due to amorphous Co@Nd(BO2)3 core-shell nanoparticles uniformly anchored on rGO sheets. These soft magnetic rGO-based nanocomposites exhibit high-frequency microwave absorption performance including a minimum reflection loss (RLmin) value of −84.09 dB at 15.38 GHz for a 2.1 mm thickness at an applied frequency range (12.31–18 GHz) covering almost the entire Ku band. Moreover, a much wider absorption band of 7.24 GHz (10.67–17.89 GHz, RL ≤ −10 dB) with a 2.3 mm thickness along with a RLmin value of −35.92 dB is also achieved. These rGO-based magnetic composites also show good structural stability, low density and easily controlled material compositions along with facile chemical fabrication suitable for mass production, which promises their latent use in high-performance microwave absorbing devices. Crystallization behavior of a new amorphous Nd(BO2)3 phase was also investigated.

A wood-inspired epoxy-based electronic packaging material with vertically aligned thermally conductive channels for electromagnetic waves absorption and thermal management

Multifunctional materials integrating electromagnetic waves absorption (EMA) and heat conductivity functions are urgently desirable to tackle the heat emission and electromagnetic interference issues of advanced electronics. However, simultaneously mustering these features into one material remains a formidable challenge as the incompatibility between high thermal conductivity and excellent EMA performance. Herein, inspired by the water transport process of trees in nature, an epoxy-based electronic packaging material (CFS/EB) with vertical thermal conduction channels is fabricated by encapsulating high thermal conductivity boron nitride/epoxy hybrids into aerogel skeleton with good electromagnetic features. This ingenious design not only can defuse the issue of difficult coexistence of outstanding EMA and thermal conduction performance, but also delivers high through-plane thermal conductivity arised from vertical aligned channels. The resulting CFS/EB composite exhibits strong EMA performance with minimum reflection loss value of −59.2 dB and broad effective absorption bandwidth of 5.82 GHz. Synchronously, the composite also holds the high through-plane thermal conductivity of 1.51 W m−1 K−1 (655 % higher than pure epoxy resin) at low filler loading of 13.15 wt% as well as electrical insulation of 1.43 × 1012 Ω·cm. Such a superior comprehensive performance endows CFS/EB composite a great application prospects in electronic packaging fields, whilst the orientation structure design triggered by this bioinspired strategy offer facile yet feasible alternatives to address heat accumulation and electromagnetic interference problems for integrated electronics.

2D Transition Metal Dichalcogenides‐Based Composites for Electromagnetic Interference Shielding and Microwave Absorption Applications

Due to the advancements in the electronics industry, the demand for new electromagnetic interference (EMI) shielding and microwave absorption (MA) materials has increased significantly in recent decades. Researchers are investigating a variety of new materials to replace conventional metal sheets in response to these growing demands. Consequently, there is a growing interest in lightweight EMI shielding materials that can meet the demand for lightweight and highly integrated electronic equipment. 2D structural transition metal dichalcogenides (TMDCs) are good candidates for EMI shielding and MA due to their unique properties. This article examines the latest developments in TMDCs and their composite nanomaterials, focusing on their EMI shielding effectiveness and MA performance. The investigation includes a thorough examination of these materials’ shielding effectiveness, maximum reflection loss value, and effective absorption bandwidth. Moreover, this review analyzes the challenges and opportunities that arise in the development of TMDCs.

Construction of CoO/Co9S8/NC composites with low-frequency and broadband electromagnetic wave absorption

Low-frequency electromagnetic wave absorption (EMWA) materials were crucial for addressing electromagnetic pollution and radar stealth. However, achieving low-frequency and broadband absorption still faces challenges. In this work, a succession of CoO/Co9S8/N-doped carbon (NC) composites were fabricated via a partial sulfidation strategy of Co-Prussian blue analogue (Co-PBA). The as-prepared CoO/Co9S8/NC composites featured a porous architecture. The electromagnetic parameters were effectively modulated via varying the sulfidation time. When the sulfidation time was 9 h, the minimum reflection loss (RLmin) value was −50.40 dB at 2.93 mm and a maximum effective absorption bandwidth value was 5.76 GHz (12.24–18.00 GHz) at 1.80 mm. Notably, when the sulfidation time was 12 h, the composites exhibited enhanced EMWA capability in the low-frequency S-band (3.52 GHz) with an RLmin value of −28.91 dB. The superior EMWA performance of composites were primarily attributed to appropriate dielectric constants and optimized impedance matching due to magnetic loss. Moreover, the radar cross section simulation consequences further verified that dissipation capability of electromagnetic wave of the CoO/Co9S8/NC composites in the actual far field. This work afforded novel perspectives into the rational develop of PBA-derived carbon-based EMWA materials with the low-frequency and broadband absorption.

Carbon nanotubes-encapsulated Co/Co7Fe3 nanocomposites: Achieving wideband electromagnetic wave absorption at ultrathin-thickness by regulating magnetic phase ratio

Nowadays, through various strategies such as composition regulation and structural design, the electromagnetic wave (EMW) attenuation ability of composites has been significantly improved. Nevertheless, at ultra-thin sample matching thicknesses, it is still a challenge for absorbing materials to possess high-intensity and wide bandwidth simultaneously. In this work, the cobalt/iron nitrilotriacetic acid chelates (Co/Fe-NAC) were fabricated by a one-step hydrothermal self-assembly strategy. Then, a series of carbon nanotubes-encapsulated Co/Co7Fe3 (Co/Co7Fe3@CNTs) nanocomposites were constructed by coating glucose hydrothermal carbon on Co/Fe-NAC precursors and subsequent calcination process. By controlling the Co/Fe ion content, the magnetic phase ratio in the product can be efficiently regulated to comprehensively optimize microwave absorption (MA) performance. The minimum reflection loss (RL) of the optimized sample is −42.6 dB at only 1.1 mm thickness, and the effective absorption bandwidth (EAB) reaches up to 10.1 GHz (7.9–18 GHz). Surprisingly, for all samples, the widest EAB can exceed 8.2 GHz at the ultra-thin thickness (thinner than 1.3 mm) and the strongest RL values are all below −30 dB (99.9 % EMW can be absorbed). Such excellent MA performance is attributed to the strong magnetic loss of highly dispersed magnetic nanoparticles, the strong dielectric properties of carbon nanotubes and shells, optimized impedance matching, as well as the synergistic effect of multi-dimensional heterogeneous components and structures. Moreover, the high-frequency structure simulator (HFSS) was used to further analyze the multi-polarization behaviors and heterogeneous magnetic coupling effect. This work may provide a new direction to the fabrication of efficient and ultra-thin absorbers, and Co/Co7Fe3@CNTs nanocomposites may become a promising candidate for practical application in the MA field.

Customized heterostructure of transition metal carbides as high-efficiency and anti-corrosion electromagnetic absorbers

The ever-increasing presence of electronic devices and communication equipment imposes a critical demand for the development of highly efficient microwave absorption materials, as a means to combat the detrimental effects of electromagnetic (EM) wave pollution. The extraordinary advantages offered by heterointerface and defect engineering, coupled with their distinctive electromagnetic traits, infuse boundless energy into the development of MXene-based absorbers for EM attenuation. However, there is still a lack of understanding regarding the consequences of irreversible oxidation on the surface chemistry and dielectric properties of MXenes. Through the employment of heterointerface engineering strategy to promote interfacial charge accumulation and polarization, remarkable EM absorption properties coupled with corrosion resistance have been realized. The partially oxidized MXenes, particularly Ti3C2Tx and V2CTx, displayed remarkable reflection loss (RL) values of −56.83 dB and −52.13 dB, respectively. Additionally, the Nb2CTx composites showcased exceptional performance, offering a significantly broader bandwidth of 9.84 GHz. By conducting an extensive examination of the structural changes in MXenes, this work aims to elucidate the oxidation mechanisms and proposes a feasible method for producing MXenes with excellent absorption properties.

“Dual-armor” strategy to prepare multifunctional carbonyl iron particle with corrosion resistance, self-healing and high microwave absorbing performances

As a common and high microwave absorbing material, the application fields of carbonyl iron particle (CIP) are limited because of its poor corrosion resistance when working in harsh environments such as ocean, rainforest, or other high-humidity, high-salt places. Therefore, it is necessary to design a multifunctional CIP with good corrosion resistance and self-healing properties for ensuring its stable microwave absorbing performance. Herein, a “dual-armor” strategy is proposed to prepare multifunctional CIP (Composite particle), which is assembled with CIP coated by polyaniline (PANI/CIP) and Fe-DSe-M. Fe-DSe-M is Fe3+ responsive microcapsule whose shell contains -Se-Se-bonds and is magnetically adsorbed on the surface of PANI/CIP. PANI/CIP and Fe-DSe-M jointly undertake the function of microwave absorbing, anti-corrosion and self-healing. It is worth to note that the microwave absorbing performance of CIP after multi-functionalization has been greatly improved, and the minimum reflection loss value after accelerated corrosion is only reduced by 5.46 dB, which is much lower than PANI/CIP. These excellent properties of functional Composite particle benefit from PANI protective layer, Fe3+ responsive self-healing Fe-DSe-M and their synergistic effect. Our work provides a new approach to fabricate multifunctional microwave absorbing particle, which has a potential application in the corrosive environment.

Laser‐induced self‐propagating synthesis and electromagnetic wave absorption properties of MoAlB powders

AbstractMoAlB powders with a purity of 96 wt.% were successfully fabricated by a laser‐induced self‐propagating method using molybdenum boride (MoB) and aluminum powders as starting materials under the conditions of an n(MoB): n(Al) ratio of 1.0:1.4 and the laser linear energy density (El) of 0.9 J/mm, and the effect of raw material composition and El on the phase composition and microstructure of the resultant MoAlB powders were investigated. The minimum reflection loss (RLmin) value and effective absorption bandwidth (EAB) of the as‐prepared MoAlB absorber with a thickness of 5.0 mm were only determined as −12.5 dB (at 16.9 GHz) and 0.9 GHz (16.4–17.3 GHz) in the frequency of 1–18 GHz, respectively. Nevertheless, the RLmin and EAB of as‐prepared MoAlB powders oxidized after 3 h at 773 K increased to −18.59 dB (at 15.82 GHz) and 2.13 GHz (15.22–17.35 GHz), respectively, demonstrating that the as‐prepared MoAlB powders are potential candidates for high‐temperature microwave absorption applications. This study proposes a new efficient strategy for the preparation of boron‐based ternary compounds for high‐temperature electromagnetic wave absorption application.

Study on the microwave absorbing properties of SiC@Ni powders with core@shell structure

Hybridization of dielectric and magnetic materials is considered a promising option for the preparation of electromagnetic wave absorbing materials with excellent properties. In this paper, SiC@Ni powders were prepared by a surface heat-assisted process, in which SiC was first cleaned sequentially with anhydrous ethanol and NaOH solutions, and the samples were etched into a mixed solution of HF and HCl, the SiC@Ni powders were then mixed at high speed at 120 °C under argon atmosphere. The sample were characterized by Scanning electron microscopy (SEM) and vector network analyzer (VNA). It is found that the absorption characteristics of SiC@Ni in the 2–18 GHz band are significantly enhanced due to the introduction of the ni layer which enhances the loss of the sample to solve the problem of a single absorption mechanism and high impedance of SiC. The reflection loss value of SiC@Ni in the 8.7 GHz band decreases to − 22.45 dB when the material thickness is 2.5 mm, the effective absorption frequency width is 2.5 GHz, which is a significant advantage over the initial SiC. The experimental methodology of this work is simple and easy to follow, and provides some guidance for the large-scale production of SiC-based microwave absorbing materials.

Glucose derived carbon encapsulated boron nitride core-shell composites for efficient electromagnetic microwave absorption

Hexagonal boron nitride (h-BN) has the advantages of outstanding insulation, high thermal conductivity and excellent chemical stability, which promote the wide application of h-BN in thermal interface electronic packaging and other related fields. However, due to the poor dielectric loss ability of h-BN, which leads to its weak absorption capacity of electromagnetic waves (EMW), so it limits its practical application in related advantageous fields. In this paper, glucose-derived carbon-encapsulated BN core-shell composites (C@BN) were prepared by a simple hydrothermal reaction followed by high-temperature pyrolysis. The dielectric loss capacity of the C@BN was investigated by manipulating the concentration of glucose solution and pyrolysis temperature. Specifically, by adjusting the glucose derived carbon defect to induce polarization loss and impedance matching performance, so that more EMW entering the interior of the composite is absorbed and dissipated. The results show that C@BN obtained at 800 °C shows the best EMW absorption performance when the concentration of glucose solution is 3.6 wt%. The minimum reflection loss value (RLmin) is −43.5 dB and the maximum width effective absorption bandwidth (EABmax) of 6.72 GHz. Therefore, this study provides a reliable reference for the preparation of h-BN based EMW absorbing materials.

Electromagnetic wave absorbing biomass kelp derived porous carbon anchored by Fe3O4 nanocomposites

Increasingly serious electromagnetic pollution problems bring the threaten for national defense security and personal health, biomass carbon materials derived absorbers have arouse widespread interest due to their green, easy accessibility, structural diversity, rich functional groups. Herein, biomass kelp derived three-dimension (3D) porous carbon/Fe3O4 (KPC/Fe3O4) nanocomposites were successfully synthesized vis KOH activation as well as in-situ growth of Fe3O4 and following pyrolysis. Attributed to multiple transmission paths for electromagnetic wave from 3D porous structure, dielectric-magnetic synergistic effect, and numerous defects in the kelp-derived carbon with polarization loss caused by heteroatom doping and interfacial polarization, KPC/Fe3O4 nanocomposites possess outstanding impedance matching and extraordinary attenuation ability. In particular, the minimum reflection loss (RLmin) value of KPC/Fe3O4-0.1 nanocomposite reaches −75.02 dB at 10.5 GHz as well as the effective absorption bandwidth (EAB, RL < -10 dB) value achieves 4.83 GHz with a thickness of 2.85 mm. Unique structures and excellent EWA performance demonstrate that KPC/Fe3O4 nanocomposites can serve as potential absorbers for military and civilian fields.

Magnetic-dielectric synergistic enhancement effect of anti-perovskite medium-entropy alloy nitride foams designed by lattice expansion engineering

A single-phase anti-perovskite medium-entropy alloy nitride foams (MEANFs), as innovative materials for electromagnetic wave (EMW) absorption, have been successfully synthesized through the lattice expansion induced by nitrogen doping. This achievement notably overcomes the inherent constraints of conventional metal-based absorbers, including low resonance frequency, high conductivity, and elevated density, for the synergistic advantages provided by multimetallic alloys and foams. Microstructural analysis with comprehensive theoretical calculations provides in-depth insights into the formation mechanism, electronic structure, and magnetic moment of MEANFs. Furthermore, deliberate component design along with the foam structure proves to be an effective strategy for enhancing impedance matching and absorption. The results show that the MEANFs exhibit a minimum reflection loss (RLmin) value of −60.32 dB and a maximum effective absorption bandwidth (EABmax) of 5.28 GHz at 1.69 mm. This augmentation of energy dissipation in EMW is predominantly attributed to factors such as porous structure, interfacial polarization, defect-induced polarization, and magnetic resonance. This study demonstrates a facile and efficient approach for synthesizing single-phase medium-entropy alloys, emphasizing their potential as materials for electromagnetic wave absorption due to their adjustable magnetic-dielectric properties.

Screw dislocation growth defects enhancing electromagnetic wave absorption performance of GdB6

In this study, a purity of up to 98.36 wt. % GdB6 with screw dislocation growth morphology were successfully fabricated using an in-situ reaction approach. The terraced-like structure of the GdB6 enhanced the interfacial polarization and multiple interface scattering of the electromagnetic waves. As a result, the as-obtained high purity GdB6 powder presented superior electromagnetic wave absorption performance. The minimum reflection loss value can be −49.24 dB at the frequency of 13.12 GHz with a thin matching thickness of 1.44 mm. In addition, the widest effective absorption bandwidth can be up to ∼4 GHz (14–18 GHz) with a thin matching thickness of 1.25 mm. The remarkable electromagnetic wave absorption performance of GdB6 ceramics could be attributed to conductance loss and polarization loss enhanced by the screw dislocation growth defects, as well as synergistic effects with magnetic loss. The as-obtained GdB6 with synergistic dielectric loss and magnetic loss is to be a novel single-phase with excellent electromagnetic wave absorbing material, which will pave the way on the investigation of rare earth hexaborides for the ultra-high temperature environment applications.

Multidimensional and hierarchical design of biomass-derived carbon nanofiber networks for efficient microwave absorption

Carbon materials have gained significant attention for their potential as highly efficient microwave absorbers. However, it remains a challenge to attain a perfect integration of thin thickness, wide frequency bandwidth, lightweight and strong absorption through structural design of carbon materials. Herein, we design multidimensional and hierarchical carbon nanofiber networks consisting of core-shell carbon nanofibers wrapped by hollow carbon nanoparticles, named CPDA@RCNFs. CPDA@RCNFs which are derived from cellulose and polydopamine (PDA) were prepared by electrostatic spinning, deacetylation, self-polymerization, and carbonization, successively. Thanks to the cooperation of three-dimensional conductive networks, core-shell/hollow/porous structures, as well as doped nitrogen and oxygen heteroatoms, CPDA@RCNFs exhibit excellent comprehensive microwave absorption performance. Specifically, an ultra-strong reflection loss value of −63.31 dB and a wide frequency bandwidth of 5.60 GHz (12.32–17.92 GHz) are achieved at a very thin thickness of 1.8 mm with an ultra-low filler loading of 5 wt%. This work provides a new insight into the structural design of advanced high-performance microwave absorption carbon materials.

Cross‐Scale Synergistic Manipulation of Dielectric Genes in Polymetallic Sulfides from Micropolarization to Macroconductance Toward Wide‐Band Microwave Absorption

AbstractRecently, the design and development of efficient microwave absorbents by facile engineering approaches have attracted much attention. Particularly, some unique structures caused by cross‐scale design are promising in enhancing the absorbing capability toward microwave irradiation. Herein, the cross‐scale design strategy is implemented to enhance the electromagnetic wave absorption performance of polymetallic sulfides (PMS). In PMS, the dipole polarization unit is optimized, and the distribution of electronic states is improved by doping Ti atoms; Meanwhile, the MS/M3S4 homogeneous hetero‐phases interfaces is constructed in PMS using a phase separation strategy; and the conductivity of PMS is modulated by the addition of acetylene black (ACET). The cross‐scale synergy of microwave absorption leads to a significant enhancement of the microwave absorption (MA) performance of PMS/ACET composites. The optimal reflection loss value of Ti‐LES with 10% ACET addition reaches −55.49 dB and the effective absorption bandwidth reaches 6.73 GHz. The 17.5% ACET‐conditioned Ti‐HES achieves a reflection loss of −37.2 dB at a low frequency of 4.8 GHz. This study not only provides a novel strategy for the development of new broadband MA materials but also validates a new idea for the multi‐scale synergistic optimization of MA materials.

Integrating Sulfur Doping with a Multi-Heterointerface Fe7S8/NiS@C Composite for Wideband Microwave Absorption.

Heterointerface engineering is presently considered a valuable strategy for enhancing the microwave absorption (MA) properties of materials via compositional modification and structural design. In this study, a sulfur-doped multi-interfacial composite (Fe7S8/NiS@C) coated with NiFe-layered double hydroxides (LDHs) is successfully prepared using a hydrothermal method and post-high-temperature vulcanization. When assembled into twisted surfaces, the NiFe-LDH nanosheets exhibit porous morphologies, improving impedance matching, and microwave scattering. Sulfur doping in composites generates heterointerfaces, numerous sulfur vacancies, and lattice defects, which facilitate the polarization process to enhance MA. Owing to the controllable heterointerface design, the unique porous structure induced multiple heterointerfaces, numerous vacancies, and defects, endowing the Fe7S8/NiS@C composite with an enhanced MA capability. In particular, the minimum reflection loss (RLmin) value reached -58.1dB at 15.8GHz at a thickness of 2.1mm, and a broad effective absorption bandwidth (EAB) value of 7.3GHz is achieved at 2.5mm. Therefore, the Fe7S8/NiS@C composite exhibits remarkable potential as a high-efficiency MA material owing to the synergistic effects of the polarization processes, multiple scatterings, porous structures, and impedance matching.

The effects of phase interfaces in SmFeN/YSZ composite thermal barrier materials on electromagnetic wave-absorbing properties

Yttria-stabilized zirconia (YSZ) oxide ceramic powder is a thermal-barrier material used to fabricate thermal barrier coatings (TBC). In this study, to improve the electromagnetic wave (EMW) absorbing properties of TBCs, microwave-absorbing samarium iron nitrogen (SmFeN) particles were used to prepare SmFeN/yttria-stabilized zirconia (YSZ) composites. To study the effect of the SmFeN/YSZ interfaces on the EMW-absorbing properties of the SmFeN/YSZ composite, SmFeN/YSZ interfaces were built in different ways in composite materials having the same mass ratio of 1:1, for example, SmFeN and YSZ particles homogeneously mixed together, SmFeN/YSZ interfaces perpendicular and parallel to the EMW incident direction, and different interfaces between YSZ and SmFeN. Thus, the microwave absorbing performance of the samples, including the electromagnetic parameters, attenuation coefficient, eddy-loss current (C0), impedance matching, and minimum reflection loss (RLmin) values were examined and analyzed. The results demonstrate that interfaces perpendicular to the direction of the EMWs can increase the contact area and enhance the interfacial absorption effect. Further, when the wave-absorbing agent was placed in the middle of the composite, its wave-absorbing effect was the best among all the samples, yielding RLmin = −27.824 dB and effective absorption bandwidth (EAB) = 8.5453 GHz (effective absorption frequency range 7.9256–16.4709 GHz for a 7.2-mm-thick layer). Crucially, the frequency and bandwidth at which the best absorption occurred could be tuned by adjusting the thickness of the coating. This is because the interfaces in the samples resulted in polarization enhancement and anomalous dispersion, leading to large dielectric losses. Overall, the use of a coaxial measurement technique is highly efficient for EMW absorbing body design and process simulations.

Surface engineering strategy for MXene to tailor electromagnetic wave absorption performance

The emerging two-dimensional material, Ti3C2Tx MXene, has attracted significant attention in the realm of electromagnetic wave absorption owing to its exceptional inherent conductivity and distinctive microstructure. However, similar to other conductive materials, MXene encounters the challenge of impedance mismatch, thereby impeding the electromagnetic wave absorption capability in single-component MXene materials. In this study, a molten chlorine-salt method was employed to gain MXene samples with varying surface-chlorine/oxygen (Cl/O) ratios by surface engineering. Notably, among these samples, Cl/Ni-MX-6 exhibited an impressive minimum reflection loss value of −45.72 dB (1.6 mm) and an effective absorption bandwidth of 3.44 GHz (1.3 mm). This study revealed that increasing the etchant content enhances the delamination effect of MXene and leads to adjust Cl/O ratio. Importantly, the modulation of −Cl/O surface functional groups can limit the electronic conductivity, while the number and species of different kinds of surface dipoles will control the polarization effect, ultimately optimizing the electromagnetic wave absorption performance of pure MXene. These insights contribute to ongoing efforts aimed at enhancing the performance of MXene-based materials in the field of electromagnetic wave absorption as well as get a better understanding of the electromagnetic loss mechanism.