Transmission Election Microscopy Research Articles

Efficient degradation of wastewater by ultra-low platinum doped ZnO lamellar nanoflowers via photoinduced formation of hydroxyl radicals

Photocatalytic degradation technology is a promising strategy for the water treatment, which has many advantages such as saving time, cleanliness and environmental friendliness. In this study, ultra-low amount (0.01 wt%) of nano platinum (Pt) obtained from one-pot reduction method, was doped onto zinc oxide (ZnO) to form a lamellar nanoflower (Pt-ZnO). The characterization of Pt-ZnO was put forwards via scanning electron microscopy, high-angle annular dark-field scanning transmission election microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, liquid chromatography-mass spectrometry, etc. The highest degradation efficiencies of methylene blue (MB), rhodamine B (Rh B), methylene orange (MO), and acid black ATT (ATT) after being treated by Pt-ZnO for about 60 min reached 99.9%, 99.9%, 96.0%, and 97.8% respectively. While the MB and Rh B remained at a degradation efficiency of 99.9% even after being reused 5 times. Surprisingly, Pt-ZnO showed the removal rate of industrial effluent containing acid dyes was 93.9% and the chemical oxygen demand (COD) of wastewater was significantly reduced. Experimental results of LC-MS and free radical scavenging testing indicated MB was mainly split through the continuous open-ring cleavage of C-N bond in N, N-dimethylamine group by ·OH, and finally decomposed into H2O and CO2 achieving the decolorization.

Demetallation and reduction induced ultra-dispersed PtZn alloy confined in zeolite for propane dehydrogenation

Developing efficient bimetallic Pt-based catalyst is highly desired for propane dehydrogenation (PDH) process. Typical co-impregnation method often results in inhomogeneous distributions of metal species on supports. Herein, we reported a facile method to support PtZn bimetal alloy nanoparticles onto Beta zeolite, mainly existing as highly dispersed Pt1Zn1 alloy species. Zn@Beta was first synthesized by hydrothermal method with the aid of ethylenediamine (EDA), leading to the introduction of Zn atoms into zeolite lattice. An impregnation process was subsequently employed to support Pt species. During this process, skeleton Zn atoms migrated out of the framework and were then reduced together with Pt in flowing H2, leading to the formation of PtZn alloy with mainly Pt1Zn1 structures. Cs-corrected high-angle annular dark-field scanning transmission election microscope and X-ray absorption fine structure analyses revealed that this method was more conducive to the formation of PtZn alloy compared with the co-impregnation method. The obtained catalyst of 0.3Pt1Zn@Beta exhibited initial propane conversion of 36.8% and propylene selectivity of 99.3% combined with low deactivation rate (0.004 h–1) over 24 h with propane WHSV of 4.7 h–1 at 550 °C. The catalyst also exhibited good PDH performance in a long-term reaction (180 h) and robustness during regeneration reactions by simply flushing hydrogen.

Current transport in Ni Schottky barrier on GaN epilayer grown on free standing substrates

In this paper, the Ni Schottky barrier on GaN epilayer grown on free standing substrates has been characterized. First, transmission electrical microscopy (TEM) images and nanoscale electrical analysis by conductive atomic force microscopy (C-AFM) of the bare material allowed visualizing structural defects in the crystal, as well as local inhomogeneities of the current conduction. The forward current-voltage (I-V) characteristics of Ni/GaN vertical Schottky diodes fabricated on the epilayer gave average values of the Schottky barrier height of 0.79 eV and ideality factor of 1.14. A statistical analysis over a set of diodes, combined with temperature dependence measurements, confirmed the formation of an inhomogeneous Schottky barrier in this material. From a plot of ΦB versus n, an ideal homogeneous barrier close to 0.9 eV was estimated, similar to that extrapolated by capacitance-voltage (CV) analysis. Local I-V curves, acquired by means of C-AFM, displayed the inhomogeneous distribution of the onset of current conduction, which in turn resembles the one observed in the macroscopic Schottky diodes. Finally, the reverse characteristic of the diodes fabricated in the defects-free region have been acquired at different temperature and its behaviour has been described by the thermionic field emission (TFE) model.

Interplay between dislocation glide and ω precipitation in a Ti–15Mo alloy investigated by TEM

The mechanical response of ω precipitations in a Ti–15Mo alloy during compression test is investigated by transmission election microscopy (TEM) observation. The interaction between the dislocation slips and ω precipitations was focused, by which some of the ω variants were absent, while others were detected, in deformation bands. Two mechanisms including the shear and the disordering mechanisms are proposed to uncover the underlying mechanisms of mechanical responses of ω precipitations. This understanding will provide new insight onto the strengthening strategy and alloy design of titanium.

CdS Nanoparticles Decorated 1D CeO2 Nanorods for Enhanced Photocatalytic Desulfurization Performance

CdS nanoparticles were constructed onto one-dimensional (1D) CeO2 nanorods by a two-step hydrothermal method. The X-ray diffraction (XRD), transmission election microscopy (TEM), Raman spectra, X-ray photoelectron spectra (XPS) and UV-Vis diffuse reflection spectroscopy (DRS) techniques were used to characterize these CdS/CeO2 nanocomposites. It was concluded that when the molar ratio of CdS and CeO2 was 1:1, the nanocomposites exhibited the best photocatalytic desulfurization activity, reaching 92% in 3 h. Meanwhile, transient photocurrent (PT) measurement, photoluminescence (PL) spectra and electrochemical impedance spectroscopy (EIS) measurement indicated that the modification of CeO2 nanorods by CdS nanoparticles could significantly inhibit the recombination of photogenerated electrons and holes. In addition, the possible mechanism of photocatalytic oxidation desulfurization of the nanocomposites was proposed. This study may provide an effective CeO2-based photocatalyst for photocatalytic desulfurization applications.

Redox-active benzoquinone-intercalated layered vanadate for high performance zinc-ion battery: Phenol-keto conversion and the anchoring effect of V-O-V host framework

• ( o -BQ) 0.25 V 2 O 5 ·0.5H 2 O and ( p -BQ) 0.25 V 2 O 5 ·0.5H 2 O (BQ = benzoquinone) were synthesized. • Rietveld refinements and HAADF-STEM reveal the successful intercalation of BQ into V 2 O 5 . • ( p -BQ) 0.25 V 2 O 5 ·0.5H 2 O shows an excellent rate performance and an ultralong cycle life. • The sandwiched BQ in layered V 2 O 5 can be prevented from leaching into the electrolyte. • DFT calculations disclose a small Zn 2+ -migration barrier in ( p -BQ) 0.25 V 2 O 5 · x H 2 O. Utilizing a facile one-step hydrothermal technique, oxygen-deficient ( o -BQ)-VO and ( p -BQ)-VO nanosheets were synthesized, which were formulated as ( o -BQ) 0.25 V 2 O 5 ·0.5H 2 O and ( p -BQ) 0.25 V 2 O 5 ·0.5H 2 O (BQ = benzoquinone), respectively. Rietveld refinements and high-angle annular dark-field (HAADF)-scanning transmission election microscope (STEM) reveal the successful intercalation of o -BQ or p -BQ into the layered V 2 O 5 with large interlayer spacings of ∼ 13.7 Å, in which all the V centers are coordinatively unsaturated due to the elongation of V-O bonds. ( p -BQ)-VO shows an excellent rate performance of 487/446/405/371/333/280 mAh g −1 at 0.1 ∼ 5 A g −1 and an ultralong cycle life with a capacity retention of 96.0 % after 4000 discharge/charge cycles at 5 A g −1 , which is due to the dual redox-activity from BQ and vanadium oxide. The phenol-keto conversion of BQ can provide extra capacity. Furthermore, the sandwiched BQ in layered V 2 O 5 can be prevented from leaching into the electrolyte. On the other hand, ( p -BQ)-VO shows better electrochemical performance than ( o -BQ)-VO, indicating that the redox property of quinone is associated with the para - or ortho -position of keto-group and their possible coordination modes with Zn 2+ . Density functional theory (DFT) calculations disclose that the deep intercalation of Zn 2+ on certain site in ( p -BQ)-VO can improve electron conductivity, giving rise to enhanced electrochemical behavior. And the Zn 2+ -migration along b axis of the ( p -BQ)-VO cell shows a small energy barrier of 0.80 eV, thus leading to the outstanding rate and cycling performances. Redox-active benzoquinone (BQ)-intercalated layered vanadate ( p -BQ) 0.25 V 2 O 5 ·0.5H 2 O exhibits excellent rate performance and ultralong cycle life in zinc-ion battery, which is due to the dual redox-activity from BQ and vanadium oxide. Furthermore, the sandwiched BQ in layered V 2 O 5 can be prevented from leaching into the electrolyte. DFT calculations disclose a small Zn 2+ -migration barrier of 0.80 eV.

Long-lifespan benzoquinone-intercalated vanadium oxide with vacancies and disorders on the (00l) facets for efficient sodium-ion battery: A facile approach to Na+ capture and pre-sodiation

Via a facile one-step hydrothermal method, it was synthesized (m-BQ)0.15V2O5·0.5H2O (m-BQ = m-benzoquinone) (denoted as (m-BQ)-VO) three-dimensional (3D) porous hierarchical microflowers, which possesses a large (001) lattice spacing of 13.7 Å with crystalline vacancies and disorders on the (00l) facets. Rietveld refinement and high-angle annular dark field-scanning transmission election microscopy (HAADF-STEM) of (m-BQ)-VO unveil that the successful intercalation of m-BQ into layered V2O5 leads to the elongation of V-O bonds. As a result, the V centers of the sample are unsaturated with structural oxygen vacancies, and the V-O-V bilayer is split into two V-O-V monolayers with the (001) facet as the division plane. Consequently, upon lower-temperature annealing, the dehydrated sample can deliver a high initial capacity of 252 mAh/g at 0.05 A/g with excellent capacity retentions of 90 % over 210 cycles at 0.1 A/g, and 87 % over 2100 cycles at 2 A/g, respectively, in which no apparent phase change is observed. It is associated with the large interlayer channel with a lower Na+ migration barrier of 0.48 eV. And the anchoring effect of layered V-O-V framework can prevent the leaching of m-BQ into electrolyte. Furthermore, the redox-active m-BQ can provide extra capacity, whose affinity towards Na+ can induce the partial inclusion of Na+ ions in the sample even only immersion in Na+ solution undisturbed under room temperature, giving rise to improved electron conductivity and a facile approach to pre-sodiation, as evidenced by density functional theory (DFT) calculations.

Benzoquinone-intercalated vanadium oxide in the electrolyte with Al3+ for zinc-ion storage: dual-pillar effect and reversible disorder–order conversion

It was synthesized oxygen-deficient (1, 2, 3-BQ)-VO formulated as (1, 2, 3-BQ)0.25V2O5·0.5H2O (BQ = benzoquinone) via a facile one-step hydrothermal technique. Continuous rotation electron diffraction (cRED), Rietveld refinement and spherical aberration-corrected transmission election microscopy unravel the successful pre-intercalation of the BQ organic species into the layered vanadium oxide, in which two neighboring V-O-V monolayers are observed with the (001) facet as the division plane. (1, 2, 3-BQ)-VO possesses a good electrochemical property in 3 M Zn(CF3SO3)2. And in the electrolyte with Al3+, it shows improved rate capability and remarkably enhanced cycling performance. Its average capacity is up to an unprecedented value of 446/400 mAh/g at 0.2/1 A/g with a capacity retention exceeding 100 % over 550 cycles at 1 A/g (411 mAh/g), which is associated with the dynamic reversible conversion between disorder and order on the (001) facets. The inserted Al3+ into the inner channel of (1, 2, 3-BQ)-VO during the discharge process, not only acts as the interlayer pillar to prevent the collapse of the layered structure, but also can improve the crystallinity of the charged (1, 2, 3-BQ)-VO sample due to the more ordered atomic arrays from the interlayer (00l) facets. And the dual pillars of BQ and Al3+ in the sample can boost the exposure of active sites, thus enhance the storage capacity. In addition, density functional theory (DFT) calculations disclose a small Zn2+ diffusion barrier of 0.85 eV in (1, 2, 3-BQ)-VO. Moreover, it is found that the electrolyte with Al3+ is not only beneficial for the modification of the (1, 2, 3-BQ)-VO cathode, but also can inhibit the Zn dendrite formation at the Zn anode.

Investigation of the microstructural evolution of the as-extruded Mg–6Zn–1Mn alloy sheets under high strain rate tensile loading

To study the microstructural evolution of the as-extruded Mg–6Zn–1Mn alloy sheets with different initial microstructures during high strain rate tensile deformation, the interruptible tensile tests were performed at the strain rate of 1000 s−1, with controlled strain of 2.5%, 7.5% and 12.5%. The microstructure of the samples was characterized by electron backscatter diffraction and transmission electrical microscopy. The results demonstrate that the microstructural evolution of alloys during high strain rate tensile deformation is strongly influenced by the grain size and texture. Twins are suppressed during deformation in the fine-grained samples with strong basal texture, and only a few tension twins are observed at the large strain. Conversely, tension twins are activated greatly in the coarse-grained samples with the weaker basal texture. Twins are firstly activated at a small strain, and then more twins form and grow up as the strain increases. Regardless of the degree of twinning activity, the plastic deformation of the samples with different initial microstructures under high strain rate tensile loading is mainly provided by dislocation slip, and the dislocation density increases with the increase of strain. Moreover, the large grain size and relatively weak basal texture promote the formation of more dislocations.

Green synthesis of cobalt sulphide nanoparticles using synthesised cobalt (II) complex as a single route intermediate

Nanotechnology is increasing at a very fast rate due to its many possible applications in the biomedical, industry, pharmaceuticals, commercial and their areas. In this paper, we have reported the biosynthesis of chalcogenide nanostructured pharmacologically active cobalt sulphide nanoparticles (CoS) using 3-ethylidene oxopropanamide thiosemicarbazone Co(II) chloride complex. The synthesised cobalt (II) complex of schilf base ligand was reacted with freshly prepared aqueous leaves extract of Nyctanthes arbour tistis (harsingar leaves) for synthesis of CoS nanoparticles. The biofabrication of CoS nonoparticles is a very simple, efficient, fast, eco-friendly and inexpensive method. In this method we use the aqueous environment for green synthesis of CoS nanoparticles. The use of aqueous medium plays a very important role in reducing reaction time, reducing minimum possibilities of side reactions and proper execution in conversion of very good quality of nanoparticles in a very less time. The synthesized compounds like schiff base, Co (II) complex and CoS nanoparticles were analyzed through various structure, morphological, electronic, vibrational and pharmacological characterizations. Powdered xray diffraction studies confirm the formation of well defined equispaced crystalline nanoparticles. Transmission election microscopy and FESEM microscopy exhibit rod like structures of CoS nanoparticles with an average particle size of 56 nm. Sharp electronic absorption band at 280 nm indicates the synthesis of good quality CoS nanoparticles. The FT-IR spectral studies confirmed the presence of Co –S stretching, N-H bending and C=N stretching vibrations in Cobalt complex of Schiff base ligand. The thermal analysis of cobalt complex was performed to investigate the thermal stability of complex. The cobalt complex was stable up to 300°c. The effective results of all pharmacological activities like in vitro antimicrobial, antioxidant and anti inflammatory activities explained the presence of strong electron withdrawing and election releasing functional groups are present in schiff base ligand and its Co (II) complex The biofabrication of CoS nanoparticles via aqueous extract of fresh leaves of Nyctanthes arbour tristis in proper stoichiometric ratio is a good method for synthesizing highly efficient bioactive agents which can be consider as a good drug candidate for various biological applications in future for mankind.

Unsaturated coordination modes of Mn/V in manganese vanadate: Inner capture and surface migration of zinc ions for high performance zinc-ion battery

It was synthesized Mn0·2V2O5(H2O)·H2O (MnVO) porous microflowers and Ti0·055V2O5(H2O)2·H2O (TiVO) nanosheets. Rietveld refinements and high-angle annular dark-field (HAADF)-scanning transmission election microscope (STEM) reveal they are both constructed by two-dimensional (2D) V-O-V monolayers, lamellar hydrated metal ions and uncoordinated water molecules, in which all the V centers exhibit unsaturated coordination modes. Density functional theory (DFT) calculation proves that the exposed unsaturated V centers on the MnVO (001) surface can boost Zn2+ migration along the surface with a low barrier of 0.61 eV. Therefore, MnVO shows a dominant surface-controlled capacity. MnVO displays excellent Zn2+ storage behavior (435 mAh g-1 at 0.1 A g-1) with a capacity retention of 96.4 % after 1000 discharge/charge cycles at 5 A g-1, which is superior to TiVO. And MnVO and TiVO both show higher capacities than the commercial V2O5. Ex situ characterizations of MnVO discover a conversion of MnVO → Znm(MnVO) and a partial phase transformation mechanism of MnVO → Zn3(OH)2V2O7·2H2O during discharge/charge process. And DFT calculations reveal the intercalation of Zn2+ into some sites in the inner channel of MnVO is irreversible, leading to the accumulation of Zn2+ with almost unchanged interlayer spacing.

Pulicaria undulata Extract-Mediated Eco-Friendly Preparation of TiO2 Nanoparticles for Photocatalytic Degradation of Methylene Blue and Methyl Orange.

Eco-friendly approaches for the preparation of nanomaterials have recently attracted considerable attention of scientific community due to rising environmental distresses. The aim of the current study is to prepare titanium dioxide (TiO2) nanoparticles (NPs) using an eco-friendly approach and investigate their performance for the photocatalytic degradation of hazardous organic dyes. For this, TiO2 NPs were prepared by using the aqueous extract of the Pulicaria undulata (L.) plant in a single step at room temperature. Energy-dispersive X-ray spectroscopy established the presence of both titanium and oxygen in the sample. X-ray diffraction revealed the formation of crystalline, anatase-phase TiO2 NPs. On the other hand, transmission election microscopy confirmed the formation of spherical shaped NPs. The presence of residual phytomolecules as capping/stabilization agents is confirmed by UV–vis analysis and Fourier-transform Infrared spectroscopy. Indeed, in the presence of P. undulata, the anatase phase of TiO2 is stabilized at a significantly lower temperature (100 °C) without using any external stabilizing agent. The green synthesized TiO2 NPs were used to investigate their potential for the photocatalytic degradation of hazardous organic dyes including methylene blue and methyl orange under UV–visible light irradiation. Due to the small size and high dispersion of NPs, almost complete degradation (∼95%) was achieved in a short period of time (between 1 and 2 h). No significant difference in the photocatalytic activity of the TiO2 NPs was observed even after repeated use (three times) of the photocatalyst. Overall, the green synthesized TiO2 NPs exhibited considerable potential for fast and eco-friendly removal of harmful organic dyes.

Functionalised graphene oxide-bromobutyl rubber composites with segregated structure for enhanced gas barrier properties

ABSTRACT Graphene-based elastomer composites with a segregated structure were prepared by electrostatic self-assembly. The morphology and microstructures of the composites were characterised by scanning electron microscope (SEM) and transmission electrical microscope (TEM). The segregated network leads to a low gas permeability coefficient for BIIR composites. With the incorporation as low as 0.4 wt-% GTA-GO, the helium permeability coefficient decreased about 63% when compared with that of neat BIIR. The tensile strength and percentage elongation increased with an increase in the GTA-GO content. This is attributed to the complete exfoliation, uniform dispersion and the segregated structure of GTA-GO in the BIIR matrix. These results demonstrate that such electrostatic self-assembly method between latex and sheet-fillers is an effective strategy to design and produce polymeric nanocomposites with good gas barrier properties. The results will effectively promote the application of barrier polymer in the production of protective clothing, gas storage devices and coatings.

Morphine Prevents Ischemia/Reperfusion-Induced Myocardial Mitochondrial Damage by Activating δ-opioid Receptor/EGFR/ROS Pathway.

The purpose of this study was to determine whether the epidermal growth factor receptor (EGFR), which is a classical receptor tyrosine kinase, is involved in the protective effect of morphine against ischemia/reperfusion (I/R)-induced myocardial mitochondrial damage. Isolated rats hearts were subjected to global ischemia followed by reperfusion. Cardiac H9c2 cells were exposed to a simulated ischemia solution followed by Tyrode's solution to induce hypoxia/reoxygenation (H/R) injury. Triphenyltetrazolium chloride (TTC) was used to measure infarct size. The mitochondrial morphological and functional changes were determined using transmission election microscopy (TEM), mitochondrial stress assay, and mitochondrial swelling, respectively. Mitochondrial fluorescence indicator JC-1, DCFH-DA, and Mitosox Red were used to determine mitochondrial membrane potential (△Ψm), intracellular reactive oxygen species (ROS) and mitochondrial superoxide. A TUNUL assay kit was used to detect the level of apoptosis. Western blotting analysis was used to measure the expression of proteins. Treatment of isolated rat hearts with morphine prevented I/R-induced myocardial mitochondrial injury, which was inhibited by the selective EGFR inhibitor AG1478, suggesting that EGFR is involved in the mitochondrial protective effect of morphine under I/R conditions. In support of this hypothesis, the selective EGFR agonist epidermal growth factor (EGF) reduced mitochondrial morphological and functional damage similarly to morphine. Further study demonstrated that morphine may alleviate I/R-induced cardiac damage by inhibiting autophagy but not apoptosis. Morphine increased protein kinase B (Akt), extracellular regulated protein kinases (ERK) and signal transducer and activator of transcription-3 (STAT-3) phosphorylation, which was inhibited by AG1478, and EGF had similar effects, indicating that morphine may activate Akt, ERK, and STAT-3 via EGFR. Morphine and EGF increased intracellular reactive oxygen species (ROS) generation. This effect of morphine was inhibited by AG1478, indicating that morphine promotes intracellular ROS generation by activating EGFR. However, morphine did not increase ROS generation when cells were transfected with siRNA against EGFR. In addition, EGFR activity was markedly increased by morphine, but the effect of morphine was reversed by naltrindole. These results suggest that morphine may activate EGFR via δ-opioid receptor activation. Morphine may prevent I/R-induced myocardial mitochondrial damage by activating EGFR through δ-opioid receptors, in turn increasing RISK and SAFE pathway activity via intracellular ROS. Moreover, morphine may reduce myocardial injury by regulating autophagy but not apoptosis.

Toughness enhancing mechanisms in age hardened Fe–Mn–Al–C steels

Continued research on advanced high strength steels is an important step in reducing weight and fuel consumption of modern vehicles. Fe–Mn–Al–C steels that have increased concentrations of both Al and Mn, are currently under development to achieve these goals. Alloys with sufficiently high Al and C contents are precipitation hardenable, strengthening the steel by forming nano-sized κ-carbide precipitates, (Fe,Mn)3AlC. In this study, the toughness and phase stability of a Fe–Mn–Al–C steel was investigated by examining evolution of the γ-austenite matrix and κ-carbide precipitates using scanning electron microscopy (SEM), transmission election microscopy (TEM), and synchrotron radiation x-ray diffraction (SR-XRD). Impact toughness was examined using hardness and Charpy impact testing, and results are compared with CALPHAD predictions. This study illuminates proposed mechanisms for simultaneously improving strength and toughness in age-hardenable Fe–Mn–Al–C steels by examining the effect of various heat treatments on the γ-austenite matrix and κ-carbide precipitates.

Experimental evaluation of direct current magnetron sputtered and high-power impulse magnetron sputtered Cr coatings on SiC for light water reactor applications

Two types of physical vapor deposition Cr coatings were deposited on chemical vapor deposited SiC coupons using conventional direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) to mitigate the corrosion of SiC, an advanced fuel and structural material in light water nuclear reactor cores. Coating microstructure was characterized using scanning electron microscopy and scanning transmission election microscopy. X-ray diffraction analysis was conducted for phase identification and qualitative analysis of residual stresses. The mechanical integrity of the coatings was evaluated using scratch testing, micro-indentation, and nano-indentation tests. The microstructure of the DCMS coating consisted of fine columnar grains with nanoscale intercolumnar channels, while the HiPIMS microstructure was denser and free of any columnar defects. The DCMS coating showed a small tensile residual stress, while the HiPIMS coating was under compressive stress. Both types of coatings showed good mechanical integrity in terms of ductility and adhesion to the substrate. Corrosion performance of the coatings was assessed with a 30-day high temperature water autoclave test. Both types of coatings formed a protective Cr2O3 surface layer 20-30 nm thick during the autoclave test. In the DCMS coating, the columnar defects provided permeation pathways for water penetration resulting in oxide formation in the intercolumnar regions in the interior of the coating. Overall, both types of Cr coatings offer promise for the mitigation of hydrothermal corrosion of SiC in light water reactor operating environments.

Microstructure and mechanical properties of Al−Mg−Si alloy U-shaped profile

Abstract To get a full understanding of hot extrusion, solid solution treatment and aging process on the Al−0.56Mg− 0.63Si alloy, the microstructure and mechanical properties of a U-shaped profile were studied through optical microscopy, scanning electrical microscopy, transmission electrical microscopy, hardness, and tensile tests. The coarse equiaxed grains existed near the profile edge as a result of the dynamic recrystallization nucleation and exceeding growth during hot extrusion. The fibrous deformed and sub-structured grains located between the two coarse grain layers, due to the occurrence of work-hardening and dynamic recovery. Perpendicular needle β′′ precipitates were distributed inside the grain, and obvious precipitates-free zone appeared after aging treatment. The tensile strength, yield strength and elongation of the aged Al−Mg−Si alloy U-shaped profile were no less than 279.4 MPa, 258.6 MPa, and 21.6%, respectively. The fracture morphology showed dimple rupture characteristics. The precipitates and grain boundaries played key role in the strengthening contribution.

Facile fabrication of CeF3/g-C3N4 heterojunction photocatalysts with upconversion properties for enhanced photocatalytic desulfurization performance

Cerium fluoride (CeF3) semiconductor with upconversion property was constructed on graphite carbonitride (g-C3N4) nanosheets by microwave hydrothermal method. The X-ray diffraction, transmission election microscopy, Fourier transform infrared, and X-ray photoelectron spectra techniques were used to characterize the CeF3/g-C3N4 nanocomposite. The study shows that CeF3 has upconversion property and can convert visible light (Vis) and near-infrared light (NIR) into ultraviolet light (UV). Moreover, CeF3 and g-C3N4 can form well-defined heterojunction and promote the effective separation of photogenerated electrons and holes. The synergistic effect of the CeF3/g-C3N4 nanocomposite was evaluated by photocatalytic degradation of dibenzothiophene (DBT). The optimum photocatalyst of CeF3/g-C3N4 (40 wt%) composites exhibit the highest photocatalytic desulfurization rate of the model oil under visible light radiation.

Microstructural Refinement and α‐Dispersoid Evolution in Direct‐Chill Cast Al–Mg–Si–Fe Alloy

High Fe levels, coarse grains, microstructural inhomogeneities, and coarse dispersoids for recrystallization suppression remain problems for industrial application of Al–Mg–Si (6xxx) alloys. Herein, Al–0.81%Mg–0.81%Si–0.7%Fe alloy billets are fabricated by direct chill (DC) casting at different casting speeds. The results indicate that high‐speed (300 mm min−1) DC casting can provide fine grains, refined Fe‐containing phases, relatively high solid–solute content, and improved distribution of Mn and Cr. After homogenization at 500 °C for 6 h, the α‐AlFeMnCrSi dispersoids in the high‐speed cast billet decrease in size and increase in number density, compared with the conventional cast billet (100 mm min−1). The low homogenization temperature (440 °C) also contributes to the size reduction and increases the number density of dispersoids. Air cooling after homogenization (holding temperature ≥500 °C) results in Q‐AlCuMgSi precipitation, which depends on the precipitated substrate of the α‐AlFeMnCrSi dispersoids. Moreover, the precipitation processes of α‐dispersoids and Q phases are discussed according to transmission electron microscopy (TEM) and high‐angle annular dark‐field scanning transmission election microscope (HAADF‐STEM) results. These results mean that high‐speed DC casting can effectively improve the as‐cast microstructure by increasing the cooling rate, and the as‐cast microstructural evolution promotes the precipitation of fine and dense α‐dispersoids from the α‐Al matrix.

MoS2 as highly efficient co-catalyst enhancing the performance of Fe0 based electro-Fenton process in degradation of sulfamethazine: Approach and mechanism

Molybdenum sulfide (MoS2) was for the first time used as a co-catalyst to enhance the performance of Fe0 based heterogeneous electro-Fenton (Fe0-EF) process for the degradation of sulfamethazine (SMT), which was belonging to the sulfonamide family and extensively used as growth promoters and antibacterial drugs. Compared with Fe0-EF process, MoS2/Fe0-EF process could enhance the rate constant of SMT degradation 2 times under the optimal conditions of current 50 mA, MoS2 dosage 0.02 g L-1, Fe0 dosage 0.224 g L-1, and initial pH 4, in which SMT could be completely degraded within 10 min while 42% TOC could be achieved after 60 min reaction. The role of MoS2 as co-catalyst in MoS2/Fe0-EF process and Fe2+/Fe3+ cycle was supported by iron elemental analysis, transmission election microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterizations. Owing to the characteristics of co-catalysis, MoS2 could greatly facilitate the Fe3+/Fe2+ recycle reaction by the exposed Mo4+ active sites, which significantly promoted the decomposition of H2O2 that generated in Fe0-EF system and improved the generation of hydroxyl radical. Besides, a possible degradation pathway of SMT was proposed and the stability of MoS2/Fe0-EF process for SMT removal and TOC mineralization was certified base on five consecutive runs. The real wastewater test and energy consumption and economic analysis confirmed its advantage and cost-effectiveness for application. In all, this study provides a new perspective for improving heterogeneous Fe0-EF process with MoS2 for highly efficient and rapid degradation of antibiotics.