Electromagnetic Pollution Research Articles

A Developed Approach for Synthesizing Novel Fe3O4/FeO/BaCl2 Composites with Broadband and High-Efficiency Microwave Absorption Performance.

Designing high-performance microwave absorbing materials that are thin and exhibit strong absorption capabilities across a wide frequency range is critical for mitigating electromagnetic pollution through a simple, highly adaptable, and cost-effective approach. However, achieving these three targets remains a significant challenge. In this research a simple approach suitable for large-scale production of microwave absorbing materials, namely, Fe3O4/FeO/BaCl2 composites, is proposed, which includes the processes of chemical coprecipitation and calcination. The above approach can adjust the mass ratio of Fe3O4/FeO while prompt the formation of BaCl2 with mesoporous structure on the surface of Fe3O4/FeO, meeting the need for desirable microwave absorbing performance. Subsequently, the impacts of varying mass ratios of the Fe3O4/FeO/BaCl2 composites on microstructures, magnetic properties, and microwave absorption properties were examined. Based on this investigation, a mass ratio close to 3.5:5.5:1 was determined to be optimal. At this ratio, the Fe3O4/FeO/BaCl2 composites realize an effective absorption bandwidth of 6.70 GHz at only 1.16 mm thickness, covering the whole Ku-band, and the maximum reflection loss can be close to -46.8 dB at 1.4 mm. The robust microwave absorption performance of Fe3O4/FeO/BaCl2 composites can be attributed to heterostructured multi-interface structural design, the comprehensive effects of multiple reflections and dielectric/magnetic losses induced by BaCl2 with mesoporous structure as well as the aggregated Fe3O4/FeO particles. This work may offer insights into designing and preparing effective microwave absorption materials.

Hollow size optimization of α-MoC modified nitrogen-doped carbon spheres for efficient microwave absorption

Recently, electromagnetic pollution has become a serious concern. Existing microwave absorbers cannot achieve the goals of being lightweight, broadband, and strongly absorbing simultaneously. The design of hollow structures has attracted a great deal of attention because they can optimize impedance matching and enhance microwave attenuation while reducing mass. However, the effect of the hollow size on microwave absorption is not yet clear. In this study, we synthesized nitrogen-doped hollow carbon microspheres embedded with α-MoC nanoparticles (α-MoC/C, MNC) using template pyrolysis. The hollow size of MNC nanospheres was successfully controlled by adjusting the size of carboxylated PS nanospheres. The hollow structure improves microwave absorption in MNC nanospheres by facilitating the construction of the 3D conductive network. This prevents carbon aggregation, improves impedance matching, increases conductive loss, and promotes multiple reflections and scattering. Additionally, the α-MoC nanoparticles embedded in the carbon shells generate abundant nano-interfaces, which promote interfacial polarization and further attenuate the electromagnetic waves. The MNC-3 sample with the carbon sphere size of around 300 nm achieved the best reflection loss of −58.9 dB (3.16 mm thickness) and an effective absorption bandwidth of 4.80 GHz (2.07 mm thickness). This work demonstrates that the microwave absorption capacity of nanoscale carbonaceous spheres is effectively enhanced by adjusting the hollow size, providing the basis for designing and optimizing wave-absorbing materials by hollow structure.

Synthesis of nano-diamond modified Ti3C2Tx MXene heterostructure for enhanced electromagnetic wave absorption

The highly efficient electromagnetic wave (EMW) absorption materials are considered a promising approach to combatting electromagnetic radiation pollution. We synthesized a novel heterostructure 2D Ti3C2Tx MXene composite film modified by 0D nano-diamond (ND) particles using simple mechanical stirring and a vacuum filtration method. Subsequently, we investigated its microstructure and EMW absorption properties. The ND modification not only regulated the impedance matching of the composite films but also enhanced the diversity of EMW losses, demonstrating excellent microwave absorption performance. With a 40 wt% ND content, the minimum reflection loss (RLmin) of the films reached −43.0 dB, corresponding to a film thickness of 2.5 mm. This study explored a novel and promising microwave absorption film, expanding the application of diamond in microwave absorption, and addressing the theoretical gap in diamond-enhanced MXene microwave absorption performance.

Fabrication of hollow Fe3O4 microspheres encapsulated by single-walled carbon nanohorns for high-performance microwave absorption

Due to the increasingly serious electromagnetic radiation and pollution problems, it is urgent to develop high-performance electromagnetic wave absorbing materials. Herein, the hollow Fe3O4 microspheres encapsulated by single-walled carbon nanohorns (H-Fe3O4@SWCNHs) have been synthesized via facile solvothermal approach. The obtained H-Fe3O4@SWCNHs composite exhibits a unique hollow core-shell structure and superior microwave absorption performance. When the matching thickness is 2.0 mm, the composite shows a minimum reflection loss value of −42.2 dB at 13.6 GHz and a maximum effective absorption broadband value of 6.2 GHz covering from 11.8 to 18 GHz. The excellent microwave absorption performance of the H-Fe3O4@SWCNHs composite is mainly attributed to the unique hollow core-shell structure, optimal impedance matching, and synergistic effects of dielectric loss and magnetic loss. Therefore, the present work provides a new kind of ideal microwave absorbing material with light weight, thin thickness, wide bandwidth and strong absorption capability for high-performance microwave absorption.

Nitrogen-doped modified graphene aerogel enhancing interfacial bonding with lithium aluminium silicate ceramics for broadband microwave absorption

The swift progression of e-communication technology has resulted in significant electromagnetic pollution, necessitating the urgent need for effective microwave-absorbing materials to mitigate this issue. Augmenting heterogeneous phase interfaces and incorporating heteroatoms constitute viable strategies for enhancing the electromagnetic properties of functional materials. In this study, a series of lithium aluminium silicate glass-ceramic/nitrogen-doped graphene (LAS/N-GF) aerogels was synthesised via the hydrothermal and freeze-drying methods. An innovative bonding mechanism for the heterogeneous phase interface was revealed, in which nitrogen doping enabled the formation of lattice defects in LAS ceramic particles and graphene and promoted a closed approach for unsaturated carbon and silicon atoms to form carbon-silicon bonds through the electrostatic force generated by interfacial polarisation. Given that covalent bonds are widely recognized as stable carrier channels, the presence of carbon-silicon bonds at the interface facilitates electron migration, ultimately leading to improved microwave absorption. The maximum absorptivity of the LAS/N-GF aerogels could reach -47.98 dB at 8.96 GHz with a filler loading as low as 10 wt.%. It is noteworthy that the LAS/N-GF aerogel exhibits an effective absorption bandwidth of 8.34 GHz, which fully spans the entire X-band and more than two-thirds of the Ku-band. Such exceptional performance is rarely observed in dielectric loss materials. Finally, the application potential of the LAS/N-GF aerogels in microwave absorbers was simulated and analysed. The unique chemical phenomenon stemming from the bonding at the carbon material-ceramic interface offers a fresh perspective in interface science, enabling a deeper comprehension of the underlying mechanism of microwave absorption.

Flexible CoNiZn@Ti3CNTx MXene@carbon fabrics with hierarchical structure for efficient electromagnetic wave absorption

The widespread application of 5G technology has significantly exacerbated concerns regarding electromagnetic radiation. However, the rigidity and lack of flexibility of traditional electromagnetic wave (EMW) absorption materials make them ill-suited for protecting humans and certain specialized, complex shapes of equipment. Therefore, there is an increasing urgency to develop flexible EMW absorbing fabrics to effectively mitigate electromagnetic pollution. In this study, hierarchical structure CoNiZn@Ti3CNTx MXene@carbon fabrics (CoNiZn@Ti3CNTx@CF) were constructed from nano-flower structure CoNiZn-MOF, Ti3CNTx MXene and fabrics by self-assembly, in-situ growth and pyrolysis. The carbon fabric acts as a skeleton to form a 3D interconnected conductive network, in which loaded nano-flower structure CoNiZn@Ti3CNTx MXene (CoNiZn@Ti3CNTx@C) composites exists excellent dielectric loss and magnetic loss, so that EMW enters the fabric and optimizes the impedance matching, increasing the multiple reflection and scattering of EMW, thereby effectively attenuating EMW. The minimum reflection loss (RLmin) of CoNiZn@Ti3CNTx@CF reaches −44.51 dB at 14.88 GHz with filling ratio of 15 % and thickness of 1.50 mm and the effective absorption bandwidth (EAB) of CoNiZn@Ti3CNTx@CF reaches 4.32 GHz (13.04 ∼ 17.36 GHz) at 1.55 mm. The EAB of CoNiZn@Ti3CNTx@CF is expanded to 14.56 GHz (3.44 ∼ 18.00 GHz) through thickness adjustment (1 ∼ 5.50 mm), covering most of the S, C, X, and Ku bands. The radar cross-section (RCS) value of CoNiZn@Ti3CNTx@CF is 17.3 dB m2 lower than the perfect electrical conductor (PEC), which effectively reduces the probability of the target being detected by the radar detector. This work provides ideas for design and development of flexible EMW absorbing materials.

Supercritical N2 induced sandwich type lightweight and strong PP/CF foams with excellent electromagnetic shielding properties

The tremendous advances in communication technology and the explosion of electronic products led to an intensification of electromagnetic pollution, yet the efficient development of lightweight, high-strength fiber composite foams with excellent electromagnetic shielding properties was still a great challenge. Herein, this study, inspired by the sandwich structure, proposes a green foaming method with supercritical N2 to prepare a multilayered structure of carbon fiber reinforced polypropylene (PP/CF) foams, with a dense cellular structure in the core layer and a solid layer in the surface layer. The incorporation of CF improves the crystallization and rheological behavior of PP/CF, which guarantees a fine, dense and uniform cellular structure. This inner fine cellular structure and the solid layer on the surface contribute to the excellent mechanical properties. PP/30 %CF foam with a 1 mm mold opening distance displays an enhancement of 189.9 % in tensile strength and 196.3 % in flexural strength compared to pure PP. This also indicates more lightweight, high-strength and high-rigidity microcellular parts was obtained with less raw materials. Moreover, the formation of CF conductive network and internal foam structure contribute to excellent electromagnetic interference (EMI) shielding performance. The PP/CF composite foams maintain a level of EMI shielding performance greater than 30 dB despite the higher mold opening distance. Specifically, the PP/30 %CF foams at opening distance of 5 mm was enhanced to 58.3 dB·cm3/g with an improvement of 76.7 %. This implies that lightweight microcellular parts with both excellent strength and EMI shielding properties can be prepared, which enables PP/CF foams to possess a wide range of applications in various fields.

Hierarchical Assembly of Ternary MOF-Derived Sandwich Composites for High-Efficiency Tunable Electromagnetic Wave Absorption.

The proliferation of electronic devices drives the adoption of electromagnetic wave (EMW) absorbing materials to mitigate electromagnetic pollution. Metal-organic frameworks (MOFs) reveal great potential in EMW absorption field due to their unique pore structure and outstanding physicochemical properties. However, single MOFs are difficult to achieve both efficient absorption and wide frequency coverage owing to the limited electromagnetic properties and structural composition. Herein, a sandwich-like ternary MOF composite is successfully synthesized through a hierarchical assembly strategy. Following high-temperature treatment, the materials are converted into nitrogen-doped porous carbon with magnetic metals, non-magnetic metal oxides, and carbon nanotubes on the surface (labeled as TiO2/C@Co/N/C@CNT). The unique sandwich structure of the resulting derivatives provides a multi-level microstructure and multi-component synergistic effects, significantly enhancing electromagnetic wave absorption capabilities and broadening the effective absorption bandwidth (EAB). At 1.8 mm matching thicknesses, the material achieves a reflection loss of -56.3 dB and a 6.6 GHz EAB. Adjusting the matching thicknesses to 2.3 and 3.1 mm extends the EAB to 6.1-18 GHz, with absorption peaks of -47.6 and -47.1 dB. This work offers a novel guidance for constructing advanced MOF-derived materials with ultra-broadband EAB and strong EMW absorption through meticulous structural design and multiple components combination.

Controlled Distribution of MXene on the Pore Walls of Polyarylene Ether Nitrile Porous Films for Absorption-Dominated Electromagnetic Interference Shielding Materials.

With the increasing application of electronic devices, absorption-dominated electromagnetic interference shielding materials (EMISM) have garnered significant attention for preventing secondary electromagnetic pollution. In this study, polyethyleneimine (PEI)-modified MXene (PEI@MXene) is fabricated and achieved its controlled distribution on the pore walls of polyarylene ether nitrile (PEN) porous films via the phase inversion method (PIM) to obtain a closed porous skeleton of MXene on the pore walls (CPS-MPW). The resulting PEI@MXene/PEN composite film (CFx) exhibited absorption-dominated EMIS efficiency (EMISE). Attributing to the strong interaction between PEI and the hydrophilic segment of amphiphilic Pluronic F127, with its hydrophobic segment anchored by the PEN matrix, PEI@MXene is directionally distributed on the pore walls of CFx. In addition, resulting from the cladding of MXene with PEI and isolating it with closed honeycomb pores, the obtained CFx are insulators without forming aconductive network. As a result, these CFx demonstrate absorption-dominated EMISE with the highest SET of 41.2 dB and coefficient A higher than 0.51. Further continuous hot pressing of CFx results in thinner and denser films with an impressive specific EMISE up to 750 dBcm-1. The successful fabrication of these CPS-MPW-type CFx with absorption-dominated EMISE provides a reference for developing and preparing novel EMISM.

Bamboo-Based Carbon/Co/CoO Heterojunction Structures Based on a Multi-Layer Periodic Matrix Array Can Be Used for Efficient Electromagnetic Attenuation.

With the popularization of wireless communication, radar, and electronic devices, the hidden harm of electromagnetic radiation is becoming increasingly serious. The design of green biomass carbon-based interface heterojunctions based on lightweight porous materials can effectively protect against electromagnetic radiation hazards. In this work, we constructed an anisotropic heterojunction interface with magnetic and dielectric coupling based on a honeycomb-like periodic matrix multi-layer array repeating unit. The removal of lignin components from bamboo through oxidation enriches the impregnation pores and uniform adsorption sites of the magnetic medium. Further, in situ pyrolysis promotes the formation of a large number of electric dipoles at the interface between the magnetic medium and dielectric coupling inside the periodic cell carbon skeleton, enhancing interface polarization and relaxation. Local carrier traps and uneven electromagnetic density enhance dielectric and hysteresis losses, resulting in excellent impedance matching. Therefore, the obtained bamboo-based carbon multiphase composite absorbent has satisfactory electromagnetic loss characteristics. At a thickness of 1.55 mm, the effective absorption bandwidth reaches 5.1 GHz, and the minimum reflection loss (RL) value reaches -54.7 dB. In addition, the far-field radar simulation results show that the sample has an excellent RCS (radar cross-section) reduction of 33.3 dB·m2. This work provides new directions for the diversified development of green biomass and the optimization of the design of magnetic and dielectric coupling in periodic array structures.

Flexible multifunctional composite films for adjustable EMI shielding behavior under self-fixed deformation

With the widespread application of electromagnetic technology, the significance of intelligent electronic devices in modern communication is increasingly prominent. Despite this, the public focuses more on the harm caused by electromagnetic pollution. However, traditional EMI shielding materials struggle to meet the diverse and dynamic application requirements. Hence, developing materials capable of adjusting EMI shielding has become imperative to satisfy various scenarios. This paper presents the composite film TAPU-MXene, which is capable of adjustable EMI SE under self-fixed deformation. Introducing tannic acid increases the innermolecular interactions of TAPU. This enhancement leads to remarkable improvements in mechanical performance, achieving a stress level of 36.6 MPa at a strain of 560 %. Furthermore, the catechol groups can establish non-covalent interactions with multiple substrates, endowing the TAPU film with remarkable adhesion and self-healing capabilities. By combining the highly conductive nano-filler MXene with TAPU, the EMI shielding composite film TAPU-MXene is obtained. The EMI SE of TAPU-MXene was up to 56.7 dB when MXene loading was 3 mg cm−2. Most importantly, TAPU-MXene exhibits the ability to adjust the EMI shielding effectiveness from 56.7 dB to 2.75 dB under self-fixing deformation through shape memory mechanism, demonstrating promising applications in the field of adjustable EMI shielding materials.

Effects of radiofrequency electromagnetic radiation with a focus on haematology parameters

The use of radiofrequency electromagnetic radiation (RF-EMR) has steadily increased since the 1950s. RF-EMR is used in medicine, industry, household appliances, security and navigation, and especially in wireless elecommunications and animal husbandry. The widespread use of RF-EMR, especially with the introduction of 5G networks, raises concerns about potential adverse effects on human and animal health. The effects and mechanisms of RF-EMR impacts of 5G network frequencies on human and animal health are still unknown orpoorly understood. Current research findings include the biological effects of RF-EMR on genotoxicity, cell proliferation, gene expression, cell signalling, cell membrane function, and the function of immune, ematopoietic, and reproductive systems. Exposure of humans and laboratory animals to RF-EMR emitted from cell phones and many other electronic devices of 4G and older technologies has been shown to have detrimental effects on blood cells and to cause changes in the complete blood count. This depends on the type of organisms exposed, sources,frequency, electric field level and duration of exposure. There is sparse data in the available literature on the effects of RF-EMR on haematology indicators and erythrocyte morphometry in domestic animals. Therefore, the aim of this scientific review is to highlight the effects of RF-EMR on haematology indicators, erythrocyte morphometry, and platelet activation in humans and animals, taking into account the findings on the effects of 5G electromagnetic radiation on these indicators. Considering the ubiquitous electromagnetic pollution, it is important to gain knowledge about the effects of RF-EMR on human and animal health. In addition, it is necessary to determine the effects following in vitro exposure of blood to RF-EMR, especially due to the storage and use of blood and blood products in transfusion medicine.

Efficient Nanofibrous Electromagnetic Wave Absorber Inspired by Spider Silk Hunting.

With the rapid advancements in wireless communication and radar detection technologies, there has been a significant uptick in the utilization frequency of electromagnetic waves across both civilian and military sectors, consequently generating substantial electromagnetic radiation and interference. These electromagnetic pollutants present a considerable threat to public health and information security. Consequently, materials capable of absorbing and mitigating electromagnetic pollution have garnered significant attention.The nanomaterials with multiple components and various heterogeneous interfaces have been considered as preferred efficient electromagnetic wave (EMW) absorbers. In this work, carbon nanofibers doped with magnetic metal oxide particles (Co/Ni-CNFs) are prepared by electrospinning and heat treatment. In these samples, the minimum reflection loss can reach -40.13dB at 4.6mm, and the widest effective absorption bandwidth is 4.4GHz. The excellent microwave absorption is attributed to the appropriate impedance matching. The electromagnetic parameters of Co/Ni-CNFs are balanced by adjusting the concentration of magnetic metal-organic framework material (MOFs) in the precursor solution. It is believed that this work can provide a reference for developing lightweight, flexible, and robust electromagnetic wave-absorbing materials.

Development of electromagnetic pollution maps utilizing Gaussian process spatial models

The rapid proliferation of wireless technologies in everyday environments demands the quick and precise estimation of electromagnetic field distribution. This distribution is commonly depicted through the electric field strength across various geographical areas. The objective of this research is to determine the most effective geospatial model for generating a national-level electric field strength map within the 30 MHz–6 GHz frequency range. To achieve this, we employed five different methodologies for constructing the electric field strength map. Four of these methodologies are based on Gaussian process regression, while the fifth utilizes the classical weighted-average method of the nearest neighbor. Our study focused on a country with a total area of 9251 km2, using a dataset comprising 3621 measurements. The findings reveal that Gaussian process spatial models, also known as Kriging models, generally outperform other methods when applied to spatial data. However, it was observed that, after excluding some outlier data points, the performance of the classical nearest neighbor models becomes comparable to that of the Gaussian process models. This indicates the potential for both approaches to be effective, depending on the data quality and the presence of outliers.

Green Strategy for a Large-Format, Superhard, and Insulated Electromagnetic Wave Absorber Inspired by a Natural Feature of a Conch Shell.

Due to the intensification of electromagnetic pollution and energy shortages, there is an urgent need for multifunctional composites that can absorb electromagnetic waves and provide insulation. However, developing low-cost electromagnetic wave-absorbing composites that are lightweight, high strength, heat-insulating, and large-format for special environments remains challenging. Inspired by the conch shell, this article proposes a green strategy of hydration recrystallization self-assembly. Highly biologically active hydroxyapatite (HAP) was used to lock in free water to prevent porous carbon fibers from absorbing a large amount of water. Meanwhile, HAP underwent ion exchange and recombined with hydrated crystals of magnesium oxychloride to form a gelatinous HAP-5 phase crystal. The cementitious HAP-5 phase crystal was interwoven and interlocked with the support skeleton carbon fibers and metal Ni powder to form conch shell composites (Bio-CSC) with multiple interfaces via electrostatic adsorption and metal complexation. This strategy utilized inorganic substances as bridges to uniformly disperse conductive materials such as carbon fibers to construct a conductive network with an enriched interface polarization. The prepared Bio-CSC was composed of multiple heterogeneous interfaces and was lightweight and high strength, with a specific strength increase of 300%. It also provided excellent thermal insulation and electromagnetic wave absorption. Its thermal conductivity was 0.071 W·m-1·k-1, and the lowest RLmin value of -21.88 dB, with a matching thickness of only 1.2 mm. The composites in this study overcame the limitations of traditional absorption materials such as high magnetism and single function and may be used in fields such as building energy conservation and electromagnetic safety.

Hollow core-shell structured Fe3O4@Polypyrrole composites for enhanced electromagnetic wave absorption

Due to the rapid development of electronic devices, the electromagnetic pollution has become increasingly serious. Developing electromagnetic wave absorption (EWA) materials with lightweight, strong absorption capacity and wide effective absorption bandwidth (EAB) becomes a research hotspot. In this work, the hollow-Fe3O4@polypyrrole (HFO@PPy) composites with core-shell structure were successfully synthesized by in situ polymerization method. The electromagnetic parameters could be adjusted by controlling the content of HFO in HFO@PPy. In addition, HFO@PPy composites show both dielectric and magnetic losses. The synergistic effect of both two losses contributes to an enhanced electromagnetic attenuation. The enhanced impedance matching is achieved by the composition (HFO and PPy) and designed unique structure (core-shell and hollow structure). The maximum reflection loss (RL) and EAB are −52.01 dB and 2.72 GHz at 3.1 mm for 60.0 wt% HFO@PPy composites. Therefore, by reasonably regulating the component content and optimizing the structural design, the EWA performance of HFO@PPy composites could be effectively improved, providing a significant inspiration for fabrication of microwave absorbers.

Investigation of the electromagnetic shielding efficiency of FeB and Fe2B: ab-initio calculations

Abstract The electromagnetic (EM) pollution that we are exposed to in our daily lives has reached levels that threaten the health of living organisms and the stable operation of sensitive systems. The most effective way to protect against this pollution is to create isolated areas framed with shielding materials that can minimize the transmission of EM radiation. The development of shielding materials with high physical endurance against external factors to meet the needs of various sectors remains a popular research topic. This process, which started with metal plates, has continued with the development of doped polymers and composite materials. In recent years, materials with 2D structures have been developed. In this study, the shielding effectiveness (SE) of FeB and Fe2B nanostructures are revealed using ab initio calculations in Perdew–Burke–ErnzerhofSol scheme. SE has been widely figuring out via optical properties which are strongly related to mechanical and electronic properties herewith magnetic phases. The ferrimagnetic FeB and Fe2B nanostructures are considered. Besides, we focus on the thickness and photon energy dependent behavior along various projections. The findings demonstrate shielding performance at levels of >20 dB. Although both materials show similar shielding performance, it is observed that Fe2B is promising when compared to FeB. This study demonstrates that FeB and Fe2B, members of the MBene family, are promising materials not only because of their superior physical and chemical properties but also because of their shielding performance.

Research on Efficient Electromagnetic Shielding Performance and Modulation Mechanism of Aero/Organo/Hydrogels with Gravity-Induced Asymmetric Gradient Structure.

To eliminate electromagnetic pollution, it is a challenging task to develop highly efficient electromagnetic shielding materials that integrate microwave absorption (MA) performance with high shielding capability and achieve tunability in shielding performance. Asymmetrically structured aero/organo/hydrogels with a progressively changing concentration gradient of liquid metal nanoparticles (LMNPs), induced by gravity, are prepared by integrating the conductive fillers Ti3C2Tx MXene and LMNPs into a dual-network structure composed of polyvinyl alcohol and cellulose nanofibers. Benefiting from the unique structure, which facilitates the absorption-reflection-reabsorption process of electromagnetic waves along with conductive fillers and the porous structure, three types of gels demonstrate efficient shielding performance. HPCML achieves a total shielding effectiveness (SET) of up to 86.9dB and a reflection shielding effectiveness (SER) of as low as 2.85dB. Especially, APCML, with an ultra-low reflection coefficient (R) of 6.4%, achieves compatibility between shielding performance and MA properties. The relationship between dispersing media (air, water, and glycerol/water) and the shielding performance of aero/organo/hydrogels is explored, thereby achieving modulation of the shielding performance of the gel system. The work has paved a clear path for integrating absorption and shielding capabilities into a composite material, thereby providing a prototype of a highly efficient shielding material with MA performance.

Asymmetric sandwich poly(lactic acid) composite films fabricated by one-step phase separation approach towards absorption-dominant electromagnetic interference shielding and hydrophobicity

The absorption-dominant electromagnetic interference (EMI) shielding polymer composites with excellent hydrophobicity and environmental friendliness are highly demanded to alleviate secondary electromagnetic radiation in high-humidity surroundings. Herein, cobalt–nickel@carbon nanotubes-polylactic acid-silver nanowires (CoNi@CNTs-PLA-AgNWs) films with asymmetrical sandwich architectures were successfully fabricated via a one-step magnetic field-assisted non-solvent-induced phase separation methodology. AgNWs are mainly spread on the rough top layer, but CoNi@CNTs are primarily distributed in the porous bottom layer of CoNi@CNTs-PLA-AgNWs composite films. Owing to the unique asymmetrical magnetic-electric dual networks, 150CoNi@CNTs-PLA-7AgNWs film displays the fantastic averaged EMI SET of 53.7 dB and optimal A of 0.61, illuminating the dominance of absorption in EMI shielding and efficiently alleviating the secondary electromagnetic pollution. In order to enhance the stability of EMI shielding in damp environment, CoNi@CNTs-PLA-AgNWs composite films are dip-coated in 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FDTS) solution for hydrophobic modification. The excellent water repellency is achieved on both top and bottom surface of CoNi@CNTs-PLA-AgNWs films with WCA > 150° and > 120°, respectively, while maintaining the superior EMI shielding performance. Such facile one-step asymmetrical sandwich structure design strategy provides valuable insight into preparing and controlling hydrophobic absorption-dominant EMI shielding composites, which is anticipated to have numerous implications for smart and portable electronic devices in high-humidity environment.

Achieving Broadband Microwave Shielding, Thermal Management, and Smart Window in Energy‐Efficient Buildings

AbstractEnergy‐efficient building materials are eye‐catching for reducing indoor energy consumption via eliminating electromagnetic interference and pollution, controlling the thermal transfer, and promoting sunlight harvesting and providing a comfortable living environment. To realize broadband microwave shielding, the elaborate control of microstructures has showed great potential and research direction. By composition regulation and structure design with various dimension, the synergistic effects including conductive networks, interfacial polarization, magnetic coupling, dipole polarization, and dielectric‐magnetic synergy, can significantly improve electromagnetic (EM) shielding capacity. Thermal management including thermal conversion, thermal storage, thermal radiation, and thermal conduction has enormous potential in enhancing the sustainability and energy efficiency for future buildings. Smart windows are able to switch optical transmittance and colors, which is contributed to saving building energy. Herein, in this review, the recent progress of broadband shielding, thermal management, and smart window in the field of energy‐efficient buildings is summarized, from the aspects of materials, mechanisms, and scenarios. Further, the main bottlenecks and problems are discussed, and potential research opportunities are further highlighted.