High-resolution Transmission Electron Microscopy Micrographs Research Articles

Elucidating the structural and spectroscopic attributes of titania-iron oxide (TiO2-([formula omitted]-Fe2O3)) nanocomposites: Showcasing a pulsed laser ablation in liquid approach

Various nanomaterials with tailored photo-electrochemical and physicochemical attributes became viable for the photo-catalysis and sensors applications. Thus, some new types of TiO2-(α-Fe2O3) nanocomposites were made via the pulse laser ablation in liquid method. These nanocomposites at each value of laser fluence were obtained by mixing the colloidal TiO2 nanoparticles and colloidal (α-Fe2O3) nanoparticles at equal ratio. The stability, structures, morphologies, and optical characteristics of the produced nanocomposites (suspended in deionized water) were customized by changing the laser fluence from 3.5–17.7 J cm−2. The high-resolution transmission electron microscopy micrographs showed the existence of homogeneous dispersion of spherical nanocrystallites (mean diameter 12.4 ± 6.0 nm) in the colloidal suspension. Both X-ray diffraction and Fourier transform infrared profiles of the specimen verified their purity and good nanocrystallinity. Two optical absorption peaks were probed in the range of 240 to 380 nm convoyed by a blue-shift. The spectral edge related to UV–Vis absorption was used to estimate the optical band gap of these nanocomposites. TiO2-(α-Fe2O3) nanocomposites made at optimum laser fluence (10.6 J cm−2) exhibited strong fluorescence with the life time decay of 3.64 μs, indicating the electronic density of states modification due to quantum size effects. The presence of Fe, Ti, and O in the X-ray photoelectron spectroscopy spectra reaffirmed the samples purity. The measured strong negative zeta potential (-33.1 mV) of the optimum TiO2-(α-Fe2O3) nanocomposites confirmed their excellent stability in the colloidal suspension. In short, these nanocomposites may be advantageous as good photo-catalysts for waste water treatment and photo-electrochemical uses.

Unexpected modulation revealed by electron diffraction in Ni-Mn-Ga-Co-Cu tetragonal martensite exhibiting giant magnetic field-induced strain

Although the modulation of martensite structure has been considered as a precondition for highly mobile twin boundary and thus a giant magnetic field induced strain, the largest strain to date has been reported in non-modulated tetragonal martensite of Ni-Mn-Ga-Co-Cu. Using high-resolution transmission electron microscopy (HRTEM), we found that nominally non-modulated tetragonal Ni46Mn24Ga22Co4Cu4 single crystal possesses a modulation. The modulation was observed in thin lamellae containing b/c twins prepared by a focused Ga-ion beam and on a sample prepared by a conventional wedge thinning method. The modulation vector q* = (0, 0.2554, 0.4642), was determined by 3D electron diffraction. The simulated HRTEM image of such a structure agrees with the HRTEM micrograph. The presence of modulation in the thin lamellae and not in bulk suggests that Ni-Mn-Ga-Co-Cu martensite is on the edge of the shear instability enabling the high mobility of twin boundaries.

Green Synthesis of TiO2 Using Impatiens rothii Hook.f. Leaf Extract for Efficient Removal of Methylene Blue Dye.

In this work, TiO2 nanoparticles (NPs) were effectively synthesized by a green method using the Impatiens rothii Hook.f. leaf (IL) extract as a capping and reducing agent. The as-synthesized TiO2 NPs were characterized by different characterization methods such as the Brunauer-Emmett-Teller (BET) analysis, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), diffused reflectance spectroscopy (DRS), and X-ray diffraction (XRD) and Raman spectroscopy. The specific surface area from BET analysis was found to be 65 m2/g. The average crystallite size from XRD analysis and average particle size from SEM analysis were found to be ∼11 and ∼25 nm, respectively. The Raman spectroscopy and XRD results showed that the biosynthesized (IL-TiO2) nanoparticles were purely anatase phase. XPS analysis illustrated the formation of Titania with an oxidation state of +4. The DRS study showcased that a blue-shifted intense absorption peak of IL-TiO2 (3.39 eV) compared to the bulk material reported in the literature (3.2 eV). HRTEM micrograph showed the presence of grain boundary with d spacings of 0.352, 0.245, and 0.190, which correspond to the lattice planes of (101), (004), and (200), respectively. From the EDX analysis, the weight percents of titanium and oxygen were found to be 54.33 and 45.67%, respectively. The photoinduced degradation of methylene blue (MB) dye was investigated in the presence of biosynthesized IL-TiO2 NPs photocatalyst. The effect of parameters like catalyst dosage (30 mg/L), initial concentration of MB (15 ppm), pH (10.5), and contact time (100 min) on the removal efficiency was optimized. The maximum photodegradation efficiency under the optimized conditions was found to be 98%.

Mechanistic analysis of chemical structure evolution for coals under igneous intrusion

Thermally altered coals (TACs) have different chemical properties compared to normally buried coals owing to the influence of igneous intrusion. This discrepancy in chemical components of TACs has not been fully revealed, which leads to their underutilization and potential risks in exploitation. Igneous intrusion causes the rearrangement of aromatic rings and the formation of graphite-like features in TACs. Several studies have examined the changes in coal rank and aromaticity during this process but have not explored the overall evolution. In particular, the lateral extension and vertical stacking of aromatic layers in TACs during graphitization are still unknown. To this aim, a range of TACs was collected, from bituminous to semi-graphite. Four experimental analyses were conducted to characterize the chemical structure evolution of TACs, including Raman spectroscopy, Fourier-transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). The analysis of the measured parameters indicates that the chemical structure of TACs undergoes evolution as it approaches igneous intrusion. These changes involve an increase in the size of the aromatic structural units, a reduction in structural defects, and an increase in the degree of order. In addition, there is a gradual transition of sp2-sp3 hybridized aromatic rings to sp2 hybridized aromatic rings, resembling the process of graphite formation. The HRTEM micrographs also reveal an enlargement in the size and angular orientation of aromatic fringes. In summary, the evolution of TACs can be categorized into three stages: a) rapid growth of basic structural units (BSU) from bituminous coal to anthracite; b) lateral connections of BSUs from anthracite to meta-anthracite; and c) lateral straightening of BSUs from meta-anthracite to semi-graphite. Understanding this evolutionary mechanism is highly significant in analyzing the formation of pores and in enhancing the utilization and safety of TACs.

Response of nonstoichiometric pyrochlore composition Nd1.8Zr2.2O7.1 to electronic excitations

AbstractIn response of swift heavy ion (100 MeV I9+) irradiation, the irradiation‐induced disordering in nonstoichiometric pyrochlore composition (Nd1.8Zr2.2O7.1) was compared to that of stoichiometric composition Nd2Zr2O7. Both compositions were prepared through auto gel‐combustion followed by sintering under the identical conditions. Systematic analysis of the compositions before and after irradiation was performed with X‐ray diffraction (XRD), Raman spectroscopy, and plane‐view high‐resolution transmission electron microscopy (HRTEM) techniques. Irradiation caused pyrochlore to amorphous phase transformation was observed in both compositions except the slower rate of amorphization in Nd1.8Zr2.2O7.1. The amorphization was achieved as a consequence of isolated disordered track overlapping at higher ion fluence with the estimated track diameter 2.73 ± 0.05 and 3.46 ± 0.30 nm for Nd1.8Zr2.2O7.1 and Nd2Zr2O7, respectively, employing the framework of single‐ion impact model to XRD results. HRTEM micrographs also revealed the less prevalence of irradiation‐induced amorphization in Nd1.8Zr2.2O7.1 with the observed irradiation‐induced modified track region composed of defect‐rich pyrochlore structure, anion‐deficient fluorite structure, and amorphous domains; with the diameter of 3.0 ± 1.0 nm and 5.0 ± 1.0 nm in Nd1.8Zr2.2O7.1 and Nd2Zr2O7, respectively. The preexisting anion‐deficient fluorite structure in Nd1.8Zr2.2O7.1 helps in its epitaxial growth as recovered structure from melted ion track during irradiation‐induced rapid cooling.

TiO2 decorated Au nanoparticle enhances wettability of glass for self-cleaning application

Understanding the hydrophilic features assisted modification of the wettability properties of glass by adding bimetallic nanoparticles (NPs) is crucial for self-cleaning applications. In this study, a series of glasses with a composition of (70 – x − y)TeO2–20ZnO–9Na2O–1Er2O3–(x)TiO2–(y) Au where x = 0, 0.3 mol% and y = 0, 0.03, 0.05, 0.10, 0.15, 0.20 mol% were prepared using the melt-quenching technique. Decorating TiO2 with Au NPs modified the optical, texture, structure, and wettability properties of glass. The X-ray diffraction (XRD) spectra affirmed the amorphous features of glass. The emergence of two vivid surface plasmon resonance (SPR) bands in the visible region is due to the addition of TiO2 and Au NPs. The atomic force microscopy (AFM) images showed the distribution of widely-scattered islands due to bimetallic TiO2/Au NPs. High-resolution transmission electron microscopy (HRTEM) micrographs manifested the growth of NPs following the coalescence process. The decrement in the water contact angle and the emergence of thin water film on the glass surface implied enhancement in the hydrophilic features of glass.

Mechanistic insights into transport properties of chemical vapour transport grown CuInS2 single crystal

Copper indium disulfide (CuInS2) single crystals are prepared by the chemical vapour transport technique and characterised by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), and high resolution transmission electron microscopy (HRTEM). The XRD outcome reveals tetragonal lattice structure. The EDS result confirms that the sample is near stoichiometry, while the FESEM and HRTEM micrographs show multilayered opaque crystals. The lattice fringe arrangement reveals d-spacing of 0.32 nm, which matches the d-spacing of primary peak (112) of XRD. Electrical resistivity value decreases as temperature varies from 303 K to 423 K, confirming the crystal is semiconducting. The negative signs in the Hall coefficient (−8.49 × 105 cm3·C−1) and Seebeck coefficient (−148 μV·K−1) confirm n-type nature. The maximum figure of merit (zT) is predicted as 3.99 × 10−4 at 423 K. It suggests that CuInS2 has the prospective to be used in thermoelectric power generation.

Toward Efficient Bactericidal and Dye Degradation Performance of Strontium- and Starch-Doped Fe2O3 Nanostructures: In Silico Molecular Docking Studies.

In this study, various concentrations of strontium (Sr) into a fixed amount of starch (St) and Fe2O3 nanostructures (NSs) were synthesized with the co-precipitation approach to evaluate the antibacterial and photocatalytic properties of the concerned NSs. The study aimed to synthesize nanorods of Fe2O3 with co-precipitation to enhance the bactericidal behavior with dopant-dependent Fe2O3. Advanced techniques were utilized to investigate the structural characteristics, morphological properties, optical absorption and emission, and elemental composition properties of synthesized samples. Measurements via X-ray diffraction confirmed the rhombohedral structure for Fe2O3. Fourier-transform infrared analysis explored the vibrational and rotational modes of the O-H functional group and the C=C and Fe-O functional groups. The energy band gap of the synthesized samples was observed in the range of 2.78-3.15 eV, which indicates that the blue shift in the absorption spectra of Fe2O3 and Sr/St-Fe2O3 was identified with UV-vis spectroscopy. The emission spectra were obtained through photoluminescence spectroscopy, and the elements in the materials were determined using energy-dispersive X-ray spectroscopy analysis. High-resolution transmission electron microscopy micrographs showed NSs that exhibit nanorods (NRs), and upon doping, agglomeration of NRs and nanoparticles was observed. Efficient degradations of methylene blue increased the photocatalytic activity in the implantation of Sr/St on Fe2O3 NRs. The antibacterial potential for Escherichia coli and Staphylococcus aureus was measured against ciprofloxacin. E. coli bacteria exhibit inhibition zones of 3.55 and 4.60 mm at low and high doses, respectively. S. aureus shows the measurement of inhibition zones for low and high doses of prepared samples at 0.47 and 2.40 mm, respectively. The prepared nanocatalyst showed remarkable antibacterial action against E. coli bacteria rather than S. aureus at high and low doses compared to ciprofloxacin. The best-docked conformation of the dihydrofolate reductase enzyme against E. coli for Sr/St-Fe2O3 showed H-bonding interactions with Ile-94, Tyr-100, Tyr-111, Trp-30, ASP-27, Thr-113, and Ala-6.

Molecular Bridges Link Monolayers of Hexagonal Boron Nitride during Dielectric Breakdown

We use conduction atomic force microscopy (CAFM) to examine the soft breakdown of monocrystalline hexagonal boron nitride (h-BN) and relate the observations to the defect generation and dielectric degradation in the h-BN by charge transport simulations and density functional theory (DFT) calculations. A modified CAFM approach is adopted, whereby 500 × 500 nm2 to 3 × 3 μm2 sized metal/h-BN/metal capacitors are fabricated on 7 to 19 nm-thick h-BN crystal flakes and the CAFM tip is placed on top of the capacitor as an electrical probe. Current–voltage (I-V) sweeps and time-dependent dielectric breakdown measurements indicate that defects are generated gradually over time, leading to a progressive increase in current prior to dielectric breakdown. Typical leakage currents are around 0.3 A/cm2 at a 10 MV/cm applied field. DFT calculations indicate that many types of defects could be generated and contribute to the leakage current. However, three defects created from adjacent boron and nitrogen monovacancies exhibit the lowest formation energy. These three defects form molecular bridges between two adjacent h-BN layers, which in turn “electrically shorts” the two layers at the defect location. Electrical shorting between layers is manifested in charge transport simulations, which show that the I-V data can only be correctly modeled by incorporating a decrease in effective electrical thickness of the h-BN as well as the usual increase in trap density, which, alone, cannot explain the experimental data. An alternative breakdown mechanism, namely, the physical removal of h-BN layers under soft breakdown, appears unlikely given the h-BN is mechanically confined by the electrodes and no change in AFM topography is observed after breakdown. High-resolution transmission electron microscope micrographs of the breakdown location show a highly localized (<1 nm) breakdown path extending between the two electrodes, with the h-BN layers fractured and disrupted, but not removed.

Efficient adsorption and antimicrobial application of bio-synthesized porous CeO2 nanoparticles

The present research demonstrates the green synthesis of CeO2 nanoparticles (NPs) using the Acacia Concinna fruit extract by sol–gel route. The synthesized CeO2 NPs are applied for the adsorptive removal of Reactive Blue (RB) azo dye and antimicrobial activities. The CeO2 NPs are characterized using different techniques e.g. X-ray Diffraction Spectroscopy (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), UV–vis Spectroscopy, Scanning Electron Microscope (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), Dynamic Light Scattering (DLS), Raman Spectroscopy, etc. The structural investigations (XRD) reveal the single-phase cubic fluorite-type structure of CeO2 with 22.7 nm of crystallite size. The spectral analysis (FTIR) shows a strong vibration band below 849 cm−1 owing to Ce-O-Ce stretching vibrations. A porous network-like morphology of the CeO2 NPs is observed by SEM, where HR-TEM micrographs reveal that the nanoparticles are roughly spherical in nature. Raman spectroscopy confirms the vibrational mode of the cubic fluorite type structure of CeO2 NPs at 462 cm−1. The maximum loading capacity of CeO2 NPS is 188.67 mg/g. The antibacterial activity of the CeO2 NPs is evaluated against S. pneumoniae and E.coli, which shows 96.17 % and 96.89 % growth inhibition at 20 mg/l.

Hydrothermally-Derived Silver-Decorated Nanocrystalline Anatase Photocatalyst for Reactive Violet 2 Photodegradation

A photocatalyst comprised of Ag nanoparticles dispersed on an anatase matrix has been prepared using a simple hydrothermal method without additional thermal treatment. The prepared material was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-Vis spectroscopy, and N2 adsorption–desorption isotherms. The prepared catalyst activity was evaluated by photocatalytic degradation of C.I. Reactive Violet 2 (RV2) aqueous solution under UVA and visible light illumination. SEM revealed the non-uniform dispersion of silver particles throughout the matrix composed of fine particles. According to XRD analysis, the matrix was composed of pure anatase with a crystallite size of 8 nm calculated through the Scherrer equation. HRTEM micrograph analysis showed that anatase nanoparticles possess a spherical morphology and a narrow size distribution with an average particle size of 8 nm with more active anatase {100} crystal surface exposed, while silver nanoparticles were between 60 and 90 nm. A bandgap of 3.26 eV has been calculated on the basis of the DRS UV-Vis spectrum, while a specific surface area of 209 m2g−1 has been established from adsorption isotherms. Thus, through a simple synthesis approach without subsequent thermal treatment, the agglomeration of nanoparticles and the reduction of specific surface area have been avoided. Prepared nano Ag/anatase photocatalyst exhibits excellent efficiency for the photodegradation of RV2 under UVA and visible irradiation.

Garlic capped silver nanoparticles for rapid detection of cholesterol

A fluorescent biosensor based on garlic (Allium sativum L.) capped Ag nanoparticles (G-Ag NPs) has been synthesized for cholesterol detection. Pristine Ag NPs and G-Ag NPs were synthesized through the chemical reduction process. The effect of different capping agents such as 3-aminopropyltriethoxysilane (APTS), glutathione, 8-hydroxyquinoline, garlic/APTS, garlic/glutathione, and garlic/8-hydroxyquinoline on Ag NPs was evaluated. These NPs were characterized using Fourier transform infrared (FTIR), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), X-Ray diffraction (XRD), UV–visible spectra, and Zeta potential. The HRTEM micrographs illustrated that Ag NPs with particles size ranging from 2.98 to 14.34 nm were aggregated. G-Ag NPs images showed uniformly distributed spherical particles with particles size from 4.52 to 12.8 nm. The reduction in the plasmonic bands of Ag NPs and G-Ag NPs occurred by 96.4% and 11.7%, respectively after 12 months. The developed sensor for cholesterol based on the fluorescence enhancement had a linear response in a concentration range of 0.4–5.17 mM with a sensitivity of 4.36 Mm−1 and a limit of detection of 0.186 mM. The high selectivity toward cholesterol in presence of different interferes such as glucose, cysteine, glycine, urea, sucrose, nickel, and copper, and their mixture was evaluated. The applicability of this developed sensor for real serum samples was detected with a recovery percentage from 99.1 to 101.3%. Repeatability and reproducibility experiments displayed relative standard deviations (RSD) of 0.88% and 0.62%, respectively.

Thermal transport properties for unveiling the mechanism of BiSbTe alloys in thermoelectric generation: A glance from synchrotron radiation Bi L3-XAFS

For thermal to electric energy conversion, designing a high efficiency thermoelectric material entails simultaneously optimizing multiple properties of the material. Although it may appear simple to increase electrical power while minimizing thermal losses, the complicated link between these parameters makes optimization difficult, necessitating a more sophisticated approach. The one-pot zone melting method was used to fabricate undoped and Sb doped Bi2Te3 (Bi2−xSbxTe3; x = 0.0, 0.2, 0.6, and 1.0) in pellets form. X-ray diffraction (XRD), Raman and selected area electron diffraction (SAED) revealed rhombohedral polycrystalline nature and a unique high intensity of the Eg2 optical mode according to the nanosheet nature of the alloys as observed in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. Besides, High Resolution TEM (HRTEM) micrographs depicted twin boundary effect with an angle of 120° for Bi1.8Sb0.2Te3 alloys, which may enhance the electronic transport and the thermoelectric properties of the fabricated compounds. To obtain selective and detailed local structural information of Bi2−xSbxTe3 matrix, synchrotron radiation-based X-ray absorption spectroscopy (XAS) measurements were performed at around Bi L3-edge. A significant influence of the Sb/Bi substitution on the local/atomic structure was observed through the gradual elongation of the average in-plane Bi–Sb bond distance. The combination of different off-line structural characterization techniques such as XRD, Raman, SEM, and HRTEM with synchrotron based XAS technique and Laser-Beam Deflection Spectroscopy (BDS) is necessary to fully describe the samples nature and to get average crystal, morphological and local/electronic structural information for unveiling the BiSbTe mechanism in thermoelectric generation.

Biosynthesis of Gold Nanoparticles Using Strobilanthes crispa Aqueous Leaves Extract and Evaluation of Its Antibacterial Activity

The role of plant phytochemicals has drawn undeniable attention for synthesizing stable and eco-friendly nanoparticles. Therefore, this work explores using locally grown Strobilanthes crispa aqueous leaves extract for the biosynthesis of gold nanoparticles (AuNPs) using HAuCl4 as the metal precursor. The AuNPs were characterized using Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, High-resolution Transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). The UV-Vis spectrum exhibits two absorption peaks due to surface plasmon resonance of gold at 530 nm and 708 nm within 2 hours. The HRTEM micrographs proved that AuNPs were predominantly spherical with mixtures of anisotropic nanoshapes. The FTIR spectra evident the presence of phytochemical compounds, which acted as the capping agent. The face-centered cubic (fcc) structure was confirmed using the XRD pattern with an average crystallite size of 9.3 nm. The antibacterial assay exhibited a positive inhibitory effect on Gram-negative bacteria (Escherichia coli ATCC 11229) compared to Gram-positive bacteria (Staphylococcus aureus ATCC 6538). Further in silico analysis between AuNPs and E. coli bacterial proteins using STITCH 5.0 revealed a high binding affinity of &gt; 0.7 to DNA and membrane-related proteins. This result unravels the antibacterial properties of S. crispa AuNPs, leading to potent bacterial death.

Characterizing Li in partially lithiated layer materials using atomic‐resolution imaging, modeling, and simulation

AbstractUnderstanding of phase‐stability and nanoscale structural modulation during lithiation of layer materials demand comprehensive analysis of the Li‐containing phases in the solid‐state reaction products. Conventional chemical analysis methods in the transmission electron microscope (TEM) are not ideal to detect Li in partially intercalated nanodomains because Li atoms do not remain stationary under the focused electron beam. An alternate approach combining density functional theory (DFT) modeling and multislice image simulation has been explored in the present study to analyze the intercalated structures and to detect and quantify Li from the recorded high‐resolution TEM (HRTEM) micrographs of partially intercalated phases. HRTEM micrographs from partially lithiated graphite and MoS2 show variations in the interlayer spacings, but are not usually directly interpretable. Hypothetical intercalated microstructures of graphite and MoS2 supercells have been generated using atomic‐scale simulations with systematically varying Li concentrations. The measured interplanar spacings are compared with those of experimentally recorded HRTEM micrographs from lithiated graphite and MoS2. The results confirm the coexistence of different lithiated phases at localized domains. This understanding of phase transformation and the lithium quantification provides a basis for understanding the structural accommodation of layered materials during intercalation.

Effective Disposal of Methylene Blue and Bactericidal Benefits of Using GO-Doped MnO2 Nanorods Synthesized through One-Pot Synthesis.

Graphene oxide (GO)-doped MnO2 nanorods loaded with 2, 4, and 6% GO were synthesized via the chemical precipitation route at room temperature. The aim of this work was to determine the catalytic and bactericidal activities of prepared nanocomposites. Structural, optical, and morphological properties as well as elemental composition of samples were investigated with advanced techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV–visible (vis) spectroscopy, photoluminescence (PL), energy-dispersive spectrometry (EDS), and high-resolution transmission electron microscopy (HR-TEM). XRD measurements confirmed the monoclinic structure of MnO2. Vibrational mode and rotational mode of functional groups (O–H, C=C, C–O, and Mn–O) were evaluated using FTIR results. Band gap energy and blueshift in the absorption spectra of MnO2 and GO-doped MnO2 were identified with UV–vis spectroscopy. Emission spectra were attained using PL spectroscopy, whereas elemental composition of prepared materials was recorded with scanning electron microscopy (SEM)-EDS. Moreover, HR-TEM micrographs of doped and undoped MnO2 revealed elongated nanorod-like structure. Efficient degradation of methylene blue enhanced the catalytic activity in the presence of a reducing agent (NaBH4); this was attributed to the implantation of GO on MnO2 nanorods. Furthermore, substantial inhibition areas were measured for Escherichia coli (EC) ranging 2.10–2.85 mm and 2.50–3.15 mm at decreased and increased levels for doped MnO2 nanorods and 3.05–4.25 mm and 4.20–5.15 mm for both attentions against SA, respectively. In silico molecular docking studies suggested the inhibition of FabH and DNA gyrase of E. coli and Staphylococcus aureus as a possible mechanism behind the bactericidal activity of MnO2 and MnO2-doped GO nanoparticles (NPs).

Characterization of TiC ceramics with SiC and/or WC additives using electron microscopy and electron probe micro-analysis

This investigation aimed to assess the discrete and synergic impacts of SiC whiskers (SiCw) and nano-sized WC (WCn) on the microstructure of TiC-based materials. Three dense specimens of TiC−3 wt% WCn, TiC−30 vol% SiCw, and TiC−30 vol% SiCw−3 wt% WCn were yielded using the spark plasma sintering (SPS). The X-ray diffraction patterns (XRD), as well as the microstructural observations, suggested unreactive sintering processes; however, thermodynamic studies showed that some minor chemical interactions could take place, leading to surface oxide removal. Furthermore, the field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) micrographs, as well as the field emission electron probe micro-analyzer (FEEPMA) images, proved the WCn dissolution into the TiC matrix, forming (Ti,W)C solid solution in the TiC-WCn and TiC-SiCw-WCn ceramics, and also the graphite precipitation from the TiC in all samples. Glassy SiO2 phase, available as the surface oxide of starting SiCw or produced as the in-situ phase, could form some amorphous interfaces in the relevant composites.

Lead Sulphide Nanoparticles as Photocatalyst for the Degradation of Methylene Blue: Effects of pH, Time, Adsorption Kinetics and Recyclability Studies

We report the synthesis and morphological studies of lead sulphide nanoparticles prepared from lead(II) complexes of morpholine dithiocarbamate (PbS1), thiomorpholine dithiocarbamate (PbS2), and N-(2-hydroxyethyl)phenyl dithiocarbamate (PbS3). Powder X-ray diffraction patterns (p-XRD) of the PbS nanoparticles are indexed to face-centered cubic phase of PbS. High-resolution transmission electron microscopy (HRTEM) micrograph revealed quasi-spherical PbS nanoparticles with particle size in the range 13.86–36.06 nm while scanning electron microscopy (SEM) revealed flaky/spherical/rough surface morphology. Photocatalytic degradation of methylene blue dye by the PbS nanoparticles showed degradation efficiency of 72.6 % for PbS1, 75.9 % for PbS2, and 47.4 % for PbS3. The photodegradation efficiency shows a correlation between efficiency and morphological properties. Total organic content removal by PbS2 is 69.5 % while that of PbS1 is 64.2 % and PbS3 is 40.1 %. The as-prepared PbS nanoparticles exhibited remarkable photostability in the recyclability studies.

Nanocomposite of CuInS/ZnS and Nitrogen-Doped Graphene Quantum Dots for Cholesterol Sensing.

In this paper, nitrogen graphene quantum dots (N-GQDs) and copper indium sulfide/zinc sulfide (CIS/ZnS) QDs were synthesized via facile hydrothermal and aqueous solution routes, respectively. Herein, a fluorescent nanocomposite has been synthesized between N-GQDs and CIS/ZnS QDs in an aqueous phase. This nanocomposite was characterized by photoluminescence, Raman, and ultraviolet–visible (UV–vis) spectroscopies, high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). This fluorescent nanocomposite was developed as a highly sensitive, selective nonenzymatic cholesterol optical biosensor in 0.312–5 mM cholesterol. HRTEM micrographs confirmed the preparation of CIS/ZnS QDs and N-GQDs with average diameters of 3 and 5 nm, respectively. The as-prepared NG/CIS/ZnS QD nanocomposite had a high sensitivity for cholesterol with a wide linear range of concentration of 0.312–5 mM with an excellent correlation coefficient (R2) of 0.9688 and limit of detection (LOD) of 0.222 mM.

Changes in the mechanical, structural and electrical properties of glassy carbon due to strontium and silver co-implantation and annealing

The effect of Sr and Ag co-implantation and recovery annealing on the structural, mechanical and electrical properties of glassy carbon is reported. Glassy carbon was co-implanted with 200 keV Sr and Ag ions to a fluence of 1 × 1016 ions/cm2 at room temperature. Combination of Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) showed that the co-implantation of Sr and Ag resulted in amorphisation of the glassy carbon substrate. Raman spectra and HRTEM micrographs obtained after annealing indicated recovery of the glassy carbon structure, however, the recovered structure appears to be graphite-like. Instrumented indentation experiments on the ion-irradiated glassy carbon substrates revealed the formation of a surface layer with considerably enhanced mechanical performance. When annealing the ion implanted samples, these effects were only partially reversible. The effect of the irradiation-induced amorphisation and graphitisation of glassy carbon on its conductivity was also studied. The sample became less conductive after Sr and Ag co-implantation, whereby annealing resulted in an increase in conductivity.