Nanomaterials最新文献

Zwitterionic polymers have garnered significant attention for their distinctive properties, such as biocompatibility, antifouling capabilities, and resistance to protein adsorption, making them promising candidates for a wide range of applications, including drug delivery, oil production inhibitors, and water purification membranes. This study reports the synthesis and characterization of zwitterionic monomers and polymers through the modification of linear, vinyl, and aromatic heterocyclic functional groups via reaction with 1,3-propanesultone. Four zwitterionic polymers with varying molecular structures-ranging from linear to five and six membered ring systems-were synthesized: poly(sulfobetaine methacrylamide) (pSBMAm), poly(sulfobetaine-1-vinylimidazole) (pSB1VI), poly(sulfobetaine-2-vinylpyridine) (pSB2VP), and poly(sulfobetaine-4-vinylpyridine) (pSB4VP). Their molecular weights, thermal behavior, and self-assembly properties were analyzed using gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and zeta potential measurements. The glass transition temperatures (Tg) ranged from 276.52 °C for pSBMAm to 313.69 °C for pSB4VP, while decomposition temperatures exhibited a similar trend, with pSBMAm degrading at 301.03 °C and pSB4VP at 387.14 °C. The polymers' self-assembly behavior was strongly dependent on pH and their surface charge, particularly under varying pH conditions: spherical micelles were observed at neutral pH, while fractal aggregates formed at basic pH. These results demonstrate that precise modifications of the chemical structure, specifically in the linear, imidazole, and pyridine moieties, enable fine control over the thermal properties and self-assembly behavior of polyzwitterions. Such insights are essential for tailoring polymer properties for targeted applications in filtration membranes, drug delivery systems, and solid polymer electrolytes, where thermal stability and self-assembly play crucial roles.

Carbon catalysts have shown promise as an alternative to the currently available energy-intensive approaches for nitrogen fixation (NF) to urea, NH₃, or related nitrogenous compounds. The primary challenges for NF are the natural inertia of nitrogenous molecules and the competitive hydrogen evolution reaction (HER). Recently, carbon-based materials have made significant progress due to their tunable electronic structure and ease of defect formation. These properties significantly enhance electrocatalytic and photocatalytic nitrogen reduction reaction (NRR) activity. While transition metal-based catalysts have solved the kinetic constraints to activate nitrogen bonds via the donation-back-π approach, there is a problem: the d-orbital electrons of these transition metal atoms tend to generate H-metal bonds, inadvertently amplifying unwanted HER. Because of this, a timely review of defective carbon-based electrocatalysts for NF is imperative. Such a review will succinctly capture recent developments in both experimental and theoretical fields. It will delve into multiple defective engineering approaches to advance the development of ideal carbon-based electrocatalysts and photocatalysts. Furthermore, this review will carefully explore the natural correlation between the structure of these defective carbon-based electrocatalysts and photocatalysts and their NF activity. Finally, novel carbon-based catalysts are introduced to obtain more efficient performance of NF, paving the way for a sustainable future.

The results of a comprehensive investigation into the structure and properties of nanodiamond soot (NDS), obtained from the detonation of various explosive precursors (trinitrotoluene, a trinitrotoluene/hexogen mixture, and tetryl), are presented. The colloidal behavior of the NDS particles in different liquid media was studied. The results of the scanning electron microscopy, dynamic light scattering, zeta potential measurements, and laser diffraction analysis suggested a similarity in the morphology of the NDS particle aggregates and agglomerates. The phase composition of the NDS nanoparticles was studied using X-ray diffraction, Raman spectroscopy, electron diffraction, transmission electron microscopy, atomic force microscopy, and scanning tunneling microscopy. The NDS particles were found to comprise both diamond and graphite phases. The ratio of diamond to graphite phase content varied depending on the NDS explosive precursor, while the graphite phase content had a significant impact on the electrical conductivity of NDS. The study of the mechanical and tribological characteristics of polymer nanocomposites, modified with the selected NDS particles, indicated that NDS of various types can serve as a viable set of model nanofillers.

Biomass, though a major energy source, remains underutilized. Biochar from biomass pyrolysis, with its high porosity and surface area, is especially useful as catalyst support, enhancing catalytic activity and reducing electron recombination in photocatalysis. Indonesia, the world's top palm oil producer, generated around 12 million tons of empty fruit bunches (EFBs) in 2023, making EFBs a promising biochar source. This study synthesizes biochar from leftover EFB fibers at 500, 800, and 1000 °C, analyzing structural changes via infrared and Raman spectroscopy, along with particle size and surface area analysis, laying the groundwork for future biochar research. The smallest particle size and highest surface area gained was 71.1 nm and 10.6 × 10² m²/g. Spectroscopic analysis indicates that biochar produced at 1000 °C has produced nano-crystalline graphite with a crystallite size of approximately 5.47 nm. This provides higher defect density, although with lower conductivity. Other studies indicate that our biochar can be used as catalyst support for various green energy-related applications, i.e., counter electrodes, electrocatalysts, and photocatalysts.

Nanomaterials and nanostructures with different morphologies or geometrical shapes that exploit plasmons, and particularly surface plasmon polaritons, are useful for a wide range device fabrication-related applications [...].

This study is the first to convert two waste materials, waste rice noodles (WRN) and red mud (RM), into a low-cost, high-value magnetic photocatalytic composite. WRN was processed via a hydrothermal method to produce a solution containing carbon quantum dots (CQDs). Simultaneously, RM was dissolved in acid to form a Fe³⁺ ion-rich solution, which was subsequently mixed with the CQDs solution and underwent hydrothermal treatment. During this process, the Fe³⁺ ions in RM were transformed into the maghemite (γ-Fe₂O₃) phase, while CQDs were incorporated onto the γ-Fe₂O₃ surface, resulting in the CQDs/γ-Fe₂O₃ magnetic photocatalytic composite. Experimental results demonstrated that the WRN-derived CQDs not only facilitated the formation of the magnetic γ-Fe₂O₃ phase but also promoted a synergistic interaction between CQDs and γ-Fe₂O₃, enhancing electron-hole pair separation and boosting the production of reactive radicals such as O₂^·- and ·OH. Under optimized conditions (pH = 8, carbon loading: 10 wt%), the CQDs/γ-Fe₂O₃ composite exhibited good photocatalytic performance against methylene blue, achieving a 97.6% degradation rate within 480 min and a degradation rate constant of 5.99 × 10^-3 min^-1, significantly outperforming RM and commercial γ-Fe₂O₃ powder. Beyond methylene blue, this composite also effectively degraded common organic dyes, including malachite green, methyl violet, basic fuchsin, and rhodamine B, with particularly high efficiency against malachite green, reaching a degradation rate constant of 5.465 × 10^-2 min^-1. Additionally, due to its soft magnetic properties (saturation magnetization intensity: 16.7 emu/g, residual magnetization intensity: 2.2 emu/g), the material could be conveniently recovered and reused after photocatalytic cycles. Even after 10 cycles, it retained over 98% recovery and 96% photocatalytic degradation efficiency, underscoring its potential for cost-effective, large-scale photocatalytic water purification.

As an emerging two-dimensional (2D) Group-VA material, bismuth selenide (Bi₂Se₃) exhibits favorable electrical and optical properties. Here, three distinct morphologies of Bi₂Se₃ were obtained from bulk Bi₂Se₃ through electrochemical intercalation exfoliation. And the morphologies of these nanostructures can be tuned by adjusting solvent polarity during exfoliation. Then, the nonlinear optical and absorption characteristics of the Bi₂Se₃ samples with different morphologies were investigated using open-aperture Z-scan technology. The results reveal that the particle structure of Bi₂Se₃ exhibits stronger reverse saturable absorption (RSA) than the sheet-like structure. This is attributed to the higher degree of oxidation and greater number of localized defect states in the particle structure than in the sheet-like structure. Electrons in these defect states can be excited to higher energy levels, thereby triggering excited-state and two-photon absorption, which strengthen RSA. Finally, with increasing the RSA, the optical limiting threshold of 2D Bi₂Se₃ can also be increased. This work expands the potential applications of 2D Bi₂Se₃ materials in the field of broadband nonlinear photonics.

The electrochemical conversion of CO₂ into high value-added carbon materials by molten salt electrolysis offers a promising solution for reducing carbon dioxide emissions. This study focuses on investigating the influence of molten salt composition on the structure of CO₂ direct electroreduction carbon products in chloride molten salt systems. Using CaO as a CO₂ absorber, the adsorption principle of CO₂ in LiCl-CaCl₂, LiCl-CaCl₂-NaCl and LiCl-CaCl₂-KCl molten salts was discussed, and the reasons for the different morphologies and structures of carbon products were analyzed, and it was found that the electrolytic efficiency of the whole process exceeded 85%. Furthermore, cathode products are analyzed through Scanning Electron Microscope (SEM), X-Ray Diffractometer (XRD), Thermal Gravimetric Analyzer (TGA), Raman Spectra and Fourier Transform Infrared (FTIR) techniques with a focus on the content and morphology of carbon elements. It was observed that the carbon content in the carbon powder produced by molten salt electrochemical method exceeded 99%, with most carbon products obtained from electrolysis in the Li-Ca chloride molten salt system being in the form of carbon nanotubes. In contrast, the Li-Ca-K chloride system yielded carbon nanospheres, while a mixture was found in the Li-Ca-Na chloride system. Therefore, experimental results demonstrate that altering the composition of the system allows for obtaining the desired product size and morphology. This research presents a pathway to convert atmospheric CO₂ into high value-added carbon products.

In the original publication [...].

In this work, within the framework of a self-consistent model of arc discharge, a simulation of plasma parameters in a mixture of argon and methane was carried out, taking into account the evaporation of the electrode material in the case of a refractory and non-refractory cathode. It is shown that in the case of a refractory tungsten cathode, almost the same methane conversion rate is observed, leading to similar values in the density of the main methane conversion products (C, C₂, H) at different values of the discharge current density. However, with an increase in the current density, the evaporation rate of copper atoms from the anode increases, and a jump in the I-V characteristic is observed, caused by a change in the plasma-forming ion. This is due to the lower ionization energy of copper atoms compared to argon atoms. In this mode, an increase in metal-carbon nanoparticles is expected. It is shown that, in the case of a cathode made of non-refractory copper, the discharge characteristics and the component composition of the plasma depend on the field enhancement factor near the cathode surface. It is demonstrated that increasing the field enhancement factor leads to more efficient thermal field emission, lowering the cathode's surface temperature and the gas temperature in the discharge gap. This leads to the fact that, in the arc discharge mode with a cathode made of non-refractory copper, the dominant types of particles from which the synthesis of a nanostructure can begin are, in descending order, copper atoms (Cu), carbon clusters (C₂), and carbon atoms (C).