Sandwich-Structured Mxene/Waste Polyurethane Foam Composites For Highly Efficient Electromagnetic Interference, Infrared Shielding and Joule Heating.

Electromagnetic interference (EMI) shielding and infrared (IR) stealth materials have attracted increasing attention owing to the rapid development of modern communication and military surveillance technologies. However, to realize excellent EMI shielding and IR stealth performance simultaneously remains a great challenge. Herein, a facile strategy is demonstrated to prepare high-efficiency EMI shielding and IR stealth materials of sandwich-structured MXene-based thin foam composites (M-W-M) via filtration and hot-pressing. In this composite, the conductive Ti3C2Tx MXene/cellulose nanofiber (MXene/CNF) film serves as the outer layer, which reflects electromagnetic waves and reduces the IR emissivity. Meanwhile, the middle layer is composed of a porous waste polyurethane foam (WPUF), which not only improves thermal insulation capacity but also extends electromagnetic wave propagation paths. Owing to the unique sandwich structure of "film-foam-film", the M-W-M composite exhibits a high EMI shielding effectiveness of 83.37 dB, and in the meantime extremely low emissivity (22.17%) in the wavelength range of 7-14 µm and thermal conductivity (0.19 W m-1 K-1), giving rise to impressive IR stealth performance at various surrounding temperatures. Remarkably, the M-W-M composite also shows excellent Joule heating properties, capable of maintaining the IR stealth function during Joule heating.

Direct Growth of Low Thermal Conductivity WTe2 Nanocrystalline Films on W Films.

WTe2 has attracted much attention because of its layered structure and special electronic energy band structure. However, due to the difficulty of evaporating the W element itself and the inactivity of the Te element, the obtained large-area WTe2 thin films are usually accompanied by many defects. In this paper, WTe2 nanocrystalline films were successfully prepared on quartz substrates using magnetron sputtering and chemical vapor deposition techniques. Various analytical techniques such as X-ray Diffraction, Raman spectra, X-ray Photoelectron Spectroscopy, Scanning Electron Microscope, and photoluminescence spectra are employed to analyze the crystal structure, composition, and morphology. The effects of different tellurization temperatures and tellurization times on the properties of WTe2 thin films were investigated. WTe2 nanocrystalline films with good crystallinity were obtained at 600 °C for 30 min. The thermal conductivity of the WTe2 films prepared under this condition was 1.173 Wm-1K-1 at 300 K, which is significantly higher than that of samples prepared using other methods.

Sustainable Starch/Lignin Nanoparticle Composites Biofilms for Food Packaging Applications.

Construction of sustainable composite biofilms from natural biopolymers are greatly promising for advanced packaging applications due to their biodegradable, biocompatible, and renewable properties. In this work, sustainable advanced food packaging films are developed by incorporating lignin nanoparticles (LNPs) as green nanofillers to starch films. This seamless combination of bio-nanofiller with biopolymer matrix is enabled by the uniform size of nanofillers and the strong interfacial hydrogen bonding. As a result, the as-prepared biocomposites exhibit enhanced mechanical properties, thermal stability, and antioxidant activity. Moreover, they also present outstanding ultraviolet (UV) irradiation shielding performance. As a proof of concept in the application of food packaging, we evaluate the effect of composite films on delaying oxidative deterioration of soybean oil. The results indicate our composite film could significantly decrease peroxide value (POV), saponification value (SV), and acid value (AV) to delay oxidation of soybean oil during storage. Overall, this work provides a simple and effective method for the preparation of starch-based films with enhanced antioxidant and barrier properties for advanced food packaging applications.

Rheology-Guided Assembly of a Highly Aligned MXene/Cellulose Nanofiber Composite Film for High-Performance Electromagnetic Interference Shielding and Infrared Stealth.

Delicately aligned structures of two-dimensional (2D) MXene nanosheets have demonstrated positive effects on applications, especially in electromagnetic interference (EMI) shielding and infrared (IR) stealth. However, precise regulation of structural assembly by theory-guided solution processing is still a great challenge. Herein, one-dimensional (1D) cellulose nanofibers (CNFs) with a high aspect ratio are applied as a reinforcing agent and a rheological modifier for MXene/CNF colloids to fabricate aligned MXene-based materials for EMI shielding and IR stealth. Notably, a systematical rheological study of the MXene/CNF colloids is proposed to determine the optimal solution-processing conditions for finely oriented component arrangement requirements and provides in-depth information on the interactions between the components. The delicately regulated orientation structure assembled by shear inducement is convincingly demonstrated through micro-CT and wide-angle X-ray diffraction/small-angle X-ray scattering (WAXD/SAXS), which endows the MXene/CNF film with a significantly enhanced electrical conductivity of 46 685 S m-1, a tensile strength of 281.7 MPa, and Young's modulus of 14.8 GPa. Furthermore, the highly aligned structure of the ultrathin film possesses a great enhancement in EMI shielding effectiveness (50.2 dB) and IR stealth (0.562 emissivity). These findings provide a fruitful understanding of the optimized fabrication in solution processing of high-performance MXene-based functional composite films and open up a great opportunity for the development of multifunctional stealth materials.

Synthesis of amorphous FeNiCo trimetallic hybrid electrode from ZIF precursors for efficient oxygen evolution reaction.

Development of non-noble multi-metallic electrocatalyst with high oxygen evolution reaction (OER) activity via a simple and low-cost method is of great importance for improving the efficiency of water electro-chemical splitting. Herein, a solution impregnation strategy was proposed to synthesize novel FeNi-doped Co-ZIF-L trimetallic hybrid electrocatalyst using Co-ZIF-L as sacrificial templates and Fe and Ni ions as etchants and dopants. This synthetic strategy could be realized via the etching-coprecipitation mechanism to obtain an amorphous hybrid containing multi-metal hydroxides. The as-prepared electrocatalyst loaded on Ni foam displays a low overpotential of 245 mV at 10 mA·cm-2, a small Tafel slope of 54.9 mV·dec-1, and excellent stability at least 12 h in the OER process. The facile and efficient synthetic strategy presents a new entry for the fabrication of ZIFs-derived multi-metallic electrocatalysts for OER electrocatalysis.

Facile Fabrication of Densely Packed Ti3C2 MXene/Nanocellulose Composite Films for Enhancing Electromagnetic Interference Shielding and Electro-/Photothermal Performance.

The development of modern electronics has raised great demand for multifunctional materials to protect electronic instruments against electromagnetic interference (EMI) radiation and ice accretion in cold weather. However, it is still a great challenge to prepare high-performance multifunctional films with excellent flexibilty, mechanical strength, and durability. Here, we propose a layer-by-layer assembly of cellulose nanofiber (CNF)/Ti3C2Tx nanocomposites (TM) on a bacterial cellulose (BC) substrate via repeated spray coating. CNFs are hybridized with Ti3C2Tx nanoflakes to improve the mechanical properties of the functional coating layer and its adhesion with the BC substrate. The densely packed hierarchical structure and strong interfacial interactions endows the TM/BC films with good flexibility, ultrahigh mechanical strength (>250 MPa), and desirable toughness (>20 MJ cm-3). Furthermore, benefiting from the densely packed hierarchical structure, the resultant TM/BC films present outstanding EMI shielding effictiveness of 60 dB and efficient electro-/photothermal heating performance. Silicone encapsulation further imparts high hydrophobicity and exceptional durability against solutions and deformations to the multifunctional films. Impressively, the silicone-coated TM/BC film (Si-TM/BC) exhibits desirable low voltage-driven Joule heating and excellent photoresponsive heating performance, which demonstrates great feasibility for efficient thermal deicing under actual conditions. Therefore, we believe that the Si-TM/BC film with excellent mechanical properties and durability holds great promise for the practical applications of EMI shielding and ice accretion elimination.

S-allyl cysteine reduces osteoarthritis pathology in the tert-butyl hydroperoxide-treated chondrocytes and the destabilization of the medial meniscus model mice via the Nrf2 signaling pathway.

In this study, we used murine chondrocytes as an in vitro model and mice exhibiting destabilization of the medial meniscus (DMM) as an in vivo model to investigate the mechanisms through which S-allyl cysteine (SAC) alleviates osteoarthritis (OA). SAC significantly reduced apoptosis and senescence and maintained homeostasis of extracellular matrix (ECM) metabolism in tert-butyl hydroperoxide (TBHP)-treated chondrocytes. Molecular docking analysis showed a -CDOCKER interaction energy value of 203.76 kcal/mol for interactions between SAC and nuclear factor erythroid 2-related factor 2 (Nrf2). SAC increased the nuclear translocation of Nrf2 and activated the Nrf2/HO1 signaling pathway in TBHP-treated chondrocytes. Furthermore, Nrf2 knockdown abrogated the antiapoptotic, antisenescence, and ECM regulatory effects of SAC in TBHP-treated chondrocytes. SAC treatment also significantly reduced cartilage ossification and erosion, joint-space narrowing, synovial thickening and hypercellularity in DMM model mice. Collectively, these findings show that SAC ameliorates OA pathology in TBHP-treated chondrocytes and DMM model mice by activating the Nrf2/HO1 signaling pathway.

Effect of Potassium Sorbate and Ultrasonic Treatment on the Properties of Fish Scale Collagen/Polyvinyl Alcohol Composite Film.

Composite films containing different amounts of potassium sorbate (KS) were prepared by using fish scale collagen (Col) and polyvinyl alcohol (PVA). Fourier transform infrared spectroscopy (FTIR), light transmittance, mechanical, water vapor transmission rate (WVTR), and the antibacterial properties of the composite films were analyzed. The results showed that the addition of Col significantly reduced the light transmittance of the composite film, but KS had no significant effect on the light transmission. The tensile strength decreased first and then increased with the addition of KS, while the WVTR increased first and then decreased. The composite film exhibited a certain degree of antibacterial properties against E. coli and S. aureus. In addition, we found that ultrasonic treatment reduced the WVTR, and also improved tensile strength and elongation at break of the composite films, but had no significant effect on other properties. The KS/Col/PVA films have the potential to be used as antimicrobial food packaging.