Nanomaterials最新文献

Aluminum nanoparticles (Al NPs) are interesting for energetic and plasmonic applications due to their enhanced size-dependent properties. Passivating the surface of these particles is necessary to avoid forming a native oxide layer, which can degrade energetic and optical characteristics. This work utilized a radiofrequency (RF)-driven capacitively coupled argon/hydrogen plasma to form surface-modified Al NPs from aluminum trichloride (AlCl₃) vapor and 5% silane in argon (dilute SiH₄). Varying the power and dilute SiH₄ flow rate in the afterglow of the plasma led to the formation of varying nanoparticle morphologies: Al-SiO₂ core-shell, Si-Al₂O₃ core-shell, and Al-Si Janus particles. Scanning transmission electron microscopy with a high-angle annular dark-field detector (STEM-HAADF) and energy-dispersive X-ray spectroscopy (EDS) were employed for characterization. The surfaces of the nanoparticles and sample composition were characterized and found to be sensitive to changes in RF power input and dilute SiH₄ flow rate. This work demonstrates a tunable range of Al-SiO₂ core-shell nanoparticles where the Al-to-Si ratio could be varied by changing the plasma parameters. Thermal analysis measurements performed on plasma-synthesized Al, crystalline Si, and Al-SiO₂ samples are compared to those from a commercially available 80 nm Al nanopowder. Core-shell particles exhibit an increase in oxidation temperature from 535 °C for Al to 585 °C for Al-SiO₂. This all-gas-phase synthesis approach offers a simple preparation method to produce high-purity heterostructured Al NPs.

A nanomaterial life-cycle risk assessment (Nano LCRA) was conducted for second-generation functionalized cellulose nanomaterials (CNs) in five case studies, including applications in water filtration, food contact packaging (including as an additive and coating), and food additives, to identify and prioritize potential occupational, health, consumer, and environmental risks. Exposure scenarios were developed and ranked for each product life-cycle stage. A Safer-by-Design Toolbox (SbD Toolbox) representing a compendium of high-throughput physical, chemical, and toxicological new approach methodologies (NAMs) was used for a screening-level hazard assessment. Overall, risks identified for the CN-enabled products were low. Of the exposure scenarios, occupational inhalation exposures during product manufacturing and application ranked the highest. Despite differences in chemistry and morphology, the materials behaved similarly in oral, dermal, and inhalation models, supporting their grouping and read-across. The screening-level hazard assessment identified potential lung inflammation associated with CN exposure, and a review of the literature supported this funding, suggesting CNs behave as poorly soluble, low-toxicity dusts with the potential to irritate the lung. Key research gaps to reduce uncertainty include evaluating long-term, low-dose exposures typical of the workplace, as well as the potential release and toxicity of CN-containing composite particles.

With the growth of the population and the development of industry and agriculture, water resources are experiencing contamination by numerous pollutants, posing a threat to the aquatic environment and human health. Zeolitic imidazolate framework (ZIF) membranes, as a solution for water pollutant treatment, not only have the advantages of high efficiency adsorption, good selectivity, stability, and easy recyclability, but they also can be modified or derivatized through surface functionalization, compositing, or structural tuning, which can further endow the membranes with other functions, such as catalysis and degradation. In order to improve the performance of ZIF membranes, it is crucial to select suitable preparation methods to optimize the microstructure of the membranes and to improve the separation performance and stability of the membranes. This review systematically summarizes the current major preparation methods of ZIF membranes and their respective advantages and disadvantages, providing an overview of the applications of ZIF membranes in the treatment of water pollutants, such as dyes, antibiotics, and heavy metal ions. Future development prospects are also discussed, with the expectation that future research will optimize the synthesis methods to enhance the mechanical strength of the membranes and improve their selectivity, permeability, and anti-fouling properties through modifications or functionalization. This article is expected to provide theoretical support for the application of ZIF membranes in water pollution treatment.

We systematically investigated the morphology-controlled synthesis of Cu₂O micro-nano crystals, especially under surfactant-free conditions, targeting a simple, rapid, and morphologically controllable preparation strategy for polyhedral Cu₂O micro-nano crystals. By systematically investigating the effects of NaOH concentration, types of reducing agents, and copper salt precursors on crystal growth, precise control over the morphology of Cu₂O crystals under surfactant-free conditions was achieved. This method can rapidly prepare variously faceted Cu₂O crystals under mild conditions (70 °C, 7 min), including regular polyhedra with low-index facets exposure including cubes, octahedra and rhombic dodecahedra, as well as more complex polyhedra with high-index facets exposure such as 18-faceted, 26-faceted, 50-faceted and 74-faceted crystals. NaOH concentration is found to be the key factor in controlling Cu₂O crystal morphology: as the concentration of NaOH increases, the morphology of Cu₂O crystals gradually transforms from cubes that fully expose the {100} faces to regular polyhedra that expose the {110}, {111} faces, and even other high-index faces, ultimately presenting octahedra that fully expose the {111} faces. Additionally, Cu₂O crystals with unique morphologies such as hollow cubes and 18-faceted with {110} face etched can be obtained by introducing surfactants or prolonging reaction durations. This work provides new insights into the morphology control of Cu₂O crystals and establishes foundation in acquiring distinct Cu₂O polyhedra in a facile manner for their application in catalysis, optoelectronics, sensing, and energy conversion fields.

The effect of metal nanoparticles on the anaerobic digestion of sludge and the sludge bacterial community are still not well-understood, and both improvements and inhibitions have been reported. This study investigated the impact of 2, 10, and 30 mg/g TS silver and copper oxide nanoparticles (AgNPs and CuONPs) on the mesophilic anaerobic digestion of sludge and the bacterial community structure. The reactors were monitored for changes in tCOD, sCOD, TS, VS, biogas generation, and cell viability. Also, the relative abundance and taxonomic distribution of the bacterial communities were analyzed at the phylum and genus levels, including the genera involved in anaerobic digestion. Both AgNPs and CuONPs exhibited some inhibition on anaerobic digestion of sludge and biogas generation, and the inhibition was more evident at higher concentrations. CuONPs had a stronger inhibitory effect compared to AgNPs. After the introduction of AgNPs and CuONPs, cell viability initially decreased over the first two weeks but recovered after that. At high concentrations, AgNPs and CuONPs decreased the overall bacterial diversity, and inhibited the dominant bacterial species, allowing those in less abundance to flourish. The relative abundance of the bacteria responsible for hydrolysis and acidogenesis increased and the relative abundance of acetogenic bacteria decreased with higher AgNP and CuONP concentrations. The majority of the parameters measured for monitoring the anaerobic digestion performance and bacterial community were not statistically significant at 2 mg/g TS of AgNPs and CuONPs, which represents naturally present concentrations in wastewater sludge that are below the USEPA ceiling concentration limits.

Clay pores are important storage spaces in shale oil reservoirs. Studying the adsorption behavior of shale oil in clay nanopores is of great significance for reserve assessment and exploitation. In this work, illite clay pore models and multi-component shale oil adsorption models considering light hydrocarbon correction are constructed for carrying out molecular dynamics simulation. We studied the adsorption behavior and characteristics of shale oil in illite pores, and analyzed the effects of reservoir environmental factors such as temperature, pressure and pore size on the adsorption behavior. The results show that in illite nanopores, shale oil can form multiple adsorption layers. The heavier the component, the stronger the interaction with the wall. The adsorption ratio of the component is closely related to the solid-liquid interaction and the molar fraction, which preliminarily reveals the reason why the heavy component content in the produced oil is considerable. The increase in temperature promotes the desorption of light and medium components, while the heavy components and dissolved gas are less affected; although the increase in pressure inhibits diffusion, the adsorption amount changes little, and only the light component increases slightly. This study deeply reveals the adsorption mechanism of shale oil in illite pores, providing a theoretical basis for the optimization and development of shale reservoirs.

Cinnabar has been used as a red pigment for centuries, but its degradation significantly impacts the aesthetic quality of historical paintings, particularly murals. Therefore, investigating the preparation method and transformation process of HgS is highly significant for mural research. In this study, we compared different sulfur sources for HgS synthesis and precisely synthesized α-HgS and β-HgS by adjusting the S/HgCl₂ ratio. SEM and XRD analyses under optimal conditions demonstrated that spherical β-HgS-1.2 exhibited significant morphological differences in comparison with α-HgS-1.0 and α-HgS-1.5. Elemental analysis of HgS was conducted using XPS and ICP-MS for qualitative and quantitative insights. Based on the potential mechanism of cinnabar discoloration, two strategies for converting black β-HgS to α-HgS were proposed and successfully implemented by adding sulfur or HgCl₂.

Purification of soot particles from automobile exhaust has closely to do with the synergistic effect between catalyst metals. Here, several binary Ni-Fe oxide catalysts were elaborately prepared via a modified solvothermal method. A non-noble-metal (Ni)-modified hexagonal Fe₂O₃ nano-sheet catalyst (Ni-Fe₂O₃) was prepared. The introduced heteroatoms replace some of the Fe atoms, which take up the surface of the [FeO₆] octahedron, and the synergistic effect formed between the heteroatoms which are on the surface and the adjacent Fe atoms promotes the formation of coordination unsaturated ions of the activated reactants. The optimal performance was obtained with the Ni-Fe₂O₃-20 composition, with catalytic soot oxidation resulting in T₅₀, SCO₂^m, E_a and TOF of 366 °C, 99.1%, 72.7 kJ mol^-1 and 0.156 min^-1 (at 310 °C), respectively. The combination of Ni and Fe₂O₃ cells increases the ratio of Fe³⁺/Fe²⁺, making the interaction among electrons between the Ni, which was proved highly dispersed over the catalyst, and the Fe₂O₃ strong. Both exist on the catalyst surface in the form of NiFe₂O₄. Ni atoms and Fe₂O₃, which demonstrate a synergistic effect, promoting the formation of coordination unsaturated ions of the activated reactants and generating more oxygen vacancies, thus promoting the adsorption of NO and accelerating the ignition of soot in O₂ at a low temperature. The novel Ni-Fe₂O₃-X oxide cocatalyst is an improved noble-free catalyst that promotes the synergistic effect between heteroatoms and metal oxides through surface regulation. This is of great significance for the further development of economic and efficient catalysts for soot particle removal from automobile exhaust.

After the thermal-mechanical processing of Mg alloys, extensive 30°⟨0001⟩ grain boundaries (GBs) are present in the recrystallized structure, which strongly affects the mechanical properties via interactions with lattice dislocations. In this work, we systematically investigate how the 30°⟨0001⟩ GBs influence the slip transmission during plastic deformation. We reveal that basal dislocations can be transmuted into its neighboring grain and continue gliding on the basal plane. The prismatic dislocation can transmit the GB remaining on the same Burgers vector. However, a mobile pyramidal c+a dislocation can be absorbed at GBs, initiating the formation of new grain. These findings provide a comprehensive understanding on GB-dislocation interaction in hexagonal close-packed (HCP) metals.

In conventional phase change memory (PCM) technology, the melting process required to create an amorphous state typically results in extremely high power consumption. Recently, a new type of PCM device based on a melting-free crystal-to-crystal phase transition in MnTe has been developed, offering a potential solution to the problem. However, the electronic and atomic mechanisms underlying this transition remain unclear. In this work, by first-principles calculations, the resistance contrast is attributed to the differences in hole effective mass and vacancy formation energy of the two phases. Moreover, two phase transition pathways of the α-MnTe-to-β-MnTe transition, namely, the 'slide-and-stand-up' transitions, are identified based on coherent atomic movements. The energy barriers for the two pathways are 0.17 eV per formula unit (f.u.) and 0.38 eV/f.u., respectively. Furthermore, the energy barriers can be reduced to 0.10 eV/f.u. and 0.26 eV/f.u. via c-axis tensile strains, which makes the phase transition easier. The current result provides new insights into the non-melting phase transition process in MnTe, facilitating the development of low-power PCM technology.