Characterization Of Nanostructures Research Articles

Synthesis, Characterization, and Optical Properties of NiCr2O4 and CoCr2O4 Spinel Nanostructures for Photocatalytic Applications

This study focuses on the synthesis and characterization of two cubic spinel oxides, NiCr2O4 and CoCr2O4, utilizing X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and UV-Visible (UV-Vis) spectroscopy. The investigation aimed to explore their structural and optical properties for potential applications in advanced technologies such as catalysis, sensors, and optoelectronics. XRD analysis confirmed that both NiCr2O4 and CoCr2O4 crystallize in the cubic spinel structure with the space group Fd-3m. The lattice parameters, 8.307 Å for NiCr2O4 and 8.285 Å for CoCr2O4, reveal slight variations attributed to the differing ionic radii of Ni2+ and Co2+, with both compounds exhibiting high crystallinity. FT-IR spectroscopy confirmed the presence of metal-oxygen bonding characteristic of spinel structures. In NiCr2O4, the Ni-O and Cr-O stretching vibrations were identified at 681 cm⁻1 and 485 cm⁻1, respectively, while CoCr2O4 exhibited similar vibrations at 570 cm⁻1 and 485 cm⁻1. UV-Vis spectroscopy demonstrated significant optical absorption in the UV and visible regions. NiCr2O4 displayed absorption peaks at 237 nm, 295 nm, 406 nm, and 580 nm, whereas CoCr2O4 exhibited peaks at 247 nm, 295 nm, 411 nm, and 574 nm. Analysis using Tauc plots determined optical band gaps of 2.969 eV for NiCr2O4 and 2.015 eV for CoCr2O4, confirming their semiconducting nature and suitability for visible-light-driven applications.

Innovative Silica Acorn Core-Shell Nanostructures: Morphological Control and Applications in Chromatography.

This study introduces the synthesis and characterization of advanced silica core-shell nanostructures, with an emphasis on the innovative Si-ACS (Silica Acorn Core-Shell) design and its modified counterparts. Employing the classic Stöber method, SiCore particles were first produced, followed by the creation of the acorn-like Si-ACS structures. A key aspect of this research is the exploration of the effects of CTAB and TEOS concentrations on the morphology and properties of the silica shells. The study reveals that surfactant concentration influences shell morphology from corn-like to uniformly thin structures, as well as the shell thickness. Specifically, increasing the CTAB concentration from 45.8 mM to 166.9 mM increased the silica shell thickness from 160 to 280 nm, demonstrating the significant impact of surfactant concentration on shell formation. Si-ACS particles exhibited a surface area of 55.54 m2/g and a pore volume of 0.64 cm3/g, as evidenced by BET measurements, indicating successful mesopore formation critical for catalytic and adsorption applications. The materials were further modified with cholesterol and tetraethyl pentaamine (TEPA), which was confirmed by FT-IR analysis. Additionally, the study demonstrates the application of these functionalized nanostructures as chromatographic columns. In particular, the dual-mode interactions of Si-ACS-CHOL-TEPA significantly improve the separation of phthalate esters, thereby highlighting the potential of these materials in advanced analytical and biotechnological applications.

Amphiphilic self-assembling peptides: formulation and elucidation of functional nanostructures for imaging and smart drug delivery.

The rational design of self-assembled peptide-based nanostructures for theranostics applications requires in-depth physicochemical characterization of the peptide nanostructures, to understand the mechanism and the interactions involved in the self-assembly, allowing a better control of the objects' physicochemical and functional properties for theranostic applications. In this work, several complementary characterization methods, such as dynamic light scattering, transmission electron microscopy, circular dichroism, Taylor dispersion analysis, and capillary electrophoresis, were used to study and optimize the self-assembly of pH-sensitive short synthetic amphiphilic peptides containing an RGD motif for active targeting of tumor cells and smart drug delivery. The combined methods evidenced the spontaneous formation of nanorods (L = 50nm, d = 10nm) at pH 11, stabilized by β-sheets. To complement with imaging properties for diagnosis, a new strategy was developed by designing an optimized peptide sequence to allow for efficient functionalization with a contrast agent, while preserving the self-assembling properties. Co-assemblies of the peptide and its derivatives, after peptide modification with a gadolinium complex, exhibited similar nanorod structures and required properties for drug delivery and imaging applications in vivo.

Synthesis and Characterization of Aluminum-doped ZnO Nanostructures via a Simple Solution Method for Effective Passivation of a Silicon Surface

Synthesis and Characterization of Aluminum-doped ZnO Nanostructures via a Simple Solution Method for Effective Passivation of a Silicon Surface

Synthesis, Characterization, and Hydrogen Evolution Reaction Activity of MoS2 Nanostructures Prepared Using Nonionic Surfactant

Molybdenum disulfide (MoS2) has garnered significant interest as an auspicious catalytic material for the hydrogen evolution reaction (HER). Here, MoS2 nanostructures are synthesized using the hydrothermal method with ammonium molybdate tetrahydrate ((NH4)6Mo7O24∙4H2O) as the Mo source; thioacetamide (CH3CSNH2) as the reducing agent and S source; and nonylphenols 9, nonylphenols 40, and polysorbate 80 as the surfactants. The impact of the different nonionic surfactants on the materials is comprehensively investigated. Moreover, the MoS2 fine structure was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, scanning electron microscopy (SEM), and transmission scanning microscopy (TEM). The HER characteristics of the MoS2 composites are assessed through electrochemical experiments, including linear sweep voltammetry and chronoamperometry measurements. Among the prepared specimens, MoS2/NP 9 exhibits the best electrocatalytic performance in a neutral medium. Furthermore, 240 mV is required to reach the current density of 10 mAcm−2.

Snowflake Iron Oxide Architectures: Synthesis and Electrochemical Applications

The synthesis and characterization of iron oxide nanostructures, specifically snowflake architecture, are investigated for their potential applications in electrochemical sensing systems. A Raman spectroscopy analysis reveals phase diversity in the synthesized powders. The pH of the synthesis affects the formation of the hematite (α-Fe2O3) and goethite (α-FeOOH). Scanning electron microscopy (SEM) images confirm the distinct morphologies of the particles, which are selectively obtained through recrystallization during the elongated reaction time. An electrochemical analysis demonstrates the differing behaviors of the particles, with synthesis pH affecting the electrochemical activity and surface area differently for each shape. Cyclic voltammetry measurements reveal reversible dopamine detection processes, with snowflake iron oxide showing lower detection limits than a mixture of snowflakes and cube-like particles. This research contributes to understanding the relationship between iron oxide nanomaterials’ structural, morphological, and electrochemical properties. It offers practical insights into their potential applications in sensor technology, particularly dopamine detection, with implications for biomedical and environmental monitoring.

A Lab Prototype for Rapid Electrochemical Detection of Escherichia coli in Water Using Modified Screen-Printed Electrodes.

Recognizing the need for a hand-held device capable of quantitatively measuring the concentration of bacteria in water, this paper describes a label-free method for rapid detection of Escherichia coli (E. coli) in water via H2O2 decomposition using screen-printed electrodes (SPE) modified with nanostructured metal oxide layers. The study encompasses sensor preparation, bacteria culture, synthesis and characterization of nanostructures, and development of a readout circuitry for lab prototyping. During sensing measurements, the bacteria are first made to interact with H2O2 and subsequently, the H2O2 solution is exposed on the sensing surface. The electrochemical sensors are fabricated by modifying the working electrode of SPE with nanostructured metal oxide layers of MnO2 and TiO2 as these play a crucial role in the detection of E. coli in water. The sensing experiments of MnO2-modified SPE show a significant response to bacteria with a sensitivity of 0.82 mV.mL/log CFU and a limit of detection (LOD) of 1.8 CFU/mL, while the TiO2-modified SPE exhibits a linear response over a wide range of bacterial concentrations with a sensitivity of 1.12 mV·mL/log CFU and a limit of detection of 2.23 CFU/mL. Both sensors demonstrate a rapid response, stability, repeatability, and a recovery time of 70 ms. Additionally, selectivity with respect to other bacteria, wastewater components such as glucose, ammonium sulfate, and sodium carbonate, and testing with RO, DI, and tap water samples are conducted to evaluate the sensors' performance. A detailed sensing mechanism has been developed to comprehend the results, including chemical and biological reactions, metal oxide interfaces, morphology, and other surface studies of the sensing surface. A prototype comprising a sensor chip, an Arduino board, and other necessary circuit components is tested with various bacterial solutions. This enables its use for on-field rapid detection of bacteria in water using smaller volumes and a portable system.

Tailoring the Li+ Intercalation Energy of Carbon Nanocage Anodes Via Atomic Al-Doping for High-Performance Lithium-Ion Batteries.

Graphitic carbon materials are widely used in lithium-ion batteries (LIBs) due to their stability and high conductivity. However, graphite anodes have low specific capacity and degrade over time, limiting their application. To meet advanced energy storage needs, high-performance graphitic carbon materials are required. Enhancing the electrochemical performance of carbon materials can be achieved through boron and nitrogen doping and incorporating 3D structures such as carbon nanocages (CNCs). In this study, aluminum (Al) is introduced into CNC lattices via chemical vapor deposition (CVD). The hollow structure of CNCs enables fast electrolyte penetration. Density functional theory (DFT) calculations show that Al doping lowers the intercalation energy of Li+. The Al-boron (B)-nitrogen (N-doped CNC (AlBN-CNC) anode demonstrates an ultrahigh rate capacity (≈300 mAhg-1 at 10 Ag-1) and a prolonged fast-charging lifespan (862.82 mAhg-1 at 5 Ag-1 after 1000 cycles), surpassing the N-doped or BN-doped CNCs. Al doping improves charging kinetics and structural stability. Surprisingly, AlBN-CNCs exhibit increased capacity upon cycling due to enlarged graphitic interlayer spacing. Characterization of graphitic nanostructures confirms that Al doping effectively tailors and enhances their electrochemical properties, providing a new strategy for high-capacity, fast-charging graphitic carbon anode materials for next-generation LIBs.

Atomic Structure and 3D Shape of a Multibranched Plasmonic Nanostar from a Single Spatially Resolved Electron Diffraction Map.

Despite the interest in improving the sensitivity of optical sensors using plasmonic nanoparticles (NPs) (rods, wires, and stars), the full structural characterization of complex shape nanostructures is challenging. Here, we derive from a single scanning transmission electron microscope diffraction map (4D-STEM) a detailed determination of both the 3D shape and atomic arrangement of an individual 6-branched AuAg nanostar (NS) with high-aspect-ratio legs. The NS core displays an icosahedral structure, and legs are decahedral rods attached along the 5-fold axes at the core apexes. The NS legs show an anomalous anisotropic spatial distribution (all close to a plane) due to an interplay between the icosahedral symmetry and the unzipping of the surfactant layer on the core. The results significantly improve our understanding of the star growth mechanism. This low dose diffraction mapping is promising for the atomic structure study of individual multidomain, multibranched, or multiphase NPs, even when constituted of beam-sensitive materials.

Shape tailored nano-ceria as high performance supercapacitor electrode material

Electrochemical energy storage devices herald a brighter future, offering efficient and sustainable solutions to meet the escalating global energy demands. The current work investigates the development and characterization of different ceria nanostructures (nanorod, nanocube, and nanopolyhedra) as effective electrode materials for supercapacitor applications. The electrode materials are systematically characterized using various spectroscopic and non-spectroscopic techniques. Galvanostatic charge-discharge, electrochemical impedance spectroscopy, and cyclic voltammetry techniques are used to evaluate the electrochemical performance of the electrode materials. The optimum material for the said application is cerium nanorod which has the maximum specific capacitance of 437.27 F/g in acid electrolytes. The current-voltage (I-V) characteristics of the ceria nanostructures exhibit hysteresis behavior; ceria nanorod showing coexistence of memristive and memcapacitive nature. The loop area of the hysteresis curve, derived from the ratio of OFF resistance to ON resistance (ROFF/RON) at 4 V, yields approximate values of 1.08, 1.33, and 1.57 for ceria nanocubes, ceria nanopolyhedra, and ceria nanorods, respectively. Impedance vs. frequency analysis of the samples was also carried out to study their electrical and transport properties. The results obtained from electrochemical analyses are complimented by electrical studies.

Exploring the effect of exchange coupling in (SrFe9.8Al2La0.2O19)1-x/(Co0.7Zn0.3Fe2O4)x nanocomposites synthesised by sol–gel auto combustion method

Extensive research has been conducted over the last decade to develop permanent magnets utilizing less rare earth materials. Exchange-coupled nanocomposite magnets are a fascinating development in the field of permanent magnets. They involve the combination of hard and soft ferrites, resulting in a unique and evolving magnet. Here we present an in-depth structural, morphological and magnetic characterization of ferrite-based nanostructures obtained through a bottom-up sol−gel approach. The combination of high coercivity of a hard phase SrFe9.8Al2La0.2O19 (SFALO) and high saturation magnetization of a soft phase, Co0.7Zn0.3Fe2O4 (CZFO), allowed us to develop exchange-coupled bi-magnetic nanocomposites by varying the mass percentage (x = 0, 0.1, 0.2, 0.3, 0.4, 1). Thermogravimetric analysis (TGA) up to 1200 °C was used to investigate the material’s thermal properties with the phase formation temperature. Detailed atomic/nano-scale structural characterizations of these nanocomposites were performed by X-ray diffraction and Transmission Electron Microscopy. The average particle size was calculated from the SEM analysis and it was observed that most of the composites with ratio x = 0.1, 0.3 & 0.4 was 145 nm and x = 0.2 was 165 nm. The Switching Field Distribution (SFD) curve revealed the exchange coupling between soft and hard magnetic particles. The findings indicate that the inclusion of a soft magnetic phase has a considerable impact on the exchange coupling between the hard and soft ferrite phases. As the spinel concentration increased, in the composite the saturation magnetization increased from 18 emu/g to 48 emu/g. From the stroner-wholfrathmodel, the decrease in the remanence ratio below 0.5 concludes the crystallites are randomly oriented. The nanocomposite with the ratio x = 0.1 was observed with the high magneto crystalline anisotropy of 2183.23 × 102 (J/m3) and a high energy product (BH)max of 5.5 kJ/m3. The aforementioned features of nanocomposites demonstrate their potential for use in permanent magnet applications.

Laboratory-based 3D X-ray standing-wave analysis of nanometre-scale gratings.

The increasing structural complexity and downscaling of modern nanodevices require continuous development of structural characterization techniques that support R&D and manufacturing processes. This work explores the capability of laboratory characterization of periodic planar nanostructures using 3D X-ray standing waves as a promising method for reconstructing atomic profiles of planar nanostructures. The non-destructive nature of this metrology technique makes it highly versatile and particularly suitable for studying various types of samples. Moreover, it eliminates the need for additional sample preparation before use and can achieve sub-nanometre reconstruction resolution using widely available laboratory setups, as demonstrated on a diffractometer equipped with a microfocus X-ray tube with a copper anode.

Innovative approach to tailoring upconversion luminescence in Yb3+/Eu3+ doped CaZrO3 perovskite host matrix

This study presents the synthesis and characterization of upconverter nanostructures consisting of a perovskite host matrix, CaZrO3, co-doped with trivalent ytterbium (Yb3+) and europium (Eu3+), denoted as CaZrO3:Yb3+/Eu3+. Single-doped CaZrO3:Eu3+ samples were excited using a 394 nm UV source, while CaZrO3:Yb3+/Eu3+ samples were excited with a 980 nm diode laser source. Yb3+ ions efficiently absorb the 980 nm light and transfer the absorbed energy to the nearby ion Eu3+ ions, leading to the emission of visible light around 590, 614, and 655 nm, respectively. The emission spectra of Eu3+ ions exhibit an initial increase with increasing Yb3+ concentration, peaking at 7 mol%, followed by a decrease due to luminescence quenching. The decay lifetime of Eu3+ ions under 300 nm excitation decreases simultaneously with increasing Yb3+ concentration, indicating energy migration between Yb3+ and Eu3+. Detailed explanations of the energy transfer mechanism between Yb3+ and Eu3+ ions are provided, supported by equations and diagrams. This study provides valuable insights into the optimization of dopant concentrations for enhancing upconversion luminescence in CaZrO3:Yb3+/Eu3+ nanostructures, with 3 mol% Eu3+ concentration identified as optimal based on preliminary experiments. The findings presented in this paper contribute to the understanding of energy transfer processes in luminescence upconversion materials and highlight the potential of CaZrO3:Yb3+/Eu3+ nanostructures for applications in lighting, displays, and bio-imaging. This work represents a significant advancement in the field of upconversion luminescence emission, particularly in the utilization of CaZrO3 codoped with Yb3+ and Eu3+, and lays the foundation for further research in this area.

Effect of sample dimensions on the stiffness of PA12 Lattice materials fabricated using Powder Bed Fusion

Powder Bed Fusion fabrication techniques, including selective laser sintering, have made the fabrication of lattice meta-materials consisting of periodic cells formed by interconnected struts possible. It is generally observed that cell size has a strong influence on the lattice’s effective Young’s modulus, following in the case of typical polymers used for printing a trend of the smaller the softer. However, there is no clear understanding of the origin of the effective elastic modulus reduction with lattice cell size. In this paper, an integrated study is performed to unravel the reasons behind this effect. The analysis performed encompasses mechanical characterization (compression tests and nanoindentation), microstructure characterization (X-ray tomography, DSC, SAXS, and WAXS), and numerical analysis of the effect of defects (FFT and Finite element simulations of cells with roughness and defects) of PA12 printed single cells of different sizes and full lattice specimens containing many cells. It is found that the effect of porosity and roughness is not enough to explain the reduction of the effective elastic modulus with the cell size, suggesting that this effect is necessarily a combination of the defects, incomplete melting of particles and the changes of PA12 nanostructure induced by the different printing conditions as function of full specimen size . The results of the micro- and nanostructure characterization validate this assumption.

Computer simulation and modeling of glow discharge optical emission coded aperture elemental mapping

BackgroundElemental mapping (EM) yields necessary insights into mechanisms of interest in solid samples across multiple disciplines. There are several EM techniques available but long acquisition time is a common limitation. Glow discharge optical emission spectroscopy (GDOES) allows direct quantitative multi-EM at very high throughput (∼10 s s) when coupled to traditional hyperspectral imaging (HSI) techniques. However, GDOES consumes the sample via sputtering, such that traditional HSI sequential scanning requirements lead to loss of information/resolution, which is compounded for multi-EM and limits nanomaterials analysis. Thus, there is a need for faster HSI to enable GDOES multi-EM of nanoscale materials. ResultsHere, a new technique is described, Glow discharge Optical emission Coded Aperture elemental Mapping (GOCAM), that takes advantage of compressive coded aperture spectral imaging to enable multi-EM in a single camera exposure. In this first phase of development, computer model simulations were implemented to study the effects of coded aperture parameters on data fidelity, which showed the best fidelity is achieved at smaller mask element sizes and transmittance of 60 %. In addition, SeSCIGPU demonstrated the best fidelity performance compared to several compressed sensing reconstruction algorithms, including TwIST, GAP-TV, SeSCICPU, and ADMM-TV, as evaluated by studying the effects of varying the corresponding hyperparameters. SignificanceThis study shows GOCAM's feasibility and provides a starting point for the second phase hardware development currently underway. GOCAM's potential to allow multi-EM from solid surfaces in a fraction of a second will be particularly enabling for nanostructured materials characterization.

Multi-Dimensional Characterization of Nanostructures in Titanium Alloys using 2D Aberration-Corrected STEM and 3D Atom Probe Tomography

Multi-Dimensional Characterization of Nanostructures in Titanium Alloys using 2D Aberration-Corrected STEM and 3D Atom Probe Tomography

Synthesis and Characterization of Nickel Ferrite Nanostructures by DC Reactive Sputtering Technique Using New Target Configuration

Synthesis and Characterization of Nickel Ferrite Nanostructures by DC Reactive Sputtering Technique Using New Target Configuration

Phytogenic aqueous extract mediated fabrication of Ag-Fe2O3 nanohybrids for detoxification of carcinogenic Congo Red dye: An Environmental Remediation approach

<p>In current study environment benign silver-iron oxide (Ag-Fe2O3) nanohybrid structures are fabricated as catalyst for CR dye decolorization. Industrial wastewater stream possesses several toxic dyes which are toxic carcinogen pollutants cause severe environmental disorders. Detoxification of Congo Red dye is carried out by silver-iron oxide nanohybrid structures having latent catalytic efficiency for dye decolorization. Silver iron oxide nanohybrid materials are fabricated from AgNO3, FeSO4/ FeCl3 and Citrus limon aqueous extract by doping AgNPs on Fe2O3 materials. For characterization of Ag-Fe2O3 nanostructures, UV-Visible, X-ray diffraction (XRD), Scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) techniques are used. The crystallite size is measured from Debye Scherer equation and average size calculated is 54.3 nm. Furthermore, UV-Visible spectrophotometer is used to study the catalytic efficiency of Ag-Fe2O3 nanohybrid material which is observed to be >80% within 10 minutes. Moreover, parameters like contact time, dosage of catalyst, temperature and pH are measured to optimize reaction conditions for the dye degradation by adding prepared nanohybrids. The kinetic studies were performed for the degradation reaction and were originate to follow first order kinetics. Reusability test is also applied to check the stability of nanohybrid catalyst that affirmed it to be as highly stable nanomaterial.</p>

ZnO:CuO Composites Obtained by Rapid Joule Heating for Photocatalysis.

Semiconductor oxides belonging to various families are ideal candidates for application in photocatalytic processes. One of the challenges facing photocatalytic processes today is improving their efficiency under sunlight irradiation. In this study, the growth and characterization of semiconductor oxide nanostructures and composites based on the ZnO and CuO families are proposed. The selected growth method is the resistive heating of Zn and Cu wires to produce the corresponding oxides, combined with galvanic corrosion of Zn. An exhaustive characterization of the materials obtained has been carried out using techniques based on scanning electron microscopy and optical spectroscopies. The method we have followed and the conditions used in this study present promising results, not only from a degradation efficiency point of view but also because it is a cheap, easy, and fast growth method. These characteristics are essential in order to scale the process beyond the laboratory.

Nanostructural characterization of surfaces and interfaces of Portland cement mortars using high resolution microscopy

In Portland cement mortars it is of paramount importance to investigate the bond strength between mortar and masonry by means of the study of interfaces and surfaces that make up the system mortar/ceramic block. In this work the aim was to characterize the chemical compositions, microstructures, surfaces and interfaces of mortars applied on ceramic blocks. Therefore, two important characterization tools were used: field-effect gun (FEG) scanning electron microscope (SEM) - FEI Quanta 200 with energy-dispersive (X-ray) spectrometer (EDS) and SEM system with EGF Nanofabrication FIB - FEI Quanta 3D FEG also with an EDS coupled. To date the results obtained from the research show that the characterization of cementitious materials with high resolution SEM is an important tool in the detection and differentiation of hydrated calcium silicates (CSH), calcium hydroxide (Ca(OH)2), ettringite and calcium carbonate by means of morphological, topographical and chemical data, thus providing extremely reliable as well as qualitative data from the structure of cementitious materials.