Search

Enhanced electromagnetic wave absorption through the unique hollow double shell structure and the synergistic effect of dielectric loss magnetic and loss. [Display omitted] • CoS 2 coated with metal-doped carbon was prepared by a soft template method and wet impregnation method. • The double-layer hollow shell structure is retained after the modification of metal nanoparticles. • Metal doping optimizes the electromagnetic wave loss mechanism of the material. • The RL min is −48.90 dB at 2.23 mm, and the maximum Effective Absorption Bandwidth is 5.04 GHz at 1.98 mm. Tunable designs of polymorphic structured transition metal dichalcogenide (TMDC) demonstrate promising applications in the field of electromagnetic wave absorption (EMW). However, it remains a technical challenge for achieving a balanced relationship between well-matched impedance characteristics and dielectric losses. Therefore, the co-modification strategies of polydopamine coating and wet impregnation are chosen to construct CoS 2 magnetic double-shell microspheres with phase component modulation to achieve the optimized performance. Dopamine hydrochloride forms a coating on the surface of CoS 2 microspheres by self-polymerization and forms a double-shell structure during the pyrolysis process. Then the different metal is doped to generate heterogeneous components in the process of heat treatment. The results show that the cobalt doped double-shell microspheres have an ultra-high electromagnetic wave absorption absorption capacity with an effective absorption bandwidth of 5.04 GHz (1.98 mm) and a minimum reflection loss value of −48.90 dB. The double-shell layer structure and metal ion hybridization can improve the interfacial polarization and magnetic loss behavior, which provides an explicit inspiration for the development of transition metal dichalcogenide and even transition metal compounds with tunable absorption properties. [ABSTRACT FROM AUTHOR]

[Display omitted] It has become greatly significant to achieve structurally tunable electromagnetic wave absorption materials (EMAs) derived from metal-organic frameworks (MOFs) via controllably continuous phase inversion. Herein, a series of core–shell Ag@C EMAs were successfully fabricated from Ag-MOFs via adjustable phase inversion. Replacing terephthalic acid (H 2 BDC) with 2-methylimidazole (Hmim) continuously led to the gradual transformation of Ag-MOF-5 structure into ZIF-L, which determined the crystal and morphological structure of Ag@C EMAs. In addition, due to the optimization of relaxation loss, the minimum reflection loss (RL min) of S2 reached −50.14 dB with a thickness of 3.0 mm. The EMA derived from the original Ag-MOF had the widest absorption bandwidth (f E) of 5.44 GHz and RL min of −47.36 dB at only 2.2 mm, respectively. This work can shed new light on the core–shell EMAs derived from phase inversion MOFs, and provide guidance to design novel high-performance EMAs. [ABSTRACT FROM AUTHOR]

Multiple reflection and scattering along with dielectric loss and magnetic loss are contributed to excellent electromagnetic wave absorption performance. [Display omitted] • CoFe alloys and ZnO are uniformly distributed on the two-dimensional porous carbon sheet. • The synergistic effect of multiple loss mechanism were contributed to excellent performance. • The absorption was up to −40.63 dB at 2.2 mm and widest EAB of 5.68 GHz at 2.4 mm. To obtain lightweight and efficient electromagnetic wave absorbing materials, Fe 2 O 3 @ZnCo-MOF composites were prepared in this paper by in-situ growth method, and CoFe alloys@ZnO@C composites were obtained by subsequent annealing process. By varying the loading of Fe 2 O 3 during the synthesis process, a series of composites were obtained. Among them, CoFe alloys@ZnO@C-0.1 has the best electromagnetic wave absorption performance, which can reach a reflection loss (RL) of −40.63 dB at a thickness of 2.2 mm, while the reflection loss is −44.13 dB at a thickness of 5.0 mm, and the maximum effective absorption bandwidth (EAB) is 5.84 GHz at a thickness of 2.4 mm. The excellent performance can be attributed to the synergistic effect of the dielectric and magnetic properties of the composites as well as the effective impedance matching properties. Thus, the CoFe alloys@ZnO@C composite is expected to be a lightweight and efficient material for electromagnetic wave absorption. [ABSTRACT FROM AUTHOR]

• Three different morphologies of MnCo 2 O 4.5 spinel oxides prepared via structural regulation. • Various MnCo 2 O 4.5 structures optimize dielectric properties and impedance matching and introduce polarization processes. • The microcubic spheres structure of MnCo 2 O 4.5 achieved satisfactory EMW absorption performance in the X-band. • The MCO-MSs exhibit RL min of −51.52 dB at a thickness of 2.3 mm and EAB max of 5.36 GHz at a thickness of 2.2 mm. The cobalt-based spinel structure oxides with synergistic effect of magnetic loss and dielectric loss have important applications in electromagnetic wave absorption. And the excess 0.5 oxygen atoms in MnCo 2 O 4.5 provide more vacancies than traditional MnCo 2 O 4 spinel structure and improve the electrical conductivity. In the current study, MnCo 2 O 4.5 microsphere clusters, MnCo 2 O 4.5 microcubic spheres and MnCo 2 O 4.5 flowery spheres were prepared by solvothermal method and annealing process. Among the final samples with different morphologies, MnCo 2 O 4.5 microcubic spheres showed outstanding microwave absorption capabilities, with a minimum reflection loss (RL min) of -51.52 dB at 2.2 mm. When the thickness was further increased to 2.3 mm, the effective absorption bandwidth could be as wide as 5.36 GHz, covering most of the X-band. The excellent absorption performance of electromagnetic waves is related to the modulability of the complex dielectric parameters, the optimization of impedance matching, and the enhancement of the polarization relaxation process through the improvement of the morphologies. This work provides guidance and support for refining the electromagnetic wave absorption potential of cobalt-based spinel oxides and for designing highly efficient electromagnetic wave absorbers in the X-band. MnCo 2 O 4.5 with multiple morphologies was prepared to modulate the complex dielectric parameters of the materials and to optimize the impedance matching, further enhancing the polarization relaxation process. [Display omitted] [ABSTRACT FROM AUTHOR]

Multiple loss mechanisms involving multiple scattering and reflection, conductive loss, interface polarization, dipolar polarization as well as magnetic loss caused by exchange resonance, natural resonance and eddy current loss contribute to effective electromagnetic wave absorption behavior. • rGO/N-C/FeNi hybrids were synthesized via an environmentally friendly process. • Nitrogen was doped in the carbon matrix through exploiting pyrrole. • The hierarchical structure provides absorbers with favorable EM properties. A unique reduced graphene oxide (rGO)/nitrogen doped carbon (N-C)/FeNi hybrid was successfully synthesized via a green and environmentally friendly process by means of one pot method. The morphology, phase structure, composition and electromagnetic (EM) wave absorption behavior of all hybrids were studied in detail. All rGO/N-C/FeNi hybrids are composed of rGO sheets on which there are nitrogen doped carbon and FeNi nanoparticles, and the novel structure endows the absorber with multiple scattering and reflection, interfacial polarization, dipole polarization and so on, further bringing remarkable EM wave absorption behavior. Moreover, the complex permittivity of rGO/N-C/FeNi hybrids is able to be controlled through changing the amount of GO. All results show that the rGO/N-C/FeNi-3 hybrid displays a substantial improvement in EM wave absorption performance compared with other hybrids. The minimum reflection loss (RL min) value is −68.87 dB at 12.08 GHz with the thickness of 2.5 mm and the largest effective absorption bandwidth (EAB) achieves 6.88 GHz at 2.2 mm with RL min value of −14.73 dB at 12.16 GHz. Our research proves that the unique structure and composition have the potential to elevate EM wave absorption performance. [ABSTRACT FROM AUTHOR]

• Synthesized accordion-like Ti 3 C 2 T x MXene with large layer spacing. • Synthesized Ti 3 C 2 T x /TiO 2 /PANI composites with sandwich structure. • The optimal absorption was up to −65.61 dB at 2.18 mm and EAB to 5.92 GHz at 2.10 mm. Ti 3 C 2 T x MXene is an excellent electromagnetic wave (EMW) absorber with excellent electrical conductivity and abundant surface functional groups. In this research, Ti 3 C 2 T x /TiO 2 /PANI multi-layer composites were successfully synthesized by HCl and LiF etching, one-step hydrothermal method and in-situ polymerization. Ti 3 C 2 T x can provide more electron transfer paths due to its unique multilayer structure and high specific surface area. The growth of TiO 2 particles on the surface of Ti 3 C 2 T x through hydrothermal reaction enhances the interface polarization, and then polyaniline (PANI) is doped on the surface of Ti 3 C 2 T x where TiO 2 particles are grown by in-situ polymerization. Due to the excellent dielectric properties and synergistic effects of the material itself, Ti 3 C 2 T x /TiO 2 /PANI composites have excellent EMW absorption property. In this study, the Ti 3 C 2 T x /TiO 2 /PANI composites showed the strong reflection loss (RL) of at 13.92 GHz, which was −65.61 dB, and the thickness was only 2.18 mm. Moreover, the composites also exhibit a wide absorption band, with an effective absorption bandwidth (RL < -10 dB) of 5.92 GHz (11.84 GHz to 17.76 GHz) at 2.10 mm. The results show that the Ti 3 C 2 T x /TiO 2 /PANI composites are expected to become EMW absorber with thin thickness and high absorption strength. [ABSTRACT FROM AUTHOR]

• NiCo/Co 4 S 3 @C hybrid materials were prepared by a simple two-step process. • The complete carbon shell cladding and Co 4 S 3 doping can be observed. • The minimum RL value of −56.96 dB at 10.32 GHz with the matching thickness is only 2.71 mm. • The effective absorption bandwidth can be covered 13.36 GHz with the thickness is 1.8–5.0 mm. Producing electromagnetic wave absorbers with high absorption capacity and wide absorption bandwidth is still a challenge task, which limits its application in human life. In this study, a novel carbon-coated NiCo alloy/Co 4 S 3 hybrid material was fabricated by a simple strategy. By adjusting the annealing temperature, the electromagnetic wave absorption property of NiCo/Co 4 S 3 @C hybrid material can be further improved. Herein, the NiCo/Co 4 S 3 @C hybrid material obtained at 750 °C exhibits satisfactory electromagnetic wave absorption performance. The minimum reflection loss value of −56.96 dB is obtained at 10.32 GHz, and the matching thickness is only 2.71 mm. When the thickness of the absorber is in the range of 1.8–5.0 mm, the effective absorption bandwidth is controlled between 4.64 and 18 GHz. The satisfactory properties of the hybrid materials are attributed to the space charge polarization caused by heterogeneous NiCo alloys, interfacial polarization between components and good impedance matching characteristics. The results show that NiCo/Co 4 S 3 @C hybrid material is a potential electromagnetic wave absorber. [ABSTRACT FROM AUTHOR]

Multiple loss mechanisms of conductive loss, interface polarization loss, dipolar polarization and magnetic resonance loss endow excellent performance of Fe 3 N@C composites. • Fe 3 N@C hybrid composites were synthesized by using amino acids as nitrogen sources. • The relaxation times were calculated by Debye theory to investigate dielectric behavior of hybrid composites. • The optimal performance with RL min of −77.6 dB and EAB max of 7.76 GHz were achieved. Fe 3 N has been considered as a new generation of ideal ferromagnetic materials with the virtues of high saturated magnetization and high resistance to oxidation. However, a facile and eco-friendly fabrication of Fe 3 N still needs to be investigated. Herein, the gelatin derived from fish skin was chosen as the raw material of carbon and the amino acid inherent in fish skin can act as a nitrogen source for the generation of Fe 3 N. Besides, the influence of graphitization degree to dielectric behavior of composites was further investigated. In this work, the composites fabricated by 0.8 mmol Fe(NO 3) 3 exhibited optimal absorption performance with the minimum reflection loss of −77.6 dB at 2.2 mm. Besides, the absorption bandwidth was detected as 7.76 GHz (covering from 10.24 to 18 GHz) at the matching thickness of 2.7 mm. According to the analysis of dielectric constant, the degree of graphitization affects the dielectric behavior mainly in determining the orientation speed of the dipole and the conductive loss. This work provides a new thought for the investigation of the electromagnetic absorption mechanism of composite. [ABSTRACT FROM AUTHOR]

Multiple interface polarization along with conductive loss, dipolar polarization and magnetic loss are contributed to excellent electromagnetic wave absorption performance. • NiCo alloy nanospheres and CoNiO 2 nanoflowers were successfully embedded on the porous carbon skeleton. • The outstanding reflection loss was up to −74.3 dB in 3.8 mm and widest effective absorption was 6.32 GHz in 2.4 mm. • The synergistic effect of magnetic loss and dielectric loss are contributed to excellent absorbing performance. A series of NiCo/CoNiO 2 @C hybrid composites were successfully prepared by a hydrothermal method and subsequent heat-treatment process. Porous carbon was synthesized through a fabric carbonization process derived from fish skin. The micro-morphology and minor component of NiCo/CoNiO 2 @C hybrid composites could be tuned by controlling the adjunction amount of Co2+ and Ni2+. The NiCo/CoNiO 2 @C hybrid composite exhibited strong electromagnetic wave absorption performance when the adjunction amount of Co2+ and Ni2+ was 0.4 mmol and 0.2 mmol. The optimal reflection loss could up to −74.3 dB at the matching thickness of 3.8 mm, while the corresponding widest effective absorption bandwidth (reflection loss values lower than −10 dB) is up to 6.32 GHz covering from 11.78 GHz to 18.0 GHz at the matching thickness of 2.4 mm. Based on the Maxwell-Garnet theory, the pore size of porous carbon materials could influence the dielectric constant which has a great effect on impedance. Previous work has illustrated that porous carbon carbonized at 650 °C processes the proper pore size for excellent impedance matching. Besides, NiCo alloy nanosphere and CoNiO 2 nanoflower would provide magnetic loss and interface polarization for attenuating electromagnetic wave energy. Moreover, the conductive loss derived from porous carbon and dipolar loss which originated from the defects are also beneficial to decay electromagnetic energy. This work indicates that the as-prepared NiCo/CoNiO 2 @C hybrid composites accompanied with excellent electromagnetic wave absorption performance could act as a promising absorber to deal with the increasingly serious electromagnetic pollution. [ABSTRACT FROM AUTHOR]

Abstract Carbon hollow microspheres with a uniform mesoporous shell (PCHMs) were designed and fabricated using a template-assistant method followed by a pyrolysis-etching process. Through tuning the pyrolysis temperature, PCHMs with various pore size and shell thickness can be obtained. In particular, the PCHMs carbonized at 650 °C (PCHMs-650) are composed of a mesoporous shell (thickness: 52 nm) and an interior void of 153 nm, endowing the materials with large surface area of 925.9 m2/g. The unique core-shell structure generated by carbon shell and void core is critical for the attenuation capability of EM energy. The composites containing 20 wt% PCHMs-650 exhibit favorable microwave absorbing performance with the minimum reflection loss (RL min) of −39.4 dB at 3.6 mm. The broadest effective absorption bandwidth (EAB) can extend to 5.28 GHz (9.68–14.96 GHz) at only 2.6 mm. It is believed that PCHMs can be used as a promising absorber with lightweight, impressive bandwidth and strong absorption efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D MXene-supported magnetic carbon nanotube composites are prepared. • Composite materials combine the advantages of dielectric and magnetic losses. • NiCo/TiC/TiO/CNTs exhibit the RL min of −51.98 dB (1.9 mm) and the EAB of 7.76 GHz (2.1 mm). • Detailed revelation of possible EMW absorption mechanisms. The widespread use of communication equipment has exacerbated the deterioration of the electromagnetic environment, urgently requiring the development of more efficient electromagnetic wave (EMW) absorption materials. Two-dimensional metal carbides are highly regarded for their characteristic structure and excellent electrical conductivity. Here, to break the single way of designing Ti 3 C 2 T x MXene composites and to compensate for their lack of magnetic loss capability, an attempt was made to prepare composites with magnetic NiCo/Carbon nanotubes (CNTs) modification to achieve EMW absorption. Such CNTs-encapsulated Ni and Co metal particles anchored in the matrix, coupled with a multilayer laminate structure, enable the composite to have enhanced EMW absorption. Remarkably, the NiCo/TiC/TiO/CNTs composites exhibit excellent EMW absorption performance at a filling level of only 14.2 wt%. The minimum reflection loss (RL) of −51.98 dB and the maximum effective absorption bandwidth of 7.76 GHz were obtained at thicknesses of 1.9 mm and 2.1 mm, respectively. In addition to this, the possible mechanisms involved in EMW absorption have been elucidated in detail. These results demonstrate an environmentally friendly and simple strategy for the preparation of EMW absorbers based on Ti 3 C 2 T x MXene substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-assembly of flower-like MoS 2 encapsulated with CuFe 2 O 4 nanoparticles was achieved. • The synergy between components can receive outstanding impedance matching. • The reflection loss (RL) of − 40.33 dB at 2.3 mm and an effective absorption bandwidth (EAB) of 8.16 GHz can be achieved. Transition metal sulfides (TMDs) are considered to be high-performance electromagnetic absorbing materials on account of their small band gap and excellent dielectric properties. As a typical TMDs, two-dimensional MoS 2 nanosheet, has attracted extensive research. However, single absorption mechanism has no longer satisfy the pursuit for novel absorbers. Herein, we introduce magnetic ferrite CuFe 2 O 4 to construct novel absorber of CuFe 2 O 4 /MoS 2 composite. The CuFe 2 O 4 particles are encased in the 2D MoS 2 nanosheets, forming a unique flower-like structure. Under the cooperative interaction of dielectric and magnetic loss, the CuFe 2 O 4 /MoS 2 composite absorber realizes a wide effective absorption bandwidth (EAB) of 8.16 GHz (9.84 GHz −18 GHz) at 2.3 mm, when the optimum reflection loss is −40.33 dB, it means that electromagnetic waves in the entire Ku-band and part of the X-band can be effectively absorbed by the absorber. Moreover, an optimum reflection loss of −49.43 at 2.7 mm can be achieved. In brief, this work presents a strategy for obtaining novel high-performance absorbers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel accordion-like structure was synthesized by ZIF-67 derivation strategy. • Their morphological evolution in various stages is clarified. • Revealing the contribution of dielectric property modulation to absorption performance. • The EAB reached 5.68 GHz at a thickness of 2.6 mm for NiSe 2 -CoSe 2 @C/Ti 3 C 2 T x composite. Two-dimensional metal carbide or nitride materials are considered as a new class of electromagnetic wave absorbing materials due to their unique multilayer structure and metal-like properties. The NiSe 2 -CoSe 2 @C/Ti 3 C 2 T x composites were prepared through a facile hydrothermal treatment and selenization reaction. Distinctly, the maximum reflection loss (RL) is −60.46 dB with the mass fraction of NiSe 2 -CoSe 2 @C/Ti 3 C 2 T x of 40 wt% at 2.6 mm. The bandwidth of RL < −10 dB reaches up to 5.68 GHz (10.32–16 GHz). The synergistic mechanism of the multiple scattering and multi-interface polarization effects of NiSe 2 -CoSe 2 @C compounded with Ti 3 C 2 T x is reviewed to interpret the significant improvement of electromagnetic wave absorption performance. The results indicate that NiSe 2 -CoSe 2 @C/Ti 3 C 2 T x composites have potential applications as realistic electromagnetic wave absorbing materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Controlling the load of Co-CoFe 2 O 4 can receive exceptional impedance matching. • The minimum reflection loss is −65.31 dB at 2.1 mm. • The maximum effective absorption bandwidth is 8.48 GHz at 2.4 mm. Carbon nanomaterials have attracted a great deal of attention in various fields especially in electromagnetic wave absorption due to unique physical and chemical properties. Herein, a novel Co-CoFe 2 O 4 @mesoporous hollow carbon spheres (PCHMs) nanocomposites were prepared by two-facile steps, which included synthesizing three-dimensional mesoporous hollow carbon nanospheres (3D PCHMs) by hard template method, pyrolysis and etching process and in-situ growth of ultra-small Co-CoFe 2 O 4 nanoparticles on PCHMs. The microscopic morphology and electromagnetic wave absorption mechanisms were discussed in depth. The synthesized Co-CoFe 2 O 4 @PCHMs maintained a stable hollow and mesoporous structure and the Co-CoFe 2 O 4 nanoparticles are uniformly distributed on the PCHMs. The complex permittivity and complex permeability could be effortlessly controlled by the content of Co-CoFe 2 O 4 nanoparticles. Benefitting from the remarkable impedance matching under the influence of moderate complex permittivity and complex permeability, the minimum reflection loss (RL min) of S2 exhibited −65.31 dB at 2.1 mm. The maximum effective absorption bandwidth (EAB) reached up to 8.48 GHz. The Co-CoFe 2 O 4 @PCHMs nanocomposites will have great potential application in electromagnetic wave absorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1. An anion substitution strategy is employed to improve conductivity and dielectric property. • 2. The type of anionic elements has a great influence on the EM wave absorption performance. • 3. NiCo 2 Se 4 and NiCo 2 Te 4 are reported for the first time in the field of EM wave absorption. With the extensive development of electrical communication equipment, the requirements for electromagnetic (EM) wave absorption materials have become more stringent to eliminate electromagnetic interference issues. Rational regulation of permittivity is an efficacious path to optimal EM wave absorption performance. NiCo based spinel materials (NiCo 2 X 4 , X = O, S, Se, Te) have been regarded as promising EM wave absorbing materials due to the advantage of controllable structure, inexpensive procedure and excellent dielectric property. Particularly, the element of anionic sites acts as a considerable role in determining the conductivity and permittivity of materials. Herein, spiny globose like NiCo 2 X 4 (X = O, S, Se, Te) are successfully prepared through hydrothermal and subsequent oxidation, sulfidation, selenization and tellurization methods, respectively. Due to the difference in electronegativity of the anion site elements, NiCo 2 Se 4 and NiCo 2 Te 4 show ameliorative conductivity and dielectric loss. An optimal reflection loss (RL) of −78.5 dB at 2.8 mm and an effective absorption bandwidth (EAB) of 5.28 GHz at 2.3 mm can be achieved for NiCo 2 Se 4. Moreover, due to enhanced dielectric performance, the matching thickness of NiCo 2 Te 4 is greatly improved, which the RL is −54.3 dB at 1.8 mm and EAB of 4.88 GHz at 1.6 mm. The synthesis of NiCo 2 Se 4 and NiCo 2 Te 4 , with remarkable absorption performance, is expected to provide an important reference for broadening the application of NiCo-based spinel in the field of EM wave absorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesized flower-like NiCo-LDH and Ti 3 C 2 T x MXene flakes. • Synthesized NiCo-LDH/MXene hybrids with heterojunction surface. • The optimal absorption was up to −64.24 dB at 2.18 mm and EAB to 4.48 GHz at 2.00 mm. In this research, a flower-like nickel/cobalt layered double hydroxide (NiCo-LDH) was synthesized and mixed with flaky MXene to obtain a series of NiCo-LDH/MXene hybrids. The NiCo-LDH/MXene hybrids with excellent electromagnetic wave (EMW) absorption performance were obtained by adjusting the load of MXene in the mixture. For a NiCo-LDH/MXene hybrid, its excellent EMW performance comes from the synergistic effect of dielectric loss and magnetic loss as well as the excellent attenuation ability and impedance matching characteristics of the material. The results showed that only with a thickness of 2.18 mm at 12.0 GHz, a minimum reflection loss (RL min) of −64.24 dB was obtained when the MXene content is 75 wt%. For the same sample, a maximum effective absorption bandwidth (EAB, RL <−10 dB) of 4.48 GHz (11.04 ~15.52 GHz) was obtained only with a thickness of 2.00 mm. This research proved the effect of the structure and composition of EMW absorber on its performance, and developed ideas for the design and development of high-performance EMW absorption materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The 2D MXene-based accordion-like hybrid structure was obtained. • Controlling the addition of Ti 3 C 2 T x can effectively control the dielectric parameters. • The effective bandwidth is up to 4.24 GHz with a matched thickness of 1.5 mm. Owing to their unique structure and high dielectric loss, two-dimensional transition metal carbides and nitrides (MXenes) are widely used in electromagnetic wave absorption. The novel Co 9 S 8 /C/Ti 3 C 2 T x hybrid material with a multilayer structure was successfully fabricated by hydrothermal and annealing processes. The unique multilayered hybrid material is assembled from Ti 3 C 2 T x film layers, Co 9 S 8 particles, and carbon flakes. The Co 9 S 8 particles were uniformly anchored on Ti 3 C 2 T x and carbon flakes. The Co 9 S 8 /C/Ti 3 C 2 T x -100 hybrid material has demonstrated impressive electromagnetic absorption performance after the multi-component introduction and interface design were optimized. Besides, the hybrid material exhibits the maximum reflection loss of −50.07 dB at 7.6 GHz under a matched thickness of 2.51 mm, and the effective absorption bandwidth (RL ≤ -10 dB) is covered 4.24 GHz. The synergistic effect of dielectric and magnetic loss, interfacial polarization, and multilayer structure was beneficial to the improvement of electromagnetic wave absorption performance. This research provides a simple demonstration of the design and synthesis of high-performance MXenes-based absorbing materials. [ABSTRACT FROM AUTHOR]

Porous carbon materials have been widely reported on dealing with the electromagnetic (EM) wave interference. However, monotonous EM loss mechanism still performed an obstacle to achieve exceptional absorption. In this paper, a series of three-dimensional porous carbon·@PANI (polyaniline) composites were synthesized via facile roasting and subsequent coating process. The morphology, nanostructure and EM wave absorption properties of porous carbon@PANI (PC@PANI) were discussed in detail. Obviously, porous carbon derived from EDTA-2Na coated by PANI (PC@PANI-2) composites exhibited significantly enhanced EM wave absorption performance compared to pure porous carbon. The widest absorption bandwidth (RL < 10 dB) of the PC@PANI-2 could reach to 6.64 GHz (10.16–16.8 GHz) at 2.6 mm, and the minimum reflection loss (RL min) at 2.6 mm was −72.16 dB. Compared with pure porous carbon materials, the composite material shows improved dielectric loss, such as interface polarization loss. After the polyaniline is coated, the conductivity loss of the composite material is sharply increased, so that the EM wave absorption capacity of the material is enhanced. The synthesized PC@PANI-2 can be used as the first choice for low-cost and environmentally friendly EM absorbers. In addition, this work can provide a reference for enriching the electromagnetic loss mechanism of the absorber. Defects and heteroatoms originating in the porous structure can be used as polarization centers, and electrons will gather between a large number of heterogeneous interfaces, which is conducive to interface polarization loss. PC@PANI composite material causes dielectric loss to attenuate EM waves. Image 1 • Porous carbon prepared by EDTA-2Na derivatization. • A novel PC@PANI composite material was synthesized based on EDTA-2Na. • The composite material can be used as an ideal EM wave absorber. • The effective absorption bandwidth reaches 6.64 GHz, and the matching thickness is 2.6 mm. [ABSTRACT FROM AUTHOR]

Reasonable nanostructure design and composition are conducive to the electromagnetic wave (EM) absorption behavior of absorbers. Herein, Fe 3 O 4 @C/reduced graphene oxide (rGO) nanocomposites with layered structure were fabricated by a feasible solvothermal method. By adjusting the amount of graphene oxide (GO), different dielectric characteristics and impedance matching conditions of Fe 3 O 4 @C/rGO nanocomposites could be obtained. Moreover, with amorphous carbon as the matching layer, Fe 3 O 4 and rGO provide strong magnetic loss and dielectric loss, respectively. The results exhibit that Fe 3 O 4 @C/rGO nanocomposites own salient EM absorption properties under the combined action of various components and three-level layered structure. In addition, the Fe 3 O 4 @C/rGO-20 nanocomposites (the addition of GO is 20 mg) are endowed with the best EM absorption performance, which demonstrates a minimum reflection loss (RL min) value of −59.23 dB at 6.24 GHz with a sample thickness of 3.57 mm and effective absorption bandwidth (EAB) is 6.72 GHz. Moreover, the widest EAB is 8.24 GHz at a thinner thickness of 2.6 mm with the RL value of −25.80 dB at 14 GHz. This work could be a reference for lightweight, broadband, strong absorption composite absorber. Image 1 • The Fe 3 O 4 @C/rGO composites were synthesized via a simple solvothermal method. • By introducing carbon as a matching layer and rGO as a carrier to preparing efficient electromagnetic wave absorbers. • The minimum RL value is -59.23 dB with the thickness of 3.57mm and the effective absorption bandwidth is 6.72 GHz. [ABSTRACT FROM AUTHOR]