High-resolution Transmission Electron Microscopy Techniques Research Articles

Evaluation of synthesis time in the growth of vertical-aligned MWCNTs by spray pyrolysis

Multi-Wall Carbon Nanotubes (MWCNTs) were analyzed on crystalline silicon substrates (type P) under optimal temperature conditions, using different synthesis times (2, 3, 4, 5, 10, 20, 30, 60, 120, and 180 min) in order to examine the effect on the structural quality and length of the CNTs produced by ultrasonic spray pyrolysis, using pure toluene and ferrocene as precursor solutions under argon flow. Structural, optical, and morphological differences of the MWCNTs grown were analyzed. Raman spectroscopy evidenced the MWCNTs' high quality, noted by the ID/IG (from 0.41 to 0.68) and I2D/IG intensity ratios around 0.75. Morphological differences of the MWCNTs grow evaluated by Field Emission Scanning Electron Microscopy (FE-SEM); the micrographs examined the thickness of CNTs' layers. High-Resolution Transmission Electron Microscopy (HRTEM) technique was used to determine the diameters of CNTs, which were found from 15 to 140 nm. X-Ray Diffraction (XRD) showed two characteristic peaks around 26° and 44°, which corroborated that the MWCNTs were well-graphitized. The influence of the time in these CNTs demonstrated that the final length of these nanotubes could easily reach micrometers. The alienation was better as time increased, and the graphitization extent is good in most cases compared to other more expensive synthesis methods.

Nano-refinement of the face-centered cubic Zr(Fe,Cr)2 secondary phase particles in Zircaloy-4 alloy via localized-shearing/bending-driven fracture under high-temperature compression

Nanoparticles are extensively introduced to improve the mechanical, physical, and chemical properties of alloys. In the present study, the underlying nano-refinement mechanisms of face-centered cubic Zr(Fe, Cr)2 secondary phase particles (SPPs) that precipitated in Zircaloy-4 alloy under high-temperature compression were investigated in detail by utilizing high-resolution transmission electron microscopy (HRTEM) and conventional TEM techniques. The frequently observed Zr(Fe, Cr)2 SPPs were incoherent with the matrix and exhibited brittle fracture behaviors without measurable plasticity. HRTEM observations revealed two mechanisms underlying the nano-refinement of incoherent micro-sized SPPs via localized shear fracture on {112¯}SPP and nanoprecipitate-assisted bending fracture, respectively. The latter was, for the first time, found to occur when the movements of large SPPs were blocked by nanometer-sized SPP during alloy deformation. Accordingly, two force models were proposed to visualize their potential nano-refinement processes. The knowledge attained from this study sheds new light on the deformation behaviors of Zr(Fe, Cr)2 SPPs and their associated size refinement mechanisms under high-temperature compression, and is expected to greatly benefit the process optimization of zirconium alloys to achieve precipitate nano-refinement.

Optical Properties of Cationic Perylenediimide Nanowires in Aqueous Medium: Experimental and Computational Studies

Cationic perylenediimide derivative, namely N,N’-di(2-(trimethylammoniumiodide)ethylene) perylenediimide (TAIPDI), has been synthesized and characterized in an aqueous medium by using dynamic light scattering (DLS), X-ray diffraction (XRD), fourier-transform infrared (FTIR), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The optical absorption and fluorescence spectra of TAIPDI revealed the formation of aggregated TAIPDI nanowires in water, but not in organic solvents. In order to control the aggregation behavior, the optical properties of TAIPDI have been examined in different aqueous media, namely cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS). Furthermore, the utilization of the examined TAIPDI for constructing supramolecular donor–acceptor dyad has been achieved by combining the electron accepting TAIPDI with the electron donating 4,4’–bis (2-sulfostyryl)-biphenyl disodium salt (BSSBP). The formed supramolecular dyad TAIPDI-BSSBP through the ionic and electrostatic π-π interactions have been well examined by various spectroscopic techniques, e.g., steady-state absorption and fluorescence, cyclic voltammetry, and time-correlated single-photon counting (TCSPC), and first principle computational chemistry methods. Experimental results suggested the occurring of intra-supramolecular electron transfer from BSSBP to TAIPDI with rate constant and efficiency of 4.76 × 109 s−1 and 0.95, respectively. The ease of construction, absorption in the UV–Visible region, and fast electron transfer process render the supramolecular TAIPDI-BSSBP complex as a donor–acceptor material for optoelectronic devices.

Quenching effect in luminescent and magnetic properties of Fe3O4/α-Fe2O3/Y2O3:Eu3+ nanocomposites

In this paper, Fe3O4/α-Fe2O3/Y2O3:Eu3+ multifunctional nanocomposites were synthesized using a hydrothermal method. Fe3O4/α-Fe2O3/Y2O3:Eu3+ nanocomposites are core-shell nanostructures consisting of a superparamagnetic nanomagnetite core, which is converted to hematite during the synthesis. As a theranostic material, hematite could be used in drug-release processes, while nanomagnetite generates heat in a hyperthermia cancer treatment. An outer shell of Y2O3:Eu3+ nanophosphor is added to give nanocomposites photoluminescent properties and to render them visible in bioimaging. Structural, optical, and magnetic features of nanocompositesare studied using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), Raman, photoluminescence (PL), vibrating-sample magnetometer (VSM), and high-resolution transmission electron microscope (HRTEM) techniques. Photoluminescence properties of nanocomposites show a quenching effect related to the proportion of magnetite and Y2O3:Eu3+. A luminescence quenching mechanism is proposed based on the optical effects of a core-shell structure. Magnetic saturation grows proportionally with the amount of magnetite present, which indicates that Fe3O4 magnetic structure is not altered, even by the hematite that forms around it. The synthesized nanocomposites possess a core-shell morphology modified by the different proportions of their components. The optical, structural, and magnetic nanocomposite properties found will be of interest in theranostic materials research in the biomedical field.

Synthesis of Boron-Doped Carbon Nanomaterial

A new method for the synthesis of boron-doped carbon nanomaterial (B-carbon nanomaterial) has been developed. First, graphene was synthesized using the template method. Magnesium oxide was used as the template that was dissolved with hydrochloric acid after the graphene deposition on its surface. The specific surface area of the synthesized graphene was equal to 1300 m2/g. The suggested method includes the graphene synthesis via the template method, followed by the deposition of an additional graphene layer doped with boron in an autoclave at 650 °C, using a mixture of phenylboronic acid, acetone, and ethanol. After this carbonization procedure, the mass of the graphene sample increased by 70%. The properties of B-carbon nanomaterial were studied using X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and adsorption-desorption techniques. The deposition of an additional graphene layer doped with boron led to an increase of the graphene layer thickness from 2-4 to 3-8 monolayers, and a decrease of the specific surface area from 1300 to 800 m2/g. The boron concentration in B-carbon nanomaterial determined by different physical methods was about 4 wt.%.

Dual-Functional CuO-Decorated Bi3.84W0.16O6.24/Bi2WO6 Nanohybrids for Enhanced Electrochemical Hydrogen Evolution Reaction and Photocatalytic Cr(VI) Reduction Performance

The development of dual-functional nanohybrid-based electrocatalysts/photocatalysts for producing renewable energy and removing heavy metal pollutants describes an environmentally sustainable technique to address the challenges in energy and environment applications. Herein, we adopted microwave-assisted synthesis to develop CuO-decorated Bi3.84W0.16O6.24/Bi2WO6 (CuO/biphase-BW) dual-functional nanohybrids for electrochemical hydrogen evolution reaction (HER) and photocatalytic Cr(VI) reduction applications. CuO nanoparticles with ∼50 nm were uniformly distributed on an octahedron-shaped bismuth tungstate analyzed via a high-resolution transmission electron microscope technique. Biphase bismuth tungstate optimization was meticulously controlled via the amount of copper precursor added to the reaction. Among synthesized materials, CuO1.0/biphase-BW catalysts exhibit excellent HER activity in neutral media (0.5 M Na2SO4) with a relatively low overpotential of 111 mV at a current density of 10 mA/cm2, and also it exhibits a lower Tafel slope of 237 mV/dec. Moreover, CuO1.0/biphase-BW catalyst-coated carbon cloth exhibits good conductivity and excellent electrochemical stability for 24 h. Maximum photocatalytic reduction of aqueous Cr(VI) was achieved on the CuO1.0/biphase-BW catalyst. It is worth mentioning that the tremendous activity of the synthesized electrocatalyst/photocatalyst can be ascribed to the formation and electronic interaction of CuO with biphase Bi3.84W0.16O6.24/Bi2WO6, thus increasing its surface-active sites and charge transfer. Our work provides a facile and effective way to engineer dual-functional nanohybrids for efficient water splitting in a neutral medium and reducing toxic (Cr(VI)) metal.

Synthesis and Characterization of Highly Crystalline Bi-Functional Mn-Doped Zn2SiO4 Nanostructures by Low-Cost Sol-Gel Process.

Herein, we demonstrate a process for the synthesis of a highly crystalline bi-functional manganese (Mn)-doped zinc silicate (Zn2SiO4) nanostructures using a low-cost sol-gel route followed by solid state reaction method. Structural and morphological characterizations of Mn-doped Zn2SiO4 with variable doping concentration of 0.03, 0.05, 0.1, 0.2, 0.5, 1.0, and 2.0 wt% were investigated by using X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) techniques. HR-TEM-assisted elemental mapping of the as-grown sample was conducted to confirm the presence of Mn in Zn2SiO4. Photoluminescence (PL) spectra indicated that the Mn-doped Zn2SiO4 nanostructures exhibited strong green emission at 521 nm under 259 nm excitation wavelengths. It was observed that PL intensity increased with the increase of Mn-doping concentration in Zn2SiO4 nanostructures, with no change in emission peak position. Furthermore, magnetism in doped Zn2SiO4 nanostructures was probed by static DC magnetization measurement. The observed photoluminescence and magnetic properties in Mn-doped Zn2SiO4 nanostructures are discussed in terms of structural defect/lattice strain caused by Mn doping and the Jahn-Teller effect. These bi-functional properties of as-synthesized Zn2SiO4 nanostructures provide a new platform for their potential applications towards magneto-optical and spintronic and devices areas.

Alkynyl carbon functionalized N-TiO2: Ball milling synthesis and investigation of improved photocatalytic activity

Herein, a series of alkynyl carbon functionalized N-TiO2 is fabricated by ball milling of CaC2 and pre-prepared N-TiO2. Based on the X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy techniques, it is confirmed that the alkynyl carbon materials are successfully doped into N-TiO2. The visible light catalytic performance of the alkynylated N-TiO2 (CNT-0.1) for degradation of Rhodamine B, methylene blue, levofloxacin, and p-nitrophenol is higher than that of the N-TiO2. Further, the photocatalytic NH3 production over the alkynylated N-TiO2 is 83.11 μmol·h−1·g−1 in the presence of CH3OH as the proton source, which is 2.41 folds higher than that of the N-TiO2 under UV-Visible light irradiation. The dominant active species for the photodegradation of Rhodamine B are determined to be h+ and O2·- radicals. The photocatalytic stability is verified by the recyclable tests, demonstrating a little decrease in the Rhodamine B photodegradation performance. It can be concluded from the photo-current, photo-voltage, electrochemical impedance spectroscopy, photoluminescence spectra, UV–vis absorption spectra, and Mott-Schottky plots that modification of alkynyl carbon materials can decrease charge recombination and improve the visible light response capacity of the photocatalyst, finally resulting in the enhanced photocatalytic performance. This work illustrates that the introduction of alkynyl carbon into semiconductor materials is a very promising modification strategy for promoting their photocatalytic properties.

Facile synthesis of ZnO/CuO/Eu heterostructure photocatalyst for the degradation of industrial effluent

Zinc oxide-based ternary heterostructure ZnO/CuO/Eu(1%, 3%, and 5% of Eu) nanoparticles were effectively produced by employing Vigna unguiculata(cowpea)waste skin extract as fuel in a simple one-pot combustion process. The as-synthesized heterostructure was analyzed by X-ray diffraction studies, ultraviolet-visible spectroscopy, Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, and High-Resolution Transmission Electron Microscopy techniques. Besides, the photocatalytic degradation efficiency of the as-obtained ternary nanocomposite was evaluated under UV light for the degradation of model organic pollutants including methylene blue (MB), Rhodamine-B (RB), and an effluent sample collected from the textile industrial waste. During this study, the effect of a variety of parameters on the photodegradation activity of the photocatalysts has been thoroughly evaluated, such as light source, catalyst dose, irradiation period, dye concentration, solution pH, etc. Under UV irradiation(100 mins), the ternary ZnO/CuO/Eu photocatalyst demonstrated excellent degradation activity of ∼99 and ∼93% for MB and RB, respectively, while for the industrial effluent, a decent degradation activity of 42% has been recorded. Further experiments have revealed a pH and concentration-dependent photocatalytic behavior of the heterostructure photocatalyst. Therefore, the results suggest that the heterostructure photocatalyst can be potentially applied for wastewater treatment and other environmental applications.

Antiproliferiative Activity of Biogenic Silver Nanoparticles Synthesized from Leonotis nepetifolia (L) on Human Cancer Cell lines

Currently, nanobiotechnology is the growing science in the field of medicine employing silver nanoparticles to deliver drugs to target cancer cells and proved to be potential anticancer agents. In this study, silver nanoparticles were synthesized using leaf extract of Leonotis nepetifolia (L). Gas chromatography-mass spectrometry data showed a total of 13 phytochemical constituents identified from ethanolic leaf extract of Leonotis nepetifolia (L). The effect of physicochemical factors such as the reaction time, temperature, concentration of Silver nitrate, concentration of leaf extract and pH in the synthesis of silver nanoparticles. For biosynthesis, the optimal conditions were 1 mM silver nitrate, 0.1 ml of leaf extract at 80° for 90 min. Ultra violet-visible spectroscopy, field emission scanning electron microscopy; high-resolution transmission electron microscopy and various techniques characterized the synthesized AgNPs. The silver nanoparticles obtained had absorbance maxima at 398 nm, were spherical in shape, had an average particle size of 11.32 nm, polydispersity index 0.44, the zeta potential of -23.75.69 mv and were crystalline. A cytotoxicity study was conducted on two human cancer cell lines, pancreatic and ovarian, using sulforhodamine B assay. We had compared the cytotoxicity of biogenic silver nanoparticles with that of synthetic silver nanoparticles. Treatment of pancreatic and ovarian with different concentrations of silver nanoparticles inhibited the cell viability with half maximal inhibitory concentration values of 25.4 μg/ml and 23.9 μg/ml. In contrast, silver nanoparticles inhibited cell viability with half maximal inhibitory concentration values of 48.2 μg/ ml and 42 μg/ml, which were statistically significant (p<0.001), when compared with that of doxorubicin and Camptothecin. Leonotis nepetifolia mediated silver nanoparticles effectively reduced the proliferation of pancreatic and ovarian cancer cell lines than that of synthetic nanoparticles.

Green synthesis of ZnO nanoparticles from Neem and Eucalyptus leaves extract for photocatalytic applications

Green synthesis of Zinc oxide (ZnO) nanoparticles (NPs) from leaf extracts involves simple, stable, cost-effective, eco-friendly, economically viable, sustainable and feasible approach. This method is more beneficial than conventional methods like physical and chemical methods, as they are toxic, expensive, non-biocompatible and causes environmental contamination. The present work focuses on Neem, and Eucalyptus leaves mediated synthesis of ZnO NPs and its photocatalytic capability towards the degradation of methylene blue (MB) dye. Here, the phytochemicals present in the leaf extract play a binary role by acting as effective capping and reducing agents in the synthesis process. In this work, we have synthesized three samples of ZnO NPs; one is using Neem leaf extract (ZnO-Nee.), second one is using Eucalyptus leaf extract (ZnO-Euc.) and the third one is using both the leaves extract together (ZnO-N&E). The structural, morphological and optical properties were analysed using X-ray diffraction (XRD), UV–Vis, Raman, fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM) techniques. The structural data confirmed single hexagonal phase wurtzite crystalline structure for all the three samples. The absorption spectra showed variation in the band gap of three NPs, evaluated using Tauc method. Mixed morphology of polygon, rod and sphere is observed for all the NPs. The photocatalytic degradation of MB pollutant using ZnO photocatalyst followed green protocol and achieved an excellent result with slight variation in the photocatalytic efficiency percentage. The highest photocatalytic decomposition of MB pollutant is observed for ZnO-Nee. sample as 97.98%. This photocatalytic study can make the synthesised ZnO NP as an efficient agent for water pollution by varying physicochemical parameters.

A CTAB-assisted PANI-MoS2 nanosheet flower morphology for the highly sensitive electrochemical detection of hydrazine.

In this work, cetyl trimethylammonium bromide (CTAB)-assisted polyaniline-molybdenum disulfide (CPANI-MoS2) nanosheets with a flower morphology have been synthesized through in situ polymerization and a hydrothermal method. The composite was analyzed for structural modification through X-ray diffraction (XRD) to examine chemical changes and the presence of functional groups via Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The surface morphology was identified by field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HR-TEM) techniques. The CPANI-MoS2 nanosheet glassy carbon electrode (GCE) offers a novel strategy for the electrochemical detection of carcinogenic hydrazine. The cyclic voltammetry (CV) curve demonstrated a quasi-reversible behaviour with a high-surface area. Furthermore, differential pulse voltammetry (DPV) analysis of hydrazine detection showed a wide linear range from 10 μM to 100 μM, a low limit of detection of 0.40 μM, and a high sensitivity of 7.23 μA μM cm-2. The determination of hydrazine in a water sample and the recovery percentage were found to be 100.31% and 103.73%, respectively. The CPANI-MoS2 nanosheet GCE significantly contributed to the high electroanalytical oxidation activity due to the CTAB surfactant modifying the flower-like nanosheet morphology, which enables the easy adsorption of hydrazine analyte species and exhibits a high current rate with a rapid detection response.

Enhanced mechanical strength in hot-rolled La-Fe-Si/Fe magnetocaloric composites by microstructure manipulation

La-Fe-Si-based alloys possess a giant magnetocaloric effect due to the sharp itinerant-electron metamagnetic transition. However, the relatively poor mechanical strength of these alloys impedes their practical application in the magnetic refrigeration system. In this study, we employed hot rolling to manipulate the microstructure, and thus to improve the mechanical strength of LaFe11.6Si1.4/Fe composites. The microstructure and magnetic phase transition behavior have been systematically investigated by X-ray tomography, high-resolution transmission electron microscope and digital image correlation technique. We found that the bending strength of the hot-rolled LaFe11.6Si1.4/Fe reached up to 176 MPa, which is about 26% higher than the non-rolled one. The refinement of the α-Fe particles plays a key role in hindering crack propagation and enhancing the mechanical strength of the hot-rolled sample. Additionally, the reduction of the La-rich phase and large-size pores is found to be beneficial to the mechanical strength enhancement. The hot-rolled composite shows a sharp metamagnetic transition with a maximum magnetic entropy change of 17 J kg−1 K−1 for 2 T magnetic field change. This study demonstrates that microstructure manipulation based on hot rolling is a feasible approach to improve the mechanical strength of La-Fe-Si materials.

Quantitative spatial mapping of distorted state phases during the metal-insulator phase transition for nanoscale VO2 engineering

ABSTRACT Vanadium dioxide (VO2) material, known for changing physical properties due to metal-insulator transition (MIT) near room temperature, has been reported to undergo a phase change depending on the strain. This fact can be a significant problem for nanoscale devices in VO2, where the strain field covers a large area fraction, spatially non-uniform, and the amount of strain can vary during the MIT process. Direct measurement of the strain field distribution during MIT is expected to establish a methodology for material phase identification. We have demonstrated the effectiveness of geometric phase analysis (GPA), high-resolution transmission electron microscopy techniques, and transmission electron diffraction (TED). The GPA images show that the nanoregions of interest are under tensile strain conditions of less than 0.4% as well as a compressive strain of about 0.7% (Rutile phase VO2[100] direction), indicating that the origin of the newly emerged TED spots in MIT contains a triclinic phase. This study provides a substantial understanding of the strain-temperature phase diagram and strain engineering strategies for effective phase management of nanoscale VO2.

Ultrathin epitaxial NbNx film deposited by PEALD method on C-plane sapphire: Growth, structure and superconducting properties

Here we report on the results of obtaining and study of epitaxial ultrathin superconductive films of niobium nitride (NbNx) grown on a C-plane sapphire substrate. The films were deposited from the TBTDEN metal-organic precursor using the plasma-enhanced atomic layer deposition (PEALD) technique at 350 °C and NH3/Ar and H2/Ar gas mixtures as reactants. We employed X-ray diffraction (XRD), X-ray reflectometry (XRR), and high-resolution transmission electron microscopy (HRTEM) techniques to study the structural properties of the films. The investigation demonstrated that NbN layers grow in the plane (111) and consist of twins which axes 11¯0 are parallel to the substrate axes 11¯00 in the basal plane. The cubic lattice of layers is subject to rhombohedral deformation involving distortion of right angles up to 89° due to the four NbNx lattices coincide with the three sapphire lattices with misfit of 0.31%. We have also determined the quasiparticle diffusion constant and the coherence length of the NbNx films. The values of superconducting transition temperature and critical current density were determined as 12 K and 6.2 МА/cm2, respectively.

Morphology of Transition Metal Carbonate Cathode Precursors

Increasing the capacity of cathode materials used for lithium-ion batteries is desirable, as it ultimately enhances the energy density. Due to their lower cost and reversible cycling capacity of 250 – 300 mAh/g, Li- and Mn-rich LMR-NMC oxides are strong candidates as next generation cathodes used in lithium-ion batteries. Apart from the atomic structure, morphology of the cathode particles also influence their performance. LMR-NMC cathode particles are usually constructed through a two-step cathode fabrication process, which involves initial coprecipitation of the Mn-rich carbonate based cathode precursors, and later calcination of these precursors with a lithium salt at elevated temperatures. The secondary particles generally maintain their as precipitated precursor morphologies even after high temperature calcination. Even though the primary particles do change their size during calcination, the rate of oxidation and lithiation experienced by the transition metal precursors depend substantially on the primary particle morphology. Hence, it is critical to understand and control both the primary and secondary particle morphologies obtained after the coprecipitation process. In the present context, carbonate based NMC cathode precursors containing only Mn, only Ni and only Co, is precipitated, along with equal amount of the transition metals (Ni0.33Mn0.33Co0.33CO3), using conventional batch reactors. NH4HCO3 is used as the source of carbonate anions during the coprecipitation process, and the entire reaction is conducted at 50°C. The obtained particle morphologies for different transition metals are shown in Figure 1(a) as visualized using high resolution TEM techniques. Except MnCO3, all other transition metals demonstrate aggregated morphologies, which most probably form through surface growth mechanisms. Competition between growth rate and surface energies that leads to the formation of single crystalline particles for MnCO3, and particulate features for other transition metals, are demonstrated in Figure 1(b). Multiscale computational methodologies are developed to elucidate the impact of reaction kinetics and thermodynamics on determining the overall primary and secondary particle morphologies. Influence of transition metal content and ammonia concentration in determining the final particle size and size distribution will be discussed as part of this study. Figure 1

Synergetic and charge transfer properties of a metal oxide heterojunction: Photocatalytic activities

Improvement in the synthesis techniques and their optimum properties to be up-to-date is the global need for industrially scalable applications. The sol–gel solution combustion synthesis (SG-SCS) approach is an easy, time-/energy-efficient, and creates regularly ordered porous materials that have significance in the ion-/mass-transport phenomenon. Furthermore, the approach also yields a decent heterojunction once optimized via the HSAB theory. Forming a heterojunction also tunes the crucial properties of the materials, thus, boosting the photocatalytic ability through charge transfer or/and synergistic roles. From the stability investigation results, the calcination temperature of 500°C is determined to be ideal. The X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) techniques confirmed the nanoscale size of the NPs and NCs. The porous nature of the materials is revealed from the scanning electron microscopy micrographs and BET analysis; consistent results are also noted from selected area electron diffraction and HRTEM. The detected stacking faults on the IFFT image of HRTEM also confirmed the porous properties of the NCs. The precise elemental composition and local heterojunction within Zn/Fe(III)/Mn(III) oxides were confirmed in the HRTEM, X-ray photoelectron spectroscopy, and energy-dispersive X-ray studies. The significant charge transfer capability of the NCs more than bare ZnO was evidenced from the electrochemical analysis. The NCs were also effective on acid orange 8 (AO8) and Congo red (CR) dye degradations.

Viscoelastic Covalent Organic Nanotube Fabric via Macroscopic Entanglement.

Covalent organic nanotubes (CONTs) are one-dimensional porous frameworks constructed from organic building blocks via dynamic covalent chemistry. CONTs are synthesized as insoluble powder that restricts their potential applications. The judicious selection of 2,2'-bipyridine-5,5'-dicarbaldehyde and tetraaminotriptycene as building blocks for TAT-BPy CONTs has led to constructing flexible yet robust and self-standing fabric up to 3 μm thickness. The TAT-BPy CONTs and TAT-BPy CONT fabric have been characterized by solid-state one-dimensional (1D) 13C CP-MAS, two-dimensional (2D) 13C-1H correlation NMR, 2D 1H-1H DQ-SQ NMR, and 2D 14N-1H correlation NMR spectroscopy. The mechanism of fabric formation has been established by using high-resolution transmission electron microscopy and scanning electron microscopy techniques. The as-synthesized viscoelastic TAT-BPy CONT fabric exhibits high mechanical strength with a reduced modulus (Er) of 8 (±3) GPa and hardness (H) of 0.6 (±0.3) GPa. Interestingly, the viscoelastic fabric shows time-dependent elastic depth recovery up to 50-70%.

Single crystalline manganite (γ‒MnOOH) rods enclosed with high index facets and its excellent catalytic conversion of lignin‒derived feedstock

Single crystalline manganite (γ‒MnOOH) materials with rod shape have been synthesized via hydrothermal method. Interestingly, the extent of the hydrothermal duration of the syntheses had a significant impact on the crystal's growth of manganite rather than morphogical or phase tuning. Hydrothermal duration and amount of SDS had a significant impact on the crystal's growth. During synthesis, SDS template preferentially bind on the (111) than (101) surface. The rod shaped manganite has been identified by powder X‒ray diffraction (XRD), Raman spectroscopy, high‒resolution transmission electron microscopy (HRTEM), field‒emission scanning electron microscopy (FESEM), and X‒ray photoelectron spectroscopy (XPS) studies. PXRD and HR TEM techniques were shown that the rod shaped manganite are single crystalline in nature. FESEM, HRTEM and SAED techniques revealed that the rod shaped manganite were enclosed with {11‒1}, {‒111}, {111} and {110} exposed facets. XPS analysis revealed that Mn exhibits a mixed‒valence state (Mn3+ and Mn4+) at the surface of the rods. The rods exhibit good catalytic activities towards the oxidation of isoeugunol (lignin‒derived feedstock) to vanillin.

Functionalized Microbial Consortia with Silver-Doped Hydroxyapatite (Ag@HAp) Nanostructures for Removal of RO84 from Industrial Effluent

Considering that freshwater is a necessity for human life, sewage treatment has been a serious concern for an increasing number of scientists and academics in recent years. To clean industrial effluents, innovative catalysts with good adsorption, chemical stability, and physicochemical properties have been constructed. Here, a prospective microbial consortium was extracted from the wastewater and used as a low-cost catalyst that was functionalized with silver and silver-doped hydroxyapatite (Ag@HAp) nanostructures made using a sonochemical approach. The structural, optical, and crystal phases of Ag and Ag-doped hydroxyapatite (Ag@HAp) nanostructures were studied using ultraviolet-visible (UV-Vis), Fourier transfer infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The degradation action of functionalized microbial consortia was examined against reactive orange 84 (RO84) organic discharge. Excellent efficiency for the removal of industrial effluents was found for the Ag NPs and Ag-doped hydroxyapatite (Ag@HAp) loaded with microbial consortia. A maximum of 95% of the decolorization properties of the RO84 dye were obtained in the case of microbial consortia with Ag and Ag@HAp, which was better than the consortia alone (80.32% for 5 ppm and 69.54% for 20 ppm). The consortia/Ag showed 93.34% for 5 ppm and 85.43% for 20 ppm, while was higher for consortia/Ag@HAp (95.34 and 88.43%). The use of these surface-modified nanocatalysts for wastewater treatment and waste effluents discharged from laboratories, the chemical industry, and other sources could be expanded.