Lightweight and Hydrophobic Three-Dimensional Wood-Derived Anisotropic Magnetic Porous Carbon for Highly Efficient Electromagnetic Interference Shielding

Electromagnetic porous lignocellulosic matrix composites: A green electromagnetic shielding material with high absorption efficient electromagnetic interference

Electromagnetic interference (EMI) shielding materials play a vital role in human society, especially in light of the rapid development of electronic communication equipment. Therefore, it is urgent to develop green, high-efficiency EMI shielding materials. Wood, as a renewable raw material, possesses significant structural advantages in studying EMI materials due to its unique 3D pore structure. Herein, we report magnetoelectric lignocellulosic matrix composites derived from the delignified wood for efficient EMI shielding. The composite was fabricated by in-situ polymerization of PEDOT conductive coating and magnetic Fe3O4 in delignified wood. The conductive 3D pore structure of Fe3O4/PEDOT@wood could effectively cause dielectric loss and multiple internal reflections. Combined with the magnetic loss of Fe3O4, the material exhibited excellent EMI shielding effectiveness (SE), which could be attributed to the synergistic effect of dielectric and magnetic losses. The Fe3O4/PEDOT@wood showed excellent conductivity (103 S/m), good magnetism (26.7 emu/g), the EMI SE up to 59.8 dB, and high SEA/SET ratios of∼84.2 % to 95.7 % at 2 mm in X -band. Moreover, the material exhibited a high compressive strength and tensile strength of 100.8 MPa and 18.1 MPa, respectively. Therefore, this work provided a reference for the preparation of high-efficiency EMI shielding materials.

Cellulose-derived carbon scaffolds with bidirectional gradient Fe3O4 distribution: Integration of green EMI shielding and thermal management

Cellulose papers (CPs) possess a pore structure, rendering them ideal precursors for carbon scaffolds because of their renewability. However, achieving a tradeoff between high electromagnetic shielding effectiveness and low reflection coefficient poses a tremendous challenge for CP-based carbon scaffolds. To meet the challenge, leveraging the synergistic effect of gravity and evaporation dynamics, laminar CP-based carbon scaffolds with a bidirectional gradient distribution of Fe3O4 nanoparticles were fabricated via immersion, drying, and carbonization processes. The resulting carbon scaffold, owing to the bidirectional gradient structure of magnetic nanoparticles and unique laminar arrangement, exhibited excellent in-plane electrical conductivity (96.3 S/m), superior electromagnetic shielding efficiency (1805.9 dB/cm2 g), low reflection coefficients (0.23), and a high green index (gs, 3.38), suggesting its green shielding capabilities. Furthermore, the laminar structure conferred upon the resultant carbon scaffold a surprisingly anisotropic thermal conductivity, with an in-plane thermal conductivity of 1.73 W/m K compared to a through-plane value of only 0.07 W/m K, confirming the integration of thermal insulation and thermal management functionalities. These green electromagnetic interference shielding materials, coupled with thermal insulation and thermal management properties, hold promising prospects for applications in sensitive devices.

Multi-interfacial bridging engineering of flexible MXene film for efficient electromagnetic shielding and energy conversion

Accompanied by the progressive development of electronic equipment, excellent electromagnetic interference (EMI) shielding materials display a satisfying prospect in protecting electronic devices against electromagnetic pollution/radiation, while integrating energy conversion. Heretofore, it remains a conundrum to availably construct thin films with multi-interfacial bridging engineering as multifunctional shielding devices. To effectively achieve electromagnetic wave attenuation and integrate energy conversion, a co-mixed vacuum-assisted filtration strategy is designed to synthesize Au@MXene/cellulose nanocrystal/dodecylbenzenesulfonic acid-doped polyaniline (AMCP) films. Profited from the interfacial engineering, the total EMI shielding effectiveness (SE) can be increased by 27 % with the highest value of 67.9 dB. MXene with localized surface plasmon resonance characteristics gives the composite films good energy conversion performance, that is, the composite film can be rapidly heated up to 100 °C under the irradiation of an infrared lamp, and its surface temperature remains stable after continuous irradiation. Additionally, the infrared emissivity is as low as 0.173 within the 8-14 μm, which is necessary to adapt various application scenarios. Therefore, it is reliable that the AMCP films constructed by multicomponent offer a facile strategy for MXene-based EMI shielding devices with integration characteristics.

Premise setting for sustainable developing adsorption in environmental remediation using graphitic carbon nitride@agar-derived porous carbon composite

In the adsorption process for wastewater treatment, the adsorbent plays an important role. A composite adsorptive material composed of graphitic carbon nitride and agar-derived porous carbon (CNPC) was fabricated from simple precursors (melamine, thiourea, and agar) and through a facile procedure with different melamine and thiourea ratios. Characterization of CNPC proved a successful formation of a porous structure consisting of mesopores and macropores, wherein CNPC holds distinctive electrochemical (lowered resistance and higher specific capacity) and photochemical properties (lowered bandgap to 2.33 eV) thanks to the combination of graphitic carbon nitride (CN) and agar-derived porous carbon (PC). Inheriting the immanent nature, CNPC was subjected to the adsorption of methylene blue (MB) dye in an aqueous solution. The highest adsorption capacity was 133 mg/g for CNPC-4 which was prepared using a melamine to thiourea ratio of 4:4 - equivalent to the removal rate of 53.2 % and following the pseudo-I-order reaction rate. The effect of pH points out that pH 7 and 9 were susceptible to maximum removal and pretreatment is not required while the optimal ratio of 7.5 mg of MB and 30 mg of material was also determined to yield the highest performance. Furthermore, the reusability of the material for three consecutive cycles was evaluated based on two methods pyrolysis at 200 °C and photocatalytic degradation by irradiation under visible light. In general, the photocatalytic regeneration pathway is more ample and efficient than pyrolysis in terms of energy efficiency (saving energy over 10 times) and adsorption capacity stability. As a whole, the construction of accessible regenerative and stable adsorbent could be a venturing step into the sustainable development spearhead for industries.

AgNWs/Fe3O4@NC Conductive Network Hierarchical Assembly to Prepare Flexible EMI Shielding Textile

With the rapid development of high-power electronic instruments and communication technology, efficient electromagnetic shielding materials with strong absorption of electromagnetic waves and low reflection characteristics have become the focus of the world's attention. This study designs and synthesizes N-doped carbon-coated hollow Fe3O4 nanospheres (Fe3O4@NC) by spraying Ag nanowires (AgNWs) on textiles as conductive networks. Because of the high permeability and hollow structure Fe3O4@NC, electromagnetic wave goes through a unique process of "absorption, reflection, and reabsorption" when it passes through the surface of the composite textile. In X-band (≈8.2-12.4 GHz), the average electromagnetic interference shielding effectiveness (EMI SE) reaches 50.1 dB, while the reflectance shielding efficiency (SER) is only 2.6 dB, and the average reflectance power coefficient (R) is as low as 0.45. The composite fabric has excellent properties and provides an effective strategy for electromagnetic interference shielding based on absorption.

Enhanced polarization via Joule heating in wood-derived carbon materials for absorption-dominated EMI shielding

To cope with sophisticated application scenarios, carbon materials can provide opportunities for integrating multi-functionalities into superior electromagnetic interference (EMI) shielding properties. Nevertheless, carbon materials usually possess high electrical conductivity, which allows them to counteract electromagnetic waves by reflection. Moreover, the identification of factors that dominate the shielding mechanisms has typically been result-oriented, leading to a reliance on a trial-and-error approach for the development of shielding materials. Thus, it is crucial to identify the dominant factors for EMI shielding and elucidate the mechanism underlying the coordination of the balance between reflection and absorption in carbon materials. In this study, we developed a promising and viable approach to create Co@CNTs embedded in carbonized wood (CW) via chemical vapor deposition, producing Co@CNTs/CW foams. The CNTs, densely grown on the CW surface, tightly encapsulated the Co nanoparticles within them. By manipulating the Co content, the defect density and CNT length varied within the Co@CNTs. Through first-principles calculations, these variations substantially influenced the work function, charge density, and dipole moment of the Co@CNTs. Thus, defect-induced and interfacial polarizations were improved, inducing a transformation of the shielding mechanism from reflection to absorption. Regarding the Co@CNTs/CW foams, while high conductivity was essential for achieving satisfactory shielding performance, the enhanced polarization loss dominated the contribution of absorption to the overall shielding effectiveness. Taking advantage of the enhanced polarizations, the Co@CNTs/CW foams exhibited an impressive shielding effectiveness of 42.0 dB, along with an absorptivity of 0.64, which were instrumental in effectively minimizing secondary reflections. Remarkably, these as-prepared foams possessed outstanding hydrophobicity and Joule heating features with a water contact angle of 138° and a saturation temperature of 85.5 °C (2.5 V). Through the stimulation of voltage-driven Joule heating, the absorptivity of Co@CNTs/CW foams can be significantly enhanced to a range of 0.61 to 0.73, irrespective of the Co content. This research would provide a new avenue for designing carbon materials with an absorption-dominated mechanism integrated into EMI shielding performance.

Liquid metal assisted fabrication of MXene-based films: Toward superior electromagnetic interference shielding and thermal management

The development of thin and flexible films that possess both electromagnetic interference (EMI) shielding and thermal management capabilities has always been an intriguing pursuit, but itisnevertheless a crucialproblemtoaddress. Inspired by the deformability of liquid metal (LM) and film forming capacity of MXene, here we present a series of ternary compositing films prepared via cellulose nanofiber (CNF) assisted vacuum filtration technology. Originating from the highly conductive LM/MXene network, the MLMC film presents a maximum EMI shielding effectiness (EMI SE) of 78 dB at a tiny thickness of 45 μm, together with a high specific EMI SE of 3046 dB mm-1. Meanwhile, these compositing films also deliver excellent flexibility and mechanical reliability, showing no obvious decline in EMI shielding performance even after 1000 bending and 500 folding cycles, respectively. Moreover, notable anisotropic thermal conductive property was successfully achieved, allowing for a highly desirable in-plane thermal conductivity of 7.8 W m-1 K-1. This accomplishment also yielded an exceptional electro-thermal conversion capacity, enabling efficient low-voltage (3 V) heating capabilities. These captivating features are expected to greatly drive the widespread adoption of LM-based films in future flexible electronic and wearable technologies.

High-performance EMI shielding effectiveness of Fe3O4-3D rPC nanocomposites: a systematic optimization in the X-band region

In this work, the microwave absorption (MWA) performance of a Fe3O4-3D reduced porous carbon nanocomposite (3D rPC NC) in the X-band region is reported. Three different shields are fabricated by altering the ratio of Fe3O4 nanoparticles (NPs) and 3D rPC and evaluating their microwave (MW) shielding performance with appropriate in-wearing instruments due to their minimum thickness. The chemical interaction between Fe3O4 NPs and 3D rPC is examined from chemical composition analysis of Fe3O4-3D rPC (1 : 2 ratio), which is confirmed by the presence of the Fe-O-C bond in the O 1s spectrum obtained from XPS analysis and subsequent analysis using FESEM images. Furthermore, it is found from N2 adsorption/desorption analysis that 3D rPC possesses a huge surface area of 787.312 m2 g-1 and showcases a type-V isotherm (mesoporous and/or microporous) behavior. The dielectric and magnetic losses of Fe3O4-3D rPC with a 1 : 2 ratio (tan δεr = 1.27 and tan δμr = 5.03) are higher than those of Fe3O4 NPs, 3D rPC and their NCs due to its magnetic and electrical conducting pathways modifying the material's polarization and dipole moment. The lightweight, polymer-free Fe3O4-3D rPC (1 : 2) NCs with minimum thickness on the order of 0.5 mm exhibited a higher total shielding effectiveness (SET = 41.285 dB), and it effectively blocked 99.9963% of the transmittance due to electric and magnetic polarization resulting from the presence of a heterogeneous interface surface.

In-situ magnetite deposited wood composites with extensive electromagnetic interference shielding performance

Wood is an insulator material, using its porous structure to endow it with efficient microwave absorption and broaden its application range is still a major challenge. Here, wood-based Fe₃O₄ composites with excellent microwave absorption properties and high mechanical strength were prepared by alkaline sulfite method, in-situ co-precipitation method and compression densification method. The results showed that the magnetic Fe₃O₄ was densely deposited in the wood cells, and the prepared wood-based microwave absorption composites had both high electrical conductivity, magnetic loss, excellent impedance matching performance and attenuation performance, as well as effective microwave absorption properties. In the frequency range of 2-18 GHz, the minimum reflection loss value was -25.32 dB. At the same time, it had high mechanical properties. Compared with the untreated wood, its modulus of elasticity (MOE) in bending increased by 98.77%, and modulus of rapture (MOR) in bending improved by 67.9%. The developed wood-based microwave absorption composite is expected to be used in electromagnetic shielding fields such as anti-radiation and anti-interference.

"Three-in-One" Multi-Scale Structural Design of Carbon Fiber-Based Composites for Personal Electromagnetic Protection and Thermal Management

Wearable devices with efficient thermal management and electromagnetic interference (EMI) shielding are highly desirable for improving human comfort and safety. Herein, a multifunctional wearable carbon fibers (CF) @ polyaniline (PANI) / silver nanowires (Ag NWs) composites with a "branch-trunk" interlocked micro/nanostructure were achieved through "three-in-one" multi-scale design. The reasonable assembly of the three kinds of one-dimensional (1D) materials can fully exert their excellent properties i.e., the superior flexibility of CF, the robustness of PANI, and the splendid conductivity of AgNWs. Consequently, the constructed flexible composite demonstrates enhanced mechanical properties with a tensile stress of 1.2 MPa, which was almost 6 times that of the original material. This is mainly attributed to the fact that the PNAI (branch) was firmly attached to the CF (trunk) through polydopamine (PDA), forming a robust interlocked structure. Meanwhile, the composite possesses excellent thermal insulation and heat preservation capacity owing to the synergistically low thermal conductivity and emissivity. More importantly, the conductive path of the composite established by the three 1D materials greatly improved its EMI shielding property and Joule heating performance at low applied voltage. This work paves the way for rational utilization of the intrinsic properties of 1D materials, as well as provides a promising strategy for designing wearable electromagnetic protection and thermal energy management devices.

Electrostatic self-assembly sandwich-like 2D/2D NiFe-LDH/MXene heterostructure for strong microwave absorption

MXene has great application potential in electromagnetic (EM) wave absorbers because of its high attenuation ability; however, self-stacking and excessively high conductivity are major obstacles to its widespread use. To address these issues, a NiFe layered double hydroxide (LDH)/ MXene composite with two-dimensional (2D)/2D sandwich-like heterostructure was constructed through electrostatic self-assembly. The NiFe-LDH not only acts as an intercalator to prevent self-stacking of the MXene nanosheets, but also serves as a low-dielectric choke valve to optimize impedance matching. At a thickness of 2 mm and filler loading of 20 wt%, the minimum reflection loss (RL_min) value could reach -58.2 dB, and the absorption mechanism was analyzed based on multiple reflection, dipole/interfacial polarization, impedance matching, and synergy between dielectric and magnetic losses. Furthermore, the simulation of the radar cross section (RCS) further confirmed the efficient absorption properties and application prospects of the present material. Our work demonstrates that designing sandwich structures based on 2D MXene is an effective way to improve the performance of EM wave absorbers.

High Value Utilization of Waste Wood toward Porous and Lightweight Carbon Monolith with EMI Shielding, Heat Insulation and Mechanical Properties

With the increasing pollution of electromagnetic (EM) radiation, it is necessary to develop low-cost, renewable electromagnetic interference (EMI) shielding materials. Herein, wood-derived carbon (WC) materials for EMI shielding are prepared by one-step carbonization of renewable wood. With the increase in carbonization temperature, the conductivity and EMI performance of WC increase gradually. At the same carbonization temperature, the denser WC has better conductivity and higher EMI performance. In addition, due to the layered superimposed conductive channel structure, the WC in the vertical-section shows better EMI shielding performance than that in the cross-section. After excluding the influence of thickness and density, the specific EMI shielding effectiveness (SSE/t) value can be calculated to further optimize tree species. We further discuss the mechanism of the influence of the microstructure of WC on its EMI shielding properties. In addition, the lightweight WC EMI material also has good hydrophobicity and heat insulation properties, as well as good mechanical properties.

Transparent and Flexible Electromagnetic Interference Shielding Materials by Constructing Sandwich AgNW@MXene/Wood Composites

Electromagnetic interference (EMI) shielding materials have attracted intensive attention with the increased electromagnetic pollution, which are required to possess high transparency and flexibility for applications in visualization windows, aerospace equipment, and wearable devices. However, it remains a challenge to achieve high-performance EMI shielding while maintaining excellent light transmittance. Herein, a sandwich composite is constructed by coating the core material of transparent wood (TW) with silver nanowire (AgNW)@MXene, exhibiting a maximum transmittance of 28.8% in the visible range and a longitudinal tensile strength of 47.8 MPa. The average EMI shielding effectiveness can reach up to 44.0 dB under X-band (8-12.4 GHz), ascribed to the increased absorption shielding induced by the multireflection of electromagnetic waves within microchannels of the TW layer and the interfacial polarization between AgNW and MXene. Simultaneously, large-scale EMI shielding films can be conveniently produced by our proposed method, which provides inspiration for the development of advanced EMI shielding materials for wide applications.

Natural Hollow Fiber-Derived Carbon Microtube with Broadband Microwave Attenuation Capacity

Constructing hierarchical structures is indispensable to tuning the electromagnetic properties of carbon-based materials. Here, carbon microtubes with nanometer wall thickness and micrometer diameter were fabricated by a feasible approach with economical and sustainable kapok fiber. The carbonized kapok fiber (CKF) exhibits microscale pores from the inherent porous templates as well as pyrolysis-induced nanopores inside the wall, affording the hierarchical carbon microtube with excellent microwave absorbing performance over broad frequency. Particularly, CKF-650 exhibits an optimized reflection loss (RL) of −62.46 dB (10.32 GHz, 2.2 mm), while CKF-600 demonstrates an effective absorption bandwidth (RL < −10 dB) of 6.80 GHz (11.20−18.00 GHz, 2.8 mm). Moreover, more than 90% of the incident electromagnetic wave ranging from 2.88 GHz to 18.00 GHz can be dissipated by simply controlling the carbonization temperature of KF and/or the thickness of the carbon-microtube-based absorber. These encouraging findings provide a facile alternative route to fabricate microwave absorbers with broadband attenuation capacity by utilizing sustainable biomass.

Wood-Based Composites with High Electromagnetic Interference Shielding Effectiveness and Ultra-Low Reflection

With the aggravation of electromagnetic radiation pollution, it is urgent to develop green, lightweight, ultra-thin and high-performance electromagnetic interference shielding materials to eliminate unnecessary electromagnetic interference; however, the construction of wood-based high-performance electromagnetic shielding materials by simple methods remains a challenge. Based on the layer-by-layer assembly strategy, a lightweight Ni/Wood/Ni composite (NWNC) with an interlayer structure was constructed by a simple electroless plating method using natural wood as a substrate for electromagnetic interference shielding. The synthesized NWNC has a smooth surface, and its minimum surface roughness is only 8.34 μm. After 15 min of electroless nickel plating, the contact angle (CA) of NWNC with an ultra-thin nickel layer (65 μm) was 118.3°. When the thickness of the nickel layer is only 0.102 mm, the conductivity can reach 1659.59 S/cm when the three electroless nickel plating time is 15 min. In the L-band, the electromagnetic shielding effectiveness can reach 94.1 dB after three times electroless nickel plating for 20 min. This is due to the conductive loss, magnetic loss and interface polarization loss generated by the electromagnetic network constructed by the nickel layer, which makes the composite material produce an electromagnetic shielding mechanism dominated by absorption. The L-band absorption efficiency can reach 39.01 dB, and due to the porous structure of the original wood, the multiple reflection and absorption inside the wood further lose the electromagnetic wave. This study provides a low-cost and simple method for the design of light, ultra-thin and efficient controllable wood-based electromagnetic shielding materials and has broad application prospects in the fields of construction and aerospace.

Microstructure Design of High-Entropy Alloys Through a Multistage Mechanical Alloying Strategy for Temperature-Stable Megahertz Electromagnetic Absorption

Developing megahertz (MHz) electromagnetic wave (EMW) absorption materials with broadband absorption, multi-temperature adaptability, and facile preparation method remains a challenge. Herein, nanocrystalline FeCoNiCr_0.4Cu_0.2 high-entropy alloy powders (HEAs) with both large aspect ratios and thin intergranular amorphous layers are constructed by a multistage mechanical alloying strategy, aiming to achieve excellent and temperature-stable permeability and EMW absorption. A single-phase face-centered cubic structure with good ductility and high crystallinity is obtained as wet milling precursors, via precisely controlling dry milling time. Then, HEAs are flattened to improve aspect ratios by synergistically regulating wet milling time. FeCoNiCr_0.4Cu_0.2 HEAs with dry milling 20 h and wet milling 5 h (D20) exhibit higher and more stable permeability because of larger aspect ratios and thinner intergranular amorphous layers. The maximum reflection loss (RL) of D20/SiO₂ composites is greater than - 7 dB with 5 mm thickness, and EMW absorption bandwidth (RL < - 7 dB) can maintain between 523 and 600 MHz from - 50 to 150 °C. Furthermore, relying on the "cocktail effect" of HEAs, D20 sample also exhibits excellent corrosion resistance and high Curie temperature. This work provides a facile and tunable strategy to design MHz electromagnetic absorbers with temperature stability, broadband, and resistance to harsh environments.

Hydrophobic, flexible electromagnetic interference shielding films derived from hydrolysate of waste leather scraps

With the rapid development of wireless telecommunication technologies, it is of fundamental and technological significance to design and engineer high-performance shielding materials against electromagnetic interference (EMI). Herein, a three-step procedure is developed to produce hydrophobic, flexible nanofiber films for EMI shielding and pressure sensing based on hydrolysate of waste leather scraps (HWLS): (i) electrospinning preparation of HWLS/polyacrylonitrile (PAN) nanofiber films, (ii) adsorption of silver nanowires (AgNWs) onto HWLS/PAN nanofiber films, and (iii) coating of HWLS/PAN/AgNWs nanofiber films with polydimethylsiloxane (PDMS). Scanning electron microscopy studies show that AgNWs are interweaved with HWLS/PAN nanofibers to form a conductive network, exhibiting an electrical conductivity of 10⁵ S m^-1 and shielding efficiency of 65 dB for a 150 μm-thick HWLS/PAN/AgNWs film. The HWLS/PAN/AgNWs/PDMS film displays an even better electromagnetic shielding efficiency of 80 dB and a water contact angle of 132.5°. Results from this study highlight the unique potential of leather solid wastes for the production of high-performance, environmentally friendly, and low-cost EMI shielding materials.

ZIF-67/wood derived self-supported carbon composites for electromagnetic interference shielding and sound and heat insulation

Co/C@WC composites showed better electromagnetic shielding performance and also exhibited sound insulation, temperature resistance and good mechanical performance.

Sulfur-doped wood-derived porous carbon for optimizing electromagnetic response performance

Bio-mass materials have been selected as one of the advanced electromagnetic (EM) functional materials due to their natural porous framework for dynamically and flexibly optimizing the EM response property. Herein, we demonstrate sulfur-doped wood-derived porous carbon EM materials (SPC) for optimizing the EM response performance via the coupling between doped heterostructures and the original 3D microchannels. The experimental results reveal that both the dielectric loss capacity and interfacial impedance matching could be increased by the sulfur-doped heterostructures. By tailoring the sulfur content, the microwave absorption (normalized RL_min) of SPC could be optimized to -15.90 dB mm^-1, while the effective absorption bandwidth (EAB_{RL≤-10 dB}) could cover the K band. Moreover, the shielding effectiveness of SPC can be enhanced from 10 dB to 30 dB with the assistance of water, ascribed to the super-wettability performance. This present study provides a novel strategy to further optimize the EM response performance of wood-derived materials, and meanwhile could be widely extended to other bio-mass absorbers.

Construction of a Phytic Acid-Silica System in Wood for Highly Efficient Flame Retardancy and Smoke Suppression

The intrinsic flammability of wood restricts its application in various fields. In this study, we constructed a phytic acid (PA)-silica hybrid system in wood by a vacuum-pressure impregnation process to improve its flame retardancy and smoke suppression. The system was derived from a simple mixture of PA and silica sol. Fourier transform infrared spectroscopy (FTIR) indicated an incorporation of the PA molecules into the silica network. Thermogravimetric (TG) analysis showed that the system greatly enhanced the char yield of wood from 1.5% to 32.1% (in air) and the thermal degradation rates were decreased. The limiting oxygen index (LOI) of the PA/silica-nanosol-treated wood was 47.3%. Cone calorimetry test (CCT) was conducted, which revealed large reductions in the heat release rate and smoke production rate. The appearance of the second heat release peak was delayed, indicating the enhanced thermal stability of the char residue. The mechanism underlying flame retardancy was analyzed by field-emission scanning electron microscope coupled with energy-dispersive spectroscopy (SEM-EDS), FTIR, and TG-FTIR. The improved flame retardancy and smoke-suppression property of the wood are mainly attributed to the formation of an intact and coherent char residue with crosslinked structures, which can protect against the transfer of heat and mass (flammable gases, smoke) during burning. Moreover, the hybrid system did not significantly alter the mechanical properties of wood, such as compressive strength and hardness. This approach can be extended to fabricate other phosphorus and silicon materials for enhancing the fire safety of wood.

Silk Sericin As a Green Adhesive to Fabricate a Textile Strain Sensor with Excellent Electromagnetic Shielding Performance

Although flexible textile-based electronics and lightweight electromagnetic shielding materials have attracted increasing attention due to their wide application, the seamless integration of textile sensors and electromagnetic shielding materials is still a challenge. Herein, we designed a simple, cost-effective, and environmentally friendly method to fabricate nickel-plated acetate fabrics coated with carbon nanotubes, using silk sericin to disperse carbon nanotubes in water and adsorb abundant nickel ions easily on the surface of carbon nanotubes via hydroxyl groups without other additives. The as-prepared composites exhibited excellent conductivity and electromagnetic interference (EMI) shield effectiveness (>30 dB) at X-band with around 0.8 mm thickness. The low-loading carbon nanotubes could offer more loss mechanism and had a positive effect upon EMI. The conductive textiles had higher tensile strength and negative relative resistance changes in strain, and had a great potential as wearable sensors in response to finger folding and wrist bending. Silk sericin as a green adhesive and dispersant provides an alternative strategy to large-scale produce multifunctional conductive wearable textiles for applications in EMI shielding and/or human-machine interaction.

High-Performance and Reliable Silver Nanotube Networks for Efficient and Large-Scale Transparent Electromagnetic Interference Shielding

The development of flexible and transparent electromagnetic interference (EMI) shielding materials with excellent comprehensive properties is urgently demanded as visual windows and display devices in aeronautic, industry, medical, and research facilities. However, the method of how to obtain highly efficient and reliable transparent EMI shielding devices is still facing lots of obstacles. Here, a high-performance silver nanotube (AgNT) network with stable and integrated interconnects is prepared by physical depositing technology, based on a uniform and large-scale nanofiber skeleton. This unique structure enables the AgNT network to achieve one order higher conductivity (∼1.0 Ω/sq at >90% transmittance) than previous research studies and keeps <10% variation with random deformations (>5000 times). Moreover, the manufactured AgNT shielding film with a thickness of less than 1 mm can be easily transferred to arbitrary surfaces as a transparent and flexible EMI shielding film at commercial ∼35 dB EMI shielding effectiveness, with large-scale, low-cost, and simple preparation processes. These excellent properties endow the AgNT shielding film to achieve great potential for future flexible and transparent scenarios.

From Waste to Wealth: A Lightweight and Flexible Leather Solid Waste/Polyvinyl Alcohol/Silver Paper for Highly Efficient Electromagnetic Interference Shielding

With the popularization of 5G communications and the internet of things, electromagnetic wave (EW) radiation pollution has aroused much concern from the public, and the search for new materials and technologies for preparing electromagnetic shielding materials still continues all around the world. However, the contradiction among high shielding performance, economic applicability, and flexibility is still not well balanced. Herein, we fabricated a novel foldable leather solid waste (LSW)/polyvinyl alcohol (PVA)/silver (Ag) paper with excellent electromagnetic interference (EMI)-shielding ability using a facile but sustainable electroless plating (ELP) method with LSW as the resource. Taking PVA as a cross-linker, debundled leather fibers (LFs) generated by solid-state shearing milling could generate a flexible LSW/PVA substrate with a high specific surface area, and eventually the deposited Ag layer served as a protective layer not only to significantly improve the mechanical and thermal robustness, but also to endow the LSW/PVA/Ag paper with good hydrophobicity, which could protect from potential moisture damage. In addition to the reflection effect of metallic Ag on EW, the hierarchical structure of collagen fibers played an important role in superior high EMI-shielding effectiveness (∼55-∼90 dB) by an absorption-dominant EMI-shielding mechanism. Furthermore, a multilayer LSW/PVA/Ag paper was also prepared with enhanced EMI-shielding effectiveness of 111.3 dB benefited by constructing multiple reflection-absorption interfaces. The high-performance, environmentally friendly, and low-cost EMI-shielding materials not only offered a new avenue toward recycling LSW in a more value-added way, but also displayed promising potential for application in flexible shielding materials or wearable clothing.