Natural wood templated hierarchically cellular NbC/Pyrolytic carbon foams as Stiff, lightweight and High-Performance electromagnetic shielding materials

Ultralight Flexible Collagen Fiber Based Aerogels Derived from Leather Solid Waste for High Electromagnetic Interference Shielding

Designing and developing high-performance shielding materials against electromagnetic interference is of utmost importance due to the rapid advancement of wireless telecommunication technologies. Such materials hold both fundamental and technological significance. A three-stage process is presented for creating ultralight, flexible aerogels from biomass to shield against electromagnetic interference. Collagen fibers sourced from leather solid waste are used for: (i) freeze-drying preparation of collagen fibers/poly(vinyl alcohol) (PVA) aerogels, (ii) adsorption of silver nanowires (AgNWs) onto collagen fiber/PVA aerogels, and (iii) Hydrophobic modification of collagen fiber/PVA/AgNWs aerogels with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (POTS). Scanning electron microscopy studies reveal that an interweaving of AgNWs and collagen fiber/PVA porous network has formed a conductive network, exhibiting an electrical conductivity of 103 S·m-1. The electromagnetic interference shielding effectiveness reached more than 62 dB, while the density was merely 5.8 mg/cm3. The collagen fiber/PVA/AgNWs/POTS aerogel displayed an even better electromagnetic shielding efficiency of 73 dB and water contact angle of 147°. The study results emphasize the distinctive capacity of leather solid waste to generate cost-effective, ecofriendly, and highly efficient electromagnetic interference shielding materials.

Facile synthesis of a rod-like Ni/TiO2/C nanocomposite for enhanced electromagnetic wave absorption

In this study, we utilized a simple calcination method to prepare a Ni/TiO2/C composite, which was synchronously grown from magnetic, semiconductor, and conductive materials. XRD, SEM, Raman, and XPS characterization methods were used to analyze the crystal structure, graphitization degree, morphology size, and valence state of Ni/TiO2/C, and its electromagnetic wave absorption performance was tested. It was revealed that rod-like Ni/TiO2/C had good electromagnetic wave absorption performance at a thickness of 1-5.5 mm; in particular, its reflectance reached -40 dB at 3.5 mm and its absorption bandwidth (reflectivity < -10 dB) reached 4.4 GHz (6.0-10.4 GHz) at a thickness of 4.0 mm. It was thus revealed that its electromagnetic wave absorption rate and absorption bandwidth can be regulated by its thickness. Compared with Ni/TiO2, it was proven that the conductive materials (carbon), magnetic materials (Ni), and semiconductor materials (TiO2) in the rod-like Ni/TiO2/C composite can synergistically absorb electromagnetic wave energy through dielectric and magnetic losses.

Mechanism of bonding, surface property, electrical behaviour, and environmental friendliness of carbon/ceramic composites produced via the pyrolysis of coal waste with polysiloxane polymer

A simple mixing-pressing followed by thermal curing and pyrolysis process was used to upcycle coal waste into high-value composites. Three coal wastes of different physicochemical properties were investigated. The hypothetical mechanisms of bonding between the coal particles and the preceramic polymer are presented. The textural properties of the coals indicated that the lowest volatile coal waste (PCD) had a dense structure. This limited the diffusion and reaction of the preceramic polymer with the coal waste during pyrolysis, thereby leading to low-quality composites. The water contact angles of the composites up to 104° imply hydrophobic surfaces, hence, no external coating might be required. Analysis of the carbon phase confirmed that the amorphous carbon structure is prevalent in the composites compared to the coal wastes. The dc volume resistivity of the composites in the range of 22 to 82 Ω-cm infers that the composites are unlikely to suffer electrostatic discharge, which makes them useful in creating self-heating building parts. The leached concentrations of heavy metal elements from the composites based on the end-of-life scenario were below the Toxicity Characteristic Leaching Procedure regulatory limits. Additionally, the release potential or mobility of the metals from the composites was not influenced by the pH of the eluants used. On the basis of the reported results, these carbon/ceramic composites show tremendous prospects as building materials due to these properties.