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Energetic solid propellants are critical technologies for advancing strategic and tactical weaponry. To further develop the application of CL-20 to energetic solid propellants, it is necessary to explore more efficient catalysts to enhance their thermal decomposition characteristics. In this paper, three composites of nickel–iron layered double oxides doped with 0 wt%, 5 wt% and 20 wt% g-C 3 N 4 (NiFe-LDO/g-C 3 N 4 ) were synthesized by co-precipitation and heat treatment methods. These composites were characterized using Scanning electron microscope (SEM), X-Ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectrometer, and X-ray photoelectron spectrometer (XPS). Three prepared composites were tested for catalytic pyrolysis performance of CL-20 using Differential scanning calorimeter (DSC). The results show that NiFe-LDO/g-C 3 N 4 has an excellent layered structure and can significantly enhance the thermal decomposition performance of CL-20. Compared with 253.52 °C for raw CL-20, the thermal decomposition peak temperatures decreased to 246.61 °C, 245.64 °C and 244.08 °C after addition of the three catalysts, respectively. Additionally, the activation energies declined from 234.02 kJ·mol −1 to 192.55 kJ·mol −1 , 176.33 kJ·mol −1 and 160.78 kJ·mol −1 . Then, a potential catalytic mechanism is proposed. This study shows that NiFe-LDO/g-C 3 N 4 serves as a high-quality catalyst for the enhancement of CL-20 thermal decomposition performance, with further prospective applications in solid propellants. 相关产品

To address increasing climate deterioration, it is of great value to prepare highly permselective separation membranes for CO2 enrichment and separation. In this study, zirconium-based metal-organic frameworks (Zr-MOFs) containing defective structures (defected-UiO-66-NH2, D-UN) with a high volume yield (12 g L–1 in a single batch) were prepared at room temperature for the first time using a simple green-synthesis strategy. After the modification with pentafluorobenzaldehyde, the fluorine-containing D-UN (named F-g-UN) nanoparticles showed the characteristics of local and dense distribution of fluorine elements. Due to the optimized CO2 affinity and improved dispersion of fluorination modification, the prepared mixed-matrix membrane (MMM) F-g-UN@AO-PIM-1 achieved synergistic improvement in CO2 permeability and selectivity, exceeding the 2008 Robeson upper bound (CO2 664.1 Barrer and CO2/CH4 34.2) and the 2018 binary CO2/CH4 mixed-gas upper bound (CO2/CH4 28.7). The substantial cause was the introduction of fluorine species, verified by relevant experiments and mechanism analyses such as CO2 adsorption. This work proves the feasibility of using crystal defect engineering and post-treatment strategies to enhance separation functions and offers new insights into designing efficient and low-cost MMMs for gas separation, promoting their application in separation membranes including but not limited to gas separation. 相关产品

Silica aerogel, renowned for its ultra-low thermal conductivity, holds significantpotential as an advanced thermal insulation material. However, its practical application is hindered by limitations in strength and mechanical properties, particularly under harsh, high-temperature conditions, which compromise both mechanical resilience and insulation. To mitigate this, we synthesized silica nanofibers via electrostatic spinning and subsequently crafted thermally and mechanically robust cellulose fiber/silica nanofiber aerogel composites through freeze-drying. The resulting aerogel demonstrates remarkable physical properties: an ultra-lightweight bulk density of 1.3 mg/cm³, low thermal conductivity (47 mW·m⁻¹·K⁻¹ at 1000 °C), and high resilience. The internal fiber network is densely cross-linked, enhancing collapse resistance, structural stability, and rigid support. Mechanical testing revealed a high stress of 0.88 kPa at 80% compressive strain, which reached 1.02 kPa following 900 °C treatment. Thermal stability and insulation tests demonstrated the aerogel’s ability to withstand extreme temperatures (no combustion under a 1,300 °C flame) and maintain effective thermal insulation while retaining good recovery at 600 °C. These findings indicate that the novel aerogel composites surpass traditional ceramic fiber aerogel materials in mechanical and thermal insulation properties at high temperatures, presenting widespread application potential in extreme high-temperature environments. 相关产品

ZIF-8 is considered as a promising functional material in anti-corrosion coating applications. However, ZIF-8 hydrolyzes easily, especially in acidic and salty media, due to its unstable Zn–N coordination bonding and hydrophilic crystal surface, which reduces anti-corrosion durability of the coatings. In this study, highly hydrophobic modification of ZIF-8 particles was performed through simple surface ligand exchange with 5,6-dimethylbenzimidazole (DMBIM). The as-prepared ZIF-8/DMBIM particles showed high water-repellency and enhanced chemical stability in acidic, neutral, and alkaline media, and excellent compatibility and barrier function in epoxy coatings. As a consequence, ZIF-8/DMBIM modified epoxy coatings showed significantly enhanced corrosion resistances in acid, alkali and salt aqueous solutions with pH 3.0–11.0. Electrochemical impedance spectroscopy tests demonstrated that, after 20 days of immersion in 3.5 wt% NaCl solution at all the studied pH, the |Z| 0.01 Hz values of ZIF-8/DMBIM modified epoxy coatings were approximately two orders of magnitude higher than of the original epoxy coatings. This work provides an idea for the development and application of ZIF materials in more fields, and innovative anti-corrosion coatings based on functional modification of materials. 相关产品

A novel and simple one-step method was proposed for the preparation of multifunctional microencapsulated phase change materials to satisfy the requirements of different application scenarios. Here, with the help of the super reaction ability and coordination effect of metal ions Zn 2+ , the paraffin (PCM) was well encapsulated by the sodium alginate (SA) shell by the cross-linking between SA and Zn 2+ . At the same time, Na 2 S·9H 2 O and 2-MeIM were selected to realize the loading of ZnS quantum dots and ZiF-8 in the materials by their coordination with excess Zn 2+ in the system. The results of differential scanning calorimeter (DSC), Ultraviolet-visible-near-infrared (UV–vis-NIR), Photoluminescence and Brunauer–Emmett–Teller (BET) indicated that the obtained PCM@SA/ZnS and PCM@SA/ZiF-8 not only retained good heat resistance and heat storage properties, but also had new functions such as fluorescence and adsorption. This work would provide a new idea for the development of multi-functional composite materials. 相关产品

Fluorine-functionalized covalent organic frameworks (F-COFs), owing to their multiple interactions such as F-F forces and hydrophobicity, have been widely used as candidate materials for stationary phases and other analytical purposes. How to incorporate F-COFs with a silica matrix (SiO 2 ) through a low-energy consumption method, and investigating the chromatographic properties for pharmaceutical targets, is of vital importance and requires significant further research. In this study, pentafluorophenyl (PFP) was used as a functional group to prepare PFP-COF@SiO 2 at room temperature through two distinct synthetic approaches. The resulting PFP-COF@SiO 2 materials, designated as I and II, were systematically characterized, and their chromatographic performances, influential factors, and retention mechanisms were investigated. These two COF materials demonstrated similar material properties and effective separation towards phenolic acids, alkaloids and antiviral drugs. The results indicated that the designed two synthetic routes were to some extent tolerable and compatible with the order of reagent addition. This work offers a novel method for preparing PFP-COF@SiO 2 stationary phases oriented for pharmaceutical chromatographic applications. 相关产品

Biochar has great potential for capacitive deionization (CDI) because of its economy and low pollution. Nevertheless, a porous and eco-friendly biochar electrode with high performance and an in-depth stability investigation are lacking in existing studies. In this work, tobacco stalk and shrimp shell were chosen to fabricate activated composite biochar (ACB) through a thermal process combining with KOH activation. The pore volume of composite biochar was nearly 2 times larger than that of tobacco stalk or shrimp shell biochar. ACB exhibited much richer microporous and mesoporous structure (1.17 cm 3 g −1 ) and specific surface area (1753.11 m 2 g −1 ) at KOH concentration of 0.05 mol L −1 . Capacitive-controlled process played a dominant role in the charge storage mechanism. ACB showed an enhanced salt adsorption capacity of 61.24 mg g −1 in 500 mg L −1 NaCl solution and faster adsorption kinetics at a voltage of 1.2 V and a flow rate of 20 mL min −1 . What's more, this preparation had less environmental impact through environmental assessment, and membrane capacitive deionization, as an energy-saving technique, could improve the stability of biochar electrode. These findings not only provided a facile strategy using mixed-biomass engineering but also paved the basis for the practical application of CDI. 相关产品

As the prevalence of bacterial infections on diverse material surfaces continues to rise globally, the demand for the development of surfaces with durable and effective antibacterial properties becomes more imperative. Herein, we developed a cationic polymer coating consisting of quaternized 4-vinylpyridine groups, 4-vinylpyridine groups, and butyl acrylate groups. Quaternized 4-vinylpyridine groups were utilized to confer antibacterial properties, while butyl acrylate groups were incorporated to enhance adherence to the substrate and flexibility of the material. The presence of the quaternary 4-vinylpyridine endowed the coating with excellent broad-spectrum antibacterial properties, with a maximum sterilization rate above 99%. The antibacterial properties assay revealed that the content of cationic group, the kind of substrates, as well as the length and type of alkyl chains significantly influenced the effectiveness and stability of antibacterial properties of cationic coatings. Cationic polymers can efficiently disrupt the integrality of the bacterial cell membrane, leading to the death of bacteria, which can be observed by scanning electron microscopy. In summary, the obtained cationic polymers that serve as effective, durable, and environmentally friendly antibacterial coatings without releasing harmful substances will have a much broader application potential in diverse application fields. 相关产品

Concrete is extensively used in construction, roadways, and other engineering fields. However, its hydrophilic and porous structure renders it susceptible to oxidative corrosion, sand erosion, and acid rain when exposed to outdoor environments. Therefore, developing superhydrophobic coatings with superior waterproofing properties is a critical strategy to protect concrete. Nevertheless, existing superhydrophobic concrete coatings suffer from issues, such as poor durability, complex application processes, restricted color options, and difficulties in large-scale production. Herein, a spraying method is developed that utilizes nano-SiO 2 , epoxy resin, cetyltriethoxysilane, and iron oxide dyes to produce a robust, corrosion-resistant, and multicolored superhydrophobic concrete coating with red, yellow, blue, and green colors. The produced coatings exhibit a water contact angle (CA) of 156° ± 1° and a sliding angle (SA) of 5° ± 1°. The hydrophobicity of the coatings arises from the synergistic effects of cetyltriethoxysilane, which provides low surface energy, and SiO 2 , which creates micro and nanoscale roughness on the coating surface. Meanwhile, the coating's robustness stems from the adhesive properties of epoxy resin and hydrogen-bonding interactions between SiO 2 and the concrete substrate. Thus, the developed superhydrophobic coating shows significant potential for extending the lifespan of concrete building facades, enhancing decorative and waterproofing features, and ensuring surface cleanliness. 相关产品

Due to the increased concern on the environmental issues, the desulfurization process in fuel is of great importance in the recent decades. Herein, a series of decavanadate-based poly (ionic liquids) with varied substituents were successfully prepared by a facile ion exchange method, which were employed in aerobic oxidative desulfurization of aromatic sulfides. The prepared samples can achieve deep desulfurization on different aromatic sulfides under optimal reaction conditions. Additionally, the experimental results indicated that the long carbon chains in the imidazole ring could hinder the ion exchange process between decavanadate and PILs due to steric hindrance effect, resulting in the poor desulfurization activity. Finally, a possible reaction mechanism was proposed according to the results of XPS, ESR and GC–MS analysis. 相关产品

In response to the escalating demand for lightweight, broadband and high-efficiency microwave-absorbing materials driven by the rapid advancement of electronic information technology, this study proposes a novel solution involving the fabrication of aluminum nitride (AlN)-decorated cobalt carbide (CoC) nanocomposites via an oil-bath method. The incorporation of rigid and insulating AlN significantly enhances the thermal stability and microwave absorption (MA) performance of the AlN/CoC composites. Notably, in the 80 wt% AlN/paraffin composite system, a minimum reflection loss (RL min ) of − 43.2 dB and an effective absorption bandwidth of 1.76 GHz (13.92–15.68 GHz) were achieved, which is markedly superior to that of the CoC/paraffin composite under the same filling ratio (− 8.28 dB). The results indicate that the substantial enhancement in the MA properties of the AlN/CoC composites is primarily attributed to the influence of varying AlN contents on the dielectric loss, polarization loss, and impedance matching behavior of the material. This study provides new insights and methodologies for the development of lightweight, broadband, and high-efficiency microwave-absorbing materials. The design strategy of AlN/CoC composites holds great potential for widespread application in fields such as aerospace, electromagnetic shielding, and radar stealth. 相关产品

Transition metal sulfides are widely recognized for their low cost, low toxicity, high safety, and potential as a positive electrode material for supercapacitors. However, due to its own volume effect, it usually has poor capacitance retention as positive electrode materials. Herein, the NiS/NiCo-LDH (Layered double hydroxide, LDH) electrodes with considerable practical application potential is designed and prepared. The composite electrodes are prepared by a simple two-step electrodeposition process. The NiS/NiCo-LDH electrode, with its rational design, exhibits more superior electrochemical performance compared to a single NiS electrode. The NiS/NiCo-LDH electrode shows a mass specific capacitance of 2620 F/g at a current density of 1 A/g, which is 1.88 times that of the single NiS electrode. Furthermore, the assembled NiS/NiCo-LDH//AC hybrid supercapacitor (HSC) device achieves an energy density of 93.3 Wh kg −1 at a power density of 800 W kg −1 . Therefore, this work provides a new strategy for preparing supercapacitor electrode materials with excellent electrochemical performance. 相关产品