High-resolution Electron Microscopy Research Articles

Microwave-Assisted Green Synthesis of Fluorescent Graphene Quantum Dots: Metal Sensing, Antioxidant Properties, and Biocompatibility Insights.

Graphene quantum dots (GQDs) are highly valued for their chemical stability, tunable size, and biocompatibility. Utilizing green chemistry, a microwave-assisted synthesis method was employed to produce water-soluble GQDs from Mangifera Indica leaf extract. This approach is efficient, cost-effective, and environmentally friendly, offering reduced reaction times, energy consumption, and uniform particle sizes, and has proven advantageous over other methods. Water-soluble GQDs were synthesized using Mangifera Indica leaf extract, which ranged less than 15nm in diameter, confirmed by high-resolution transmission electron microscopy with a lattice spacing of 0.34nm. The GQDs exhibited strong photoluminescence with bright red fluorescence under UV light and excitation-independent emission at 662nm with excitation wavelengths ranging from 300 to 500nm, achieving a quantum yield of 10.3%. A peak at 27.2˚ was recorded corresponding to the graphite's (002) plane diffraction peak. Raman spectroscopy confirmed their graphitic nature and sp2 crystallinity, with an intensity ratio of D and G peak ID/IG ratio of 1.12. Biocompatibility assays (MTT and live/dead) showed better results at lower concentrations (1mg/ml) while higher concentrations (2mg/ml) showed reduced efficacy. Antioxidant tests revealed increased DPPH scavenging activity with higher GQD concentrations and longer incubation times. The GQDs demonstrated excellent performance as fluorescent biosensors for Ni2⁺ (0.15ppm) and Fe3⁺ (0.20ppm), with high selectivity in river water samples, highlighting their potential for environmental and health applications.

Unraveling the Stoichiometric Interactions and Synergism between Ligand-Protected Gold Nanoparticles and Proteins.

Nanomaterials that engage in well-defined and tunable interactions with proteins are pivotal for the development of advanced applications. Achieving a precise molecular-level understanding of nano-bio interactions is essential for establishing these interactions. However, such an understanding remains challenging and elusive. Here, we identified stoichiometric interactions of water-soluble gold nanoparticles (Au NPs) with bovine serum albumin (BSA), unraveling their synergism in manipulating emission of nano-bio conjugates in the second near-infrared (NIR-II) regime. Using Au25(p-MBS)18 (p-MBS = para-mercaptobenzenesulfonic acid) as paradigm particles, we achieved precise binding of Au NPs to BSA with definitive molar ratios of 1:1 and 2:1, which is unambiguously evidenced by high-resolution mass spectrometry and transmission electron microscopy. Molecular dynamics simulations identified well-defined binding sites, mediated by electrostatic interactions and hydrogen bonds between the p-MBS moieties on the Au25(p-MBS)18 surface and BSA. Particularly, positively charged residues on BSA were found to be pivotal. By careful control of the molar ratio of Au25(p-MBS)18 to BSA, atomically precise [Au25(p-MBS)18]x-BSA conjugates (x = 1 or 2) could be formed. Through a comprehensive spectroscopy study, an electron transfer process and synergistic effect were manifested in the Au25(p-MBS)18-BSA conjugates, leading to drastically enhanced emission in the NIR-II window. This work offers insights into the precise engineering of nanomaterial-protein interactions and opens new avenues for the development of next-generation nano-bio conjugates for nanotheranostics.

Superior charge storage performance of optimized nickel cobalt carbonate hydroxide hydrate nanostructures for supercapacitor application

In our work, we report superior electrochemical performance of optimized 3D nanostructured, nickel-cobalt carbonate hydroxide hydrate (Ni3 − xCox-CHH (1 ≤ x ≤ 2)) materials with flower like morphology synthesised via one-step hydrothermal methods. A Ni rich sample (x = 1) demonstrate better specific capacitance and the improvement is attributed to more oxygen deficient neighbourhood of Ni compared to that of Co. The structural, morphological and electronic properties of the samples were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM), field emission electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). A comprehensive characterization was used for physicochemical properties-electrochemical performance correlation. Cyclic voltammetry (CV), Galvanostatic charging and discharging (GCD) shows the supercapacitor feature of the samples for the composition containing the highest nickel concentration achieving a specific capacitance of 1649.51 F g− 1 at a current density of 1 A g− 1 and excellent rate capability of 1610.30 F g− 1 at a high current density of 5 A g− 1. The sample shows high cyclic stability of 80.86% after 3000 cycles. Improved specific capacitance is attributed to the synergy effect of bimetallic transition metals as well as improved surface area of flower like morphology. These findings show that Ni2Co-CHH electrode material demonstrates great potential as electrode material for supercapacitor device fabrication.

NiCo2O4/P,N‐doped Carbon with Engineered Interface to Improve the Rechargeability of Zn‐Air Batteries at High Energy Demands

The search for cost‐effective, high‐performance bifunctional catalysts for Zn‐air batteries (ZABs) requires extensive research into precious‐metal‐free materials. This study provides insight into the synergy between nickel cobaltite and P,N‐doped carbon modified through interface engineering by inducing oxygen vacancies in the spinel and non‐metallic heteroatoms in the carbon material. NiCo2O4 with various oxygen vacancy levels was synthesized via an ethylene glycol‐assisted solvothermal route. This resulted in significant changes in the structural and morphological properties, such as reduced crystallite size, lattice distortion, and increased oxygen vacancies, as observed from the physicochemical results. This was further verified by X‐ray photoelectron spectroscopy (XPS) and high‐resolution transmission electron microscopy (HR‐TEM), which showed a homogeneous dispersion of nickel cobaltite nanorods on the carbonaceous matrix, along with an increased concentration of pyridinic nitrogen and the formation of P–N and P–C bonds, both of which enhance electrocatalytic activity. NiCo2O4DI/P,N‐C exhibited superior discharge polarization behavior, achieving power and current densities of 124.4 mW cm−2 and 215.8 mA cm−2. The catalyst presented excellent stability (up to 100 h), while Pt‐IrO2/C lasted near 21 h. These results demonstrate the great potential of tailoring surface defects and heteroatom doping via interface engineering, resulting in high‐performance precious‐metal‐free electrocatalysts for long‐lasting and high‐efficiency ZABs.

Fabrication of MoS2@Fe3O4 Magnetic Catalysts with Photo-Fenton Reaction for Enhancing Tetracycline Degradation

Tetracycline (TCs) is widely used in the treatment of human and animal infectious disease. TCs gives rise to a growing threat to the human health and environment protection due to its overuse. Therefore, it is important to remove TCs contaminants from waste effluents. In this work, MoS2@Fe3O4 catalytic material was fabricated by the simple hydrothermal method, which was applied in the photo-Fenton system to degrade TCs. The crystal structure, surface morphology, elemental composition, chemical state, electrochemical properties, and separability of MoS2@Fe3O4 catalytic materials were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), conventional and high-resolution transmission electron microscopy (TEM/HRTEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and vibrating sample magnetometry (VSM). Furthermore, MoS2@Fe3O4 could degrade 98.6% of TCs within 60 min under the optimum reaction conditions (the catalyst dosage of 3 g/L, H2O2 concentration of 5 mmol/L, the initial TCs concentration of 50 mg/L, and the initial pH of 5), which was a significant increase compared with pure Fe3O4. MoS2 can accelerate the Fe3+/Fe2+ cycle through electron transfer from Mo4+ to Fe3+, resulting in the improvement in the degradation efficiency of TCs. The quenching and electron paramagnetic resonance (EPR) results showed that OH• and photogenic hole h+ was the main active species in the photo-Fenton system. What is more, MoS2@Fe3O4 catalytic materials had remarkable stability and reusability, and can be handily regained via magnetic separation technology in a real scenario.

Electrochemical and physical properties of magnesioferrite nanomaterial and photocatalytic degradation of methylene blue

This research successfully synthesized semiconductive magnesioferrite (MgFe2O4) nanomaterials using a green chemistry method that utilizes the natural extract of Moringa olefeira serving as both a reducing and oxidizing agent. The optical characteristics and crystalline structure of the MgFe2O4 nanomaterials were analysed using photoluminescence, diffuse reflectance spectroscopy, and X-ray diffraction. Additionally, Fourier transform infrared spectroscopy provided valuable insights into the chemical bonding and composition. High-resolution transmission electron microscopy was employed to obtain extensive information on crystalline size and distribution. Furthermore, the electrochemical properties were assessed through cyclic voltammetry and electrochemical impedance spectroscopy, revealing an excellent voltametric response and pseudo-capacitive behaviour associated with faradaic reactions, as well as outstanding conductivity linked to the unique charge transport mechanisms present in the MgFe2O4 structure. The effectiveness of the MgFe2O4 nanomaterials in the photodegradation of methylene blue from aqueous solutions was evaluated under visible light irradiation. Photocatalytic experiments measured the influence of various parameters, including catalyst loading, dye concentration, and pH. The MgFe2O4 nanomaterials exhibited impressive photocatalytic degradation efficiency, achieving an 81% degradation rate at pH 5.0 within 120 min. Kinetic studies indicated that the degradation process adhered to a pseudo-first-order model, with a rate constant of 0.01533 min−1, signifying a rapid reaction under optimal conditions. This study provides a thorough understanding of the electrochemical properties and enhanced photocatalytic capabilities of MgFe2O4 nanomaterials, thereby advancing green nanotechnology for environmental remediation.

Modulation of RuO2 Nanocrystals with Facile Annealing Method for Enhancing the Electrocatalytic Activity on Overall Water Splitting in Acid Solution.

RuO2-based materials are considered an important kind of electrocatalysts on oxygen evolution reaction and water electrolysis, but the reported discrepancies of activities exist among RuO2 electrocatalysts prepared via different processes. Herein, a highly efficient RuO2 catalysts via a facile hydrolysis-annealing approach is reported for water electrolysis. The RuO2 catalyst dealt with at 200 °C (RuO2-200) performs the highest activities on both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acid with overpotentials of 200 mV for OER and 66 mV for HER to reach a current density of 100 mA cm-2 as well as stable operation for100 h. The high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) characterizations show that the activities of as-prepared RuO2 rely on the hydroxide group/lattice oxygen (OH-/O2-) ratio, size, and crystalline of RuO2. The density functional theory (DFT) calculation also reveal that the OH- would enhance the activities of RuO2 for HER and OER via modifying the electronic structure to facilitate intermediate adsorption, thereby reducing the energy barrier of the rate-determining step. The water electrolysis by using RuO2-200 as the catalyst on both anode and cathode demonstrates a stable generation of hydrogen and oxygen with high Faradic efficiency at a current density of ≈30 mA cm-2 and a potential of below 1.47 V.

Bifunctional NiCo-CuO Nanostructures: A Promising Catalyst for Energy Conversion and Storage.

This investigation explores the potential of co-incorporating nickel (Ni) and cobalt (Co)into copper oxide (CuO)nanostructures for bifunctional electrochemical charge storage and oxygen evolution reactions (OER). A facile wet chemical synthesis method is employed to co-incorporate Ni and Co into CuO, yielding diverse nanostructured morphologies, including rods, spheres, and flake. The X-ray diffraction (XRD) and Raman analyses confirmed the formation of NiCo-CuO nanostructure, with minor phases of nickel oxide (NiO)and cobalt tetraoxide (Co3O4). High-resolution Transmission Electron Microscope (HRTEM) also confirms the diverse morphologies and the minor phases of oxides. Synchrotron X-ray absorption spectroscopy revealed higher charge states of Cu, Ni, and Co in the NiCo-CuO nanostructure, enhancing its charge storage and OER. Site-selective X-ray absorption near edge structure analysis elucidated the spatial distribution of Cu, Ni, and Co in the nanostructure. Furthermore, extended X-ray absorption fine structure spectroscopy provided insights into the local atomic structures, revealing increased coordination numbers and interatomic distances in the NiCo-CuO nanostructure. In situ Raman analysis discloses the transformation of Co3O4 into cobalt hydroxide (Co(OH)2) and cobalt oxide (CoO) into cobalt oxyhydroxide (CoOOH) The NiCo-CuO nanostructures exhibited superior specific capacitance, favorable Tafel behavior, and low overpotential positioning as promising bifunctional materials for energy storage and conversion applications. This work contributes to the development of efficient CuO nanocatalysts.

Unveiling the Electrocatalytic Performances of the Pd-MoS2 Catalyst for Methanol-Mediated Overall Water Splitting

Herein, this work elucidates the synthesis of the Pd-MoS2 catalyst for application in methanol-mediated overall water splitting. The scanning electron microscope (SEM) and transmission electron microscope (TEM) pictures offer an exciting nanostructured shape of the Pd-MoS2, depicting a high surface area. Further, high-resolution TEM (HRTEM) pictures confirm the lattice plane (100), lattice spacing (0.26 nm), and hexagonal crystal structure of the Pd-MoS2. Moreover, high-angle annular dark-field (HAADF) images and related color maps disclose the Mo, S, and Pd elements of the Pd-MoS2. The Pd-MoS2 catalyst exhibits lower overpotentials of 224.6 mV [methanol-mediated hydrogen evolution reaction (MM-HER)] at −10 mA cm−2 and 133 mV [methanol-mediated oxygen evolution reaction (MM-OER)] at 10 mA cm−2. Further, the Pd-MoS2 illustrates noteworthy stability for 15.5 h for MM-HER and 18 h for MM-OER by chronopotentiometry test. Excitingly, the Pd-MoS2∥Pd-MoS2 cell reveals a small potential of 1.581 V compared to the MoS2∥MoS2 cell (1.648 V) in methanol-mediated overall water splitting. In addition, the Pd-MoS2∥Pd-MoS2 combination reveals brilliant durability over 18 h at 10 mA cm−2.

Thermal conductivity of AlN thin films deposited by reactive DC magnetron sputtering on different substrates using ultra-fast transient hot strip technique

In the frame of this work, we report a profound insight into the thermal conductivity (k) of aluminum nitride (AlN) thin films deposited on AlN-molecular beam epitaxy (MBE)/Si(111) and AlN-Kyma/Si(111) substrates at low temperatures (<200 °C) using reactive direct current magnetron sputtering (DCMS). Our concern is not on the thermal properties at the nanoscale, but rather on relating thermal macroscopic properties to the microstructure for submicronic to micronic AlN films. As the mean free path for AlN material is about 100 nm, the thickness of our films lies between 400 nm and 2 μm. The k measurements were conducted using the ultra-fast transient hot strip technique. It was found that the k values of the deposited films change depending on both the substrate type and the film thickness. For the 500 nm AlN thick film, k value was about 250 W m−1 K−1 for AlN-DCMS films grown on 10 nm AlN-MBE/Si against 90 W m−1 K−1 for those deposited on 200 nm AlN-Kyma/Si. The thermal boundary resistance has been computed equal to (0.25 ± 0.08) × 10−9 K m2 W−1 on 10 nm AlN-MBE/Si against (3.56 ± 1.50) × 10−9 K m2 W−1 on 200 nm AlN-Kyma/Si. Additionally, both pole figures and high resolution transmission electron microscopy confirm k results. In fact, pole figures confirm the good crystal quality of the film on both substrates, but HR-TEM analyses show that the AlN films grown on 10 nm AlN-MBE/Si template exhibit good crystalline quality with an epitaxial regrowth and abrupt interface compared to those obtained for 200 nm AlN-Kyma/Si. It also appears that the thermal boundary resistance plays a major role in the thermal properties of AlN films.

Dielectric Constant of a Single MoO3 Nanostructure.

MoO3 is a promising transition metal oxide due to its high dielectric constant (κ) and multifunctionality in electronic and optoelectronic applications. Oxidation-induced nanoscale MoO3, synthesized via oxidation scanning probe lithography (o-SPL) of MoS2, requires in-depth characterization of its dielectric properties. In this study, we measured the κ of a single MoO3 nanostructure, which was confirmed to be in the amorphous phase through water solubility tests and high-resolution transmission electron microscopy (HRTEM). Using electrostatic force microscopy (EFM) and numerical calculations, we determined a high κ value of approximately 25, nearly six times higher than that of SiO2. Additionally, nanoscale κ imaging revealed that the κ of MoO3 nanostructures is independent of their size. These findings suggest that oxidation-induced MoO3 nanostructures are promising candidates as high-κ dielectric materials for future nanoscale devices.

Pick-and-Place Transfer of Arbitrary-Metal Electrodes for van der Waals Device Fabrication.

Van der Waals electrode integration is a promising strategy to create nearly perfect interfaces between metals and 2D materials, with advantages such as eliminating Fermi-level pinning and reducing contact resistance. However, the lack of a simple, generalizable pick-and-place transfer technology has greatly hampered the wide use of this technique. We demonstrate the pick-and-place transfer of prefabricated electrodes from reusable polished hydrogenated diamond substrates without the use of any sacrificial layers due to the inherent low-energy and dangling-bond-free nature of the hydrogenated diamond surface. The technique enables transfer of arbitrary-metal electrodes and an electrode array, as demonstrated by successful transfer of eight different elemental metals with work functions ranging from 4.22 to 5.65 eV. We also demonstrate the electrode array transfer for large-scale device fabrication. The mechanical transfer of metal electrodes from diamond to van der Waals materials creates atomically smooth interfaces with no interstitial impurities or disorder, as observed with cross-section high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. As a demonstration of its device application, we use the diamond transfer technique to create metal contacts to monolayer transition metal dichalcogenide semiconductors with high-work-function Pd, low-work-function Ti, and semimetal Bi to create n- and p-type field-effect transistors with low Schottky barrier heights. We also extend this technology to air-sensitive materials (trilayer 1T' WTe2) and other applications such as ambipolar transistors, Schottky diodes, and optoelectronics. This highly reliable and reproducible technology paves the way for new device architectures and high-performance devices.

Microwave Plasma-Driven Synthesis of Graphene and N-Graphene at a Gram Scale

The large-scale microwave plasma synthesis of graphene and nitrogen-doped graphene with tailored structural properties, crucial for their successful usage applications, has been demonstrated. The developed atmospheric pressure plasma method offers several advantages, including the continuous production of high-quality, free-standing graphene without the use of chemicals, solvents, catalysts, or additional heating. This non-toxic process eliminates the need for vacuum systems while achieving high temperatures. The method enables the precise control over graphene’s properties, such as the layer number, defects, sheet size, uniformity, and functionality, as well as the doping type and configuration, by adjusting the plasma parameters. Protocols for the synthesis of specific nanostructures with a controlled structural quality, production rate, and chemical composition have been established using methane and methylamine as precursors. The comprehensive physicochemical characterization of the graphene and nitrogen-doped graphene was carried out using scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy.

Influence of the Sodium Titanate Crystal Size of Biomimetic Dental Implants on Osteoblastic Behavior: An In Vitro Study

Treating the surfaces of dental implants in an alkaline medium allows us to obtain microstructures of sodium titanate crystals that favor the appearance of apatite in the physiological environment, producing osteoconductive surfaces. In this research, 385 discs made of titanium used in dental implants underwent different NaOH treatments with a 6M concentration at 600 °C and cooling rates of 20, 50, 75, and 115 °C/h. Using high-resolution electron microscopy, the microstructures were observed, and the different crystal sizes were determined and compared with control samples (those without biomimetic treatment). Roughness, wettability, surface energy and the sodium content of the surface were determined. The different surfaces were cultured with human osteoblastic cells; cell adhesion was determined at 3 and 14 days, and the degree of mineralization was determined at 14 days via alkaline phosphatase levels. Variations in the microstructure and size of sodium titanate crystals in NaOH solutions rich (1 g/L) or low in calcium (approximately 100 ppm) were determined. The results show that as the cooling rate increases, the size of the crystals decreases (from 0.4 μm to 0.8 μm) except for the case of 115 °C/h, when the rate is too fast for crystalline nucleation to occur on the surface of the titanium. The thermochemical treatment does not influence the roughness or the cooling rate since a Sa of 0.21 μm is maintained. However, the presence of titanate causes a decrease in the contact angle from 70° to 42° and, in turn, causes an increase in the total surface energy from 35 to 49.5 mJ/m2, with the polar component standing out in this energy increase. No variations were observed in the thermochemical treatments in the presence of sodium, which was around 1200 ppm. It was observed that as the size of the crystals decreases, cell adhesion increases at 3 days and decreases at 14 days. This is because finer crystals on the surface are already in the mineralization process, as demonstrated using the level of alkaline phosphatase that is maximal for the cooling rate of 75 °C/h. It was possible to confirm that the variations in the concentrated NaOH solutions with different calcium contents did not affect the crystal sizes or the microstructure of the surface. This research makes it possible to obtain dental implants with different mineralization speeds depending on the cooling rate applied.

Raman Signature of Stripe Domains in Monolayer WxMo1-xS2 Alloys.

We study the Raman signature of stripe domains in monolayer WxMo1-xS2 alloys, characterized using experimental techniques and density functional theory (DFT) calculations. These stripe domains were found in star-shaped monolayer WS2 exhibiting a high concentration of molybdenum (Mo) atoms in its central region, and unique Raman peaks that were not previously reported. We attribute these peaks to the splitting of the original doubly degenerate E2g modes, arising from the lower symmetry of the W-Mo stripe domains. We confirm the stripe presence and location using high-resolution scanning transmission electron microscopy (STEM) imaging and use DFT to elucidate the structural, electronic, and vibrational properties of the stripes when the stoichiometry corresponds to W0.5Mo0.5S2. The findings provide insight into the evolution of the Raman spectra as stripe domains arise in TMD alloys, thus contributing to a broader understanding of the influence of atomic-level structural modifications on material properties.

Synthesis of three-dimensional covalent organic frameworks through a symmetry reduction strategy.

Three-dimensional (3D) covalent organic frameworks (COFs) hold significant promise for a variety of applications. However, conventional design approaches using regular building blocks limit the structural diversity of 3D COFs. Here we design and synthesize two 3D COFs, designated as JUC-644 and JUC-645, through a methodology that relies on using eight-connected building blocks with reduced symmetry. Their structures are solved using continuous rotation electron diffraction and high-resolution transmission electron microscopy, which reveal a unique linkage with a double chain structure, a rare phenomenon in COFs. We deconstruct these structures into [4 + 3(+ 2)]-c nets, which leads to six different topologies. Furthermore, JUC-644 demonstrates high adsorption capacity for C3H8 and n-C4H10 (11.28 and 10.45 mmol g-1 at 298 K and 1 bar, respectively), surpassing most known porous materials, with notable selectivity for C3H8/C2H6 and n-C4H10/C2H6. This approach opens avenues for designing intricate architectures and shows the potential of COFs in C2H6 recovery from natural gas liquids.

Synergistic Effect of Nickel Hydroxide/Hexagonal Boron Nitride Hybrid: An Efficient Electrocatalyst for Detecting 5-Fluorouracil in Human Blood Serum.

5-Fluorouracil (5-Fu) is the third-most often used chemotherapeutic medication and has been scientifically demonstrated to be effective in treating solid tumors, including colorectal, stomach, cutaneous, and breast cancers. When used in excess, it accumulates toxic metabolites, which can have deadly and very harmful effects on people, including neurotoxicity and the induction of morbidity. Therefore, sensitive and rapid analytical techniques for detecting 5-Fu in human blood serum are needed to enhance chemotherapy and forecast the possible adverse effects of 5-Fu residues in the human body. In this report, we developed a simple preparation of three-dimensional/two-dimensional (3D/2D) Nickel hydroxide/hexagonal boron nitride modified with a glassy carbon electrode [Ni(OH)2/h-BN/GCE] for effective electrochemical detection of the 5-fluorouracil with high selectivity. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution scanning electron microscopy (HR-SEM), and HR-Transmission electron microscopy (HR-TEM) were used to characterize the crystalline, structural, and chemical properties of the as-synthesized materials. Moreover, the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and i-t curves examined the electrode's electrochemical properties and sensor applications. Therefore, under ideal circumstances, Ni(OH)2/h-BN/GCE demonstrated outstanding 5-Fu selectivity, durability, a low LOD (0.001 μM), and a good linear range (0.02-12 μM). Finally, excellent results were obtained while testing this sensor for 5-Fu sensing in human blood serum.

Temperature Dependence on Microstructure, Crystallization Orientation, and Piezoelectric Properties of ZnO Films.

This study has investigated the effects of different annealing temperatures on the microstructure, chemical composition, phase structure, and piezoelectric properties of ZnO films. The analysis focuses on how annealing temperature influences the oxygen content and the preferred c-axis (002) orientation of the films. It was found that annealing significantly increases the grain size and optimizes the columnar crystal structure, though excessive high-temperature annealing leads to structural degradation. This behavior is likely related to changes in oxygen content at different annealing temperatures. High resolution transmission electron microscopy (HR-TEM) reveals that the films exhibit high-resolution lattice stripes, confirming their high crystallinity. Although the films exhibit growth in multiple orientations, the c-axis (002) orientation remains the predominant crystallographic growth. Further piezoelectric property analysis demonstrates that the ZnO films annealed at 400 °C exhibit enhanced piezoelectric performance and stable linear piezoelectric behavior. These findings offer valuable support for optimizing the piezoelectric properties of ZnO films and their applications in piezoelectric sensors.

Biosynthesis, characterization of Ag2O nanoparticles for enhancement of antioxidant and photo degradation activities

Silver oxide (Ag2O) nanoparticles were synthesized via Biosynthesis methods using Croton macrotachyus leaf extract silver sulphate (Ag2SO4) was used as precursors and the extract was used in the reactions as reducing, stabilizing and capping agents which is a very easy and inexpensive synthesis method. Metal oxide nanoparticles characterized using UV–visible, TGA, Fourier transform infrared(FTIR),powder X-ray diffraction(XRD), X-ray photoelectron(XPS), and Scanning Electron Microscopy(SEM) with Energy Dispersive X-Ray(EDX) and Transmission Electron Microscopy(TEM), High Resolution Transmission Electron Microscope(HRTEM), and Selected Area Electron (SAED) which is used for determination of crystalline size, morphology,particle size and oxidation state with composition of elements in the sample. Metal oxide nanoparticles have a significant photo catalytic performance under visible light source confirmed that study supported Ag2O spherical structure, which exhibits enhanced photo catalytic activity and anti-oxidant activities as well as the size of the Ag2O nanoparticles was between 16 nm and 21 nm from the XRD(Scherrer equation),SEM & TEM) imaje software and Photo catalytic activity of Ag2O NPs were assessed against methylene blue (MB) dye degradation under natural sunlight illumination for 60 min. This sustainably photo degraded in direct solar irradiance with remarkable degradation percentage which is greater than 96.35 % and Scavenging activities Ag2O nanoparticles enhanced DDPH scavenging activities was 88 %

Influence of the graphene incorporation on nanostructure and thermal properties of the laser powder bed fusion processed AlSi12 matrix composites

The successful fabrication and implementation of graphene-reinforced aluminum (Al) matrix composites (AMCs) have been obstructed by the undesirable graphene-Al reactions during their casting or inability of complex part manufacturing through powder metallurgy techniques. The emergence of the laser powder bed fusion (L-PBF) process with extremely short melt duration and almost no limitations in terms of the manufacturing of intricate features has renewed the interests for fabrication of graphene-reinforced AMCs. In this study, the influence of graphene incorporation into AlSi12 on L-PBF processability and defect formation is studied. The specific heat capacity, coefficient of thermal expansion, thermal diffusivity and thermal conductivity of composites were compared to those of the monolithic AlSi12 alloy. Microstructure-thermal properties relationship was studied through transmission electron microscopy (TEM), high-resolution TEM (HRTEM), electron backscatter diffraction (EBSD), electron dispersive spectroscopy (EDS) and Raman spectroscopy. This study provides valuable insights into (i) the chance of survival of graphene, (ii) possibility of graphene changing into other forms of carbon, and (iii) graphene-Al reactions during the L-PBF process. It was found that most of the graphene/graphite particles transformed into Al4C3. Among the survived carbon material, it appears they are more disordered than the initial graphene/graphite, though highly ordered ones with almost no defects were also detected. Thermal expansion measurements showed that the coefficient of thermal expansion decreased from 27.5×10-6/˚C for AlSi12 to 25.3×10-6/˚C for AlSi12-0.25Gr and 25.5×10-6/˚C for AlSi12-0.5Gr. Regarding thermal conductivity, in the case of AlSi12-0.5Gr, it either matched or was lower than that of pure AlSi12 within the tested temperature range. In contrast, AlSi12-0.25Gr exhibited higher thermal conductivity than AlSi12 in the temperature range of 150-350 ˚C.