Selected Area Electron Diffraction Research Articles

Reaction-controlled shape evolution and insights into the growth mechanism of CsPbBr3 nanocrystals

The correlation between structural transformation and optical characteristics of cesium lead bromide (CsPbBr3) nanocrystals (NCs) suggests insights into their growth mechanism and optical performance. Systematic control of reaction parameters led to the successful fabrication of on-demand shape-morphing CsPbBr3 NCs. Transmission electron microscopy observations showed that the shape transformation from nanocubes to microcrystals could be accelerated by increasing the precursor:ligand molar ratio and reaction time. Further evidence for orthorhombic CsPbBr3 NCs was obtained from their selected-area electron diffraction pattern, which exhibits a twin domain induced by the presence of large NCs. Likewise, we observed a substantial decrease in photoluminescence (PL) intensity of CsPbBr3 due to surface decomposition or surface ligand loss resulting from increased size. In addition, fusion of smaller particles having other dimensionality induced the increase in the PL full-width at half maximum. In particular, existence of larger bulk material caused a reduction in the peak intensity in the absorption spectra and a trend of decreasing tendency in intensity of the absorption bands related to bromoplumbate species provided direct evidence of fully converted Cs-oleate.

Optimization of three-dimensional electron diffuse scattering data acquisition

The diffraction patterns of crystalline materials with local order contain sharp Bragg reflections as well as highly structured diffuse scattering. In this study, we quantitatively show how the diffuse scattering in three-dimensional electron diffraction (3D ED) data is influenced by various parameters, including the data acquisition mode, the detector type and the use of an energy filter. We found that diffuse scattering data used for quantitative analysis are preferably acquired in selected area electron diffraction (SAED) mode using a CCD and an energy filter. In this study, we also show that the diffuse scattering in 3D ED data can be obtained with a quality comparable to that from single-crystal X-ray diffraction. As electron diffraction requires much smaller crystal sizes than X-ray diffraction, this opens up the possibility to investigate the local structure of many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.

Microstructure, mechanical properties and cutting performance of CVD Ti(B,N) coatings

TiB0.19N1.06, TiB0.70N0.66, and TiB1.23N0.19 coatings were deposited on cemented carbide via the chemical vapor deposition (CVD) method based on the calculated phase diagrams of the Ti–B–N system. The microstructures, mechanical properties and cutting performances of the Ti(B,N) coatings were systematically studied via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), nanoindentation, etc. The coating compositions obtained via thermodynamic calculations show the same trend as the experimental values. The XRD and selected area electron diffraction (SAED) results of the coatings reveal that the phase assemblages transform from a dominant cubic structure of TiB0.19N1.06 to a hybrid of cubic and hexagonal structure of TiB0.70N0.66 and finally to a dominant hexagonal structure of TiB1.23N0.19. According to the XPS results, the TiB0.19N1.06 and TiB0.70N0.66 coatings consist of the crystalline phases TiN and TiB2 as well as amorphous BN and TiB, and the TiB1.23N0.19 coating mainly consists of the crystalline phases TiB2 and TiN. The hardness values of the TiB0.19N1.06, TiB0.70N0.66, and TiB1.23N0.19 coatings are 33.6, 35.1, and 39.1 GPa, respectively. The content of amorphous phase in the Ti(B,N) coatings decreases while the hardness increases as the B content increases and N content decreases. The TiB0.19N1.06 coating exhibits a composite structure of nanocrystallite embedded in amorphous matrix. The TiB1.23N0.19 coated tool prepared in this study demonstrates excellent performance in milling titanium alloy TC18 with a long cutting life up to 56.1 min, an increase of ∼9 % and ∼28 % compared to the TiB1.98 coated tool and commercial grade deposited with CVD TiB2 coating, respectively.

CuO nanoparticles for enhanced photoelectrochemical HER activity

Cupric oxide nanoparticles are a p-type semiconductor that can be used as a hole transport layer material in perovskite solar cells owing to their high electrical conductivity and stability. In the present work, CuO nanoparticles are synthesized using the hydrothermal technique, and their photoelectrochemical properties are studied through cyclic voltammetry. The X-ray diffraction patterns of the nanoparticles were analyzed for phase formation, revealing the monoclinic phase and further verified by the Rietveld Refinement. Thermogravimetric analysis shows a total weight loss of 13.47%. Transmission electron microscopy analysis suggests the formation of nanoparticles with an average size of 34 nm. The selected area electron diffraction analysis reveals the crystalline structure of the nanoparticles. The absorbance spectra of the nanoparticles were analyzed by UV–visible measurement, and Tauc's relation was used to estimate the optical bandgap. The XPS results align with the XRD results, indicating the formation of pure CuO nanoparticles. The developed catalyst's photoelectrochemical performance was investigated in the neutral solution for the hydrogen evolution reaction activity, and a high photocurrent density of −41.57 mA/cm2 was observed versus −0.6 V vs. RHE.

Morphology and crystallography of E-(Al18Cr2Mg3) nano dispersoids in 7475 Al alloy

The morphology and crystallography of E-(Al18Cr2Mg3) nano dispersoids in 7475 Al alloy have been studied by using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and electron tomography (ET). Seven distinct morphologies have been three-dimensionally distinguished at the nanoscale: (i) triangular plates on {111}Al, (ii) hexagonal plates on {111}Al, (iii) rods parallel to <110>Al, (iv) small tetrahedra with {111}Al facets, (v) small octahedra, (vi) spheres and (vii) irregular shapes. Twinning can contribute to the diverse morphologies of E nano dispersoids. The orientation relationships (ORs) between E nano dispersoids and Al matrix have been systematically investigated by selected area electron diffraction (SAED) patterns, HRTEM and matrix calculation. The results from the matrix calculation indicate the absence of clear ORs between E nano dispersoids and Al matrix in 7475 Al alloy.

A HRTEM-EDS-SAED Study of Precipitates in Mg-Zn-Zr Alloy

In this study, aging heat treatment was performed on extruded Mg-Zn-Zr alloy. Aging was performed on as-extruded samples at 180°C for 1-2-4-8 and 24 hours. Microhardness tests were made to obtain the aging curve. Detailed transmission electron microscopy (TEM) examinations such as selected area electron diffraction (SAED), energy dispersive spectrometry (EDS), and high resolution transmission electron microscopy (HRTEM) were used to investigate the microstructure, second phases, and precipitates. Size, type, and morphologies of second phases and precipitates were studied aided by advanced transmission electron microscopy techniques. With the help of hardness test results peak aged condition was found to be 8 hour aging. TEM examinations were detailed for the 8-hour aged sample. It was observed that the precipitates responsible for age hardening were MgZn2. Moreover, the majority of these precipitates were β’1 phase.

A persistent mineralization process in alveolar bone throughout the postnatal growth stage in rats

ObjectiveAlveolar bone quality is essential for the maxillofacial integrity and function, and depends on alveolar bone mineralization. This study aims to investigate the in vivo changes in alveolar bone mineralization, from the perspective of mineral deposition and crystal transition in postnatal rats. DesignNine postnatal time points of Wistar rats, ranging from day 1 to 56, were set to obtain the maxillary alveolar bone samples. Each time point consisted of ninety rats, with 45 females and 45 males. Macromorphology of alveolar bone was reconducted by Micro-Computed Tomography and the mineral content was quantified via Thermogravimetric analysis, Scanning Electron Microscope, High-Resolution Transmission Electron Microscopy and vibrational spectroscopy. Furthermore, the crystallinity and composition were characterized by vibrational spectroscopy, X-ray Diffraction, X-ray Photoelectron Spectroscopy and Selected Area Electron Diffraction. ResultsThe progressive increase of mineral deposition was accompanied by substantial growth in alveolar bone mass and volume in postnatal rats. Whereas the mineral percentage initially decreased and then increased, reaching a nadir on postnatal day 14 (P14) when tooth eruption was first observed. Besides, localized mineralization was initiated by the formation of amorphous precursors and then converted into mineral crystals, while there was no statistically significant change in the average crystallinity of the bone during growth. ConclusionMineralization of alveolar bone is ongoing throughout the early growth in postnatal rats. Mineral deposition increases with age, whereas the crystallinity remains stable within a certain range. Besides, the mineral percentage reaches its lowest point on P14, which may be attributed to tooth eruption.

Modulated crystallographic shear structure in titanium–chromium oxides: their structure and phonon-transport properties

Advancements in phonon engineering have propelled the study of heat conduction within nanostructures, focusing on the wave nature of phonons for thermal conductivity manipulation. This work investigates the annealing-induced structural transformation of titanium–chromium oxide crystals, highlighting a role in modulating thermal conductivity through the regularization of crystallographic shear (CS) plane spacing. Utilizing high-angle annular dark-field scanning transmission electron microscopy and selected-area electron diffraction, a transformation from disordered to ordered arrangements of CS planes was observed through annealing at high temperatures. The thermal conductivity increased following annealing. The variability observed in the spacing of CS planes before annealing implies that phonon Anderson localization might play a role in the changes in thermal conductivity.

The transient thermal ageing of Eurofer 97 by mitigated plasma disruptions

Plasma disruptions in a commercial-scale tokamak will impose high magnitude, short-duration thermal loads on its plasma-facing first wall. Despite a plethora of mitigation measures, these severe, off-normal events are likely to briefly expose the structural materials of the first wall to significant temperature excursions. Eurofer 97, the reference structural material for the plasma-facing first wall of the EU DEMO tokamak, is a reduced activation 9Cr steel with a normalised and tempered ferritic/martensitic microstructure. Repeated exposure to the thermal effects of disruptions over the operating lifetime of a reactor may promote a cumulative evolution of Eurofer 97′s microstructure, affecting key material properties crucial to first wall performance. This novel transient thermal degradation mechanism has been explored via a laser-based transient heating experiment, supported by time-dependent finite element thermal analysis studies of DEMO’s water-cooled lithium–lead first wall during a mitigated plasma disruption. Transient-affected samples of Eurofer 97 were characterised via scanning and transmission electron microscopy techniques (SEM/TEM), including electron backscatter diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDX), and selective area electron diffraction (SAED). Microhardness and magnetisation testing data are also presented. A single 700 °C thermal transient was found sufficient to coarsen and partially recrystallise Eurofer 97′s tempered martensite sub-grains at the tungsten-Eurofer 97 interface. Further transient exposure at 700 °C resulted in the significant growth of equiaxed grains, the nucleation of intergranular Cr-rich M7C3 and M23C6 carbides, and the coarsening of V-rich and intra-granular Ta-rich MX precipitates. The microstructural effects of 850 °C transients are also reported. Notably, after 1,000 transients at 850 °C the hardness of Eurofer 97 was found to have decreased by 32 %.

Gompherna globosa flower extract-driven ZnO nanoparticles for enhanced antimicrobial and photocatalytic properties

The aqueous extract of Gomphrena globosa flowers was utilized for the first time as an effective capping and reducing agent for the synthesis of zinc oxide nanoparticles (ZnO NPs). The synthesized nanoparticles were examined using x-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive x-ray analysis (EDAX), Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) and UV–vis spectroscopy. XRD revealed the single-phase wurtzite structure of ZnO nanoparticles with a P63mc space group with an average size of 23 nm. The band gap of synthesized ZnO nanoparticles was determined as 3.16 eV from UV–vis spectroscopy. The rod-shaped structure of the synthesized ZnO NPs was revealed by SEM. The presence of the elements Zn & O was confirmed by EDAX. TEM and SAED confirmed that the average particle size was 26 nm and that the material was polycrystalline. The bio-inspired ZnO NPs achieved outstanding degradation activity of 95.4% against Malachite Green dye after 20 min of UV illumination. The antibacterial properties of the green synthesized nanoparticles were assessed in relation to gram-positive (Staphylococcus sp., Bacillus sp.,) and gram-negative (E. coli, Klebsiella sp.) bacteria. ZnO nanoparticles possess strong antifungal property against a pathogenic fungus Aspergillus niger. This study shows that green-synthesized ZnO nanoparticles derived from Gomphrena globosa flower extract are recommended for use in anti-microbial and photocatalytic applications.

Effect of calcination temperature on structural, optical, and morphological properties of RAlO3 (R = La, Sm) perovskite oxides

RAlO3 (R = La, Sm) have attracted the research community due to their interesting optoelectronic properties and viable applications. The solution combustion method allows for a faster process and lower calcination temperature than the traditional solid-state method and is an economical alternative to wet chemical synthesis for producing RAlO3. This work explores the thermal, structural, morphological, optical, and electrical properties of RAlO3 (R = La, Sm) synthesised by the solution combustion method using urea as fuel. Thermogravimetric analysis—differential thermal analysis (TGA-DTA) showed the crystallization temperatures of lanthanum aluminate (LaAlO3) and samarium aluminate (SmAlO3) at 864 and 887 °C, respectively. The x-ray diffraction (XRD) and Rietveld analysis revealed the structure of LaAlO3 as rhombohedral (R-3c) and SmAlO3 as orthorhombic (Pbnm). The LaAlO3 and SmAlO3 samples calcinated at 800 °C showed crystallite size (D) of 19.26 nm and 19.06 nm, respectively. The field emission scanning electron microscopy (FE-SEM) images show a highly porous and large sheet-like morphology with voids and cracks. High resolution transmission electron microscopy (HR-TEM) images and the selective area electron diffraction (SAED) pattern show crystalline nature and the indexed planes agreed with the XRD results. The LaAlO3 and SmAlO3 samples had specific surface areas of 16.374 and 12.953 m2 g−1, respectively. The TGA-DTA results were affirmed by Fourier transform infrared spectroscopy (FT-IR) results which showed only the presence of metal-oxide bonds for materials annealed at and above 800 °C. These results were further validated by the electron dispersive x-ray spectroscopy (EDX) and the x-ray photoelectron spectroscopy (XPS) showing no additional peaks. The band gap of 5.08 and 4.82 eV were calculated from ultraviolet-visible spectroscopy (UV–vis) for LaAlO3 and SmAlO3, respectively. The results imply that the solution combustion technique using urea as fuel is a viable route for synthesising RAlO3.

Antioxidant, Antitumoral, Antimicrobial, and Prebiotic Activity of Magnetite Nanoparticles Loaded with Bee Pollen/Bee Bread Extracts and 5-Fluorouracil.

The gut microbiota dysbiosis that often occurs in cancer therapy requires more efficient treatment options to be developed. In this concern, the present research approach is to develop drug delivery systems based on magnetite nanoparticles (MNPs) as nanocarriers for bioactive compounds. First, MNPs were synthesized through the spraying-assisted coprecipitation method, followed by loading bee pollen or bee bread extracts and an antitumoral drug (5-fluorouracil/5-FU). The loaded-MNPs were morphologically and structurally characterized through transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Dynamic Light Scattering (DLS), and thermogravimetric analysis. UV-Vis spectroscopy was applied to establish the release profiles and antioxidant activity. Furthermore, the antibacterial and antitumoral activity of loaded-MNPs was assessed. The results demonstrate that MNPs with antioxidant, antibacterial, antiproliferative, and prebiotic properties are obtained. Moreover, the data highlight the improvement of 5-FU antibacterial activity by loading on the MNPs' surface and the synergistic effects between the anticancer drug and phenolic compounds (PCs). In addition, the prolonged release behavior of PCs for many hours (70-75 h) after the release of 5-FU from the developed nanocarriers is an advantage, at least from the point of view of the antioxidant activity of PCs. Considering the enhancement of L. rhamnosus MF9 growth and antitumoral activity, this study developed promising drug delivery alternatives for colorectal cancer therapy.

Nanobiological synthesis of silver oxide-doped titanium oxide bionanocomposite targeting foodborne and phytopathogenic bacteria

Fungi possess remarkable capabilities for metal speciation, dissolution, and mineral formation, which contribute to the production of mycogenic nanostructures. This study explores a green chemistry approach for synthesizing silver oxide-doped titanium oxide (Ag2O-doped TiO2) bionanocomposite utilizing Trichoderma virens. The light yellowish fungal filtrate transformed into a dark brownish colloidal suspension after reacting with silver nitrate and rutile titanium (IV) oxide. X-ray diffractometry (XRD) unveiled the crystalline structure of Ag2O-doped TiO2 bionanocomposite (22.15 nm), showing the coexistence of cubic and rutile tetragonal phases of Ag2O and TiO2, respectively. Fourier-transform infrared spectroscopy (FTIR) showed the presence of functional groups of alcohols, phenols nitro compounds, and aromatic amines derived from the cultural filtrate of T. virens. Raman analysis revealed vibrational modes corresponding to Ag2O and TiO2 nanoparticles. Distinct sharp emission peaks characteristic to Ti, Ag, and O were depicted using energy dispersive X-ray analysis (EDX) analysis. X-ray photoelectron spectroscopy (XPS) confirmed the presence of elemental valence states and binding energies of Ag, Ti, and O in the mycogenic nanocomposite. Field emission scanning electron microscopy (FESEM) revealed aggregation of polydispersed Ag2O-doped TiO2 bionanocomposite, displaying spherical- and cuboctahedron-shaped nanostructures with rough surfaces. High-resolution transmission electron microscopy (HRTEM) showed the presence of circular-, semi-spherical-, hexagonal-, and polygonal-shaped monodispersed Ag2O NPs, with defined boundaries. The Ag2O NPs were obviously deposited on the sheet-like TiO2 NPs. Selected area electron diffraction pattern implied the polycrystallinity of the as-synthesized bionanocomposite. A broad antibacterial spectrum of the prepared bionanocomposite was attained against foodborne pathogenic bacteria; Escherichia coli (12.05 mm), Salmonella enterica (11.26 mm), and Staphylococcus aureus (11.44 mm) and phytopathogenic bacteria; Clavibacter michiganensis subsp. michiganensis (15.72 mm), C. michiganensis subsp. capsici (10.80 mm), streptomycin-sensitive and -resistant Xanthomonas citri pv. citri (14.11 and 14.53 mm, respectively), and streptomycin-sensitive and -resistant Pectobacterium carotovorum subsp. carotovorum (11.36 and 11.07 mm, respectively) using in vitro Kirby-Bauer method. Minimum inhibitory and minimum bactericidal concentrations were determined via a broth micro-dilution assay. FESEM revealed significant morphological alterations in bacterial cells upon treatment with the Ag2O-doped TiO2 bionanocomposite, including deformed shape, rough surface, cell thinning, wrinkled cell wall, protrusions, cavitations, and cracks. These findings signify the successful mycosynthesis of Ag2O-doped TiO2 bionanocomposite, which acted a potent antibacterial agent against a variety of foodborne and phytopathogenic bacteria, which could be employed for environmental, biomedical, agricultural, food bio-processing applications.

UV photodetector based on vertically aligned Ta2O5 nanorods

This work presents the investigation of the GLAD technique to fabricate Tantalum pentoxide (Ta2O5) Nanorods for the application of ultraviolet (UV) photodetector. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), UV–visible absorption, and electrical characterization were performed on the fabricated samples. Ta2O5 amorphous nature was revealed via XRD pattern and selected area electron diffraction (SAED) analysis. FESEM and TEM images reveal the growth of vertical nanorods. In the UV–visible region, there is strong absorption, with a direct bandgap of about 3.9 eV. The electrical analysis was conducted at room temperature for the voltage between −10 and 10 V, revealing the performance of the device, with a high responsivity of 5.7 A/W, detectivity (D*) of 11.62 × 1013, and a noise equivalent power (NEP) value of 2.975 × 10−12. In addition, it has a stable switching response at -3V with a rise time of 0.15 s and a fall time of 0.17 s.

Structural Complexities in Sodium Ion Conductive Antiperovskite Revealed by Cryogenic Transmission Electron Microscopy.

We use low-dose cryogenic transmission electron microscopy (cryo-TEM) to investigate the atomic-scale structure of antiperovskite Na2NH2BH4 crystals by preserving the room-temperature cubic phase and carefully monitoring the electron dose. Via quantitative analysis of electron beam damage using selected area electron diffraction, we find cryogenic imaging provides 6-fold improvement in beam stability for this solid electrolyte. Cryo-TEM images obtained from flat crystals revealed the presence of a new, long-range-ordered supercell with a cubic phase. The supercell exhibits doubled unit cell dimensions of 9.4 Å × 9.4 Å as compared to the cubic lattice structure revealed by X-ray crystallography of 4.7 Å × 4.7 Å. The comparison between the experimental image and simulated potential map indicates the origin of the supercell is a vacancy ordering of sodium atoms. This work demonstrates the potential of using cryo-TEM imaging to study the atomic-scale structure of air- and electron-beam-sensitive antiperovskite-type solid electrolytes.

Potential nanomedicinal applications and physicochemical nature of Hyphaene thebaica-reduced nano-samaria.

Herein we described the biofabrication of samarium oxide nanoparticles (HT-Sm2O3 NPs) by applying the aqueous fruit extract of Hyphaene thebaica was utilized as an eco-friendly chelating agent. The prepared NPs were subjected to various physicochemical properties and potential in biomedical applications. X-ray Diffraction (XRD) pattern revealed sharp peaks that corroborated with the Joint Committee on Powder Diffraction Standards (JCPDS) card no. 00-042-1464. Crystallite size obtained from Debye-Scherrer approximation and Williamson-Hall (W-H) plot was 28.73 and 69.3 nm, respectively. Optical bandgap was calculated by employing Kubelka-Munk (K-M) function and was found to be ~4.58 eV. Raman shift was observed at 121, 351, 424-, and 561 cm-1. Photoluminescence (PL) spectra revealed two major peaks positioned at 360 and 540 nm. The high-resolution transmission electron microscopy (HR-TEM) analysis of HT-Sm2O3 nanoparticles (NPs) showed that they predominantly have spherical to cuboidal shapes. Additionally, the selected area electron diffraction (SAED) pattern presented spotty rings, indicating a high level of crystallinity in these NPs. The potential nanomedicine applications were studied using diverse bioassays using different treatments. The antioxidant activity demonstrated 45.71% ± 1.13% inhibition at 1000 μg/mL. Brine shrimp lethality assay revealed the highest cytotoxicity of 46.67% ± 3.33% at 1000 μg/mL and LC50 value of 1081 μg/mL. HT-Sm2O3 NPs exhibited inhibition of angiogenesis (20.41% ± 1.18%) at of 1000 μg/mL. MTT assay results indicated that HT-Sm2O3 NPs exhibit inhibitory effects on cell lines. Specifically, these NPs showed an IC50 value of 104.6 μg/mL against 3T3 cells. Against MCF-7 cells, the NPs demonstrated an IC50 value of 413.25 μg/mL. Additionally, in the inhibition of acetylcholinesterase (AChE), the newly synthesized NPs showed an IC50 value of 320 μg/mL. The antidiabetic assessment through α-glucosidase and α-amylase inhibition assays revealed, an IC50 value of 380 μg/mL for α-glucosidase and 952 μg/mL for α-amylase was calculated. Overall, our study suggested that the Sm2O3 NPs possess moderate anticancer, cholinesterase inhibition, and antidiabetic potential, however, needs further assessment. RESEARCH HIGHLIGHTS: In this work, nano-samaria is synthesized using an eco-friendly and green approach. The nanoparticles were characterized using techniques such as Raman, HR-TEM, FTIR, DRS, XRD, and so on, and the applications were studied using multiple in vitro bioassays for Diabetes, Alzheimer, and Cancer. The nano-samaria revealed good potential for potential biomedical applications.

Green synthesis and characterization of magnesium nanoparticles using pumpkin peel extract (Tetsukabuto)

Pumpkin (Tetsukabuto) peel extract was utilized to synthesize nanoparticles of magnesium. The nanoparticles were characterized using scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS), X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), raman spectroscopy (RS) as well as Brunauer-Emmett-Teller (BET) analysis. The results showed that the synthesis of magnesium nanoparticles is possible by use of pumpkin peel extract. The characterization analyses indicated the presence of functional groups on the surface of the nanoparticles, which aided in the bioreduction of the metals to oxides. The nanoparticles can be applied in studies involving microbial agents due to their spherical shape, which allows for easy penetration into the cell wall of microorganisms. This work provides relevant information for the field of nanoparticles and the area of green synthesis.

Biosynthesis of silver nanoparticle from flower extract of Dillenia indica and its efficacy as antibacterial and antioxidant

Dillenia indica is a medicinal tree of the Dilleniaceae and its flower extract was used for the synthesis of silver nanoparticle (AgNPs). The optimal conditions for AgNPs synthesis were as such: 2 mM AgNO3, pH 4.5 and 48-h reaction time. The characteristic band of AgNPs was observed at the wavelength of 435 nm by UV–visible spectroscopic study. Fourier-transform infrared (FTIR) analysis depicted the involvement of several functional groups of plant extracts in the synthesis of AgNPs. Nanoparticles were mostly spherical shaped and uniformly distributed, when observation was made by Transmission electron microscopy (TEM). Energy Dispersive X-Ray (EDX) showed absorption peak approximately at 3 keV thus confirmed the presence of silver metal in AgNP. X-ray diffraction (XRD) investigation and selected area electron diffraction (SAED) patterns showed the crystalline nature of the AgNPs. Dynamic light scattering (DLS) analysis exhibited average size of the nanoparticles as 50.17 nm with a polydispersity index (PDI) value of 0.298. The zeta potential of nanoparticles was observed as −24.9 mV. To assess antibacterial activity, both AgNPs alone or its combination with the antibiotic were tried against six pathogenic bacteria. The combination of AgNPs with antibiotic was maximum effective against Shigella boydii (16.07 ± 0.35) and Klebsiella pneumoniae (15.03 ± 0.20). AgNPs alone showed maximum inhibition for both Gram-positive bacteria: methicillin-resistant Staphylococcus aureus (19.97 ± 0.20 mm) and Enterococcus faecium (19.80 ± 0.15 mm). Maximum inhibition of Enterobactor cloacae and Pseudomonas aeruginosa was observed by antibiotic taken alone. Evaluation through 2,2-diphenyl-1-picrylhydrazyl (DPPH) and DNA nicking assays demonstrated the antioxidant capabilities of the nanoparticles.

Magnetically recoverable CuFe2O4 nanocatalyst: Dual catalytic action in sonogashira and Chan-Lam coupling reactions

Magnetically retrievable CuFe2O4 nanocatalyst has been synthesized for Sonogashira (C-C) and Chan-Lam (C-N) coupling reactions by a facile co-precipitation method. Synthesized nanocatalyst was characterized by powder x-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM) analysis. The catalytic action of the catalyst was evaluated for both Pd-free C-C coupling and base-free C-N coupling reactions where an excellent product yield up to 96 % and 95 % respectively was obtained. The uniqueness of the catalyst was its effective performance under ambient reaction conditions in green solvents such as EtOH and EtOH:H2O (1:1) with a broad substrate scope. The catalyst can be easily retrieved from the reaction mixture with the aid of an external magnet and reused at least five times without significant loss in catalytic activity. The structural stability of the recovered catalyst was confirmed by XRD, FTIR, SEM and ICP-OES (Inductively coupled plasma - optical emission spectrometry) analysis. Thus, the synthesized catalyst works excellently well for dual applications and establishes the sustainable application of the catalyst.

Sonochemical synthesis of S-scheme CuO/CeO2 heterojunction for enhanced photocatalytic degradation of rhodamine B dye under solar radiations

CeO2 is renowned photocatalyst with 2.8 eV band gap energy and exceptional optical features. However, the slow charge transportation and the fast recombination of the electron-hole pair hindered the photocatalytic efficiency. In this pioneering research, S-scheme CuO/CeO2 heterojunctions were engineered sonochemically with rational compositions of CeO2 and CuO nanoparticles for enhanced the photocatalytic efficiency of CeO2 in destructing rhodamine B dye under full solar radiations. Diffuse reflectance spectrum [DRS], photoluminescence [PL], high resolution transmission electron microscope [HRTEM], selected area electron diffraction [SAED], N2-adsorption-desorption isotherm, X-ray photoelectron spectroscopy [XPS] and X-ray diffraction [XRD] investigated the physicochemical properties of CuO/CeO2 heterojunction. Monoclinic CuO nanoparticles of 8 nm size are facilely incorporated in cubic CeO2 crystallites of 27.3 nm through substitution of Ce4+ by Cu2+ ions which ascribed to smaller ionic radii of Cu2+ compared with Ce4+ and Ce3+ ions. Homogeneous distribution of CuO nanoparticles on CeO2 surface was further investigated by SEM and TEM analysis. HRTEM, XRD, SAED and XPS analysis recorded the co-existence of crystalline peaks of CeO2 and CuO implying the successful construction of CuO/CeO2 heterojunction. The depression in the surface area of CeO2 from 91.4 to 83.6 m2/g with incorporating 5 wt % of CuO revealed the deposition of CuO on CeO2 surface. XPS analysis implied the existence of Ce3+ and oxygen vacancies that provide more adsorption sites for oxygen, which are beneficial for enhancing the catalytic performance of catalysts. CuO nanoparticles with 1.3 eV band energy enhanced the visible light absorbability of the heterojunctions in deep visible region for broading the photocatalytic response. Significant reduction in photoluminescence signals intensity by 60 % with incorporation 5 wt % of CuO revealed the favorable reduction in the rate of electron-hole recombination. In particular, CeCu5 containing 5 wt % CuO expelled 96 % of RhB dye within 6-h under solar simulator compared with 13 % removal on pristine CeO2 and CuO surface. Hot radicals and positive holes degraded RhB dye molecules on the heterojunction surface as elucidated from scavenger experiments and PL analysis of terephthalic acid. The exceptional removal of RhB dye under solar radiation was ascribed to the alignment in the band structure of CeO2 and CuO nanoparticles and the successful production of an efficient S-scheme heterojunction with strong redox potential and better electron transportation and separation.