Deposition Of Nanostructures Research Articles

Tip-Induced 3D Printing on the Nanoscale with Field Emission Scanning Probes.

3D printing down to the nanoscale remains a significant challenge. In this paper, the study explores the use of scanning probes that emit low-energy electrons (<100eV) coupled with the localized injection and electron-induced decomposition of precursor molecules, for the precise localized deposition of 3D nanostructures. The experiments are performed inside the chamber of a scanning electron microscope (SEM), enabling the use of the in-built gas injector system (GIS) with gaseous naphthalene precursor for carbon deposition, as well as immediate inspection of the deposits by SEM. Substrate materials are planar fused silica with thin conductive coatings and non-planar copper wedges. After investigation of the deposition process parameters, various 2D and 3D carbon deposits are grown. Vertical nanowires several microns in length with a diameter <100nm are achieved and 3D deposits with a high degree of nanoscale branching are also obtained, presumably due to a charging effect. High aspect ratio carbon nanostructures such as those demonstrated here can be employed as miniaturized electrodes or field emitters. The tip-based approach presented thus paves the way toward 3D nanoscale printing of various materials and functional nanostructures.

NiFeCo-modified bucky paper electrodes for sensitive and selective uric acid detection

This study explores a convenient electroreduction-based method for developing ternary metallic alloy nanostructured self-supported buck paper electrodes (BPEs) for non-enzymatic uric acid (UA) detection. The impact of variable ratios of constituent nickel (Ni), iron (Fe), and cobalt (Co) elements on the nanostructured BPE’s electrochemical performance towards UA’s electrocatalytic oxidation was investigated. BPE’s innovative one-step electrochemical modificationwith trimetallic nanostructured alloys (NiFeCo) resulted in reproducible electrodes. The morphological and elemental composition analysis of the synthesized ternary metallic alloy nanostructured electrodes (NiFeCo/BPE) was performed using scanning electron microscopy and energy-dispersive X-ray spectroscopy, confirming the presence of Ni, Fe, and Co within the synthesized NiFeCo/BPE. The NiFeCo/BPE were comparatively evaluated against bimetallic alloy nanostructured electrodes (NiFe/BPE and NiCo/BPE). The resulting NiFeCo/BPE demonstrated a wider detection range of 10 µM to 1500 µM UA due to more electrochemical active sites when compared to the bimetallic nanostructured alloy electrodes. The NiFeCo/BPE demonstrated a sensitivity of 7.50 µAµM−1cm−2 with a detection limit of 5.02 µM towards UA. The fabricated self-supported NiFeCo/BPE sensor exhibited excellent selectivity in the presence of common interferents (e.g., ascorbic acid, dopamine, uric acid, glycine, fructose, and glucose). It showed promising utility in serum samples, with standard recoveries above 95.4 %. This study underscores the significance of uniform deposition of NiFeCo nanostructures, which is critical to unlocking the potential of bucky paper electrodes in developing flexible biosensors for broader range detection of uric acid without the need for enzymes.

Nanobiohybrid Extracellular Vesicle Nanoreactor with Improving Metabolical Activity for Biocatalytic Therapy.

Extracellular vesicles (EVs) hosting enzymatic activities that function as independent metabolic units are attractive natural biocatalytic platforms. However, directly using these metabolically active nanoreactors for effective biocatalytic applications remains challenging, mainly due to their constrained catalytic capabilities. Here, we construct an EV-templated nanobiohybrid system by engineering an EV surface with a photoresponsive zeolitic imidazolate framework (ZIF). The deposition of ZIF nanostructures on EVs not only contributes to improved biocatalytic stability but also enables interfacial coupling between photoexcited electrons from the ZIF and the enzymatic reaction of metabolically active EVs. Nearly 300% of biomass conversion efficiency increment could be achieved by EVs derived from macrophages. This enhanced biocatalysis, high catalytic stability, and low cytotoxicity endowed the EV@ZIF nanosystem with robust biosynthesis and antimicrobial activity. When evaluated in a mouse periodontitis model, we show that the autologous biocatalytic EV@ZIF demonstrated efficient therapeutic capability by killing bacteria and inhibiting inflammation. This nanoengineering strategy will benefit the future optimization of metabolically active EV nanoreactors as biocatalysts for a broad range of therapeutics.

Mechanism of Co3O4-TiO2 Nanocomposite Formation with Enhanced Photocatalytic Performance

TiO2 nanotubes are tubular structures that have garnered significant attention in materials science and engineering due to their unique properties and diverse applications. In this study, highly ordered and well aligned TiO2 nanotubes were successfully synthesized through anodization of Ti foil in ethylene glycol (C2H6O2) containing ammonium fluoride (NH4F) and hydrogen peroxide (H2O2) at 60 V for 30 minutes. The effectiveness of TiO2 as a photocatalyst under solar light is limited by its wide band gap and high recombination rate of charge carriers. To address these limitations, TiO2 nanotubes were modified with cobalt oxide. The resulting Co3O4-TiO2 nanocomposite was synthesized using a wet impregnation technique, aiming to enhance the photocatalytic performance of TiO2 nanotubes across a broader range of the solar spectrum. The formation of Co3O4-TiO2 nanocomposite is by immersing the TiO2 nanotubes in the metal salt precursor solution of Co(NO3)2 for a certain soaking period. The soaking cycle was repeated a few times to ensure the deposition of cobalt oxide nanostructures on the TiO2 nanotube samples. This diffusion interstitial process via wet impregnation was time dependent, which altered the amount of cobalt loaded on the nanotube's surface. The addition of cobalt significantly improved the photodegradation activity of the nanotubes under visible light, outperforming bare TiO2 nanotubes. This enhancement is likely due to the cobalt acting as shallow traps, which effectively promote the separation of photogenerated charge carriers.

Development of hydrophilic carbon fiber textiles using seed-assisted hydrothermal deposition of ZnO nanostructures for enhanced interfacial interaction in CFRP composites

Two-step hydrothermal deposition of zinc-oxide (ZnO) nanorods was used to functionalize carbon fiber textiles in order to produce increased hydrophilicity on fiber surface. On carbon fiber textiles, tightly packed ZnO nanorods developed after five seed cycles and 5 h of growth treatment in a 30 mM precursor salt based on the hydrothermal synthesis. Extensive characterizations have been performed on field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Energy-dispersive X-ray spectroscopy, High resolution transmission electron microscopy, Photoluminescence spectroscopy, and Raman spectroscopy to assess the different aspects such as structural, morphological, elemental, and wettability of the plain and ZnO-modified carbon fiber textiles. ZnO nanomaterial having hexagonal nanorods shape and wurtzite crystalline structure were uniformly deposited on the fabrics. Owing to the wettability study, ZnO prisms improved the hydrophilicity of virgin carbon fiber textiles to enable strong bonds with polymer matrix. The findings highlight the significant improvement in the static water contact angle as a result of the samples' ZnO coating's ability to reduce surface free energy. The improved hydrophilicity in carbon fiber may enhance the bonding between carbon fibers and matrix materials in composite materials. Hydrophilic carbon fibers are more easily wetted by the matrix materials, allowing for better penetration of the matrix into the fiber structure.

Effect of heat input on ultrahard Fe-Cr-B-C-W-Mo-Nb hardfacing

Multicomponent alloys (Cr, Mo, W, Nb, C, B) nanostructured iron base with complex carboborides have been developed to provide great protection against abrasive wear to elements of agricultural and mining machines. These overlays are subject to severe material losses due to impact and abrasion of hard particles and therefore optimizing their wear resistance is critical when it comes to their lifespan, increasing it as a result. The objective of this work was to study the influence of heat input on the wear resistance through of the analysis of the solidification rate. In this sense, the increase of welding speed was produced a decrease of heat input and refined of microstructure. In order to explain these effects, an analysis was made of of the influence of welding speed on the geometry of the deposited metal, dilution with the base metal, microstructural evolution and hardness of iron-based nanostructured deposits with complex carbides. For this, four samples were welded with different speeds; these being 1, 2.5, 5 and 12 mm/s. A semi-automatic welding process was used with a 1.6 mm wire rope used to provide gas protection. The chemical composition was analyzed on a dilution free welded sample. For the each welded sample the dilution percentage was determined, the dimensional survey of the beads was carried out and the microstructure was characterized by X-ray diffraction and optical and scanning electron microscopy. In addition, Vickers microhardness tests were measured in the central area of the beads and the microhardness of phases were measured. The dilution of the deposited metals ranged from 17% to a maximum of 28%. A microstructure formed by a matrix with complex metal carbides and carboborides was observed. The hardness of the beads varied between 960 and 1350 HV2. The highest wear resistance was found in the sample with highest speed welding.

Deposition of DNA Nanostructures on Highly Oriented Pyrolytic Graphite

Deposition of DNA Nanostructures on Highly Oriented Pyrolytic Graphite

Aptasensor based on gold nanostructure-decorated 2D Cu metal-organic framework nanosheets for highly sensitive and specific electrochemical lipopolysaccharide detection.

Detecting lipopolysaccharide (LPS) using electrochemical methods is significant because of theirexceptional sensitivity, simplicity, and user-friendliness. Two-dimensional metal-organic framework (2D-MOF) that merges the benefits of MOF and 2D nanostructure has exhibited remarkable performance in constructing electrochemical sensors, notably surpassing traditional 3D-MOFs. In this study, Cu[tetrakis(4-carboxylphenyl)porphyrin] (Cu-TCPP) and Cu(tetrahydroxyquinone) (Cu-THQ) 2D nanosheets were synthesized and applied on a glassy carbon electrode (GCE). The 2D-MOF nanosheets, which serve as supporting layers, exhibit improved electron transfer and electronic conductivity characteristics. Subsequently, the modified electrode was subjected to electrodeposition with Au nanostructures, resulting in the formation of Au/Cu-TCPP/GCE and Au/Cu-THQ/GCE. Notably, the Au/Cu-THQ/GCE demonstrated superior electrochemical activity because of the 2D morphology, redox ligand, dense Cu sites, and improved deposition of flower-like Au nanostructure based on Cu-THQ. The electron transfer specific surface area was increased by the improved deposition of Au nanostructures, which facilitates enriched binding of LPS aptamer and significantly improved thedetection performance of Apt/Au/Cu-THQ/GCE electrochemical aptasensor. The limit of detection for LPS reached 0.15fg/mL with a linear range of 1fg/mL - 100pg/mL. Theproposed aptasensor demonstrated the ability to detect LPS in serum samples with satisfactory accuracy, indicating significant potential for clinical diagnosis.

Rapid, microwave-assisted deposition of anisotropic silver nanostructures on various substrates.

A facile, rapid, and scalable in situ microwave-assisted solvothermal technique (MAST) has been developed to deposit anisotropic silver nanoparticles (AgNP) on various substrates in a solution medium. SEM-EDS and XRD were used to characterize the morphology and structure of the deposits. Deposition on non-patterned aluminium led to near-spherical AgNP agglomerates all across the surface. Deposition on the glass at optimum solution concentration led to mirror-like coatings comprising spherical ∼50 nm particles, whereas no coating occurred at lower concentrations. AgNPs decorated the hexagonal pattern formed on a nano-patterned aluminium (NPA) substrate. Among various precursor concentrations used for deposition on NPA, the 10 μM concentration resulted in conformal deposition, with nanoparticles decorating the hexagons in NPA. In contrast, AgNP density was lower in the concave dimples on NPA. Our work demonstrates a quick and easy approach for the AgNPs' deposition, with control over size, and morphology. It can be used for deposition on large substrates, potentially making it suitable for surface-enhanced spectroscopic applications.

Plasmonically-boosted high-performance UV self-biased photodetector based on SiC-based low-dimensional heterojunction via Pt nanostructures deposition

While possessing fully superior electrical, optical and mechanical capabilities, the third-generation semiconductor SiC is extensively recognized as one of the most important candidates to developing high-temperature CMOS, intense-radiation hard detectors, high-power electron devices, and other fields. However, the fabrication of low-dimensional SiC structures presents a challenge, limiting its forward-looking applications, particularly for the miniaturized and integrated self-powered ultraviolet (UV) photodetectors. Herein, a high-performance UV photodetector, which involving a p-SiC film, a Ga-doped ZnO microwire coated by Pt nanoparticles (PtNPs@ZnO:Ga MW), a single-layer graphene (Gr) as transparent electrode, was constructed. The device exhibits pronounced UV photodetection capabilities, containing a high On/Off ratio (>105), a peak responsivity approaching 0.266 A/W, a specific detectivity exceeding 1.50 × 1013 Jones, and an exceptional external quantum efficiency closing to 98.7% upon 335 nm illumination at 0 V bias. The detector shows an admirable performance and quite competitive within their class. In the device, the surface-coated PtNPs enable to optimize ZnO:Ga/SiC interfacial performances containing significant enhancement of photoelectric conversion efficiency, efficient suppression of surface/interface defects and trapping centers, and other parameters, thus giving rise to qualitative enhancement of the overall detector properties. Simultaneously, the use of Gr electrode as transparent window allows for maximum UV light absorption and boosts transport properties for the photocarriers. This work presents a valuable reference for the development of high-performance low-dimensional SiC-based photodetecting devices, exploring an important step toward potential optoelectronic applications.

Zinc Oxide Nanostructure Deposition into Sub-5 nm Vertical Mesopores in Silica Hard Templates by Atomic Layer Deposition.

Nanostructures synthesised by hard-templating assisted methods are advantageous as they retain the size and morphology of the host templates which are vital characteristics for their intended applications. A number of techniques have been employed to deposit materials inside porous templates, such as electrodeposition, vapour deposition, lithography, melt and solution filling, but most of these efforts have been applied with pore sizes higher in the mesoporous regime or even larger. Here, we explore atomic layer deposition (ALD) as a method for nanostructure deposition into mesoporous hard templates consisting of mesoporous silica films with sub-5 nm pore diameters. The zinc oxide deposited into the films was characterised by small-angle X-ray scattering, X-ray diffraction and energy-dispersive X-ray analysis.

Detection and Identification of Pesticides in Fruits Coupling to an Au-Au Nanorod Array SERS Substrate and RF-1D-CNN Model Analysis.

In this research, a method was developed for fabricating Au-Au nanorod array substrates through the deposition of large-area Au nanostructures on an Au nanorod array using a galvanic cell reaction. The incorporation of a granular structure enhanced both the number and intensity of surface-enhanced Raman scattering (SERS) hot spots on the substrate, thereby elevating the SERS performance beyond that of substrates composed solely of an Au nanorod. Calculations using the finite difference time domain method confirmed the generation of a strong electromagnetic field around the nanoparticles. Motivated by the electromotive force, Au ions in the chloroauric acid solution were reduced to form nanostructures on the nanorod array. The size and distribution density of these granular nanostructures could be modulated by varying the reaction time and the concentration of chloroauric acid. The resulting Au-Au nanorod array substrate exhibited an active, uniform, and reproducible SERS effect. With 1,2-bis(4-pyridyl)ethylene as the probe molecule, the detection sensitivity of the Au-Au nanorod array substrate was enhanced to 10-11 M, improving by five orders of magnitude over the substrate consisting only of an Au nanorod array. For a practical application, this substrate was utilized for the detection of pesticides, including thiram, thiabendazole, carbendazim, and phosmet, within the concentration range of 10-4 to 5 × 10-7 M. An analytical model combining a random forest and a one-dimensional convolutional neural network, referring to the important variable-one-dimensional convolutional neural network model, was developed for the precise identification of thiram. This approach demonstrated significant potential for biochemical sensing and rapid on-site identification.

Impact of shape of Inconel 600 substrate on deposition of carbon nanostructures by microwave plasma CVD

This study investigates the influence of shape of Inconel 600 substrate on the deposition process using Microwave Plasma Chemical Vapor Deposition (MPECVD) for carbon nanofibers (CNFs) and graphene nanowalls (GNWs) on Inconel 600 substrates. The unique shape of the substrate significantly directs the deposition, revealing a noteworthy shape influenced transition. Notably, a novel pathway emerges for the electric field-driven transformation of Carbon Nanofibers (CNFs) into GNWs—an observation unprecedented in MPECVD processes. Comprehensive characterization, incorporating FESEM, Raman spectroscopy, and fully electromagnetic 3D frequency domain simulations, illuminates the subtle yet impactful interplay between substrate morphology and nanomaterial formation, providing valuable scientific insights.

Optimizing nanostructure deposition process for optical applications

AbstractIn many physics and engineering applications requiring exceptional precision, the presence of highly reflective coatings with low thermal noise is of utmost significance. These applications include high‐resolution spectroscopy, optical atomic clocks, and investigations into fundamental physics such as gravitational wave detection. Enhancing sensitivity in these experiments relies on effectively reducing the thermal noise originating from the coatings. While ion beam sputtering (IBS) is typically employed for fabricating such coatings, electron beam evaporation can also be utilized and offers certain advantages over IBS, such as versatility and speed. However, a significant challenge in the fabrication process has been the limitations of the quartz crystal monitor used to measure the thickness of the deposited layers. This paper showcases how, through hardware and software upgrades, it becomes achievable to create high‐density coatings with layers as thin as a few angstroms by using electron beam evaporation (OAC75F coater) with a deposition rate of 1 Å/s and ion‐assisted source with a gas mixture of oxygen and argon, using a pressure of about 4 × 10−4 mbar. Furthermore, these upgrades enable the attainment of high levels of precision and uniformity in the thickness of the coatings.

Thermally annealed large-scale gold nanostructure platform for long-term and label-free electrochemical monitoring of cellular metabolism

In recent developments, an electrochemical method has emerged as a promising tool that enables real-time and non-destructive monitoring of cell viability and functionality in vitro. However, the restricted cell cultivation area and poor adhesion properties of the gold nanostructure film impede its potential as a new analytical tool for cellular research. In this study, we present an advanced platform designed for prolonged cell growth, differentiation, and drug screening, while providing electrochemical detection capability. The thermal annealing process, implemented after gold nanostructure deposition, was found to induce structural reformation on the indium tin oxide (ITO) film through Ostwald ripening and coalescence, leading to increased surface coverage and reduced height. The resulting optimized platform, referred to as the thermally annealed large-scale gold nanostructure (TLGN), offers an expanded cell culture area (about 227 mm2) with sustained resistance to gold film detachment, a critical challenge observed in previously reported electrodes, lasting up to 4 weeks under exposure to cell culture medium. Using TLGN, redox signals were successfully detected from a substantial number of human cervical cancer cells (470,000 cells) at days in vitro 5, a cell count that is 10.35 times higher compared to our previous gold nanostructure electrode. The cells were continuously monitored for up to 4 days under treatment with the anticancer drug (CB-839). Furthermore, the TLGN platform demonstrated its effectiveness in electrochemically monitoring the osteogenesis of human mesenchymal stem cells over a differentiation period of 28 days, based on observed changes in cellular metabolism. In summary, the TLGN platform proves invaluable not only for assessing drug accumulation and potential cytotoxicity at the cellular level but also for real-time monitoring of mitochondrial dynamics during cellular differentiation.

Macrocyclic Diacetylene / Sulfonate Fluorophore Hierarchical Multifunctional Nanotoroids.

Functional supramolecular materials exhibit important features including structural versatility and versatile applications. Here, this study reports the construction of unique hierarchically organized nanotoroids exhibiting fluorescence, photocatalytic, and sensing properties. The nanotoroids comprise of macrocyclic diacetylenes (MCDA) and 8-anilino-1-naphthalene sulfonate (ANS), a negatively charged aromatic fluorescent dye. This study shows that the hierarchical structure of the nanotoroids consist of MCDA nanofibers formed by stacked diacetylene monomers as the basic units, which are further bent and aligned into toroidal organization by electrostatic and hydrophobic interactions with the ANS molecules. The amine moieties on the nanotoroids surface are employed for deposition of gold nanostructures - Au nanoparticles or Au nanosheets - which constitute effective platforms for photocatalysis and surface enhanced Raman scattering (SERS)-based sensing.

Deposition of vertical carbon nanostructures by microwave plasma source on nickel and alumina

Vertical carbon nanostructures on metal and ceramic substrates are deposited successfully using planar microwave plasma source at frequency of 2.45 GHz. The PECVD (Plasma Enhanced Chemical Vapor Deposition) with microwave surface wave discharge is applied because it produces a dense plasma providing efficient decomposition of the methane and creation of a large number of reactive particles which results in lower substrate temperature for graphene deposition compared to CVD method. Optimization of the gas mixture of H2, Ar and CH4, and the gas pressure in the chamber results in a homogeneous graphene structures deposition on the substrates of Ni-foil, Ni-foam and alumina ceramics at substrate temperatures ∼600 °C. The plasma parameters of surface wave discharge such as gas temperature, electron temperature and density are obtained by measuring OH-band and Ar-lines using optical emission spectroscopy. The morphology of the vertical carbon structures is obtained using SEM analysis and the characteristics of the graphene layers were determined by Raman spectroscopy.

Model of slot antenna for MPECVD of carbon nanostructure

A model of a slotted waveguide antenna for microwave plasma enhanced chemical vapor deposition (MPECVD) of carbon nanostructures at low pressure is developed. The performance of two slot applicator for the production of dense plasma in the working gas (argon) at a frequency of 2.45 GHz is investigated by EM field simulator. Results show that dimensions of the symmetrical slots (length l ≤ λg/2, width of d = 6-10 mm) and optimized angle (φ=32° with respect to the waveguide central line) have a strong influence on the impedance matching of the waveguide to the dielectric window and plasma column (1.5 < SWR < 2.5), and on the radiation efficiency. The dielectric plate and plasma column density were taken into account in the model in the optimisation of the dimensions of the slots. The mode structure of standing surface waves in the plasma column is investigated at three values of plasma density and results for the radial (n=1) and azimuthal wave numbers (m=3, 4, 5) are in agreement with experimental results.

Interplay of graphene-DNA interactions: Unveiling sensing potential of graphene materials.

Graphene-based materials and DNA probes/nanostructures have emerged as building blocks for constructing powerful biosensors. Graphene-based materials possess exceptional properties, including two-dimensional atomically flat basal planes for biomolecule binding. DNA probes serve as excellent selective probes, exhibiting specific recognition capabilities toward diverse target analytes. Meanwhile, DNA nanostructures function as placement scaffolds, enabling the precise organization of molecular species at nanoscale and the positioning of complex biomolecular assays. The interplay of DNA probes/nanostructures and graphene-based materials has fostered the creation of intricate hybrid materials with user-defined architectures. This advancement has resulted in significant progress in developing novel biosensors for detecting DNA, RNA, small molecules, and proteins, as well as for DNA sequencing. Consequently, a profound understanding of the interactions between DNA and graphene-based materials is key to developing these biological devices. In this review, we systematically discussed the current comprehension of the interaction between DNA probes and graphene-based materials, and elucidated the latest advancements in DNA probe-graphene-based biosensors. Additionally, we concisely summarized recent research endeavors involving the deposition of DNA nanostructures on graphene-based materials and explored imminent biosensing applications by seamlessly integrating DNA nanostructures with graphene-based materials. Finally, we delineated the primary challenges and provided prospective insights into this rapidly developing field. We envision that this review will aid researchers in understanding the interactions between DNA and graphene-based materials, gaining deeper insight into the biosensing mechanisms of DNA-graphene-based biosensors, and designing novel biosensors for desired applications.

Photo-responsive analysis of branchy dendrites-like CuO/PS p-n junction visible light photodetector

A series of p-CuO/n-PS heterojunction self-powered visible light photodetector was fabricated as a function of CuO nanostructure deposition time through electrochemical process. Herein, X-ray diffraction confirmed the formation of crystalline layers, while field emission scanning electron microscopy evidenced the occurrence of nano-sized branchy dendrites-like morphology; the fabricated layers exhibited optical bandgap value of 2.07 eV. Simultaneously, the fabricated devices demonstrated a well-oriented figure of merits as a function of wavelength and illumination power at extremely low bias voltage (0.5 V). In detail, responsivity of 59 μA/W as well as detectivity of 23 ×1019Jones were obtained, respectively, for the optimum device at 635 nm; an external quantum efficiency of 115.2 at 100 mW/cm2 was attained whereas such an observation was found to be deteriorated at lower/higher wavelengths. The pronounced device exhibited response/recovery time of 0.33 and 0.83 sec. at zero bias voltage evidencing a self-powered feature of the proposed system.