X-ray Diffraction Spectroscopy Research Articles

Impact of low dose of gamma irradiation on thin films of Bismuth Tri-iodide.

Thin films of Bismuth Tri-iodide BiI3 were synthesized on a glass substrate by the thermal vacuum deposition technique. Films were exposed to gamma radiations of two doses 10Gy and 50Gy. Structural and optical properties of films were studied through X-ray Diffraction and UV spectroscopy both before and after the gamma irradiation. The effect of gamma radiations on microstructure parameters i.e. crystallite size and the micro-strain were studied qualitatively and quantitively. The observed increase in crystallite size and decrease in micro-strain is due to localized heating of crystallites which results in the merging of small crystallites and their assembly leading to the formation of larger crystallites as evident from X-ray Diffraction after gamma irradiation. Effect on the optical constants namely refractive index and extinction coefficient for different doses was also enumerated to throw light on the change in optical density of this material on gamma irradiation. It is observed that the refractive index n increases with an increase in the doses of gamma irradiation. The increase in optical density could be attributed either to the displacement of atoms from lattice sites to the interstitial sites or to the self-assembly behavior of the crystallites on irradiation. The absorption coefficient follows Urbach's empirical relation and exhibits exponential dependency on photon energy close to the band edge. Calculating Urbach's energy provides insight into the emergence of localized states at the energy gap's edges.

Biodegradable Plastics from Marine Biomass: A Solution to Marine Plastic Pollution

The growing demand for plastics has raised environmental concerns due to their non-biodegradable nature. Sustainable solutions are urgently required to decrease plastic pollution. This study explored the potential of Sargassum wightii, a seaweed found in Malaysia, as a sustainable material for bioplastic films. The seaweed-based bioplastic was produced using an extraction-based method where alginate was formed using NaOH, followed by mixing sodium alginate with isopropanol and potato starch. The bioplastic was then characterized using various analytical techniques, including Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier-Transform Infrared (FTIR) spectroscopy. Physical properties such as density and moisture content, along with environmental tests like water absorption and biodegradability, were evaluated. TGA analysis indicated that 31.12% of the sample remained as residue. FTIR spectroscopy identified the presence of bioactive compounds, with a prominent alcohol group peak at 3358cm-1. XRD analysis revealed a peak at 23.1°, indicating crystallinity within the sample. The moisture content of the bioplastic film was found to be 21.16%. The water absorption test demonstrated the film's hydrophilic nature, showing a 60% increase in weight. A soil burial test for biodegradability confirmed a 40% reduction in weight over 21 days, indicating a reasonable degradation rate. These findings suggest that seaweed holds promise as an alternative raw material for bioplastic production, contributing to more sustainable materials and reducing reliance on non-biodegradable plastics.

Biosynthesis and Application of Biological Thin Films for Heavy Metal Ion Biosorption from Aqueous Solution

This study investigates the biosynthesis and application of Mycelium Bio-Films (MBFs) derived from pure Common oyster mushroom (COM) for heavy metal ion biosorption from aqueous solutions. The research focuses on the growth mechanism of MBFs and their potential for Cu (II) ions removal. MBFs were synthesized through a hyphae cultivation process and characterized using Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and Energy-Dispersive X-ray Spectroscopy (EDS) mapping. Batch biosorption experiments were conducted to determine optimal operational parameters and adsorption mechanisms. Key findings reveal optimal biosorption conditions at pH 5, with a 40-minute contact time, and 100mg/L initial Cu (II) concentration using 0.2g of biosorbent in 10mL aqueous solution at room temperature with 150rpm agitation. Under these conditions, a maximum adsorption efficiency of 82.8% was achieved. The adsorption process best fits Pseudo-second-order kinetics and Langmuir isotherm, indicating chemisorption, complexation, and ion exchange as primary mechanisms. Functional groups involved in biosorption include carboxyl, hydroxyl, and amide groups. Importantly, MBFs demonstrate high reusability potential through diluted acid elution. This research contributes to environmental remediation by presenting a novel, sustainable biosorbent for heavy metal removal. The MBFs show promise for industrial wastewater treatment applications, offering an eco-friendly alternative to conventional adsorbents and contributing to filling the lack of biobank collections. Future studies could explore the efficacy of MBFs with other heavy metals and investigate potential scale-up for large-scale implementation.

A High-Capacity Manganese-Metal Battery with Dual-Storage Mechanism.

As a promising post lithium-ion-battery candidate, manganese metal battery (MMB) is receiving growing research interests because of its high volumetric capacity, low cost, high safety and high energy-to-price ratio. However, the low energy density, mainly constrained by scarce choices and unsatisfying capacity of cathodes, strictly bottlenecks the development of MMBs. In this work, a new class of cathodes based on novel dual-storage mechanism (DSM) are reported. Working principles of DSM are revealed and deeply understood via ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. Besides, a proof-of-concept DSM-based Cu1.8S cathode, which shows the highest specific capacity of 220 mAh g-1 and 97.1% higher energy density than previously reported cathodes in storing Mn2+ ions, is presented. The key determinants on DSM and design strategies for next-generation cathodes are revealed via theoretical calculations. This work provides a new class of high-capacity cathode materials for MMBs, which is expected to draw inspirations to further enhance the energy density of MMBs.

Ph3AsO as a Strong Hydrogen-Bond Acceptor in Cocrystals with Hydrogen Peroxide and gem-Dihydroperoxides.

Hydrogen-bonded cocrystals have attracted considerable attention as they allow fine-tuning of properties through the choice of hydrogen-bond donors and acceptors. In this study, triphenylarsine oxide (Ph3AsO) is introduced as a strong hydrogen-bond acceptor molecule. Due to its higher Lewis basicity compared to triphenylphosphine oxide (Ph3PO), it acts as a strong hydrogen-bond acceptor, which is demonstrated in six new cocrystals with H2O2 and gem-di(hydroperoxy)cycloalkanes. All cocrystals formed large, high-quality single crystals, which were analyzed by X-ray diffraction and IR spectroscopy. The cocrystal of Ph3AsO with H2O2 shows prolonged stability without loss of oxidative power. In addition, the newly formed interactions were also present in solution and were detected by NMR spectroscopy. The higher electron-donating ability of Ph3AsO compared to Ph3PO was confirmed by competition experiments. Ph3AsO exclusively binds H2O2, even in dilute aqueous solutions and in the presence of Ph3PO. This study expands the range of hydrogen-bond acceptors and demonstrates that Ph3AsO is a useful cocrystallizing tool in crystal engineering and a sensitive marker for hydrogen peroxide.

Characterisation and visible light induced antibacterial activity of Cu-doped zinc oxide nanoparticles

ABSTRACT Zinc oxide particles doped with copper were produced using a cost-effective sol-gel approach at a temperature of 80°C. The process involved combining Zn(NO3)2, Cu(NO3)2, and citrate precursors. A variety of analytical techniques, including scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (UV-Vis DRS), and energy dispersive X-ray diffraction spectroscopy (XRD), were employed to study the physical and chemical characteristics of the nanoparticles. The addition of copper resulted in a significant decrease in the size of wurtzite ZnO nanoparticles, reducing from 180 nm for undoped ZnO to 133 and 40 nm for 10% Cu-doped and 25% Cu-doped ZnO, respectively. The absorption spectra displayed a gradual shift towards the visible range as the concentration of copper in the ZnO particles increased. The calculated band gaps for the various samples were determined to be 3.1 eV for undoped ZnO, 2.3 eV and for 10% Cu-doped ZnO, and 1.8 eV for 25% Cu-doped ZnO. The antibacterial efficacy of Cu-doped ZnO was observed to be significantly greater than that of the undoped sample. Additionally, it demonstrated antibacterial activity under visible light conditions, which suggests the successful synthesis of zinc oxide particles that are induced by visible light.

Eu3+-doped ZnO quantum dots: structure, vibration characteristics, optical properties, and energy transfer process.

This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu3+-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu3+ ions using Reisfeld's approximation. Eu3+-doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu3+ ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. XRD results demonstrated the crystalline nature of the ZnO QDs, revealing their wurtzite (WZ) structure with no secondary phases. XPS analysis provided further confirmation of the presence of Eu3+ ions within the ZnO host, with clear signals corresponding to the Zn, O, and Eu elements. The valence states of Eu were verified as trivalent (Eu3+), confirming the successful doping of Eu3+ ions, as evidenced by the characteristic Eu 3d peaks in the XPS spectra. Raman spectroscopy (RS) was employed to analyze the vibrational modes, revealing shifts in ZnO lattice vibrations due to Eu3+ incorporation, indicating strong coupling between Eu3+ ions and the ZnO host. Optical properties were studied using UV-Vis absorption, photoluminescence (PL) spectroscopy, and PL decay spectroscopy, showing a significant enhancement of red emission, attributed to the 5D0 → 7F2 transition of Eu3+ ions under UV excitation. Using Judd-Ofelt (JO) analysis, the intensity parameters (Ω 2, Ω 4, Ω 6) were derived, providing insights into the asymmetry of the Eu3+ ion's local environment and the radiative transition probabilities. Energy transfer processes between the ZnO host and Eu3+ dopants were examined, showing efficient sensitization of Eu3+ through excitation of the ZnO host, with an optimal Eu3+ doping level maximizing luminescence. Eu3+-doped ZnO QDs, which emit in the visible light region and are non-toxic, have great potential for applications in photonic devices, light-emitting diodes, and bioimaging.

Enlargement of the Surface Area of High-Entropy Alloys with Acid Treatment as Positive Electrode for High Specific Capacitance Supercapacitors.

High-entropy alloys (HEAs), containing five or more elements in equal proportions, have recently made significant achievements in materials science due to their remarkable properties, including high toughness, excellent catalytic, thermal, and electrical conductivity, and resistance to wear and corrosion. This study focuses on a HEA composed of 23Fe-21Cr-18Ni-20Ti-18Mn, synthesized via ball milling. The alloy was treated with hydrochloric acid (HCl) to enhance its active surface area. The untreated HEA and the HCl-treated HEA (HEA-T) were then evaluated as potential cathode materials for supercapacitors (SCs). X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) confirmed that the HEA's composition and crystalline structure remained stable during acid treatment, with no new phases forming. The acid treatment significantly increased the surface area by ~20 times, the pore volume by ~10 times, and improved microstructural homogeneity. The HEA-T electrode demonstrated superior specific capacitance, lower internal resistance, and better cycling stability than the untreated HEA electrode. At 0.5 A/g current density, the specific capacitance (Csp) of the HEA-T was 600 F/g, approximately two times higher than the untreated HEA. This enhanced performance suggests that the HEA-T electrode could lead to the development of high-performance SCs.

Recovery of Scandium from Bauxite Residue Using Sulfation Roasting-Assisted Water Leaching Process

ABSTRACT This study presents a method for recovering scandium from Indonesian bauxite residue (red mud) through a sulfation roasting-assisted water leaching process. Ammonium sulfate, (NH4)2SO4, was chosen as the sulfate source for its lower melting point, less corrosivity, decreased toxicity, and the potential for ammonia recovery. A modified mixing system was introduced to improve the distribution of (NH4)2SO4 on red mud particles by combining them in water. A series of experiments were conducted to optimize the sulfation roasting process by examining the effects of the (NH4)2SO4/red mud ratio, temperature, and roasting time. Subsequently, water leaching was optimized while considering the effect of leaching time and liquid-to-solid (L/S) ratio. The leaching of scandium from the roasted red mud showed rapid kinetics, even when using only water. Under the roasting conditions of 1/1 (g/g) (NH4)2SO4/red mud ratio, 700°C, 60 min roasting time, and the leaching conditions of 65°C, 60 min, and 10 mL/g (L/S), over 90% of scandium was recovered, along with 64.4% Al leaching and below 8% Fe leaching. These results were further corroborated through comprehensive analyses such as x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). This study offers insights into an alternative, more environmentally friendly method for Sc recovery from red mud, promoting the sustainable use of hazardous waste like red mud.

Synthesis and Catalytic Application of Cu2O Nano Hollow Arrays in RingExpansion Aromatization Reactions

Introduction: Aromatization of dithioacetal derivatives is essential for the synthesis of bioactive compounds and drug design, playing a key role in pharmaceuticals, agrochemicals, and materials science. This study explores the synthesis and catalytic application of Cu2O nano hollow arrays in ring-expansion aromatization reactions of cyclic dithioacetal derivatives obtained from cyclohexanones. Methods: By using Cu2O nano hollow arrays prepared through molecular templates and a simple hydrothermal process, the electrophilicity of N-bromosaccharin was enhanced, allowing for efficient and selective production of aromatic compounds with yields ranging from 63-96%. Copper acetate is transformed into Cu2O nano hollow arrays in aqueous media, with polyvinylpyrrolidone acting as a capping agent and (+)-L-tartaric acid as a structure-directing surfactant and multidentate ligand. Results: The synthesized Cu2O nano hollow arrays were characterized using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive Xray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to verify their morphology, structure, and composition. Conclusion: This method not only offers a cost-effective and environmentally friendly approach to synthesizing Cu2O with unique nano hollow structures, but also demonstrates their efficacy as catalysts in organic synthesis, particularly in the rarely reported ring-expansion aromatization of cyclic dithioacetal derivatives of cyclohexanone, emphasizing their broader applicability in materials science and catalysis.

Efficient Carbon-Based Optoelectronic Synapses for Dynamic Visual Recognition.

The human visual nervous system excels at recognizing and processing external stimuli, essential for various physiological functions. Biomimetic visual systems leverage biological synapse properties to improve memory encoding and perception. Optoelectronic devices mimicking these synapses can enhance wearable electronics, with layered heterojunction materials being ideal materials for optoelectronic synapses due to their tunable properties and biocompatibility. However, conventional synthesis methods are complex and environmentally harmful, leading to issues such as poor stability and low charge transfer efficiency. Therefore, it is imperative to develop a more efficient, convenient, and eco-friendly method for preparing layered heterojunction materials. Here, a one-step ultrasonic method is employed to mix fullerene (C60) with graphene oxide (GO), yielding a homogeneous layered heterojunction composite film via self-assembly. The biomimetic optoelectronic synapse based on this film achieves 97.3% accuracy in dynamic visual recognition tasks and exhibits capabilities such as synaptic plasticity. Experiments utilizing X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) confirms stable π-π interactions between GO and C60, facilitating electron transfer and prolonging carrier recombination times. The novel approach leveraging high-density π electron materials advances artificial intelligence and neuromorphic systems.

Corrosion behavior of Fe amorphous/Al-12Si piston composites with core-shell structure

The current piston material, Al-12Si, lacks sufficient passivation in the acidic lubrication system of biodiesel engines, making it prone to corrosion in the presence of Cl−. Fe amorphous particles exhibit good compatibility with Al-12Si, possessing strong corrosion resistance, excellent passivation ability, and good high-temperature stability. They are a potential reinforcement for enhancing the Al-12Si piston material. Fe amorphous/Al-12Si core-shell structural composites (FACS) were synthesized through ball milling and hot extrusion. The composites’ composition, microstructure, and elemental distribution were characterized by X-ray diffraction, optical microscopy, and EDS spectroscopy. To accelerate the evaluation process, Potentiodynamic polarization and Electrochemical impedance spectroscopy were used to study the electrochemical corrosion behavior. By analyzing the self-corrosion current density (icorr), self-corrosion potential (Ecorr), polarization resistance, inductance, admittance absolute value (Y0), and diffusion coefficient (n), the mechanism of Fe amorphous particle doping in enhancing the corrosion resistance of Al-12Si was discussed. The research results indicate that: The Fe amorphous particles, during ball milling and hot extrusion at 440 °C, do not recrystallize and maintain their good passivation ability. Spherical Fe amorphous particles act as “balls bearings” during hot extrusion, enhancing flowability and promoting the formation of a core-shell structure FACS with uniform composition distribution, high relative density, and low porosity when doping with 2–10% Fe amorphous particles. This prevents the formation of local potential differences, making the potential on the alloy surface more uniform, which helps reduce the risk of galvanic corrosion and improves corrosion resistance. However, when the doping content of Fe amorphous particles reaches 20%, excessive doping particles squeeze and rub against each other during hot extrusion, leading to amorphous agglomeration, low relative density, and high porosity defects in the resulting FACS, which causes uneven potential, increases local potential differences, and reduces corrosion resistance. Compared to Al-12Si, FACS doped with 2–10% Fe amorphous particles shows a decrease in icorr from 254.66 µA/cm2 to 114.98 µA/cm2, and an increase in Ecorr from 766.89 mV to 794.78 mV, indicating a reduced corrosion rate with the doping of an appropriate amount of Fe amorphous particles. As the doping content of Fe amorphous particles increases from 2 to 10%, the polarization resistance increases, indicating improved corrosion resistance; the inductance increases, suggesting that corrosion primarily occurs at the surface; Y0 increases, and n decreases, indicating a reduction in the depth of the corrosion reaction, and the stability of the surface protective oxide film is improved. However, when the doping content of Fe amorphous particles reaches 20%, the opposite effect occurs, and the corrosion resistance of the FACS decreases. Notably, FACS with 10% Fe amorphous particles exhibited the strongest corrosion resistance, making it a potential candidate for biodiesel engine pistons.

Thorium(IV) and Uranium(IV) Complexes with 2,6-Dipicolinoylbis(N,N-diethylthiourea) Ligands

The reaction of thorium nitrate hydrate with 2,6-dipicolinoylbis(N,N-diethylthiourea), H2Lpic, results in the hydrolysis of the organic ligand and the formation of [Th(2,6-dipicolinolate)2(H2O)4] (1). Hydrolysis can be avoided by the use of [ThCl4(DME)2] (DME = 1,2-dimethoxyethane) as the starting material and the exclusion of water. The product, [Th(Lpic)3]2− (2), crystallizes as diammonium salt in form of yellow crystals in moderate yields. The thorium ion in the complex is nine-coordinate by the central O,N,O donor atoms of three deprotonated {Lpic}2− ligands. The sulfur atoms of the ligands do not bind to the actinide ion, but establish hydrogen bonds to the ammonium counter ions. A similar coordination sphere is also observed in the uranium(IV) complex [UAu2(Lpic)3}] (3), which was obtained from a reaction between H2Lpic, [U2I6(1,4-dioxane)3] and [AuCl(tht)] (tht = tetrahydrothiophene) in the presence of triethylamine. Charge compensation is established by the linear coordination of two Au+ ions between each two sulfur atoms of the ligands. The products have been studied by X-ray diffraction and IR spectroscopy. The actinide ions in both {Lpic}2− complexes have coordination number nine, but establish slightly different coordination spheres.

Highly Green Fluorescent Carbon Dots from Gallic Acid: A Turn-On Sensor toward Pb2+ Ions.

Carbon dots (CDs) are emerging novel fluorescent sensing nanomaterials owing to their tunable optical properties, biocompatibility, and eco-friendliness. Herein, we report a facile one-pot hydrothermal route for the synthesis of highly green fluorescent CDs using gallic acid (GA) as a single carbon source in N,N-dimethylformamide (DMF) solvent, which serves as a nitrogen source and reaction medium. The optical properties of the synthesized GA-DMF CDs were systematically characterized by using UV-vis and photoluminescence spectroscopy, revealing strong green fluorescence. Further, to gain insights into their size and structural, elemental, and chemical composition, Fourier transform infrared, dynamic light scattering, high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction, and X-ray photoelectron spectroscopy characterization techniques were performed. HR-TEM analysis confirmed the formation of uniformly spherical GA-DMF CDs with an average particle size of 16 ± 6.1 nm. Notably, the GA-DMF CDs exhibited a highly selective and turn-on fluorescent response to Pb2+ ions in aqueous solutions, which was attributed to a chelation-enhanced fluorescence mechanism. The detection limit for Pb2+ ions was determined to be as low as 7.15 × 10-7 M, with a broad linear detection range of 30-130 μM, underscoring their sensitivity and practical application in water quality monitoring. This study introduces a novel, sustainable approach for synthesizing nitrogen-doped CDs with outstanding optical properties and highlights their unprecedented selectivity toward Pb2+ ions, advancing the development of efficient and eco-friendly sensing platforms for heavy metal detection.

Effect of doping Mn ion on the crystal structure and cation distribution in Co1-xMnxFe2O4 compounds

In this study, we investigated the effect of Mn doping on the crystal structure and the distribution of cations at tetrahedral and octahedral sites in Co1-xMnxFe2O4 compounds (0 ≤ x ≤ 0.4), synthesized utilizing a solid phase reaction method, utilizing X-ray diffraction (XRD) and Raman spectroscopy measurements. The surface morphology and chemical composition of the compounds were studied using scanning electron microscope and X-ray energy dispersive spectroscopy. The Rietveld refinement of XRD data using the Fullprof package demonstrate that all studied samples are single phase spinels with no other detectable phases and have a cubic structure with the space group of Fd-3 m. The lattice constant and unit-cell volume increased with increased Mn doping concentration, which are attributed to the larger ionic radius of Mn in comparison with Co. Both the X-ray diffraction and Raman spectroscopy results demonstrated that doping Mn at the Co-site leads to the movement of Fe cations from the tetrahedral sites to the octahedral ones.

Hydrogel loaded with cerium-manganese nanoparticles and nerve growth factor enhances spinal cord injury repair by modulating immune microenvironment and promoting neuronal regeneration

BackgroundSpinal cord injury (SCI) treatment remains a formidable challenge, as current therapeutic approaches provide only marginal relief and fail to reverse the underlying tissue damage. This study aims to develop a novel composite material combining enzymatic nanoparticles and nerve growth factor (NGF) to modulate the immune microenvironment and enhance SCI repair.MethodsCeMn nanoparticles (NP) and CeMn NP-polyethylene glycol (PEG) nanozymes were synthesized via sol–gel reaction and DSPE-mPEG modification. Transmission Electron Microscopy, Selected-Area Electron Diffraction, X-ray Diffraction and X-ray Photoelectron Spectroscopy confirmed their crystalline structure, mixed-valence states, and redox properties. Size uniformity, biocompatibility, and catalytic activity were assessed via hydrodynamic diameter, zeta potential, and elemental analysis. The Lightgel/NGF/CeMn NP-PEG composite was synthesized and characterized via electron microscopy, compression testing, rheological analysis, NGF release kinetics, and 30-day degradation studies. Both in vitro and in vivo experiments were conducted to evaluate the therapeutic effects of the composite on SCI.ResultsThe Lightgel/NGF/CeMn NP-PEG composite was successfully synthesized, exhibiting favorable physical properties. At a CeMn NP-PEG concentration of 4 µg/mL, the composite maintained cell viability and demonstrated enhanced biological activity. It also showed superior mechanical properties and an effective NGF release profile. Notably, the composite significantly upregulated the expression of nerve growth-associated proteins, reduced inflammatory cytokines, scavenged reactive oxygen species (ROS), and promoted M2 macrophage polarization by inhibiting the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. In a rat SCI model, it facilitated functional recovery and attenuated inflammation.ConclusionThe Lightgel/NGF/CeMn NP-PEG composite shows significant therapeutic promise for SCI, effectively eliminating ROS, promoting M2 macrophage polarization, reducing pro-inflammatory cytokines, and supporting neuronal regeneration. These effects substantially enhance motor function in SCI rats, positioning it as a promising candidate for future clinical applications.Graphical

Raman Spectroscopy of Graphene/CNT Layers Deposited on Interdigit Sensors for Application in Gas Detection

Graphene/CNT layers were deposited onto platinum electrodes of an interdigitated sensor using radio-frequency magnetron sputtering. The graphene/CNTs were synthesized in an Argon atmosphere at a pressure of (2 × 10−2–5 × 10−3) mbar, with the substrate maintained at 300 °C either through continuous heating with an electronically controlled heater or by applying a −200 V bias using a direct current power supply throughout the deposition process. The study compares the surface morphology, carbon atom arrangement within the layer volumes, and electrical properties of the films as influenced by the different methods of substrate heating. X-ray diffraction and Raman spectroscopy confirmed the formation of CNTs within the graphene matrix. Additionally, scanning electron microscopy revealed that the carbon nanotubes are aligned and organized into cluster-like structure. The graphene/CNT layers produced at higher pressures present exponential I–V characteristics that ascertain the semiconducting character of the layers and their suitability for applications in gas sensing.

Sonochemical Functionalization of SiO2 Nanoparticles with Citric Acid and Monoethanolamine and Its Remarkable Effect on Antibacterial Activity.

Nanoparticles (NPs) are excellent antibacterial agents due to their ability to interact with microorganisms at the cellular level. However, their antimicrobial capacity can be limited by their tendency to agglomerate. Functionalizing NPs with suitable ligands improves their stability and dispersion in different media and enhances their antibacterial activity. The present work studied the functionalization of SiO2 NPs using the sonochemical method and the Influence of organic ligands on antimicrobial activity (AA). The organic ligands studied were citric acid (CA) and monoethanolamine (MEA). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the amorphous structure of SiO2 NPs and their functionalization. Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) showed that functionalization with MEA (SiO2-MEA NPs) is more favored compared to AC (SiO2-CA NPs), and the organic ligand content was 34.42% and 28.0%, respectively. Fourier-transform infrared spectroscopy (FTIR) and RAMAN spectroscopy results confirmed the functionalization of NPs through the presence of carboxyl and amino groups. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential results showed that functionalization of SiO2 NPs helped to improve their dispersion and prevent their agglomeration. Furthermore, the results of antibacterial activity against Staphylococcus aureus and Escherichia coli showed that the functionalization provided a significant improvement in the antibacterial activity (AA) of the SiO2 NPs, where the SiO2-CA NPs showed the highest activity, with a 99.99% inhibition percentage at concentrations of 200 ppm against both E. coli and S. aureus strains. The AA is maintained at high concentrations of 1200 ppm, which is essential in applications requiring high percentages of biocidal NPs, such as marine coatings.

Investigation of the effect of Si content on the structural, mechanical, and tribological properties of TiAlN/AlSi protective multilayers

Abstract Titanium aluminum nitride and aluminum silicon alloys (TiAlN/AlSi) or for simplicity (TAN/AS) bilayer system were deposited on glass and piston aluminum substrates by following three steps. First, AlSi films realized by thermal evaporation with different Si content (7, 10, 13, 22) %. Then, TiAl films were deposited on AlSi layers using a reactive DC magnetron sputtering system, and finally the realization of TAN/AS multilayers were done by nitriding via Direct Current Plasma Nitriding (DCPN) in a custom setup, with pure nitrogen gas. For each sample, the structural properties like phase’s formation and vibration modes were investigated by X-ray diffraction and Raman spectroscopy, while AFM microscopy investigated surface topography. The mechanical and tribological properties in terms of hardness and friction coefficient were determined using the nanoindentation technique and tribometer. It has been found that all the coatings TAN/AS have crystalline structures with the presence of TiAlN, TiN, AlN, TiAl, and α-Al phases. Raman spectroscopy reveals the appearance of TO/LO, 2O, and 2TO/LO modes for all layers. AFM images show that the coatings have low roughness, Ra values decrease from 17.3 nm for 7 % Si to 5.5 nm for 13 % Si and increases to 9.9 nm at 22 % Si. The grain size exhibits a reversed behavior compared to that of roughness. The hardness and Young modulus reach their optimum values at 13 % Si with no respect to Hall–Petch law. The friction coefficient of TAN/AS coatings decreases with Si content and reaches its lowest value (<0.1) at 22 % Si as a potential protective layer.

Green Synthesis of Red Fluorescent Carbon Quantum Dots: Antioxidant, Hemolytic, Biocompatibility, and Photocatalytic Applications.

A straightforward one-step hydrothermal method is introduced for synthesizing highly efficient red fluorescence carbon dots (R-CQDs), utilizing Heena leaf (Lawsonia inermis) powder as the carbon precursor. The resulting R-CQDs exhibit excitation at 540nm and emission at 675nm, a high absolute photoluminescence (PL) with quantum yield of 40% in ethanol. Various physicochemical characterization was employed to confirm successful formation of R-CQDs including UV-Vis Spectroscopy, Fourier Transform Infrared (FT-IR) Spectroscopy, X-ray diffraction Spectroscopy, Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy. The optimization of synthesis parameters including synthesis method, effect of reaction temperature, effect of reaction time and effect of reaction concentration have a significant impact on the quality and quantity of synthesized R-CQDs, as well as their properties and applications. The effect of pH and UV radiation on synthesized R-CQDs exhibited excellent photo and chemical stability. Furthermore, R-CQDs had a high ability to protect cells from hydrogen peroxide-induced damage by scavenging hydroxyl radicals.In antioxidant activity, all three methods show approximately 80% of DPPH, Fenton's reaction and KMnO4 scavenging activity. In hemolytic assay shows no damage or destruction of red blood cells after exposure of R-CQDs. Cell viability and angiogenesis assays confirmed the biocompatibility of the R-CQDs, indicating that they might be useful as agents for cell labelling and useful for bioimaging probe. In dye degradation activity shows highest % of dye degradation in eosin and fluorescein with approximately 80% of dye degradation by using R-CQDs.