X-ray Diffraction Spectroscopy Research Articles

Insights into the Morphological Effects of 1D, 2D, and 3D CoV-Layered Double Hydroxides on Their Electrochemical Performance in Supercapacitors.

In this study, bimetallic cobalt-vanadium-based layered double hydroxide (CoV-LDH) systems were developed by varying the Co/V molar ratios (1:1 and 2:1) and hydrothermal temperatures (120 and 180 °C). Structural analysis by X-ray diffraction (XRD), Raman, and Fourier-transform infrared (FTIR) spectroscopy indicated the successful formation of CoV-LDH with a unique structure and lattice distortions, reflecting the influence of both the metal concentrations and temperature on the crystal and chemical structures of the developed bimetallic systems. Similarly, the field-emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) images revealed a flaky 2D nanosheet-like structure for the bimetallic CoV-LDH with a 1:1 ratio prepared at 120 °C (CVL1-120), whereas one-dimensional (1D) and three-dimensional (3D) morphologies were observed for other bimetallic CoV-LDH systems prepared with a different molar ratio (2:1) and/or temperature (180 °C). Electrochemical analysis performed in a three-electrode setup demonstrated a specific capacitance of 314.4 F g-1 at 1 A g-1 current density for CVL1-120, which is ∼4.5 and 5.2 times higher than those of monometallic Co and V-LDH, respectively. In addition, CVL1-120 exhibited an excellent capacitance retention of ∼97% over 5000 charge-discharge cycles with 100% Coulombic efficiency at 10 A g-1. Furthermore, the developed asymmetric device delivered an energy density of 36.5 Wh kg-1 and a power density of 1208.2 W kg-1. This enhanced performance of CVL1-120 was attributed to its two-dimensional (2D) flaky structures, with rich intercalated ions serving as electroactive sites, facilitating enhanced charge storage efficiency and improved stability, making it suitable as an electrode material for sustainable supercapacitors.

Physicochemical and structural characterization of novel praseodymium and neodymium-incorporated TiO2 for photocatalytic application

Abstract Novel photocatalytic metal–organic framework (MOF) materials are an exciting research topic. However, the lack of investigating rare-earth doped semiconductor as well as understanding their physicochemical and structural characterization will prevent commercial or industrial applications. To overcome this obstacle, this study investigates the physicochemical and structural characterization of novel applied Titania-based materials synthesized via MOF strategy for photodegradation of methyl orange (MO). The studied materials are TiO2, Pr-doped TiO2 (Pr@TiO2), and Nd-TiO2 (Nd@TiO2) and applied as promising photocatalysts. The synthesized photocatalysts were prepared via metal–organic framework strategy and characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). SEM analysis revealed that only Nd resulted in smaller, more uniform particle sizes. XRD patterns confirmed the retention of the anatase phase in the case of Nd-modification, indicating successful lattice distortions. XPS results showed the chemical existence of Pr and Nd, increased oxygen vacancies, and surface hydroxyl groups, essential for enhanced photocatalytic activity. Photodegradation studies demonstrated that both Pr-TiO2 and Nd-TiO2 exhibited better performance compared to TiO2 without Pr or Nd, following pseudo-first-order kinetics. These findings highlight the potential of Pr and Nd modification in the TiO2 photocatalysts for efficient environmental remediation, particularly in the treatment of dye-containing wastewater.

Synthesis of MnS thin film: investigation of thickness-dependent physical properties

Abstract Herein, manganese sulfide (MnS) thin films are grown on glass substrates using the successive ionic layer adsorption and reaction (SILAR) method. SILAR is simple and inexpensive, does not require a high-quality substrate or vacuum environment, has no limitation on the size of the substrate material, has the ability to obtain materials at room temperature, shows easier doping process relative to other methods, and has the ability to control the growth rate and thickness of films. MnS with different thicknesses is coated on a glass surface, and various analyses are performed to examine the effect of the thickness on the film properties. Ultraviolet–visible analysis is used to examine the optical properties of the film, X-ray diffraction (XRD) spectrometry to examine its structural properties, and scanning electron microscopy and atomic force microscopy (AFM) to examine its morphological properties. XRD results indicate that the obtained MnS thin films have a cubic structure and achieve the highest peak intensity at 2θ = 32.87°. With increasing film thickness, the grain size increases from 9.20 to 13.36 nm and the energy band gap decreases from 3.32 to 3.02 eV. AFM results demonstrate that with increasing film thickness, the surface roughness value decreases from 84 to 53 nm. Moreover, increasing thickness improves the optical, structural, and morphological properties of the film.

Photocatalytic properties of Mn2O3 nanoparticles synthesized via green chemistry method

The objective of this work is to synthesize Mn2O3 nanoparticles (NPs) using green method based on olive leaf extract (OLE). These nanoparticles are intended for photocatalytic applications, specifically the degradation of pollutants and dyes using methylene blue (MB) as a test substance. The synthesized material, initially described as manganese oxide (Mn2O3), was characterized using various techniques: thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR, Raman and UV-visible spectroscopies. Additionally, the photocatalytic tests were performed. XRD analysis revealed the formation of Bixbyite (Mn2O3) phases. Raman and FT-IR spectroscopy confirmed the presence of Mn-O bonds within the synthesized material. The TGA results supported the decomposition of organic compounds and the formation of the Mn2O3. The photocatalytic degradation tests with methylene blue yielded promising results. The addition of the synthesized material (Mn2O3) significantly enhanced the degradation of methylene blue, achieving an efficiency of 87.8%.

Study of evolution for 3D structured surface with nano-balls and walls-like features with thickness variation for WO3 thin films made by spray deposition

The present work regards a unique yet study of 3D structured surface evolution of nano-balls and walls-like features with thickness variation, for tungsten oxide (WO3) thin films made by spray deposition. Since in most optoelectronic applications the surface morphology and structure play a crucial role and WO3 is one of the most studied and used metal oxide semiconductors in a significant variety of optoelectronic applications, a detailed study of recently observed and reported unique 3D complex architecture of WO3 coatings fabricated by spray pyrolysis (starting from different precursors) is of great importance for further development of thin film coatings and devices. In this scope, two different series of WO3 of 11 samples with different thicknesses each, starting from two tungsten peroxide precursor concentrations (0.05 M and 0.1 M) were fabricated by spray pyrolysis and thoroughly characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction and Raman spectroscopy. Results suggest that, for the mentioned concentrations, the main structural differences affect mostly the surface morphology and slightly the surface texturing. These observations prove the reliability of fabrication of coatings with such surface morphology by spray pyrolysis method and open new perspectives for better sensors, electrochromic or photochromic devices, and more.

Isotherms, Kinetics and Thermodynamics of Removal of Pb (II), Cd (II) and Cr (III) Ions in Wastewater onto Green Silver Nanoparticle Adsorbent

Moringa oleifera leaf extract mediated silver nanoparticles (MOR-AgNPs) were synthesized from a water-soluble leaf using a green technique. The plant's secondary metabolites served as capping and reducing agent. The spectroscopic characterization of the material was carried out by means of Scanning Electron Microscope (SEM), Ultraviolet-Visible Spectroscopy (Uv-vis), X-ray Diffraction Spectroscopy (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Transition Electron Microscope (TEM), Energy Dispersion Spectroscopy (EDS), and Dynamic Light Scattering (DLS). The UV–Vis spectrum showed absorption peak between 400 – 500 nm, while TEM revealed spherical images of sizes in the nano region. The MOR-AgNPs adsorbent uptake of the metal ions was optimized by varying concentration, shaking time, adsorbent mass, pH, and temperature conditions. The isotherm models studies revealed that the type-1 Langmuir fitted well to the adsorption showing monolayer/homogeneous adsorption. The second order kinetics fitted well to the adsorption study, while positive values of ΔH° and ΔS° indicated endothermic and increased randomness at the MOR-AgNPs-aqueous interface. The ΔG° showed that the sorption of the metal ions onto the adsorbent was spontaneous, making the adsorption process feasible. The Ea values for the metal ion adsorption onto the adsorbent used in this study suggest a physical adsorption process. The adsorption capacity of 294.15 mg/g (40 °C, and pH of 6) of Cd(II), 123.63 mg/g (40 °C, and pH 10) of Pb(II), and 122.93 mg/g (40 °C, and pH 6) of Cr (III) ions on MOR-AgNPs adsorbent were obtained.

STUDY PHASE STRUCTURE, CATION DISTRIBUTION AND MAGNETIC PROPERTIES OF COBALT, MAGNESIUM AND COPPER FERRITES

An analysis to the characteristics of Co, Mg and Cu ferrites that were prepared using sol–gel method and annealed at [Formula: see text]C for 1 hour, performed using X-ray diffraction and Raman spectroscopy for structural characteristics, while the Vibrating Sample Magnetometer (VSM), was used for the magnetic characteristics. The X-ray analysis of both cobalt and magnesium ferrites shows a reverse crystal structure of a cubic spinel, while copper ferrite shows a tetragonal crystal structure characteristic at this annealing temperature. The lattice constant (a) was found to be [Formula: see text] for CoFe2O4, [Formula: see text] for MgFe2O4 and [Formula: see text] for CuFe2O4. The Raman spectrum confirms a spinel crystalline form of the prepared ferrites where a likely distribution of cation is indicated at the tetrahedral and octahedral sites. The peaks of the Raman shift appear between 200–800[Formula: see text]cm[Formula: see text]. These peaks indicate the formation of ferrites. The hysteresis loop of CoFe2O4 indicates a hard magnet material. Cu ferrites have relatively lower remnants and magnetocrystalline anisotropy, which indicates soft magnetic characteristics even though it showed higher coercivity. The squareness ratio (Mr/Ms) values varied between 0.52, 0.13 and 0.57 for CoFe2O4, MgFe2O4 and CuFe2O4, respectively. These insights highlight the possibility of tuning the properties of ferrites using a cost-effective sol–gel method.

Effect of particle size on the oxygen reduction reaction activity of carbon‐supported niobium-oxide‐based nanoparticle catalysts

Abstract In this study, niobium oxynitride nanoparticles were examined to determine the effect of particle size on oxygen reduction reaction (ORR) activity. To this end, catalyst precursors with niobium oxides dispersed on carbon supports were prepared using the irradiation or impregnation method. Polyacrylonitrile was added to each precursor, followed by heat treatment under an ammonia‐containing atmosphere to synthesize niobium oxynitride nanoparticles. The structures of the prepared catalysts were analyzed using transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. The results indicated that two catalysts with the same crystal phase but different particle sizes were obtained. Comparing their ORR activities revealed that the effect of particle size on ORR activity was limited. Thus, it was inferred that controlling the microelectron conduction paths can help maximize the benefits of particle size reduction. In addition, niobium oxynitride nanoparticles with different structures were obtained by varying the heat-treatment temperatures, and the ORR activity of each prepared catalyst was evaluated. These findings suggest that forming graphitized carbon residues with high electrical conductivity and controlling nitrogen-doping in the oxide nanoparticles are crucial steps for enhancing the ORR activity of oxide-based catalysts. These findings offer valuable insights for developing material design strategies to improve oxide-based catalyst performance. Graphical abstract

Facile synthesis of vanadium oxide thin films by atomic layer deposition and post-annealing

We report the facile synthesis of vanadium oxide (VOx) thin films on sapphire substrates by atomic layer deposition (ALD) and post-annealing. Amorphous VOx thin films are grown by ALD employing tetrakis[ethylmethylamino]vanadium and ozone as precursors. Subsequent post-annealing of the as-grown VOx thin films at 500 °C in atmospheres of air, 1 Pa O2, and vacuum (10−4 Pa) could, respectively, result in the crystallization of V2O5, VO2, and V2O3 phases, as verified by x-ray diffraction and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) reveals that the valence states of vanadium in the annealed thin films exhibit dramatic changes with the variation of annealing atmosphere toward the targeted phases. The VO2 thin film exhibits a sharp metal–insulator transition (MIT) near 340 K with a resistivity change exceeding three orders of magnitude. The V2O3 thin film features a characteristic MIT with obvious thermal hysteresis between the cooling and warming processes, whereas the V2O5 thin film is highly insulating. The spectral weight near the Fermi level revealed by the XPS in the valence band region coincides with the changes of VOx phases and consequent transport properties due to post-annealing. Our results demonstrate that the combination of ALD and post-annealing provides a facile method for the synthesis of multivalent VOx thin films for practical applications.

Electrochemical Determination of Capsaicin at A Multiwalled Carbon Nanotubes/CuO Nanocomposite Modified Platinum Electrode

Herein, electrochemical detection of capsaicin (CAP) in sauce and rub samples at a Pt electrode modified with copper oxide nanoparticles (CuO NPs) incorporated with functionalized multi-walled carbon nanotubes (fMWCNTs) was reported. The spectroscopic and microscopic characterization of CuO NPs, fMWCNTs and CuO/fMWCNTs nanocomposite with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) spectroscopy and Fourier-transform infrared spectroscopy (FT-IR) spectroscopy confirmed that CuO/fMWCNTs was prepared from the nanomaterials. Electrochemical characterization of the bare Pt, the fMWCNTs-modified Pt, the CuO NP-modified Pt (Pt-CuO) and the CuO/fMWCNTs composite modified Pt (Pt-CuO/fMWCNTs) electrodes revealed that the Pt-CuO/fMWCNTs exhibited the best electron transfer capabilities. The limit of detection (LOD) and the linear range of CAP at Pt-CuO/fMWCNTs were 0.0881 and 0.357–2.73 µM, respectively. The proposed sensor offered outstanding percentage recovery of 106 and 102% when applied to the electroanalysis of CAP in spiked sauce and rub samples, respectively. Pt-CuO/fMWCNTs also retained about 88% of its initial current response when subjected to 25 cyclic voltammetry (CV) scans in the presence of CAP.

Immobilization of Trametes versicolor laccase on LDH/alginate composite beads for improved textile dyes decolorization.

Laccase is an oxido-reductase known for its applications in biomass valorization (lignin depolymerization), in fine chemicals (building-blocks synthesis) or in environment (wastewater treatment). It works with molecular oxygen and produces water as its only by-product. However, its practical use remains limited due to the low stability and poor reusability of free laccase. To overcome these challenges, laccase from Trametes versicolor was immobilized onto layered double hydroxide and alginate composite beads by a glutaraldehyde cross-linker to create an easily separable and stable enzyme. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD) and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the as-synthesized composite beads (laccase@MgFe(LDH)/alginate). The activity of the immobilized laccase was measured with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) model substrate. Here, the optimal conditions of laccase immobilization were explored and the effects of various conditions of immobilization, pH, storage stability and thermal resistance of the (laccase@MgFe(LDH)/alginate) were also studied. The results revealed that the optimal conditions for laccase immobilization were a concentration of glutaraldehyde of 2.5 %, an amount of laccase (0.5 U/mg) of 2 mg/mL, and an immobilization time of 6 h. The stability of (laccase@MgFe(LDH)/alginate) was >70 % of its initial activity, even after 10 cycles. The study of dye decolorization showed up to 74 % of methylene blue (MB) and 69 % of Crystal violet (CV) degradation, suggesting the use of immobilized laccase on MgFe(LDH)/alginate composite beads as a promising and environmentally friendly tool for the degradation of environmental pollutants, in particular for the removal of diazo dyes from wastewater.

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.

Preparation of the titanium-based composite coagulant PTFS and its coagulation performance on nanoparticles.

In this study, a titanium-based coagulant, (i.e., PTFS), with a three-dimensional spatial mesh structure was prepared for the coagulation removal of polystyrene (PS) and titanium dioxide (TiO2) nanoparticles in water. The results of scanning electron microscopy, TGA-DSC, Fourier infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy characterization showed that the PTFS was not a simple mixture of raw materials and a chemical reaction occurred, thereby generating new chemically connected bonds. The optimum removal of PS could reach 92.5% at the dosage of 0.6mg/L, initial concentration of 70 mg/L, pH of 7, stirring intensity of 350 rpm, settling time of 60 min, and kaolin concentration of 70 mg/L. The best removal rate of TiO2 could reach 95.3% when the dosage was 0.8mg/L, the initial concentration was 70 mg/L, the pH was 7, the stirring intensity was 350 rpm, the settling time was 60 min, and the kaolin concentration was 50 mg/L. The flocs produced by PTFS were large and dense. In the early stage of coagulation, the flocculation mechanism was dominated by electroneutralization, and in the middle and late stages of coagulation, adsorption, bridging, and netting were dominated. This study aims to provide a reference for the removal of nanopollutants by coagulation in the actual water treatment process. PRACTITIONER POINTS: A titanium-based coagulant PTFS with a three-dimensional spatial mesh structure was prepared. PTFS effectively removes nano-PS and nano-TiO2 from water. The flocs produced by PTFS were large and dense flocs. Removal of PS and TiO2 by PFTS has been a combination of multiple coagulation mechanisms.

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.