Preparation Of Nanostructures Research Articles

Controlled epitaxial growth of strain-induced large-area bilayer MoS2 by chemical vapor deposition based on two-stage strategy

Two-dimensional (2D) bilayer transition metal dichalcogenides (TMDCs) have attracted considerable attention due to their promising applications in the fields of electronics, optoelectronics, valleytronics and nonlinear optics. However, the precise synthesis of large-area, high-yield and uniform bilayer MoS2 semiconductors remains a significant challenge. Herein, we have developed one two-stage chemical vapor deposition strategy based on strain engineering, enabling the controlled preparation of large-area (4×6 cm2) bilayer MoS2 nanostructures. Systematic characterizations indicate that compressive strain was introduced during the growth of first layer MoS2, which effectively induces the synthesis of the second layer MoS2. First-principles calculations based on density functional theory further reveal the mechanism of strain induced controllable growth of bilayer MoS2. Field-effect transistors based on AA and AB stacking bilayer MoS2 have been fabricated exhibiting excellent electronic properties. Our work provides a new pathway for the precise preparation of bilayer TMDCs nanostructures, offering experimental support for their application in the field of electronic and optoelectronic devices.

Hybrid Nanoparticles from Random Polyelectrolytes and Carbon Dots.

The present study concerns the preparation of hybrid nanostructures composed of carbon dots (CDs) synthesized in our lab and a double-hydrophilic poly(2-dimethylaminoethyl methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate) (P(DMAEMA-co-OEGMA)) random copolymer through electrostatic interactions between the negatively charged CDs and the positively charged DMAEMA segments of the copolymer. The synthesis of P(DMAEMA-co-OEGMA) copolymer was conducted through RAFT polymerization. Furthermore, the copolymer was converted into a strong cationic random polyelectrolyte through quaternization of the amine groups of DMAEMA segments with methyl iodide (CH3I), and it was subsequently utilized for the complexation with the carbon dots. The molecular, physicochemical, and photophysical characterization of the aqueous solution of the copolymers and their hybrid nanoparticles was conducted using dynamic and electrophoretic light scattering (DLS, ELS) and spectroscopic techniques, such as UV-Vis, fluorescence (FS), and FT-IR spectroscopy. In addition, studies of their aqueous solution using DLS and ELS showed their responsiveness to external stimuli (pH, temperature, ionic strength). Finally, the interaction of selected hybrid nanoparticles with iron (III) ions was confirmed through FS spectroscopy, demonstrating their potential application for heavy metal ions sensing.

Luminescent Alendronic Acid-Conjugated Micellar Nanostructures for Potential Application in the Bone-Targeted Delivery of Cholecalciferol

Vitamin D, an essential micronutrient crucial for skeletal integrity and various non-skeletal physiological functions, exhibits limited bioavailability and stability in vivo. This study is focused on the development of polyethylene glycol (PEG)-grafted phospholipid micellar nanostructures co-encapsulating vitamin D3 and conjugated with alendronic acid, aimed at active bone targeting. Furthermore, these nanostructures are rendered optically traceable in the UV–visible region of the electromagnetic spectrum via the simultaneous encapsulation of vitamin D3 with carbon dots, a newly emerging class of fluorescents, biocompatible nanoparticles characterized by their resistance to photobleaching and environmental friendliness, which hold promise for future in vitro bioimaging studies. A systematic investigation is conducted to optimize experimental parameters for the preparation of micellar nanostructures with an average hydrodynamic diameter below 200 nm, ensuring colloidal stability in physiological media while preserving the optical luminescent properties of the encapsulated carbon dots. Comprehensive chemical-physical characterization of these micellar nanostructures is performed employing optical and morphological techniques. Furthermore, their binding affinity for the principal inorganic constituent of bone tissue is assessed through a binding assay with hydroxyapatite nanoparticles, indicating significant potential for active bone-targeting. These formulated nanostructures hold promise for novel therapeutic interventions to address skeletal-related complications in cancer affected patients in the future.

Preparation and characterization of TiO2 nanostructures by changing the parameters of trichloroaniline concentration, pH and annealing for dye-sensitized solar cell application

Preparation and characterization of TiO2 nanostructures by changing the parameters of trichloroaniline concentration, pH and annealing for dye-sensitized solar cell application

The Optimization of the One-Pot Synthesis of Au@SiO2Core-Shell Nanostructures: Modification with Dansyl Group and Their Fluorescent Properties.

This work describes the optimization of the one-pot synthesis of fine core-shell nanostructures based on nanogold (Au NPs) and silica (SiO2). The obtained core-shell nanomaterials were characterized by Transmission Electron Microscopy (TEM and by the method of spectroscopes such as UV-Vis Spectroscopy and Fourier Transform Infrared Spectroscopy (FT-IR). In addition, the measurement of the zeta potential and size of the obtained particles helped present a full characterization of Au@SiO2 nanostructures. The results show that the influence of reagents acting as reducers, stabilizers, or precursors of the silica shell affects the morphology of the obtained material. By controlling the effect of the added silica precursor, the thickness of the shell can be manipulated, the reducer has an effect on the shape and variety, and then the stabilizer affects their agglomeration. This work provides also a new approach for Au@SiO2core-shell nanostructure preparation by further modification with dansyl chloride (DNS-Cl). The results show that, by tuning the silica shell thickness, the intensity of the fluorescence spectrum of Au@SiO2-(CH2)3-NH-DNS nanocomposite is about 12 times higher than that of DNS-Cl.

Preparation of immunomagnetic composite nanostructures with bifunctional four-arm PEG derivatives as linkers for the ultrafast enrichment of zearalenone and its metabolites

It is challenging to prepare sample pretreatment materials with simple use, strong selectivity and satisfactory enrichment performance. In this study, the antibody (3D4) that can specifically recognize zearalenone (ZEN) and its metabolites was immobilized on the surface of gold-coated magnetic Fe3O4 nanoparticles (GMN) by streptavidin (SA)-biotin interaction using GMN as the substrate and our designed four-arm PEG derivative (HS-4ARMPEG10K-(CM)3) as the linker. The immunomagnetic nanoparticles (GMN-4ARMPEG10K-SA-3D4) prepared by this strategy can achieve rapid enrichment (only 5 min) of analytes directly in the matrix, and higher enrichment capacity compared with the previous immunomagnetic particles. The sensitive and accurate analysis of ZEN and its metabolites can be achieved coupled with HPLC-MS/MS. The LODs and LOQs were 0.02–0.05 μg/kg and 0.05–0.10 μg/kg, respectively. The recoveries were 84.13%–112.67%, and the RSDs were 1.09%–9.39%. The method can provide a powerful tool for highly sensitive and rapid monitoring of mycotoxins in complex matrices due to its’ strong selectivity and resistance to matrix interference.

Real-time imaging reveal anisotropic dissolution behaviors of silver nanorods

The morphology and size control of anisotropic nanocrystals are critical for tuning shape-dependent physicochemical properties. Although the anisotropic dissolution process is considered to be an effective means to precisely control the size and morphology of nanocrystals, the anisotropic dissolution mechanism remains poorly understood. Here, using in situ liquid cell transmission electron microscopy, we investigate the anisotropic etching dissolution behaviors of polyvinylpyrrolidone (PVP)-stabilized Ag nanorods in NaCl solution. Results show that etching dissolution occurs only in the longitudinal direction of the nanorod at low chloride concentration (0.2 mM), whereas at high chloride concentration (1 M), the lateral and longitudinal directions of the nanorods are dissolved. First-principles calculations demonstrate that PVP is selectively adsorbed on the {100} crystal plane of silver nanorods, making the tips of nanorods the only reaction sites in the anisotropic etching process. When the chemical potential difference of the Cl− concentration is higher than the diffusion barrier (0.196 eV) of Cl− in the PVP molecule, Cl− penetrates the PVP molecular layer of {100} facets on the side of the Ag nanorods. These findings provide an in-depth insight into the anisotropic etching mechanisms and lay foundations for the controlled preparation and rational design of nanostructures.

Periodic Folded Gold Nanostructures with a Sub-10 nm Nanogap for Surface-Enhanced Raman Spectroscopy.

Surface-enhanced Raman spectroscopy has emerged as a powerful spectroscopy technique for detection with its capacity for label-free, nondestructive analysis, and ultrasensitive characterization. High-performance surface-enhanced Raman scattering (SERS) substrates with homogeneity and low cost are the key factors in chemical and biomedical analysis. In this study, we propose the technique of atomic force microscopy (AFM) scratching and nanoskiving to prepare periodic folded gold (Au) nanostructures as SERS substrates. Initially, folded Au nanostructures with tunable nanogaps and periodic structures are created through the scratching of Au films by AFM, the deposition of Ag/Au films, and the cutting of epoxy resin, reducing fabrication cost and operational complexity. Periodic folded Au nanostructures show the three-dimensional nanofocusing effect, hotspot effect, and standing wave effect to generate an extremely high electromagnetic field. As a typical molecule to be tested, p-aminothiophenol has the lowest detection limit of up to 10-9 M, owing to the balance between the electromagnetic field energy concentration and the transmission loss in periodic folded Au nanostructures. Finally, by precisely controlling the periods and nanogap widths of the folded Au nanostructures, the synergistic effect of surface plasmon resonance is optimized and shows good SERS properties, providing a new strategy for the preparation of plasmonic nanostructures.

Experimental and density functional theory studies on some metal oxides and the derived nanoclusters: a comparative effects on human ferritin

A comprehensive investigation into the green synthesis of metal oxide nanoparticles (NPs) has garnered significant attention due to its commendable reliability, sustainability, and environmentally friendly attributes. Green synthesis methods play a crucial role in mitigating the adverse effects associated with conventional approaches employed for nanostructure preparation. This research endeavors to examine the impact of ginger plant extract-assisted green synthesis of metal oxides NPs on the serum ferritin levels of anemic diabetic patients in vitro, focusing specifically on α-Fe2O3 and ZnO NPs. Sixty diabetic volunteers with anemia (35–50 years) and thirty healthy volunteers were enrolled as controls. The assessment was conducted using the VIDAS Ferritin (FER) assay. Photoluminescence (PL) spectroscopy measurements were performed to elucidate the intrinsic and extrinsic transitions of these NPs, affirming the successful formation of α-structured iron oxide. Density functional theory (DFT) calculations were carried out at the B3LYP/6-311++G(d,2p) level of theory to investigate the geometry optimization and molecular electrostatic potential maps of the NPs. Furthermore, TD-DFT calculations were employed to explore their frontier molecular orbitals and various quantum chemical parameters. The binding affinity and interaction types of ZnO and α-Fe2O3 NPs to the active site of the human H-Chain Ferritin (PDB ID: 2FHA) target were determined with the help of molecular docking. Results unveiled the crystalline structure of ZnO and the α-structure of α-Fe2O3. Analysis of the frontier molecular orbitals and dipole moment values demonstrated that ZnO (total dipole moment (D) = 5.80 µ) exhibited superior chemical reactivity, biological activity, and stronger molecular interactions with diverse force fields compared to α-Fe2O3 (D = 2.65 µ). Molecular docking of the metal oxides NPs with human H-chain ferritin provided evidence of robust hydrogen bond interactions and metal-acceptor bonds between the metal oxides and the target protein. This finding could have a great impact on using metal oxides NPs-ferritin as a therapeutic protein, however, further studies on their toxicity are required.Graphical abstract

Preparation of mesoporous silica and organosilica nanostructures functionalized with C2‐symmetric diol and their catalytic performance in diethylzinc addition to aromatic aldehydes

In this study, heterogenization of C2‐symmetric (1R,2R)‐1,2‐bis(4‐(3‐(triethoxysilyl)propyl)phenyl)ethane‐1,2‐diol compound and investigation of the effect of structural arrangements of nanocatalysts on catalytic activity were carried out. For this, bissilyl derivative of (1R,2R)‐1,2‐bis(4′‐bromophenyl)‐ethane‐1,2‐diol, named as C2‐BSi, was obtained by 2‐step synthesis. Then, mesoporous silica nanocatalysts C2‐BSi@SBA‐15 and C2‐BSi@MCM‐41 were synthesized by grafting of C2‐BSi onto SBA‐15 and MCM‐41, whereas mesoporous organosilica nanocatalysts C2‐BSi‐MON‐(a) and C2‐BSi‐MON‐(b) were synthesized by co‐condenzation of C2‐BSi and tetraethyl orthosilicate (TEOS). Structure determinations of synthesized organic substances were performed by 1H, 13C NMR, Fourier transform infrared (FT‐IR), polarimeter, and mass analysis, whereas the structural properties of heterogeneous catalysts C2‐BSi@SBA‐15, C2‐BSi@MCM‐41, C2‐BSi‐MON‐(a), and C2‐BSi‐MON‐(b) were determined by FT‐IR, X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and N2 sorption analyses. The catalytic activities of novel heterogenous materials were tested in the reaction of Ti‐promoted enantioselective diethylzinc addition to aromatic aldehydes. The effects of the structural arrangements of the prepared heterogeneous catalyst on the catalytic activity were examined and compared with the catalytic activity values of their homogeneous analog. According to the results, all catalysts catalyzed the reactions and afforded the corresponding products with high conversion (82–99%) but low enantioselectivity (rac‐7% ee). The conversion values in heterogeneous catalysis were higher than those in homogeneous catalysis. C2‐BSi‐MON‐(a) with the largest pore width stood out as the most effective catalyst (99% conversion, 7% ee). The findings from the catalytic activity experiments confirmed that the structural arrangement of the nanocatalysts has an effect on the performance of the catalysts in the reaction.

Impact of Various Input Parameters on the Preparation of Different AlN Nanostructures by Hybrid Route of Hydrothermal and Carbothermal Reduction Nitridation Technique

Impact of Various Input Parameters on the Preparation of Different AlN Nanostructures by Hybrid Route of Hydrothermal and Carbothermal Reduction Nitridation Technique

Tuning the dimensional order in self-assembled magnetic nanostructures: theory, simulations, and experiments.

A major obstacle to building nanoscale magnetic devices or even experimentally studying novel nanomagnetic spin textures is the present lack of a simple and robust method to fabricate various nano-structured alloys. Here, theoretical and experimental investigations were conducted to understand the underlying physical mechanisms of magnetic particle self-assembly in zero applied magnetic field. By changing the amount of NaOH added during the synthesis, we demonstrate that the resulting morphology of the assembled FeCo structure can be tuned from zero-dimensional (0D) nanoparticles to one-dimensional (1D) chains, and even three-dimensional (3D) networks. Two numerical simulations were developed to predict aspects of nanostructure formation by accounting for the magnetic interactions between individual magnetic nanoparticles. The first utilized the Boltzmann distribution to determine the equilibrium structure of a nanochain, iteratively predicting the local deviation angle θ of each particle as it attaches to a forming chain. The second simulation illustrates the differences in nanostructure arrangement and dimensionality (0D, 1D, or 3D) that arise from random interactions at various nanoparticle densities. The simulation results closely match the experimental findings, as seen from SEM images, demonstrating their ability to capture the system's structural properties. In addition, magnetic hysteresis measurements of the samples were performed along two orthogonal directions to show the influence of dimensional order on the magnetic behavior. The normalized remanence (MR/MS||) of the FeCo alloys increases as the dimensions of nanostructures are increased. Of the three cases, the FeCo 3D network structures exhibit the highest normalized nanostructure remanence of 0.33 and an increased coercivity to above 200 Oe at 300 K. This combined numerical and experimental investigation aims to shed light on the preparation of FeCo nanostructures with tailorable dimensional order and it opens new avenues for exploring the complex spin textures and coercive behavior of these multi-dimensional nanomagnetic structures.

Dual-conversion selective dissolution of single crystal superalloy by using a fixed electrolyte

Selective dissolution of multiphase alloys can obtain porous structures. Normally, in a given electrolyte, the active phase will be dissolved and thus constructing complex structures requires varying the electrolyte. In this work, we break through this limit and realize a dual-conversion selective dissolution of single crystal superalloy in the transpassive region in a same electrolyte by adjusting applied potential, and two types of nanostructures, grid-like and columnar structures, are constructed. The underlying mechanism for the preferential dissolution of γ/γ′ phases is discussed. Our results provide a convenient means for the flexible and controllable preparation of large-scale nanostructures on multiphases alloys.

The Application of Electron-Beam Welding in Pellet Mold Preparation

This paper provides insight into the application of electron-beam welding in pellet mold preparation, highlighting the importance of the combination of electron-beam welding and pellet mold preparation in the fields of microstructure joining and micro- and nanostructure preparation. Precise material joining and microstructure fabrication can be achieved by the precise control of electron-beam welding and the shape adjustment of pellet molds. These applications hold significant potential in the modern industrial field, providing robust support for the development of new materials and the growth of the petrochemical industry. This paper asserts that in the future, the ongoing development of electron-beam welding and pelletizing template technology will unlock new possibilities in the field of petrochemicals, fostering progress in science and technology.

Preparation of Chiral Silica Nanostructures with Radial Pores through Single-templating Approach

Preparation of Chiral Silica Nanostructures with Radial Pores through Single-templating Approach

Facile Route to Achieve a Hierarchical CuO/Nickel-Cobalt-Sulfide Electrode for Energy Storage.

Herein, a novel self-supporting CuO/nickel-cobalt-sulfide (NCS) electrode was designed in a two-step electrodeposition technique followed by a calcination process. Three-dimensional copper foam (CF) was exploited as the current collector and spontaneous source for the in situ preparation of the CuO nanostructures, which ensured sufficient deposition space for the subsequent NCS layer, thus forming abundant electrochemical active sites. Such a hierarchical structure is conducive to providing a smooth path for promoting electronic transmission. Therefore, the optimized CuO/NCS electrode exhibits outstanding energy storage capability with extremely superior specific capacitance (Cs) of 7.08 F cm-2 at 4 mA cm-2 and coulombic efficiency of up to 94.83%, as well as excellent cycling stability with capacitance retention of 83.33% after 5000 cycles. The results presented in this work extend our horizons to fabricate novel hierarchical structured electrodes applied to energy storage devices.

Preparation and SERS applications of Ta2O5 composite nanostructures.

Noble metal and semiconductor composite substrates possess high sensitivity, excellent stability, good biocompatibility, and selective enhancement, making them an important research direction in the field of surface-enhanced Raman scattering (SERS). Ta2O5, as a semiconductor material with high thermal stability, corrosion resistance, outstanding optical properties, and catalytic performance, has great potential in SERS research. This study aims to design and fabricate a composite SERS substrate based on Ta2O5 nanostructures, achieving optimal detection performance by combining the urchin-like structure of Ta2O5 with silver nanoparticles (Ag NPs). The urchin-like Ta2O5 nanostructures were prepared using a hydrothermal reaction method. The bandgap was modulated through structure design and the self-doping technique, the charge transfer efficiency and surface plasmon resonance effects were improved, thereby achieving better SERS performance. The composite substrate enables highly sensitive quantitative detection. This composite SERS substrate combines the electromagnetic enhancement mechanism (EM) and chemical enhancement mechanism (CM), achieving ultra-low detection limits of 10-13 M for R6G. Within the concentration range above 10-12 M, there is a good linear relationship between concentration and peak intensity, demonstrating excellent quantitative analysis capabilities. Furthermore, this composite SERS substrate is capable of precise detection of analytes such as crystal violet (CV) and methylene blue (MB), holding broad application prospects in areas such as food safety and environmental monitoring.

The influence of anionic surfactant (SDS) on the optical, magnetic and capacitive properties of NiO nanocrystals via gas-liquid diffusion synthesis

A facile gas–liquid diffusion route with magnetic stirring was used for the preparation of black fungus-like NiO nanostructure with the assistance of SDS surfactant. The NiO obtained without addition of surfactant was used in the control test. The structure, composition and morphology of NiO nanocrystals were characterized by various methods including XRD, Raman, SEM, HRTEM, BET and XPS techniques. The optical properties were analyzed with UV–Vis DRS. The contact angle measurement and vibrating sample magnetometer were used to investigate surface wettability and magnetic properties respectively. The electrochemical behavior of two NiO samples was studied by CV and GCD tests. The characterization and test results showed that compared with surfactant-free NiO sample, the prepared NiO sample using SDS surfactant as template agent exhibited specific morphology and higher surface area, better optical properties, magnetic susceptibility and electrochemical properties.

Preparation and characterization of germanium dioxide nanostructure for gas sensor application: effect of laser parameters

In this article, a novel application of germanium dioxide (GeO2) as a gas sensor is systematically reported. In detail, GeO2 layers were deposited on quartz and n-type Si substrates, as a function of laser pulses, using combined laser ablation and thermal spray coating approaches. The attained layer/s were methodically inspected in term of their morphological, structural, and optical features; specifically, highly crystalline GeO2 structure was obtained for samples prepared using 1500 pulses and above. In the meanwhile, the obtained particle diameters were found to be within the range of 15 to 274 nm, while the estimated optical band gaps exhibited values from 3.85 to 4.0 eV. Simultaneously, the gas sensing behavior demonstrated a well-oriented performance for all devices, however, devices treated with 2500 pulses delivered stable trend with sensitivity value as high as 3 × 10−6. The rise/fall period revealed an adequate outcome (~10 𝑠𝑠𝑠𝑠𝑠𝑠.) for gas sensors fabricated via pulses of 1000 and above, with respected to the working temperature. The proposed framework delivers a substitute technique towards 2D metal oxide based eco-friendly-gas sensor.

Facile preparation of Ag flower-like nanostructures and their catalytic properties in the degradation of organic dyes

This investigation successfully synthesized silver flower-like nanostructures using Arctostaphylos pungens Kunth fruit extract. The efficiency of Ag particles was evaluated by analyzing the degradation of methylene blue and rhodamine B. Ultraviolet–visible spectroscopy (UV–Vis), XRD patterns, and scanning electron microscopy (SEM) characterized the synthesis products. SEM observations showed different morphologies appeared between 1 and 15 days during silver ion biosynthesis, with sizes ranging from 350 nm to 1 μm. After 8 days, a new nanostructure appeared, consisting of randomly oriented entangled nanorods. EDS chemical maps confirmed that the nanostructures were composed of silver. X-ray diffraction confirmed that the synthesized silver nanostructure had the typical cubic structure. This morphology showed excellent degradation efficiencies in methylene blue (96%) and rhodamine B (82%), indicating high degradation efficiency.