Transmittance Electron Microscopy Research Articles

Shielding properties of Li2B4O7:Dy3+,Yb3+ glass containing copper nanoparticles

Glass matrices of Li2B4O7 doped with Dy3+, Yb3+ and Cu were synthesized by melt quenching technique using different concentration of copper nanoparticles. The study and analysis are centered in shielding radiation. The samples amorphous nature was corroborated by X-Ray diffraction (XRD) and nanoparticles size distribution was obtained by transmittance electron microscopy (TEM). Optical characterizations used were absorbance and photoluminescence emission (PL). Radiation shielding theoretical properties: mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), mean free path (MFP) and effective atomic number (Zeff) are obtained using Phy-X/PSD software and analyzed for future applications in radiation security.

Enhancing the Tensile Properties and Ductile-Brittle Transition Behavior of the EN S355 Grade Rolled Steel via Cost-Saving Processing Routes.

Structural rolled steels are the primary products of modern ferrous metallurgy. Consequently, enhancing the mechanical properties of rolled steel using energy-saving processing routes without furnace heating for additional heat treatment is advisable. This study compared the effect on the mechanical properties of structural steel for different processing routes, like conventional hot rolling, normalizing rolling, thermo-mechanically controlled processing (TMCP), and TMCP with accelerating cooling (AC) to 550 °C or 460 °C. The material studied was a 20 mm-thick sheet of S355N grade (EN 10025) made of low-carbon (V+Nb+Al)-micro-alloyed steel. The research methodology included standard mechanical testing and microstructure characterization using optical microscopy, scanning and transmission electronic microscopies, energy dispersive X-ray spectrometry, and X-ray diffraction. It was found that using different processing routes could increase the mechanical properties of the steel sheets from S355N to S550QL1 grade without additional heat treatment costs. TMCP followed by AC to 550 °C ensured the best combination of strength and cold-temperature resistance due to formation of a quasi-polygonal/acicular ferrite structure with minor fractions of dispersed pearlite and martensite/austenite islands. The contribution of different structural factors to the yield tensile strength and ductile-brittle transition temperature of steel was analyzed using theoretical calculations. The calculated results complied well with the experimental data. The effectiveness of the cost-saving processing routes which may bring definite economic benefits is concluded.

New nanometric metal complexes based on thiazole derivative as potential antitumor and antimicrobial agents: Full structural elucidation, docking simulation and biological activity studies

Novel Mn(II), Ni(II), Zr(IV) and Cd(II) nanosized complexes of thiazole Schiff base derivative (HL) were synthesized for further medicinal applications. The inspected complexes were fully characterized using elemental and thermal analyses in addition to infrared spectroscopy (IR) and nuclear magnetic resonance (1HNMR). Electronic absorption spectra, X-ray powder diffraction (XRD), transmittance electron microscopy (TEM), molar conductance and magnetic moment were also measured and explained. The brought about data revealed that the ligand–metal chelation happened through the N atom of N = N group, and the ortho-dehydrogenated phenolic O atom to form the chelates where the metal binds with one molecule of the parent ligand. All applied spectroscopic and analytical techniques confirmed tetrahedral geometry in Mn(II) and Ni(II) complexes and octahedral geometry for Cd(II) and Zr(IV) complexes. The ligand, Mn(II), Ni(II), and Zr(IV) chelates' XRD patterns indicated an amorphous character where the Cd(II) complex's nature is crystalline. Transmission electron microscopy (TEM) images of the prepared compounds showed that the surface morphology is uniform and homogeneous. Also, the metal ions distribute through the complexes' surface in a nanosized nature. The metal complexes have been simulated by docking in the co-crystal structures of the liver cancer and breast cancer proteins with PDB IDs, 2JW2 and 3S7S, successively. Antibacterial, antifungal and anticancer activities for the ligand that has been produced and its complexes were achieved. The most encouraging antitumor results were acquired by Ni(II) chelate which exhibited an IC50 of 23.52 µg/ml contra MCF-7 cells (human breast cancer) which is lower than the reference 5-Fluorouracil (5-FU, IC50 = 28.00 µg/ml).

Synthesis, spectroscopic and biological characterizations of platinum(IV), ruthenium(III) and iridium(III) theophylline complexes

This study used micro-analyses, (FTIR, UV-Vis) spectra, magnetic, thermogravimetric, X-ray powder diffraction (XRD) patterns, and transmittance electron microscopy (TEM) techniques to characterize three synthesized theophylline (TPH) complexes with ruthenium(III), platinum(IV), and iridium(III) metal ions. The metal ions indicated above were found to align with the TPH drug chelate as a mono-dentate ligand via the deprotonated NH group at the nitrogen atom position N7, as verified by FTIR measurements. Additionally, the complexes conductivity and magnetic susceptibility were examined. The octahedral geometry for the synthesized complexes was proposed by the current data. Except for the iridium(III) complex, which has a non-electrolytic nature due to the presence of a chlorine atom inside the chelation sphere, the molar conductivity of the complexes in DMSO solution was electrolyte in nature. Theophylline complexes with a (metal: ligand) stoichiometry of 1:2 were produced. The TPH complexes have also been tested in vitro against G(+) bacteria (Bacillus subtilis and Staphylococcus Aureus) and G(-) bacteria (Pseudomonas aeruginosa and Escherichia coli) to evaluate their antibacterial efficacy. Human breast and liver cancer cell lines were used as a test for the TPH complexes in vitro anti-cancer properties.
 KEY WORDS: Theophylline, Metal ions, Chelation, Octahedral, Spectral analysis, Nano-particles, Biological evaluation
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 725-738. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.14

Optical and Dielectric Characteristics of Poly (Methyl Methacrylate)/Polyethylene Oxide/Carbon Nanoparticle Composites Loaded with Nano NiFe2O4

The current study proposes a simple, low-cost, and functional method of doping a pure matrix of poly (methyl methacrylate)/polyethylene oxide/carbon nanoparticles (PMMA/PEO/CNPs) with nano nickel ferrite (NiFe2O4) as a filler. To create NiFe2O4 nanoparticles, a straightforward chemical growth, sol-gel auto-combustion system was used. Next, environmentally friendly and cost-effective, undoped and blended polymers doped with NiFe2O4 using a solution-casting method were synthesized. Rietveld refinement analysis was used to investigate the structure and microstructure of the NiFe2O4. Transmittance electron microscopy was used to confirm the nano nature of the filler. X-ray diffraction was used to verify the crystallite nature of the undoped and doped PMMA/PEO/CNPs blends with NiFe2O4. The linear optical characteristics of the proposed blends were obtained using a diffuse reflectance spectrophotometer. The measured optical parameters included transmittance, absorbance, reflectance, direct and indirect optical bandgaps, absorption coefficient, linear refractive index, extinction coefficient, dielectric constant, energy loss functions, in addition to optical and electrical conductivities. Also, nonlinear optical constants for the synthesized blends, such as the linear and third nonlinear susceptibilities, nonlinear refraction coefficient and nonlinear absorption coefficient, were calculated. The direct and indirect optical band gap energies of the PMMA/PEO/CNPs blends were 4.97 and 4.8 eV, respectively. As the NiFe2O4 doping level increased in the blend to 2.5 wt%, the optical band gap energy values decreased to 4.54 and 4.64 eV, respectively. The fluorescence spectra of the undoped and doped PMMA/PEO/CNPs blended polymers with nano NiFe2O4 were also explored. The effect of NiFe2O4 doping amount on the energy density, electric dielectric constant, ac conductivity and electric moduli of the host blend was also studied. In conclusion, the considered NiFe2O4-doped PMMA/PEO/CNPs blends have an effective and promising role in optoelectronic applications.

Juglans regia L. fruit pellicle extract-based bioreduction of silver nanoparticles: Structural features and in vivo therapeutic effects against ethanol-induced peptic ulcers

Context: Peptic ulcers are a challenging problem. Silver nanoparticles (AgNPs) play a substantial role in bioactivity and have distinct characteristics. There are several biomedical uses for bioreduction nanotechnology. Historically, traditional healthcare has employed Juglans regia L. Aims: To evaluate how well fruit pellicle extract-derived bio-reduced silver nanoparticles (AgNP/FP) can treat peptic ulcers. Methods: Ultraviolet spectra, dynamic light scattering, transmittance electron microscopy, and Fourier transform infrared were used to characterize AgNPs and AgNP/FP. AgNPs and extracts were compared to omeprazole in ethanol-induced stomach ulcers in mice. Six groups of 36 mice were created at random. AgNPs were given orally to the experimental groups, using 300 mg/kg as a dose. The reference proton pump inhibitor, omeprazole, was employed as a control. Results: As evidenced by a falling ulcer index and an increase in the percentage of ulcer inhibition, bio-reduced AgNPs decreased the adverse effect of ethanol-induced stomach injury. Reduced mucosal damage and hemorrhagic lesions, necrobiotic alterations in the stomach epithelium, submucosal edema, and blood vessel congestion were all indicators of substantially reduced ethanol-induced gastric lesions and greater anti-inflammatory results. Conclusions: Fruit pellicle extract-derived bio-reduced silver nanoparticles have an efficacy similar to proton pump inhibitors like omeprazole and a lower incidence of possible side effects, making them a safe herbal therapy for ulcers.

Green synthesis and anti-tumor activity of curcumin @ ZnO/CuO nanoparticles

Both zinc oxide and copper oxide nanoparticles are promising biologically active materials. Green synthesis approach was used to prepare mixed ZnO/CuO nanoparticles loaded with curcumin extract. The isolated mixed oxides loaded with curcumin (curcumin @ ZnO/CuO) was characterized by UV–visible spectra, FTIR spectra, X-ray powder diffractions (XRD),Transmittance electron microscope (TEM), Energy dispersive x-ray (EDX) and x-ray photoelectron spectroscopy (XPS) spectra. X-ray powder diffractions indicated that ZnO has wurtzite structure and CuO crystallizes in a monoclinic system. XPS confirmed the existence of both CuO and ZnO nanoparticles. TEM results indicated the formation of quantum dots of curcumin @ ZnO/CuO with size in the range 6–10 nm. The optical band gaps of curcumin @ ZnO/CuO were determined and found to be 3.4 and 4.05 eV, which are higher than the bulk. The effects of curcumin @ ZnO/CuO on hepatocellular (HEPG-2) and colorectal (HCT-116) carcinoma were estimated by cell viability, cell cycle and anti-apoptotic factors (caspase-3/7, topoisomerase 2beta and annexin). Strong cytotoxicity activity and apoptosis of tumor cells were observed for curcumin @ ZnO/CuO. The cytotoxicity of the current compounds showed higher activity in comparison with other compounds that were previously studied.

Fe3O4-CdO Nanocomposite for Organic Dye Photocatalytic Degradation: Synthesis and Characterization

In this study, pure CdO nanoparticles, magnetic Fe3O4 nanoparticles, and Fe3O4-CdO nanocomposites were prepared via a solution combustion method using cetyltrimethylammonium bromide (CTAB) as a template. These prepared nanomaterial samples were characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron microscopy (XPS), transmittance electron microscopy (TEM), and scanning electron microscopy (SEM) analysis. XRD patterns confirmed the purity and the crystalline nature of the prepared samples. FTIR and Raman spectra observed the metal-oxygen (M-O) bond formation. UV-vis DRS studies were performed to investigate the optical properties and the bandgap energy determination. The surface morphology and the size of the pure CdO nanoparticles, magnetic Fe3O4, and nanocomposites of Fe3O4-CdO were determined via TEM and SEM analysis. Under optimum experimental conditions, the Fe3O4-CdO nanocomposites were applied for photocatalytic activity against Methylene blue dye. Under visible light irradiation, Fe3O4-CdO nanostructures showed an efficient photocatalytic degradation of 92% against Methylene blue organic dye and showed excellent stability for multiple cycles of reuse.

Phase transition enhanced electromagnetic wave absorption in Cs(Pb,Fe,Co,Ni,Mn)Br3‐based high‐entropy compounds

AbstractTo address challenges such as signal interference and crosstalk, the development of novel materials with the ability of electromagnetic absorption (EMA) is imperative. In this study, the composition of the B‐site of CsPbBr3 was fixed for all samples Pb0.2Fe0.2Co0.2Ni0.2Mn0.2 with varying A/B ratios of 1:1, 1:2, and 1:3. We achieved good EMA properties for the Cs1(Pb0.2Fe0.2Co0.2Ni0.2Mn0.2)3O3, including a minimum reflection loss of 75 dB at 10.2 GHz and a 2.5 mm thickness, accompanied by an exceptionally wide effective bandwidth of 8.8 GHz. X‐ray diffraction, transmittance electron microscopy, and X‐ray photoelectron spectroscopy, etc. were used to characterize the structure, morphology, and EMA‐associated properties of CsMBr3. The presence of high entropy was validated through meticulous analysis using Rietveld and grazing‐incidence wide‐angle scattering patterns. The magnetic permeability, dielectric constant, polarization, and attenuation loss were improved with a high‐entropy ratio of 3 within the 30–50 nm crystals. Notable lattice distortion within PbBr6 and phase transition within high‐entropy alloying are the driving forces behind these enhanced EMA characteristics.

Green synthesis of silver nanoparticles and its environmental sensor ability to some heavy metals

This study marks a pioneering effort in utilizing Vachellia tortilis subsp. raddiana (Savi) Kyal. & Boatwr., (commonly known as acacia raddiana) leaves as both a reducing and stabilizing agent in the green “eco-friendly” synthesis of silver nanoparticles (AgNPs). The research aimed to optimize the AgNPs synthesis process by investigating the influence of pH, temperature, extract volume, and contact time on both the reaction rate and the resulting AgNPs' morphology as well as discuss the potential of AgNPs in detecting some heavy metals. Various characterization methods, such as UV–vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), Zeta sizer, EDAX, and transmitting electron microscopy (TEM), were used to thoroughly analyze the properties of the synthesized AgNPs. The XRD results verified the successful production of AgNPs with a crystallite size between 20 to 30 nm. SEM and TEM analyses revealed that the AgNPs are primarily spherical and rod-shaped, with sizes ranging from 8 to 41 nm. Significantly, the synthesis rate of AgNPs was notably higher in basic conditions (pH 10) at 70 °C. These results underscore the effectiveness of acacia raddiana as a source for sustainable AgNPs synthesis. The study also examined the AgNPs' ability to detect various heavy metal ions colorimetrically, including Hg2+, Cu2+, Pb2+, and Co2+. UV–Vis spectroscopy proved useful for this purpose. The color of AgNPs shifts from brownish-yellow to pale yellow, colorless, pale red, and reddish yellow when detecting Cu2+, Hg2+, Co2+, and Pb2+ ions, respectively. This change results in an alteration of the AgNPs' absorbance band, vanishing with Hg2+ and shifting from 423 to 352 nm, 438 nm, and 429 nm for Cu2+, Co2+, and Pb2+ ions, respectively. The AgNPs showed high sensitivity, with detection limits of 1.322 × 10–5 M, 1.37 × 10–7 M, 1.63 × 10–5 M, and 1.34 × 10–4 M for Hg2+, Cu2+, Pb2+, and Co2+, respectively. This study highlights the potential of using acacia raddiana for the eco-friendly synthesis of AgNPs and their effectiveness as environmental sensors for heavy metals, showcasing strong capabilities in colorimetric detection.

Highly homogeneous and stable single-walled carbon nanotubes dispersion modified by polyvinylpyrrolidone and alkanolamine in water.

A novel noncovalent surface modification of commercial single-walled carbon nanotubes (SWCNTs) was successfully carried out by using ball grinding technology between SWCNTs and mixed dispersants (polyvinylpyrrolidone (PVP) and alkanolamine), affording a highly homogeneous and stable PA-SWCNTs dispersion in water. The homogeneous dispersibility and long storage stability were systematically investigated by transmittance spectroscopy, absorption spectroscopy, zeta potential analyzer, sedimentation photo and transmittance electron microscopy. Under the optimized conditions, the PA-SWCNTs dispersion modified with 0.7 wt% PVP and 0.25 wt% alkanolamine under the condition of total 6 h ball grinding time using paint shaker can be easily well-dispersed in water and has good storage stability, and no sedimentation is observed more than one month. From an industrial perspective, this method is green and easy to operate in industry.

Ag2O@UiO-66 new thin film as p-n heterojunction: permanent photoreduction of hexavalent Cr.

The new nanosphere Ag2O@UiO-66 thin-film was synthesized on a stainless steel mesh surface via an electrophoretic deposition method, and is used as an effective and low-cost photocatalyst using visible light. The synthesized nanocomposite was used to perform photo-reduction of Cr(vi) ions under white light irradiation. The best removal rate (72% after 15 minutes) was obtained by the film with 0.034 grams of deposited composite having relative percentages of Ag2O : UiO-66 of 70 : 30. The interesting obtained results confirm that the p-n heterojunction of the composite is the main cause of the desired charge separation and the photoreduction speed increase. In the following, the resulting compounds were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmittance electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy diffraction X-ray spectroscopy (EDAX) and the Brunauer, Emmett, and Teller (BET) method. Scavenging studies performed in the presence of familiar scavengers confirmed that superoxide radicals (˙O2-) and dissolved oxygen gas have a significant role in the photocatalytic reduction process.

Rational design of niobium carbide MXene quantum dots decorated with arginine for the fluorescence sensing of superoxide anion in Saccharomyces cerevisiae cells

In this work, arginine functionalized niobium carbide MXene quantum dots (arginine-Nb2C MQDs) were synthesized using Nb2AlC, NaOH and arginine as reagents. The as-synthesized probe showed bluish-green fluorescence under UV light at 365 nm. The structural and morphological changes of as-synthesized arginine-Nb2C MQDs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy and high-resolution transmittance electron microscopy (HR-TEM). The synthesized fluorescent arginine-Nb2C MQDs were stable, with an average size of 1.92 ± 0.52 nm. As-synthesized arginine-Nb2C MQDs act as a sensor for detecting superoxide anion (O2•−) via a fluorescence “turn-off” mechanism with the detection limit of 31.89 nM. The fluorescence of arginine-Nb2C MQDs is quenched by O2•− via dynamic fluorescence quenching mechanism. Fascinatingly, the synthesized arginine-Nb2C MQDs showed negligible cytotoxicity on HeLa cells and acted as promising candidates for sensing of O2•− in Saccharomyces cerevisiae cells.

Sputter-grown two-dimensional α-MoO3 thin films: Microstructure dependence on growth conditions

Van der Waals epitaxy is an emerging technology for transferring freestanding films grown at high temperatures onto arbitrary substrates using two-dimensional epitaxial layers. This study investigates the microstructure and growth of α-MoO3 thin films prepared via sputtering. Under a narrow deposition temperature range, epitaxial α-MoO3 thin films were successfully grown on SrTiO3 substrates. The films were characterized by a flat surface morphology, corresponding to (0k0) planes, without undergoing reaction with the substrates. To examine the growth behavior and surface morphological variation of the α-MoO3 thin films under various process parameters, we modified the Ar:O2 ratio, working pressure, sputtering power, and crystal structure of the substrates. Transmittance electron microscopy confirmed the epitaxial growth of the α-MoO3 thin films on (001)-oriented SrTiO3 substrates with a two-dimensional layer structure. Finally, we demonstrate the morphological evolution of the α-MoO3 thin films etched in heated water as a function of soaking time. The etching results suggest that the α-MoO3 thin films are promising sacrificial layers for the transfer of large-scale epitaxial thin films onto flexible substrates. External control of the strain states of transferred freestanding thin films by bending or stretching provides new perspectives for the design of flexible or wearable electronic devices.

Base‐assisted anionic polymerization of alkyl sorbates and subsequent ring‐closure without extreme dilution for synthesis of cyclic stereoregular poly(alkyl sorbates)

AbstractA typical base, lithium diisopropylamide (LDA) or lithium bis(trimethylsilyl)amide (LiHMDS), was found to initiate the anionic chain‐growth polymerization of ethyl sorbate (ES) in the presence of an aluminum Lewis acid, that is, methylaluminum bis(2,6‐di‐tert‐butyl‐4‐methylphenoxide) (MAD) and, after ES consumption, ring‐closure occurred without highly dilute conditions to give the cyclic poly(ES). The finding of ring closure was supported by matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF) mass spectroscopy and direct transmittance electron microscope (TEM) observations, in which a series of spectral patterns separated by the mass of ES and cyclic objects with 7.4–25.9 nm rings were observed, respectively. The results indicated that instead of the use of an expensive N‐heterocyclic carbene (NHC), employing these commodity bases to initiate chain polymerization enabled us to fabricate the intended cyclic vinyl polymers without highly dilute conditions. Also, this polymerization proceeded even at −80°C to give threo (98%)‐disyndiotactic (91%) stereoregular poly(ES) in an excellent yield with narrow molecular weight distributions (Mn = 5.9 × 103–8.4 × 103, Mw/Mn = 1.14).

Radiation Effect of Vacuum Ultraviolet on the Performance of Polyimide Films

Polyimide (PI) films equipped on the surface of spacecraft are susceptible to ultraviolet damage. Herein, the performance of two kinds of polyimide films i.e. 3,3′,4,4′-biphenyl dianhydride-p-phenylenediamine (BPDA-PDA) and pyromellitic dianhydride-4,4′-oxydianiline (PMDA-ODA) under vacuum ultraviolet (VUV, 172 nm) irradiation was studied. The failure behavior of the PI films was studied by tensile tests, thermogravimetry (TGA), thermomechanical analysis (TMA), electric breakdown, UV–visible transmittance and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to analyze the molecular structure. The results indicated that the tensile strength of BPDA-PDA PI and PMDA-ODA PI films decreased by 10.4 and 7.4% under VUV irradiation, respectively; the breakdown strength and UV-transmittance also deteriorated. Besides, the surface morphology of the PI films showed a large number of microcracks after VUV irradiation, which we ascribe to the breakage of imide rings (C-N-C) and ether bonds (C-O-C) of the PI films. However, the thermal stability (residual weight) of both PI films remained constant compared to the initial level; this can be explained by the combined effect of bond breaking and cross-linking of the polyimide films.

Trimetallic CuO/Ag/NiO supported with silica nanoparticles based composite materials for green hydrogen production

Production and utilization of grey and blue hydrogen is responsible for emission of millions of tons of carbon dioxide (CO2) across the globe. This increased emission of CO2 has severe repercussions on the planet earth and in particular on climate change. Here in, we explored advance bimetallic (BM) CuO/Ag and trimetallic (TM) CuO/Ag/NiO based nanoporous materials supported with silica nanoparticles (SiNPs) via sol–gel route. The explored nanocatalysts were characterized by Powder X-ray diffraction (P-XRD), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and Raman spectroscopic techniques. These advance nanocatalysts were evaluated for the green hydrogen production through electrocatalysis and photocatalysis. The catalysts exhibited an exceptional catalytic performance, the onset potential for hydrogen evolution reaction (HER) was determined to be − 0.9 V BMSiNPs-GCE and − 0.7 V (vs Ag/AgCl) for TMSiNPs-GCE, whereas η@10 for BMSiNPs-GCE and TMSiNPs-GCE is − 1.26 and − 1.00 V respectively. Significantly, the TMSiNPs composite and the BMSiNPs composite exhibited superior photochemical H2 evolution rates of 1970.72 mmol h−1 g−1 and 1513.97 mmol h−1 g−1, respectively. The TMSiNPs catalyst presents a highly promising material for HER. This study reveals a cost-effective approach to develop sustainable and resourceful electrocatalysts for HER.

Ti2NTx quasi-MXene modified polyamide thin film composite reverse osmosis membrane with effective desalination and antifouling performance

In this study, considering the serious problem of lack of fresh water worldwide and the effectiveness of reverse osmosis (RO) membranes in water purification, we prepared improved RO membranes with two-dimensional quasi-MXene nanosheets. In this study, the MAX phase with the chemical formula of Ti2AlN was prepared through the reactive sintering route. Prosperous preparation of the MAX phase with the hexagonal crystalline structure was approved by an X-ray diffraction pattern. Compacted sheets morphology was recognized for the prepared MAX phase from transmittance electron microscopy and scanning electron microscopy micrographs. Then, Ti2NTx quasi-MXene nanosheets were prepared by selective ultrasonic-assisted exfoliation of the MAX phase. Polyamide (PA) thin-layer composite RO membranes with different weight percentages of Ti2NTx quasi-MXene were fabricated by the interfacial polymerization (IP) method. The addition of ultrasonic-assisted prepared quasi-MXene creates numerous and coherent nanochannels on the surface of the membrane. The optimum membrane with 0.01 wt% of quasi-MXene showed the highest pure water flux of 31.9 L m−2. h−1 with an improved salt rejection of 98.2%. Therefore, these nanosheets showed that they can partially solve the trade-off between water permeability and salt rejection, which is a serious challenge in RO membranes. Also, the membranes containing quasi-MXene showed good resistance against fouling by humic acid. This research can be a scalable development in making high-performance membranes.

Functionalized Copper Nanoparticles with Gold Nanoclusters: Part I. Highly Selective Electrosynthesis of Hydrogen Peroxide.

Copper nanoparticles (CuNPs) and gold nanoclusters (AuNCs) show a high catalytic performance in generating hydrogen peroxide (H2O2), a property that can be exploited to kill disease-causing microbes and to carry carbon-free energy. Some combinations of NPs/NCs can generate synergistic effects to produce stronger antiseptics, such as H2O2 or other reactive oxygen species (ROS). Herein, we demonstrate a novel facile AuNC surface decoration method on the surfaces of CuNPs using galvanic displacement. The Cu-Au bimetallic NPs presented a high selective production of H2O2 via a two-electron (2e-) oxygen reduction reaction (ORR). Their physicochemical analyses were conducted by scanning electron microscopy (SEM), transmitting electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). With the optimized Cu-Au1.5NPs showing their particle sizes averaged in 53.8 nm, their electrochemical analysis indicated that the pristine AuNC structure exhibited the highest 2e- selectivity in ORR, the CuNPs presented the weakest 2e- selectivity, and the optimized Cu-Au1.5NPs exhibited a high 2e- selectivity of 95% for H2O2 production, along with excellent catalytic activity and durability. The optimized Cu-Au1.5NPs demonstrated a novel pathway to balance the cost and catalytic performance through the appropriate combination of metal NPs/NCs.

Synergetic catalysis of Ni@C@CeO2 for driving ab/desorption of MgH2 at moderate temperature

Multiple catalysts have exhibited high activity on improving the hydrogen storage performance of MgH2. Herein, the hydrogen ab/desorption kinetics of MgH2 is significantly improved by using Ni@C@CeO2 as the catalyst. The results show that 10 wt%-Ni@C@CeO2 doped MgH2 can absorb 4.51 wt% hydrogen within 60 min under low temperature 75 °C. Furthermore, the MgH2-Ni@C@CeO2 composites release approximately 4.88 wt% H2 within 10 min at 325 °C. Moreover, the composites show excellent cycling performance, with negligible decrease in hydrogen storage capacity, hydrogen uptake rate and hydrogen release rate after ten cycles at 350 °C. The Rietveld refinement of X-ray diffraction and transmittance electron microscopy measurements reveal that Mg2NiH4/Mg2Ni and CeH2.73 phases are in-situ formed. The mutual conversion of “Mg2Ni/Mg2NiH4” during hydrogen ab/desorption is a well-known “hydrogen pump” effect, which improvs the hydrogen storage performance of MgH2. The presence of CeH2.73 accelerate the conversion of Mg2Ni/Mg2NiH4, which we call ‘facilitated hydrogen pump’ effect. This attempt paves a potential way to achieve high performance Mg-based composites hydrogen storage materials via collaborative action between Ni and Ce species.