HRTEM Images Research Articles

Enhancing bacterial control and daylight-driven water remediation with chitosan-impregnated MoC nanosheets.

The functionalization of nanoparticles with 2D nanosheets is an effective approach to enhance their functional properties for pollutant removal. This research outlines the synthesis of a 2D-delaminated molybdenum carbide (MXene) chitosan nanocomposite (2D-d-Mo2CTx-Cs NC) with bacterial control and photocatalytic properties for dye adsorption. The nanocomposite includes Tx-surface terminating groups O, OH, and F. In this investigation, the composite was synthesized using the etching method and its formation was confirmed through UV spectra at 288nm. It was characterized through FTIR, XRD, Particle size, Zetapotential, FESEM, HRTEM, EDAX, and XPS analyses. FTIR spectral analysis of NC suggests that amines are formed through a Schiff base reaction between glutaraldehyde and Cs, or through the interaction of terminal aldehydes and carbonyl groups. The XRD analysis confirmed the crystalline structure of the composite. FESEM images revealed irregularly structured nanosheets (NSs) material in the prepared 2D-d-Mo2CTx-Cs NC samples. HRTEM images revealed 2D-d-Mo2CTx NSs impregnated onto Cs with an average size of 50nm, as confirmed by a particle size analyzer, with a zeta potential value of -15mV. Additionally, Mo, C, N, and O are the most significant elements present in the NC, as confirmed by EDAX and XPS analyses. Further, biocompatibility testing of 2D-d-Mo2CTx-Cs NC yielded positive results. Moreover, under sunlight, the composites effectively adsorbed methylene blue with a 90% adsorption capacity, as confirmed by kinetic studies. Furthermore, the synergistic effect of Cs and d-Mo2CTx NSs resulted in significant antibacterial (50-200µl of 1mg/ml) and antibiofilm activity (100µl of 1mg/ml) against pathogenic bacteria. Furthermore, this study represents the first report on the use of 2D-d-Mo2CTx-Cs NC for daylight-influenced photocatalytic applications with a bacteria-controlling effect.

Defect Density and Atomic Defect Recognition in the Middle Layer of a Trilayer MoS2 Stack.

Molybdenum disulfide (MoS2) is one of the most intriguing two-dimensional materials, and moreover, its single atomic defects can significantly alter the properties. These defects can be both imaged and engineered using spherical and chromatic aberration-corrected high-resolution transmission electron microscopy (CC/CS-corrected HRTEM). In a few-layer stack, several atoms are vertically aligned in one atomic column. Therefore, it is challenging to determine the positions of missing atoms and the damage cross-section, particularly in the not directly accessible middle layers. In this study, we introduce a technique for extracting subtle intensity differences in CC/CS-corrected HRTEM images. By exploiting the crystal structure of the material, our method discerns chalcogen vacancies even in the middle layer of trilayer MoS2. We found that in trilayer MoS2 the middle layer's damage cross-section is about ten times lower than that in the monolayer. Our findings could be essential for the application of few-layer MoS2 in nanodevices.

Development of an active agar aerogel with dual antioxidant and UV-blocking activities using chlorine-doped graphene quantum dots

Active packaging is of great interest in the modern food industry due to increasing shelf life and enhancing food quality. The importance of this technology increases when natural polymers are used in the construction of active packages. Development of a natural, biodegradable, and dual-active film was aimed in this study. So, agar aerogel containing different amounts of chlorine-doped graphene quantum dots (Cl-GQDs) was prepared. Cl-GQDs had excitation-dependent fluorimetry behavior due to the zigzag edges of graphene. The mean diameter of spherical nanoparticles of Cl-GQDs was about 12 nm, according to HR-TEM images. The results of Raman and ATR-FTIR confirmed that chlorine was well-doped on the GQD structure. Cl-GQDs showed high UV-absorption capability and very strong antioxidant activity (94.31 %), which maintained these activities after incorporation into the agar aerogel. The doped chlorine was responsible for the capacity to charge transfer of GQDs. BET and SEM results showed that adding Cl-GQDs to agar caused a porous structure. Finally, different types of agar aerogels containing Cl-GQDs can be used considering the intended application of aerogel. Agar aerogel containing 20 % Cl-GQDs is suggested if a porous aerogel with good thermal insulation properties is considered. However, agar aerogel containing 1 % Cl-GQDs is suitable as an active film. In conclusion, while Cl-GQDs hold promise as sustainable and multifunctional food packaging materials, their potential toxic effects must be thoroughly evaluated. Future studies should explore migration, potential interactions with specific food matrices, and long-term safety to ensure consumer protection.

Unveiling the impact of Fe-doping concentration on the local structure and morphological evolution of Cr2O3 nanoparticles

A series of Cr2−xFexO3 (0.0 ≤ x ≤ 0.3) nanoparticles were successfully synthesized using a sol-gel-based method. Analysis through XRD and SAED of both pure and Fe-doped Cr2O3 nanoparticles revealed a rhombohedral structure belonging to the R3‾cD3d6 space group, without the formation of secondary phases or Fe clusters. Fe ions were well integrated, as indicated by fluctuations in lattice parameters, and lattice strain. The crystallite size decreased from 38.42 to 27.54 nm with increasing doping concentration. HRTEM images depicted evenly distributed nanoparticles. At lower dopant concentrations (x = 0.1), smaller and more heterogeneous nanorod-like structures emerged, with average sizes and lengths of 36.56 and 39 nm, respectively. Increasing the doping content to x = 0.2 resulted in a morphological shift towards semi-spherical and ellipsoidal shapes, with average dimensions of 22.84 and 31 nm, respectively. At higher doping levels (x = 0.3), nanoparticles grew to 66.5 nm in size and exhibited a spherical morphology. Raman and Fourier transform infrared spectra showed red-shifting of absorption bands with increasing Fe content, attributed to variations in bond length and Cr/Fe–O–Cr/Fe structural perturbation. XPS and Mössbauer spectroscopy analyses confirmed the oxidation states of Fe3+ and ionized oxygen vacancies in the crystal lattice of Cr2O3 nanoparticles. Higher values of quadrupolar splitting Δ indicated greater structural disorder induced by Fe3+ in octahedral positions and in an oxygen-deficient environment. Atomistic simulations confirmed that Fe3+ dopants can induce the presence of vacancy-complexes, forming a stable double-defect configuration with vacant Cr sites along the c-axis, proximal to oxygen vacancies with a single positive charge. These findings offer both experimental and theoretical insights into the dynamics of structural defects in trivalent transition metal doping of Cr2O3 nanoparticles, which holds significant implications for spintronics research.

Towards realistic structural char models: Generation of stacked graphene-like layers using constrained reactive molecular dynamics simulations

For a molecular understanding of coal combustion, realistic coal and char models are pivotal. We propose a novel top-down method for the construction of char models, consisting of stacked graphene-like layers with defects. We start on the mesoscale with corrugated stacked surfaces as a template. Then the carbon atoms are pre-positioned on these surfaces and surrounded by hydrogen atoms. In a constrained reactive MD simulation the carbon atoms are then rearranged into a chemically reasonable state with dangling bonds saturated by hydrogen atoms. Importantly, the initial shape of the template is maintained to a great extent, leading to a substantial amount of defects in the graphitic planes, especially for high curvatures. In a final step, small molecular fragments and unfavorable arrangements are removed and remaining dangling bonds are saturated with hydrogen atoms. The central advantage over other approaches is the ability to choose the shape and size of the templating planes, with the possibility to use experimental input.The method is validated on single sheets with a protrusion and application examples are shown for stacked graphitic layers with up to 100 Å size and more than 20000 atoms. It represents the first step of a longer term project. In the future, heteroatoms and functional groups will be implemented, and by combining several such stacks, the approach will allow the construction of more realistic char models using the data from HRTEM images as an experimental boundary condition. On this basis important questions like the adsorption and diffusion of volatiles under high temperatures can be studied on a molecular level.

Structural, Morphological, and γ-ray Attenuation properties of m-type hexaferrite BaFe12O19 doped with V2O5, Ce2O3 and Bi2O3 for Radiation Shielding applications

This paper studies, structurally analyzes, evaluates the morphology, and assesses the gamma-ray and neutron attenuation properties of a composite material composed of M-type hexaferrite BaFe12O19 (BF) doped with three additional compounds: Bi2O3, V2O5, and Ce2O3. X-ray diffraction revealed that the structure of BF can be indexed to a hexagonal structure, BF/Bi2O3 to a tetragonal structure, BF/V2O5 to a cubic structure, and BF/Ce2O3 to a trigonal structure. These results were refined using PROFEX software. The Crystallite size of the nano-powders was determined by X-ray line broadening using the Williamson-Hall method. Morphology evaluations illustrated that HR-TEM images for BF, BF/Bi2O3, BF/V2O5, and BF/Ce2O3 reveal high crystallinity with a polycrystalline nature. Various attenuation measurements, using the FLUKA Monte Carlo code, aimed to determine the efficacy of these dopants into m-type hexaferrite BF as potential materials for radiation shielding applications. Doping with Bi2O3 into hexaferrite BF markedly enhances its attenuation properties, demonstrating superior Linear Attenuation Coefficient (LAC) values across a broad energy spectrum from 0.16 to 10 MeV. The Mass Attenuation Coefficient (MAC) analysis revealed a pivotal energy threshold at 0.3 MeV. Below this energy, BF presented the highest MAC values. Conversely, for energies equal to or greater than 0.3 MeV, BF exhibited the highest MAC values, affirming its superior gamma photon shielding efficacy. The study of the Half Value Layer (Δ0.5) and Mean Free Path (MFP) provided additional evidence of the superior shielding performance of BF/Bi2O3. The Δ0.5 values ranged between 0.128 to 1.240 cm for BF, 0.162 to 1.430 cm for BF/V2O5, 0.163 to 1.390 cm for BF/Ce2O3, and 0.162 to 1.210 cm for BF/Bi2O3, indicating that BF/Bi2O3 requires a thinner layer to halve the gamma-ray intensity, particularly at higher energies. The MFP values further support the improved shielding ability of BF/Bi2O3, with measurements showing that gamma photons travel the shortest distance before interacting with the material, thereby reducing the potential for radiation exposure.

Bioengineered sustainable phytofabrication of anatase TiO2 -adorned g-C3N4 nanocomposites and unveiling their photocatalytic potential towards advanced environmental remediation

The ecologically friendly properties, low-cost, and readily available titanium dioxide (TiO2) materials have made them a subject of considerable interest for numerous promising applications. Anatase TiO2 nanoparticles were synthesized in the current study through the utilization of a hibiscus leaf extract and the advent of TiO2-doped g-C3N4(TiCN) nanocomposites (varying 0.5 mM, 1.0 mM, 1.5 mM, and 2.0 mM) by thermal polymerization. Here, the proposed study utilized multiple analytical techniques, including UV–Vis spectroscopy, a diffraction pattern (XRD), SEM coupled with EDX analysis, TGA, and EPR, to characterize the as-prepared TiO2 nanoparticles and TiCN nanocomposites. BET analysis the adsorption-desorption isotherms of the TiCN(1.5 mM) nanocomposite, the surface area of the prepared nanocomposite is 112.287 m2/g, and the pore size is 7.056 nm. The XPS spectra support the development of the TiCN(1.5 mM) nanocomposite by demonstrating the presence of C and N elements in the nanocomposite in addition to TiO2. HRTEM images where the formation of stacked that indicates a planar, wrinkled graphitic-like structure is clearly visible. The TiCN (1.5 mM) specimen exhibited enhanced morphology, enhanced surface area, greater capacity to take in visible light, and lowered band gap when compared to g-C3N4 following z-scheme heterojunction. The sample denoted as TiCN (1.5 mM) exhibited superior performance in terms of adsorption and photocatalytic activity using rhodamine B and Bisphenol A. Furthermore, the TiCN (1.5 mM) composite exhibited satisfactory stability over four cyclic runs, indicating its potential application in minimizing the impact of organic wastewater contaminants when compared to g-C3N4.

Exploring the physical properties of pristine γ-In2S3 and its influence on Ba doping for photocatalytic degradation of 2,4-D herbicide

In this work, pristine γ-In2S3 nanoribbons were synthesized using a facile solution process and uniquely doped with Ba for the first time. XRD and Raman spectroscopy confirmed the formation of pure-phase γ-In2S3 and successful Ba doping. XPS further validated the presence of Ba 3d core level with In 3d and S 2p after the inclusion of Ba. FESEM and HRTEM images showed the formation of nanoribbons, with the width increasing from 60 to 100 nm after doping. The anticipated stoichiometry of In and S, with approximately 2 atomic % of Ba, was confirmed by EDS. After Ba-doping, the bandgap was narrowed from 3.66 eV to 3.03 eV, and the charge carrier recombination was substantially reduced, as witnessed by PL and EIS. The potential of pristine γ-In2S3 and Ba-doped γ-In2S3 as new photocatalysts was highlighted in this study, exploring their applicability for the photodegradation of the stubborn herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The materials demonstrated impressive performances, achieving degradation efficiencies of 77.08 % and 94.15 % before and after doping, respectively, within 210 min. The scavenging tests revealed a significant contribution of O2•− and •OH for 2,4-D degradation using Ba-doped γ-In2S3 photocatalyst. Besides photocatalysts used in this study demonstrated excellent stability after four cycles. These findings suggest a promising approach for developing cost-effective semiconductors to remove persistent herbicides.

Efficient removal of Pb (II) ions from aqueous solution by the Moringa oleifera synthesized magnetic ZnFe2O4 spinel nanoparticles

Water-based Pb(II)ion removal was tested on Moringa oleifera modified ZnFe2O4 nanoparticles. For the strong crystal plane, XRD analysis predicts high crystallinity and 18 nm average crystallite sizes. Tetrahedral and octahedral spikes oscillate at 650 and 482 cm−1, metal ions like Zn-O and Fe-O resonate at 400–600 cm−1. Porosity particles and complicated integration linkages with hydroxyl groups from distinct fatty acid sequences characterise omega-3 and zinc ion nanoparticles. HRTEM images revealed spherical ZnFe2O4 nanoparticles with an average diameter of 8–12 nm and interplanar spacing and lattice fringes matching the tetragonal phase's (311) crystal plane. Due to interparticle gaps, N2 equilibrium temperatures at 77.5 K produced mesoporous material with 120.6 m2 g−1 BET specific surface area and 15.6 nm pore width. Spinel ZnFe2O4 demonstrated photocatalytic activity in daylight with prolonged UV-to-visible photo absorption. Prepared nanoparticles exhibited ferromagnetic functionality, a saturation magnetic field of 10 emu/g, a permanence of 2 emu/g, and a forcefulness of 100 Oersted has, which is less than the significant value of 72 emu/g. Lead elimination kinetics show that PSO kinetics better capture adsorption kinetics than PFO kinetics. Rate diffusion-driven surface features may potentially explain Pb(II) adsorption kinetics. pH 6.2 is optimal for Pb(II) removal. Adsorption process seems endothermic and impulsive. Monolayer adsorption over a consistent region may have deposited Pb(II) on ZnFe2O4. Langmuir method found ZnFe2O4 maximum adsorption capacity of 142.2 lead (mg)/adsorbent (g) and it adsorbs lead (II) ions similarly to other adsorption agents, perhaps due to its large effective surface area.

Agglomeration and thermophysical parameters investigation of nanocrystalline Al2SiO5 particles at different heating rates

DTA, TGA, and DTG methods were applied at different heating rates to comparative study of thermal parameters of nanocrystalline Al2SiO5particles. Hydroxyl groups on the surface of the nanoparticles and the process of their release under the influence of temperature were explained by the corresponding DSC spectra. Simultaneously, the size and composition of the nanoparticles were measured by HRTEM imaging and EDX analysis. Possible andalusite − sillimanitetransitionofAl2SiO5modifications, andamorphization processes under the influence of temperaturewere investigated by the DTA approach. Around 850 K “triple point” of Al2SiO5modifications was analyzed by the DSC spectroscopy.

Biomass-derived sustainable mesoporous activated carbon as an efficient and recyclable adsorbent for the adsorption of hazardous dyes

The use of activated carbon obtained from biomass in wastewater treatment has grown in popularity due to its sustainability and low manufacturing cost. Mesoporous activated carbon (MAC), with a large surface area (480 m2/g) and remarkable adsorption capacity, was produced at 550 °C using affordable Ficus religiosa leaf as a biomass precursor. The developed MAC was used to adsorb the hazardous contaminants of acid blue 9 (AB9) and malachite green (MG) from wastewater. To characterize MAC, various analytical techniques were used, including XRD, Raman, HR-SEM, HR-TEM, EDAX, FTIR, BET surface area analysis, XPS, TGA, and the associated DTA. The observed data confirms the production of the graphitic framework in the synthesized MAC but also demonstrates the dispersion of mesopores with a diameter of 4 nm. Also, BET, HR-SEM, and HR-TEM images confirmed the presence of high pore density and dye adsorption surface area. MAC dye adsorption capacity with optimum adsorbent dosage of 0.2g and 0.3g was estimated as 1.552 × 10−4 (mol/g) (123.04 mg/g) and 1.495 × 10−4 (mol/g) (138.58 mg/g) for AB9 and MG respectively at equilibrium of 120 min. The regression coefficients derived from the Freundlich, Langmuir, and D-R adsorption isotherms peak are compared, and the R2 value of 0.99 reported by Langmuir suggests that the adsorption of AB9 and MG adheres to the Langmuir adsorption isotherm by best fitting the equilibrium, recommending monolayer coverage. The chemisorption mechanism is defined by the combination of adsorption kinetics and a pseudo-second-order model. Besides, the sustainability was shown for five adsorptions–desorption cycles judge the utility and economic viability of the adsorption process. The plausible adsorption mechanism of MAC over AB9 and MG is mediated by synergetic interactions such as π-π interactions, hydrogen bonding, and electrostatic interactions. Therefore, exceptional stability, sustainability, and reliability for up to five adsorption run cycles of MAC justify its superiority over other adsorbents in the adsorption of AB9 and MG from wastewater.

Experimental incorporation of U into xenotime at mid to lower crustal pressures and temperatures utilizing alkali-bearing fluids under reducing and oxidizing conditions

A natural gem quality, inclusion-free, U-poor xenotime has been metasomatically altered at 900 °C and 500–1000 MPa in a series of alkali-bearing fluids including 2 N KOH, 2 N NaOH, Na2Si2O5 + H2O, and NaF + H2O to which UO2 and SiO2 have been added. All experiments were buffered to CO2-CO-graphite with the exception of the NaF + H2O experiment at 900 °C and 500 MPa, which was buffered to magnetite-hematite. With the exception of the Na2Si2O5 + H2O experiment, the xenotime reacted with the fluid tried in all of the remaining experiments to varying degrees. The xenotime showed the greatest degree of reactivity in the two NaF + H2O experiments tried. This reactivity takes the form of a coupled dissolution-reprecipitation reaction, which involves enriching reacted areas of the xenotime in U + Si as well as remobilizing the HREE in these areas inherent to the original xenotime. One result was the formation of alternating bands of Y-rich and HREE- + U-rich bands in the NaF + H2O experiment when the system was oxidized, which are presumed to have formed due a combination of simple chemical zoning coupled with diffusion and coupled dissolution-reprecipitation in the altered areas of the xenotime. A total lack of fluid and mineral inclusions on the nano-scale, as well as no disturbances in the crystal lattice in the reacted areas of the xenotime under HRTEM imaging, indicated that total recrystallization of the reacted areas took place during the course of the NaF + H2O experiment. The results of these experiments has important implications for the metasomatic resetting of the xenotime geochromometer in the presence of alkali-bearing fluids, which would potentially allow metasomatised xenotime to time and record metasomatic events affecting the rock.

Deciphering the Polymorphism of CaSi2: The Influence of Heat and Composition.

The Zintl phase CaSi2 is a layered compound with stacking variants known as 1P, 3R, and 6R. We extend the series by the 21R polytype formed by rapid cooling of the melt. The crystal structure of 21R-CaSi2 (space group R3̅m) was derived from HRTEM images, and the atomic positions were optimized by using the FPLO code (a = 3.868 Å, c = 107.276 Å). We explore polytype transformations by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and thermal analysis. While 6R-CaSi2 is thermodynamically stable at ambient conditions, nanosized impurities of silicon stabilize 3R-CaSi2 as a bulk phase.

Unraveling the Influence of Shell Thickness in Organic Functionalized Cu2O Nanoparticles on C2+ Products Distribution in Electrocatalytic CO2 Reduction

AbstractCu‐based electrocatalysts exhibit enormous potential for electrochemical CO2 conversion to added‐value products. However, high selectivity, specially toward C2+ products, remains a critical challenge for its implementation in commercial applications. Herein, the study reports the preparation of a series of electrocatalysts based on octadecyl amine (ODA) coated Cu2O nanoparticles (NPs). HRTEM images show ODA coatings with thickness from 1.2 to 4 nm. DFT calculations predict that at low surface coverage, ODA tends to lay on the Cu2O surface, leaving hydrophilic regions. Oppositely, at high surface coverage, the ODA molecules are densely packed, being detrimental for both mass and charge transfer. These changes in ODA molecular arrangement explain differences in product selectivity. In situ Raman spectroscopy has revealed that the optimum ODA thickness contributes to the stabilization of key intermediates in the formation of C2+ products, especially ethanol. Electrochemical impedance spectroscopy and pulse voltammetry measurements confirm that the thicker ODA shells increase charge transfer resistance, while the lowest ODA content promotes faster intermediate desorption rates. At the optimum thickness, the intermediates desorption rates are the slowest, in agreement with the maximum concentration of intermediates observed by in situ Raman spectroscopy, thereby resulting in a Faradaic efficiency to ethanol and ethylene over 73%.

Structural, vibrational and optical characterisations of Li2Ba3(P2O7)2:Cr3+ by solid-state reaction method

ABSTRACT Cr3+ doped Li2Ba3(P2O7)2 pyrophosphate nanopowder was successfully synthesised by solid-state reaction technique. The nanopowder was characterised by several techniques. X-ray diffraction analysis reveals orthorhombic crystal structureand average crystallite size values 34.21 and 28.41 nm are determined by Debye Scherrer’s formula and Williamson-Hall (W-H) method. The morphology displayed both SEM and HR-TEM images are irregular stone-like shapes. EDS analysis confirms the constituted elements. The SAED patterns of HR-TEM with well matched with XRD data. FT-IR and Raman spectra analysis confirmed incorporation of Cr3+ in the Li2Ba3(P2O7)2 pyrophosphate nanopowder. The EPR spectrum exhibited signal at g = 1.968 which is attributed to interaction between Cr3+ and Cr3+ exchange pair. The site symmetry of Cr3+ ions occupy a distorted octahedral. Photoluminescence spectrum exhibited bands correspond to ultraviolet, blue and green regions. The evaluated CCT of 6517 K indicates yellowish-green emission near cold light which reveals that the present prepared sample is useful for LEDs applications.

Morphological studies, photocatalytic degradation of organic dyes and anticancer potential of copper sulfide nanoparticles prepared from bis(diallyl dithiocarbamato)copper(II) complex

Bis(diallyl dithiocarbamato)copper(II) complex was synthesized and characterized by single crystal X-ray crystallography. The molecular structure revealed dimeric copper(II) complex consisting of two copper(II) ions that coordinate two molecules of diallydithiocarbamato anions in bidentate chelating modes and the centrosymmetrically related diallydithiocarbamato anions bridges the S-atom of the adjacent chelating ligand to formed square pyramidal geometry around the copper(II) ions. Copper sulfide nanoparticles were prepared at 160 °C by thermolysis of the copper(II) complex in dodecylamine (DDA), hexadecylamine (HDA), and octadecylamine (ODA) to study the effect of capping agents on the structural morphologies, photocatalytic properties, and anticancer potential of the as-prepared copper sulfides nanoparticles. Powder X-ray diffraction patterns confirmed Cu9S5 digenite crystalline phases for CuS-DDA and CuS-HDA while CuS-ODA is covellite crystalline phase. HRTEM images showed spherical particles with particle sizes in the range 2–25 nm. The copper sulfide nanophotocatalysts are efficient for the degradation of bromophenol blue with the highest photocatalytic efficiency of 95.14 % for CuS-DDA followed by CuS-HDA with 94.52 % and 93.95 % for CuS-ODA. The anticancer potentials of the compounds showed that CuS-HDA is the most potent with IC50 values of 1.22 µg/mL against HEK293 and 28.78 µg/mL against HeLa.

Crystal structures and photoluminescence properties of undoped and Fe3+ doped Li2Ba3(P2O7)2 pyrophosphate nanopowders

Undoped and Fe3+ doped Li2Ba3(P2O7)2 pyrophosphate nanopowders were produced by a solid-state reaction process. The prepared samples underwent characterizations using XRD, SEM with EDS, HR-TEM with SAED, FTIR, Raman, UV-Vis, EPR and PL techniques. The XRD analysis confirms the orthorhombic crystal structure of the prepared samples and unit cell parameters were evaluated. The samples exhibited stone-like structures with low aggregation based on the micrographs obtained from SEM and HR-TEM images. Additionally, the grain and particle sizes of the powder samples were evaluated. The elements Li, O, P, Ba and Fe were confirmed to be present in the produced samples by EDS spectra. FT-IR and Raman spectral investigation revealed the fundamental vibrational and bending modes of various phosphate groups. The energy bands, identified as characteristic bands of Fe3+ ions, were produced in the UV–visible region of the optical absorption spectrum for the doped sample. The crystal field and inter-electronic parameters (Dq = 915, B = 700 and C = 2715 cm−1) were also evaluated. Furthermore, the refractive index and metallization criteria properties were calculated using energy bandgap values of 4.46 and 4.38 eV of the produced samples. The doping of Fe3+ ions led to a reduction in the bandgap energy, resulting in a red-shift. A resonance signal was observed in the EPR spectrum at g = 2.05, which can be ascribed to iron ions entering the host lattice at a distorted octahedral symmetry sites and this was also supported by optical absorption studies. The produced sample showed emission peaks at 354, 440 and 530 nm in the ultraviolet, blue and green regions of its photoluminescence spectrum. Photometric parameters, such as CCT, CRI and CIE chromatic coordinates, reveal that the prepared samples could bee used in LEDs applications. This work offers novel visions into diphosphate compounds doped with transition metal ions.

Effective removal of organic and inorganic pollutants from abattoir wastewater using magnesium oxide/activated carbon nanocomposites

This study investigated the development and characterization of activated carbon (AC), magnesium oxide (MgO), and a combination of AC and MgO nanocomposite for abattoir wastewater treatment. Activated carbon was derived from Hura crepitans pods, whereas MgO nanoparticles were produced through biosynthesis. Different composite (AC/MgO) ratios (1:1, 1:2, and 2:1) were prepared using a wet impregnation technique. The efficiency of these nanoadsorbents in eliminating heavy metal pollutants were tested through batch adsorption experiments under the influence of the dosage, temperature, and contact time. Various analytical tools were used to characterize the prepared nanoadsorbents. XRD confirmed the formation of a pure MgO periclase phase, indicating a reduction in particle size with the increase in pH. The HRSEM images of the nanocomposites showed porous carbon structures with regular mesopores and spherical MgO nanoparticles. The uniform granules with agglomerated spherical shapes were confirmed by the SAED patterns, suggesting the core/shell structure of MgO from the HRTEM images. Further imaging confirmed the dispersion of carbon and magnesium in the nanocomposites, without the formation of distinct dopant oxides. The specific surface areas were determined as 2.74 m2/g for activated carbon, 27.57 m2/g for MgO, and 40.82 m2/g for activated carbon/MgO, indicating enhanced surface area due to the addition of activated carbon. Batch adsorption studies indicated that the AC/MgO nanocomposite in the 1:2 ratio exhibited the highest pollutant adsorption rate under similar conditions. The adsorption study was calculated by the pseudo-second-order and Langmuir isotherm models. The AC/MgO nanocomposite demonstrated reusability over six cycles, with a slight reduction in removal efficiency from the first cycle (98.05 % for Fe, 96.50 % for Cd, and 94.32 % for Pb) to the sixth cycle (91.10 % for Fe, 86.56 % for Cd, and 84.03 % for Pb). Overall, these findings suggest that AC/MgO nanocomposites can effectively eliminate pollutants from abattoir wastewater.

Correlation of quantum well periods on the 3rd order nonlinear optical responses of InGaN/GaN heterostructures

Semiconductor multi quantum well (MQW) design allows for the compression of electron-interaction dimensions, offering advantages for various applications, particularly in nonlinear optics. Despite the potential improvements in nonlinear optical responses, the influence of quantum well periods remains unexplored. In this study, we report the correlation of quantum well periods on the 3rd order nonlinear optical properties in In0.15 Ga0.85 N/GaN MQW using z-scan technique under femtosecond and continous wave laser regime. In0.15 Ga0.85 N well/GaN barrier with x1, x5, x10, x15 periods were grown by MOCVD technique. Good structural quality of grown MQWs were confirmed via HRTEM imaging, EDS, AFM and XRD. Absorption coefficient from UV-Vis coupled with PL emission spectrum shows systematic response of optical linear properties which provide an insight on the overall band gap structure. Positive nonlinear refraction, n2 and nonlinear absoprtion, β trends is observed under femtosecond an CW laser albeit differences of one order magnitude in χ3 value. The increase in χ3 value is shown to be monotonous with the increasing number of quantum well suggesting that compounding effect took place. This findings indicate the possibility of manipulating and tuning nonlinear reponses of MQW structures leading to improvement in semiconductor design in various areas such as optoelectronics, photonics, solar cell research, as well as quantum information processing.

Hydrothermally synthesized fluorescent nitrogen-doped carbon dots for catalytic efficiency and anti-counterfeiting application

Here, Tylophora indica plant extract was utilized to create nitrogen-doped carbon dots by hydrothermal method. The synthesized NDCDs was employed to anti-counterfeiting and enhancing the catalytic activity of Malachite Green dye. The ultraviolet–visible spectroscopy and FT-IR measurements was used to analyze the optical properties and the development of NDCDs as well as the source of Tylophora indica. Using HR-TEM, XRD, and XPS, the structure and elemental contents of the produced NDCDs was investigated. The HRTEM images showed that the NDCDs had a d-spacing of 0.37 nm and an average particle size of 4.3 ± 1 nm. After being subjected to UV light at 365 nm, the produced NDCDs began to glow blue, with a quantum yield (QY) of 16.1 %. The ID and IG ratio values for NDCDs were found to be 0.86. With rate constant values calculated at 0.1830 min−1, respectively, the synthesized NDCDs were found to be a viable catalyst for the Malachite Green (MG) dye reduction process utilizing freshly prepared NaBH4. In addition, the NDCDs solution is used as fluorescent ink. The printed patterns retain their anti-counterfeiting properties even after being heated and stored in an environment for an extended period, indicating the NDCDs stability for prospective anti-counterfeiting applications.