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Multiple relaxation behaviors are promising for broad frequency band and strong electromagnetic wave (EMW) absorption based on polarization‐controlled electromagnetic (EM) attenuation. However, rational selection of materials and structure manipulation through tunable substitution or phase control are challenging toward optimization of EMW absorption. Herein, bi‐metallic organic frameworks (B‐MOFs) with various morphologies are employed as EMW absorbers. Remarkably, the polar units can be enhanced by introducing Ni‐metal nodes into the Cu‐coordinated MOFs, rendering the B‐MOFs with self‐polarized properties and consecutive multifrequency EMW absorption behaviors. The maximum reflection loss of acetylene black (ACET) filled NiCu‐MOFs can reach –40.54 dB together with a wide bandwidth (<‐10 dB) of 5.87 GHz at a thickness of 2.5 mm. As a counterpart of the Ni/Cu/C derivatives, significantly increased broad band absorption (6.93 GHz) and multifrequency absorbing and polarization characteristics are also maintained in bimetal coexisting carbonized architectures as prepared by calcination of CuNi‐MOFs. This work demonstrates that the performance of effective absorbing frequency band can be enhanced in multi‐metallic organic frameworks‐based architectures, and paves a novel avenue for developing broadband and strong EMW absorbers. [ABSTRACT FROM AUTHOR]

Vigorous development of 5G communication technologies can boost mobile networks yet bring in electromagnetic interferences and safety concerns in utilizing electronic devices. Particularly, 5G network can not only involve a low‐frequency band of n78 (3.3–3.8 GHz) but also cover multi‐frequency bands of n77 (3.3–4.2 GHz) and n79 (4.4–5.0 GHz), displaying multiple electromagnetic radiations. Countless efforts have been devoted to investigating electromagnetic wave (EMW) absorbers with low‐ and multi‐band absorption properties. However, in terms of emerging materials and designs, few reports propose the mechanisms related to those properties. This perspective briefly reviews the impressive achievements of low‐ and multi‐frequency EMW absorbers and analyzes the design strategies that may enable low‐ and multi‐frequency absorption. Furthermore, the cutting‐edge mechanisms of corresponding electromagnetic responses, such as Snoek limit, quarter wavelength, and dielectric‐magnetic synergy effects are elaborated. Thus, this perspective can shed light on the new trends and ongoing challenges for EMW absorbers and further promote their practical application. [ABSTRACT FROM AUTHOR]

VB‐Group transition metal disulfides (TMDs) are considered excellent materials for electromagnetic wave (EMW) absorption because of their good conductivity and abundant active sites located at their edges and substrates, as compared with VIB‐Group TMDs. Herein, for the first time, EMW absorbers based on VB‐Group NbS2 nanosheets by using a facile one‐step solvothermal method are successfully prepared. The minimum reflection loss (RLmin) can reach up to 43.85 dB with an effective absorption bandwidth of 6.48 GHz (11.52–18.00 GHz). The remarkable EMW absorption performance can also be reflected in the tunable frequency bands (C‐, X‐, and Ku‐bands), which is achieved by adjusting the contents of materials. Furthermore, the influence of the content of 2H‐phase and 1T‐phase in NbS2 on the EMW absorption performance is systematically investigated. The hierarchical hollow‐sphere structure of NbS2 promotes dielectric loss and the multiple reflection and absorption of EMW, and enhances the impedance matching and synergistic attenuation ability. This work demonstrates that the bottleneck of effective absorbing frequency band of single‐component dielectric EMW absorbing materials could be broken through, and paves a novel path towards developing broadband absorbing materials in EMW absorption. [ABSTRACT FROM AUTHOR]

In this study, MoS 2 nanosheets were prepared using a facile hydrothermal method and we studied their electromagnetic wave shielding performance for the first time. The results showed that the nanosheets synthesized with a reaction time of 10 h exhibited excellent electromagnetic shielding performance and the attenuation of electromagnetic waves was greater than 20 dB in the frequency range from 2 to 18 GHz. These findings may facilitate the development of novel layered nanomaterials with excellent electromagnetic shielding properties. • Molybdenum disulfide nanosheets with shielding properties are prepared. • Raman shifts of E 2g and A 1g peaks were 376.03 cm−1 and 402.32 cm−1. • MoS 2 nanosheets were ultra-thin with less than four layers. • Absorption loss was the main attenuation mechanism. [ABSTRACT FROM AUTHOR]

Currently, the development of low-thickness, high-efficiency electromagnetic wave (EMW) absorbing materials for practical applications is of particular importance. In this work, we used a simple one-step hydrothermal method to synthesize, for the first time, heterostructured materials with special multidimensional heterostructures by exploiting the confinement effect of grapheneIn this work, a simple one-step hydrothermal method is employed to synthesize composites with a special heterogeneous structure through utilizing the confinement effect of graphene. NbS 2 nanosheets are grown directionally along two-dimensional (2D) reduced graphene oxide (rGO) nanosheets and assembled into nanospheres on the nanosheets, resulting in a unique 2D/3D heterogeneous structure. This peculiar 2D/3D heterogeneous structure with intrinsic conductive network inside the rGO effectively enhances the EMW absorption performance of the heterostructure, with a minimum reflection loss (RL) value of −47.86 dB at 11.04 GHz at a thin thickness of 2.28 mm, and a minimum RL value of −38.64 dB at 15.28 GHz at a thinner thickness of 1.73 mm, and achieves a broadband effective absorption (RL < -10 dB) over 5 GHz, covering almost the whole Ku-band. The results reveal the influence of 2D/3D heterogeneous interfaces and the confinement effect of intrinsic conductive network on the improvement of EMW absorption performance, providing a new idea for the development of a new generation of ultrathin EMW absorption materials with high performance. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • WS 2 @BDC hybrid material is synthesized by employing one-step hydrothermal method and carbonization method. • The excellent low-frequency absorbing performance is attributed to the core-shell conductive networks. • The EMW effective absorption band of WS 2 @BDC hybrid material can be regulated by the specific ratio of WS 2 to BDC. With the continuous advances in detection and early-warning technologies, stealth technologies have widely integrated in modern combat systems and armament research. The development of high-performance electromagnetic wave absorbing materials is important for electromagnetic stealth and shielding applications. Herein, biomass-derived carbon (BDC) from glucose is coated on the surface of folded and stacked WS 2 nanosheets, forming WS 2 @BDC via a simple hydrothermal method and subsequent annealing carbonization. The amount of the BDC coating on the WS 2 nanosheets is effectively controlled by the glucose solution concentration, and the electromagnetic wave (EMW) absorption performance in the low-frequency bands can be adjusted by the regulation of annealing temperature. The effective absorption band of WS 2 @BDC is shifted to a lower frequency region and the absorption performance is substantially enhanced, compared to those of pure WS 2 nanosheets. The minimum reflection loss of WS 2 @BDC corresponding to 14 mL of glucose and a carbonization temperature of 800 °C can reach up to −51.40 dB at 5.52 GHz. The study provides a novel and facile method for improving the EMW absorption performance of WS 2 in the low-frequency bands. [ABSTRACT FROM AUTHOR]

• The WS 2 -NS/CNTs hybrids were simply synthesized by a one-step hydrothermal method. • The excellent absorption properties of the WS 2 -NS/CNTs hybrids is attributed to special 3D mesh conductive network in the system. • The effective molar ratio adjustment is towards high efficiency, lightweight, and broad absorption bandwidth. Herein, ultra-thin tungsten disulfide nanosheets/carbon nanotubes (WS 2 -NS/CNTs) hybrids were successfully synthesized by using a one-step hydrothermal method. The WS 2 -NS is evenly grown on the surfaces of CNTs, leading to a remarkable three-dimensional (3D) heterostructure. Outstanding electromagnetic wave absorption performance of the WS 2 -NS/CNTs hybrids can be achieved by tuning the amount of CNTs. The minimum reflection loss can reach up to −51.6 dB at 14.8 GHz, and the effective absorption bandwidth is 5.4 GHz for the hybrids with a thickness of 1.95 mm. Comparison of the results with those of simple mixtures of WS 2 -NS and CNTs prepared by using ultrasonic methods indicates that the absorption performance of the optimized WS 2 -NS/CNTs hybrids are closely related to that of the 3D mesh conductive network constructed by the addition of CNTs and the synergistic effect of WS 2 -NS and CNTs in the hybrids. These WS 2 -NS/CNTs hybrids open a new avenue for the development of electromagnetic wave absorbers with extraordinary absorption performance, light weight, small thickness, broad absorption bandwidth, and low cost. [ABSTRACT FROM AUTHOR]

The 2D molybdenum disulfide nanosheets (MoS 2 -NS) has exhibited great potential in electromagnetic wave absorbing (EMA) due to larger surface area and peculiar electronic properties. However, due to the poor impedance matching and limited electromagnetic loss capability of pure MoS 2 -NS, its practical applications are significantly challenging. Herein, we firstly implanted Co 3 O 4 nanoparticles (Co 3 O 4 -NPS) on MoS 2 -NS by a facile hydrothermal method to improve the EMA performance. The resulting MoS 2 /Co 3 O 4 hybrids exhibit the minimum reflection loss (RL) value of −43.56 dB at 6.96 GHz with 20 wt% Co 3 O 4 loading under the samples thickness of 4.0 mm. The widest bandwidth with the RL value less than −10 dB of MoS 2 /Co 3 O 4 hybrids was determined to be 4.76 GHz (13.24 to 18 GHz) under the absorber thickness of 2.0 mm. The excellent performance is ascribed to that implanted Co 3 O 4 -NPS on MoS 2 -NS could turn tuning impedance matching and improving synergetic magnetic loss and dielectric loss. Herein, this work not only presents a facile strategy of achieving high-performance MoS 2 -based EMA materials, but also provides important implications for designing the other EMA materials. Image 1 • The MoS 2 /Co 3 O 4 hybrids are prepared by a facile synthesis route. • The MoS 2 /Co 3 O 4 hybrids exhibit excellent electromagnetic absorption properties. • Tailoring Co 3 O 4 loading percentage and thickness tunes electromagnetic absorption for high efficiency and broad bandwidth. • The mechanisms of high-performance microwave absorption of MoS 2 /Co 3 O 4 hybrids are elucidated. [ABSTRACT FROM AUTHOR]