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The prepared NVOY electrode achieves high stability and excellent cycle performance for AZIBs by embedding polypyrrole in ammonium vanadate layers to remove excess ammonium ions, expand the interlayer spacing, and enhance electronic conductivity. [Display omitted] Ammonium vanadate with stable bi-layered structure and superior mass-specific capacity have emerged as competitive cathode materials for aqueous rechargeable zinc-ion batteries (AZIBs). Nevertheless, fragile N H...O bonds and too strong electrostatic interaction by virtue of excessive NH 4 + will lead to sluggish Zn2+ ion mobility, further largely affects the electro-chemical performance of ammonium vanadate in AZIBs. The present work incorporates polypyrrole (PPy) to partially replace NH 4 + in NH 4 V 4 O 10 (NVO), resulting in the significantly enlarged interlayers (from 10.1 to 11.9 Å), remarkable electronic conductivity, increased oxygen vacancies and reinforced layered structure. The partial removal of NH 4 + will alleviate the irreversible deammoniation to protect the laminate structures from collapse during ion insertion/extraction. The expanded interlayer spacing and the increased oxygen vacancies by the virtue of the introduction of polypyrrole improve the ionic diffusion, enabling exceptional rate performance of NH 4 V 4 O 10. As expected, the resulting polypyrrole intercalated ammonium vanadate (NVOY) presents a superior discharge capacity of 431.9 mAh g−1 at 0.5 A g−1 and remarkable cycling stability of 219.1 mAh g−1 at 20 A g−1 with 78 % capacity retention after 1500 cycles. The in-situ electrochemical impedance spectroscopy (EIS), in-situ X-ray diffraction (XRD), ex-situ X-ray photoelectron spectroscopy (XPS) and ex-situ high resolution transmission electron microscopy (HR-TEM) analysis investigate a highly reversible intercalation Zn-storage mechanism, and the enhanced the redox kinetics are related to the combined effect of interlayer regulation, high electronic conductivity and oxygen defect engineering by partial substitution NH 4 + of PPy incorporation. [ABSTRACT FROM AUTHOR]

Exploring magnetic order in nonferromagnetic substances, such as CuO:ZnO, becomes especially attractive when introducing defect states through nonmagnetic ion doping. In this study, we delved into the impact of Yb doping on the structural, morphological, optical, and magnetic properties of CuO:ZnO. The Yb doped CuO:ZnO was prepared with different Yb concentrations (x = 0.00–20 %) via the temperature-assisted co-precipitation method. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, and vibrating sample magnetometer (VSM) were used to investigate the structural, morphological, optical, and magnetic properties of Yb doped CuO:ZnO nanocomposites. The incorporation of Yb in CuO:ZnO nanocomposites leads to a notable shift of the characteristic XRD peaks of CuO and ZnO to lower angles, accompanied by an increase in the lattice parameters. UV–visible absorption spectroscopy shows an overall decrease in the optical band gap energy of ZnO as the Yb defect level increases. FE-SEM studies revealed the transformation of spherical structures into agglomerated non-spherical structures upon the introduction of Yb ions into CuO:ZnO nanocomposites. According to XPS data, the predominant valences of Yb-doped CuO:ZnO nanocomposites are Zn2+, Cu2+, and Yb3+. One noteworthy observation from the XPS results is that, in comparison to the intensity of O L or O ad peaks, the intensity of O V (Oxygen vacancy) defect peak increases when the Yb impurity concentration increases. Magnetic measurements demonstrated a diamagnetic order in pure ZnO, which converts to a ferromagnetic order with the incorporation of Yb defect states. The ferromagnetic properties of the Yb-doped CuO:ZnO nanocomposite can be ascribed to the exchange interaction of Yb3+ ions with defect states (Oxygen Vacancy) in ZnO and CuO. [ABSTRACT FROM AUTHOR]

Hydrogen energy possesses immense potential in developing a green renewable energy system. However, a significant problem still exists in improving the photocatalytic H 2 production activity of metal-free graphitic carbon nitride (g-C 3 N 4) based photocatalysts. Here is a novel Cu 3 P/CdS/g-C 3 N 4 ternary nanocomposite for increasing photocatalytic H 2 evolution activity. In this study, systematic characterizations have been carried out using techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectra, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), surface area analysis (BET), electrochemical impedance (EIS), and transient photocurrent response measurements. Surprisingly, the improved 3CP/Cd-6.25CN photocatalyst displays a high H 2 evolution rate of 125721 μmol h−1 g−1. The value obtained exceeds pristine g-C 3 N 4 and Cu 3 P/CdS by 339.8 and 7.6 times, respectively. This could be the maximum rate of hydrogen generation for a g–C 3 N 4 –based ternary nanocomposite ever seen when exposed to whole solar spectrum and visible light (λ > 420 nm). This research provides fresh perspectives on the rational manufacture of metal-free g-C 3 N 4 based photocatalysts that will increase the conversion of solar energy. By reusing the used 3CP/Cd/g-C 3 N 4 photocatalyst in five consecutive runs, the stability of the catalyst was investigated, and their individual activity in the H 2 production activity was assessed. To comprehend the reaction mechanisms and emphasise the value of synergy between the three components, several comparison systems are built. Sphere-like Cu 3 P/CdS/g-C 3 N 4 photocatalyst was developed using hydrothermal route followed by ball milling and wet impregnation assisted method. A highest hydrogen production of 125721 μmol h−1g−1 was obtained for the above nanocomposite containing 6.25 wt% of g-C 3 N 4. [Display omitted] • Sphere-like Cu 3 P/CdS/g-C 3 N 4 composites was developed for visible light activity. • Metal free composites for H 2 evolution under visible light illumination was achieved. • The improved charge separation, transfer and transport results highest H 2 production. • Best activity results are observed for 3CP/Cd-6.25CN catalysts supported on g-C 3 N 4. • First time we report highest H 2 production activity for Cu 3 P/CdS/g-C 3 N 4 composites. [ABSTRACT FROM AUTHOR]

Li–CdS/TiO 2 nanocomposite with different composition 10Li–CdS/TiO 2 , 20Li–CdS/TiO 2 , 30Li–CdS/TiO 2 , 40Li–CdS/TiO 2 , 50Li–CdS/TiO 2 were coated on FTO surface by using doctor blade followed by successive ionic layer adsorption and reaction (SILAR) method. As synthesized Li–CdS/TiO 2 photoanode is characterized with field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). FE-SEM analysis suggests that, Li–CdS/TiO 2 film is 10.2 μm thick, porous, spongy and uniformly covered on FTO surface. The HR-TEM images reveal that the CdS nanoparticles are in intimate contact with the TiO 2 nanocrystal shells with the CdS/TiO 2 interfaces and the particle size of CdS and Li 2 S lies in the range of 20 nm–50 nm. UV-DRS analysis shows that, as the loading of Li in CdS/TiO 2 films increases, there is decrease in band gap energy. The XPS analysis supports the presence of Li+ in Li–CdS/TiO 2 nanocomposite. The PL spectra suggest that, with the increase in extend of Li+ ions into Li–CdS/TiO 2 , intensity of green emission band increases and it is shifted to higher wavelength. This reflects the low recombination rate of photo generated charge carrier in Li–CdS/TiO 2 which is responsible for higher photocatalytic H 2 production. The visible light photoanodic performance of Li–CdS/TiO 2 was investigated for H 2 evolution using aqueous Na 2 SO 3 and Na 2 S solution under natural sunlight. Among the all-synthesized nanocomposite material, the highest amount of hydrogen produced over 20Li–CdS/TiO 2 was found to be 38.61 ml/g/h in natural sunlight. Photoelectrochemical (PEC) performance of Li–CdS/TiO 2 was examined. A possible mechanism for photocatalytic hydrogen generation is also discussed. • Li–CdS/TiO 2 function as photocatalyst cum photoanode during solar water splitting. • Li–CdS/TiO 2 photoanode was synthesized by doctor blade followed by SILAR method. • Li–CdS/TiO 2 photoanode produces excellent H 2 as compare to TiO 2 and CdS/TiO 2. • In natural sunlight, 38.69 ml/g/h H 2 were evolved over 20Li–CdS/TiO 2. • 20Li–CdS/TiO 2 shows excellent transfer kinetics in PEC water splitting process. [ABSTRACT FROM AUTHOR]

We have prepared CoNPs@CN that cobalt nanoparticles(CoNPs) dispersed uniformly in the carbon matrix Composite (CN) via a facile and controllable method. Samples were characterized by X-ray diffraction (XRD), UV–V spectroscopy, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). CoNPs@CN exhibited favorable photocatalytic activity under visible light irradiation. The results of quenching and photoluminescence experiments reveal the generation of main active species (•OH and •O 2 − radicals). The producing mechanism of active species can be attributed to that CoNPs@CN absorb photons and generate photogenerated electrons through localized surface plasmon resonance (LSPR) effect, then H2O and O2 in the solution react with the photogenerated hole and electrons to produce •OH and •O 2 − radicals. In the current study, CoNPs@CN are prepared that the cobalt (Co) nanoparticles dispersed uniformly in the carbon matrix via a facile and controllable method. Co@CN exhibited favorable photocatalytic activity under visible light irradiation. Co@CN can absorb photons under illumination through LSPR effect, thus the photogenerated electrons and holes were generated. H2O and O2 in the solution reacted with the photogenerated electrons to produce •OH and •O2– radicals. These two main radicals are used to decompose MO effectively. [ABSTRACT FROM AUTHOR]

Microstructural defects play a critical role in flourishing various properties of materials. Here in this article, the effect of Ag substitution on the various properties of CdS quantum dots (QDs) is studied. Ag doped CdS QDs are synthesized using chemical co-precipitation, a simple, cost-effective method suitable for mass-production. High resolution transmission electron microscopy (HRTEM) images show dopant induced change in density and types of microstructural defects. The development of multiple nanotwinning at the cost of stacking faults as well as single twin boundary via the substitution of Ag in CdS lattice is noticed. In present study, a strong quantum confinement is observed and confirmed by the crystallite sizes estimated via X-ray diffraction (XRD) and TEM studies. A systematic enhancement in the bandgap and reduction in crystallite size are observed with increasing concentration of dopant. The atomic concentration of element and chemical bonding in CdS QDs are studied using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) respectively. Unlike other elemental dopants, QDs when doped with Ag with the varying concentration exhibit a non-systematic emission behaviour with increasing concentration which is correlated to the microstructural defects and confinement strength. [ABSTRACT FROM AUTHOR]

Protonic Ceramic fuel cells (PCFCs) hold great promise for many applications; however, their high operating temperature hinders their commercial use in practice. The crucial issue that limits the electrochemical performance of PCFCs (including oxygen and proton-ion-conducting) is the sluggish oxygen redox reaction (ORR) at the cathode surface at low operating temperatures. Herein, we have developed a C aFe 2 O 4 -WO 3 heterostructure composite by interface-vacancy engineered for an efficient ORR electrocatalyst for LT-PCFCs. The C aFe 2 O 4 -WO 3 heterostructure composite exhibits very low cathodic area-specific resistance (ASR) and high oxygen reduction reaction (ORR) activity response at low operating temperatures of 400–550 °C using a BaCe 0.7 Zr 0.2 Y 0.1 O 3-δ (proton-conducting) electrolyte. We have demonstrated high-power density of 585 ± 2% mW-cm−2 with a current density of 1660 mA-cm−2 at 550 °C with H 2 fuel and atmospheric air as oxidant and even with possible operation at 400 °C. Moreover, the CaFe 2 O 4 -WO 3 heterostructure composite shows a very low proton migration energy and activation energy compared to individual CaFe 2 O 4 and WO 3 , helping to promote ORR activity. Various spectroscopic measurements, such as X-ray diffraction, high resolution transmission electron microscopy (HR-TEM), U-visible spectroscopy (UV–visible), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations are employed to understand the interfacial properties for the improved ORR electrocatalytic activity of the CaFe 2 O 4 -WO 3 heterostructure composite cathode. Our obtained experimental and theoretical results can further help to develop functional cobalt-free electrocatalysts for LT-PCFCs. [Display omitted] [ABSTRACT FROM AUTHOR]

The performance of supercapacitors strongly depends on the electrochemical characterizations of electrode materials. Herein, a composite material consisted of iron(III) oxide (Fe2O3) and multilayer graphene-wrapped copper nanoparticles (Fe2O3/MLG-Cu NPs) is fabricated on a flexible carbon cloth (CC) substrate via two-step synthesis process for supercapacitor application. Where, MLG-Cu NPs are prepared on CC by one-step chemical vapor deposition synthesis approach; thereafter, the Fe2O3 is further deposited on the MLG-Cu NPs/CC via successive ionic layer adsorption and reaction method. The related material characterizations of Fe2O3/MLG-Cu NPs are well investigated by scanning electron microscopic, high resolution transmission electron microscopy), Raman spectrometer and X-ray photoelectron spectroscopy; the electrochemical behaviors of the pertinent electrodes are studied by cyclic voltammogram, galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy measurements. The flexible electrode with Fe2O3/MLG-Cu NPs composites exhibits the best specific capacitance of 1092.6 mF cm−2 at 1 A g−1, which is much higher than those of electrodes with Fe2O3 (863.7 mF cm−2), MLG-Cu NPs (257.4 mF cm−2), multilayer graphene hollow balls (MLGHBs, 14.4 mF cm−2) and Fe2O3/MLGHBs (287.2 mF cm−2). Fe2O3/MLG-Cu NPs electrode also exhibits an excellent GCD durability, and its capacitance remains 88% of its original value after 5000 cycles of the GCD process. Finally, a supercapacitor system consisted of four Fe2O3/MLG-Cu NPs/CC electrodes can efficiently power various light-emitting diodes (i.e. red, yellow, green, and blue lights), demonstrating the practical application of Fe2O3/MLG-Cu NPs/CC electrode. [ABSTRACT FROM AUTHOR]

We report an efficient method to synthesize undoped and K-doped rare cubic tungsten trioxide nanowires through the thermal evaporation of WO3 powder without a catalyst. The WO3 nanowires are reproducible and stable with a low-cost growth process. The thermal evaporation processing was conducted in a three-zone horizontal tube furnace over a temperature range of 550–850 °C, where multiple substrates were placed at different temperature zones. The processing parameters, including pressure, temperature, type of gas, and flow rate, were varied and studied in terms of their influence on the morphology, aspect ratio and density of the nanowires. The morphologies of the products were observed with scanning electron microscopy. High resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction studies were conducted to further identify the chemical composition, crystal structure and growth direction of the nanostructures. Additionally, the growth mechanism has been proposed. Furthermore, we investigated the potassium doping effect on the physical properties of the nanostructures. Photoluminescence measurements show that there were shorter emission bands at 360 nm and 410 nm. Field emission measurements show that the doping effect significantly reduced the turn-on electric field and increased the enhancement factor. Furthermore, as compared with related previous research, the K-doped WO3 nanowires synthesized in this study exhibited excellent field emission properties, including a superior field enhancement factor and turn-on electric field. The study reveals the potential of WO3 nanowires in promising applications for sensors, field emitters and light-emitting diodes. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) is a p-type semiconductor material having versatile use in a wide number of applications. In this work, a CuO nanoleaf structure has been synthesized without any traces of Cu2O by a one-step facile method under mild refluxing conditions. The phase purity of the sample is confirmed by x-ray diffraction, x-ray photoelectron spectroscopy, and high resolution transmission electron microscopy. Photoelectrochemical performance has been evaluated by linear scan voltammetry, and transient photocurrent has been measured in the presence of a visible light source of 350 W. Transient photocurrent shows a high photocurrent density of −6.0 mA cm−2 [at −0.2 V vs reference hydrogen electrode (RHE)] in neutral pH. The enhancement of photocurrent density is due to the large space charge region potential, confirmed by a Mott–Schottky measurement. This large space charge region potential is responsible for the higher efficiency of electron–hole separation and a concurrent increase in the kinetics of the process. [ABSTRACT FROM AUTHOR]

We report the synthesis of novel quaternary AgInZn2Te4 quantum dots (QDs) utilizing organometallic hot injection procedures. By using octadecene and oleylamine as the coordinating solvents and dodecanethiol as the capping ligand, we could arrive at a phosphine-free "green route" for the synthesis. Detailed characterizations were performed using high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), energy dispersive X-ray spectroscopy (EDX), UV–Vis spectroscopy, and Photoluminescence (PL) spectroscopy for the structural, compositional, and optical analyses. The nanostructures were spherical, monodisperse, highly crystalline with cubic structure, and having an average diameter of 6. 5 ± 0. 5 nm with optical features in the visible region. [ABSTRACT FROM AUTHOR]

Low loading Pton TiO2 were prepared by an impregnation‐reduction process for chemoselective hydrogenation of chloronitrobenzenes (CNBs) to chloroanilines (CANs). The structure and physicochemical properties were characterized by N2 adsorption‐desorption, X‐ray diffraction, high resolution transmission electron microscopy, X‐ray photoelectron spectroscopy and temperature programmedreduction. The low loading Pt(≤0.08 wt %) on TiO2 exhibited outstanding chemoselectivity for the catalytic hydrogenation of CNBs to CANs, without any disturbance on carbon‐chlorine bond. The characterization data suggested that the Pt particles were highly dispersed on TiO2 and strongelectronicinteractionsoccur between the dispersedPt andTiO2support, which led toelectron deficiency of nearly all Pt and production of suboxide TiOx species (x<2) in the 0.08 wt % Pt/TiO2. The electron‐deficient Pt and suboxide TiOx species favor N=O bondactivation, leading to its unique chemoselectivity. [ABSTRACT FROM AUTHOR]

Photocatalysts based on g-C3N4 have been investigated in the CO2 reduction reaction under visible light irradiation (λ = 397, 427, 452 nm). Photocatalysts were prepared by melamine calcination at 500–600 °C with further platinum deposition (0.1–1.0 wt.%). The effect of the preparation conditions of g-C3N4 and the method of platinum deposition on the physicochemical properties and activity of photocatalysts was studied. The photocatalysts were investigated by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, X-ray diffraction, high resolution transmission electron microscopy, UV-Vis spectroscopy, and low temperature nitrogen adsorption techniques. It has been found that the efficiency of CO2 reduction is governed by the surface area of g-C3N4 and the presence of platinum in the metallic state, while the optimal content of platinum is 0.5 wt. %. The highest rate of CO2 reduction achieved over Pt/g-C3N4 photocatalyst is 13.2 µmol h−1 g−1 (397 nm), which exceeds the activity of pristine g-C3N4 by 7 times. The most active photocatalysts was prepared by calcining melamine in air at 600 °C, followed by modification with platinum (0.5 wt.%). [ABSTRACT FROM AUTHOR]

Different long-chain primary alkylamines such as octylamine, dodecylamine, tetradecylamine, hexadecylamine or octadecylamine were used to stabilize Ni-NiO nanoparticles (metal:stabilizer ratio of 1:10) by an organometallic method in organic medium to evaluate their effect on the microstructural and magnetic properties. The Ni-NiO stabilized nanoparticles were characterized by Fourier transformed infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), conventional transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and dynamic light scattering (DLS). The results indicated an adequate stabilization of Ni nanoparticles with the different primary alkylamines. The semi-quantitative analysis suggests that Ni surface composition is a combination of the metallic state with NiO, NiOOH and NiO, but the chain length modified the content and proportion of these compounds. The highest Ni metallic state (57.2 at. %) was obtained with tetradecylamine as stabilizer. The morphology of the samples is similar to a core–shell semi-spherical, but the particle size tends to reduce with the alkyl chain length of primary amines from 20 to 8 nm. The saturation magnetization (Ms) showed important variations depending on the surface composition, for which variable particle size and Ni metallic content were determining factors for the magnetic response. [ABSTRACT FROM AUTHOR]

Nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) are widely used for drug delivery. One of the main challenges is to clarify their interaction with hypoxia-inducible factor 1 alpha (HIF-1α), the lack of which leads to oncological and cardiovascular diseases. In the presented study, N-MWCNTs were synthesized by catalytic chemical vapor deposition and irradiated with argon ions. Their chemical state, local structure, interfaces, Stone–Wales defects, and doping with nitrogen were analyzed by high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Using experimental data, supercells of functionalized N-MWCNTs with an oxygen content of 2.7, 4 and 6 at. % in carboxyl groups were built by quantum chemical methods. Our analysis by the self-consistent charge density functional tight-binding (SCC DFTB) method shows that a key role in the functionalization of CNTs with carboxyl groups belongs to Stone–Wales defects. The results of research in the decoration of CNTs with HIF-1α demonstrate the possibility of wave-diffusion drug delivery. The nature of hybridization and relaxation determines the mechanism of oxygen regulation with HIF-1α molecules, namely, by OH-(OH–C) and OH-(O=C) chemical bonds. The concentration dependence of drug release in the diffusion mode suggests that the best pattern for drug delivery is provided by the tube with a carboxylic oxygen content of 6 at. %. [ABSTRACT FROM AUTHOR]

Ni nanoparticles (NiNPs) were prepared by thermal decomposition of nickel acetylacetonate in the presence of a third generation polypyridylphenylene dendrimer (G3) which acts both as a coordinating ligand due to presence of pyridine groups and as a stabilizing agent due to highly branched architecture. Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and X‐ray photoelectron spectroscopy (XPS) were used to extensively evaluate structure and morphology of the synthesized NiNPs@G3. The selected area electron diffraction (SAED) allowed us to conclude about fcc structure of NiNPs while STEM EDS analysis demonstrated a formation of core‐shell NiO@Ni NPs. Further, the catalyst was tested in selected Suzuki‐Miyaura cross‐coupling reactions at mild conditions and demonstrated a high efficiency at low Ni loading with negligible content of Ni0 on the NP surface. The functional hyperbranched dendrimer macromolecule provided an excellent stabilization for NiNPs@G3 while allowing an easy access for reactants to catalytic sites. The high activity of the catalyst in the recycling experiments was maintained by the absence of Ni leaching from the NiNPs@G3. [ABSTRACT FROM AUTHOR]

Nanostructured MFe 2 O 4 (M = Co and Zn) ferrites have been successfully synthesized by hydrothermal method using cetyltrimethylammonium bromide (CTAB) as a surfactant and ammonium hydroxide (NH 4 OH) as a precipitating agent at a moderate temperature (∼160 °C) for 10 h and subsequent calcination of the precursors at 400 and 600 °C. These ferrite materials have been characterized by X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), thermogravimetric analysis−differential scanning calorimetry (TGA−DSC), Fourier transformed infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The CoFe 2 O 4 is found to have both hexagonal and spherical surface morphologies and for ZnFe 2 O 4 a spherical morphology is obtained at 600 °C. Optical, dielectric, and magnetic properties of these ferrites have been investigated. CoFe 2 O 4 exhibits ferromagnetism at room temperature. In contrast, ZnFe 2 O 4 shows paramagnetism at room temperature. The M s and H c values are observed to increase, respectively, from 74.2 emu g−1 to 78.9 emu g−1 and 1221 Oe to 1411 Oe for CoFe 2 O 4 as the calcination temperature increases from 400 °C to 600 °C. This is related to better crystallinity because of calcination at higher temperature. Dielectric properties of the ferrite materials are also enhanced with the increase in the calcination temperature. [ABSTRACT FROM AUTHOR]

The carbon-based composite materials prepared through green synthetic approach are attracting greater interest in electrochemical applications due to their sustainable nature. Herein, we developed Fe 2 O 3 and Fe 2 O 3 @CNT composite materials via a green mechanochemical one-pot method. The as prepared composite materials were characterized by X-ray diffraction (XRD), energy dispersive X-Ray spectroscopy (EDS), field emission scanning microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS), respectively. Incorporating Fe 2 O 3 nanoparticles on CNT surface tunes its electronic structure as well increases active sites and thus enhance the oxygen evolution reaction (OER) performance. As a result, the fabricated Fe 2 O 3 @CNT is a highly effective and balanced electrocatalyst that delivers superior current density (j = 10 mA cm−2) at low overpotential (η = 270 mV) for OER compared with pristine Fe 2 O 3 (η = 290 mV) in 1 M KOH. Further, Fe 2 O 3 @CNT electrocatalyst shows high long-term durability in 1 M KOH for 100 h, fulfilling all the advantageous viable standards for OER. [ABSTRACT FROM AUTHOR]

Azithromycin is one of the most concentrated antibiotics in wastewater, as conventional wastewater treatment facilities cannot eliminate this antibiotic from the environment. In this study, we proposed using a graphene-based mesoporous electrochemical sensor to take simultaneous voltammetric measurements of azithromycin. Because of its homogeneous pore structure, large surface area, quick electron transfer rate, and superior biocompatibility, magnesium-containing mesoporous silica is a promising resource for the immobilization of biomolecule matrix. Ca2+-doped MgAl2O3-G-SiO2 was used to build an amperometric biosensor through a self-assembly process. At room temperature in a buffer solution with a pH of 7.0, the modified electrode under ideal circumstances displayed good azithromycin sensing activity, a linear range of 1 to 5 µmolL−1, a detection limit of 0.5 µmolL−1, and a reaction time of less than 2 sec. An array of morphological analysis methods—including X-ray diffraction methos, scanning electron microscopy, Brunauer-Emmett-Teller method, high resolution tunneling electron microscopy, Raman, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy—was used to examine the nanocomposite's crystalline structure. Cyclic voltammetry was used to determine the sensing effects in the mesoporous active nanomaterials. Finally, it was found that the electrochemical sensor performed as an ideal biosensor that was able to detect azithromycin in the presence of several interfering species with high stability, selectivity, and repeatability. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) films with low defect concentration were fabricated on Si substrates via RF magnetron sputtering system based on Al-rich AlN (Al-AlN) targets. The effects of Al-rich content on structure, defects and photoelectric properties of AlN films were investigated by x-ray diffraction (XRD), high resolution transmission electron microscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), ultraviolet-visible spectra, currentâ€"voltage (I â€" V) and capacitanceâ€"voltage (C â€" V) characteristics. In particular, the defects of AlN films were investigated by XPS and low-temperature PL analyses, indicating that Al-rich AlN targets can help to reduce the defects of Al vacancy and O impurity of AlN films with an optimal Al-rich content of 1.5 wt. % (A1.5). Schottky contact behavior between AlN films and Ti/Al/Ni/Au multi-layer electrodes were revealed from I â€" V curves of all samples based on parallel electrodes, and AlN metal-semiconductor-metal (MSM) devices prepared by A1.5 films exhibited the lowest leakage current of 2.43 Ă— 10âˆ'8 A at the bias of 5 V. C â€" V tests indicate the less defect density and lower carrier concentrations of vertical structure of A1.5 devices. This work offers a feasible approach to regulate the defects of AlN films for practical application. [ABSTRACT FROM AUTHOR]

The nanoparticles (NP), consisting of hydrazine grafted organo-silica with PdNPs embedded shell on the Fe 3 O 4 core, were prepared to study the adsorption and interactions of hydrogen in PdNPs and their support matrix. This material is expected to find the applications in the hydrogen technology including catalysis. The PdNPs were formed spontaneously in the organo-silica shell on magnetite nanoparticles by the reduction of Pd2+ ions with grafted hydrazine in the organo-silica shell. Thus formed NPs, termed as Fe 3 O 4 -GTEOS@PdNPs, were also thermally treated at 1033 K in Ar atmosphere to convert organic components to carbon. The chemical composition, physical structure, and magnetic properties were studied by high resolution transmission electron microscopy, X-rays diffraction, Mössbauer spectroscopy and X-ray photoelectron spectroscopy for the characterizations of physical, chemical and magnetic changes occurred in the Fe 3 O 4 -GTEOS@PdNPs after hydrogen adsorption-desorption at varying temperatures with respect to that in unused one. The hydrogen adsorption pressure-composition (PC) isotherms in Fe 3 O 4 -GTEOS@PdNPs followed the expected trend from 173 to 303 K as expected from PdNPs. However, thermally treated Fe 3 O 4 -GTEOS@PdNPs were found to adsorb lower amount of hydrogen due to oxidation of Pd0 to PdO and morphological changes during heating in Ar atmosphere. The comparison of n H /n Pd value (0.49) obtained for the PdNPs in Fe 3 O 4 -GTEOS@PdNPs with the values those reported in the literature for different Pd materials showed the decrease in n H /n Pd value with decrease in the size of Pd particles. This was attributed to stronger Pd–H bond in a nanoscale palladium, which prevented hydrogen transfer to interior matrix as compared to bigger Pd particles. The hydrogen adsorption PC isotherm at 373 K in Fe 3 O 4 -GTEOS@PdNPs could not be obtained as the unknown chemical reaction happened in the sample during the experiment. The considerably higher H 2 consumption in the Fe 3 O 4 -GTEOS@PdNPs occurred at 373 K than that expected from the hydrogen adsorption in the PdNPs alone. [Display omitted] • Hydrazine grafted organo-silica shell on magnetite NP was formed to host Pd NPs. • PC isotherms for the H 2 adsorption followed normal trend in 173–303 K temp. range. • H 2 adsorption decreased in nanoscaling of Pd particles due to stronger Pd–H bonds. • Hydrogen adsorption PC isotherm at 373 K was higher than expected from Pd NPs. • Pd NPs catalyzed hydrogenation of organo-silica shell on Fe 3 O 4 occurred at 373 K. [ABSTRACT FROM AUTHOR]

This study illustrates the synthesis of functionalized carbon quantum dots (CQDs) by the one-pot pyrolysis method. The functionalization agent used in CQD synthesis was poly l- lysine (PLL). Various physicochemical techniques were employed to confirm the successful formation of PLLCQD including High resolution transmission electron microscopy (HR-TEM), UV-Vis spectroscopy, fluorescence spectroscopy; Atomic force microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The size of PLLCQD was confirmed by HRTEM and AFM. The synthesized PLLCQD shows bright blue fluorescence and has a quantum yield of 19.35%. The highest emission band was observed at 471nm when excited to 370nm. The prepared PLLCQD exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with inhibition zone 7-20 mm. The concentrations of 0.9 to 0.1gmL-1 were studied to determine minimum inhibitory concentration (MIC) by the agar well diffusion assay method. MIC of 0.2gml -1 concentration of PLLCQD is achieved. The anti-angiogenic activity of PLLCQD was determined using (Chick Chorioallantoic Membrane) CAM assay. CAM assay is a reliable in -vivo model to study angiogenesis also; many stimulators and inhibitors have been examined by this method. This study proves higher antibacterial efficiency of PLLCQD over non functionalized CQD. PLLCQD was successfully employed in bio-imaging of the bacterial cell through fluorescence microscopy. Further, PLLCQD displayed cytotoxic effect on endothelial cells and inhibited blood vessel formation in the CAM model. [ABSTRACT FROM AUTHOR]

Metal carbides MC (HfC, NbC, ZrC, TaC and TiC) that were exposed to air under the ambient temperature condition for a period of time were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and Raman. Fresh MC samples exposed to the air for different time (fresh, one day, one week and one quarter) illustrated unexpected oxidation degree of the surfaces. XRD tests provided very limited information, since the oxidation process occurred from the surface at the nanometer scale. However, the XPS tests provided more comprehensive information for the MOx (HfO2, ZrO2, Nb2O5, Ta2O5 and TiO2) film and MC (HfC, NbC, ZrC, TaC and TiC) interlayer. Meanwhile, the HRTEM and Raman tests could give some additional or supporting information for XPS tests, when the samples were exposed to the air for longer time (one week or one quarter). Meanwhile, this research is the first to show that the oxidation progress of the metal surfaces of HfC, NbC, ZrC, TaC and TiC can take place in air under the ambient temperature condition and the oxidation film is about 2–5 nm. Meanwhile, a new oxidation mechanism of metal carbides MC (HfC, NbC, ZrC, TaC and TiC) exposed to air under the ambient temperature condition is also proposed, considering the obtained Raman, TEM and XPS results that could clearly confirm the formation of HfO2 and free carbon. [ABSTRACT FROM AUTHOR]

• An expected SnO 2 @CuO/CF heterostructure material is synthesized. • p-n heterojunction enhances the adsorption of H 2 O 2 and benefits sensing properties. • Cost-effective H 2 O 2 electrochemical sensor with excellent performance is obtained. • The developed sensor has good biocompatibility for real-time detection of H 2 O 2 released by living cells. Hydrogen peroxide (H 2 O 2) is a major messenger molecule in cellular signal transduction. It is critical to detect cellular secreted H 2 O 2 in situ for clinical diagnosis and biomedical research. Therefore a simple, fast, sensitive, and cost-effective hydrogen peroxide detection method is needed. In this study, copper foam (CF) was used as copper source and conductive substrate, the electrochemical sensor SnO 2 @CuO/CF is prepared to detect H 2 O 2 secreted by living cells. High resolution transmission electron microscopy (HRTEM), X-ray diffraction, Mott Schottky curves and X-ray photoelectron spectroscopy demonstrate the successful formation of SnO 2 @CuO heterostructure. Theoretical calculations confirm that SnO 2 @CuO heterostructure facilitates the adsorption of H 2 O 2. The designed SnO 2 @CuO/CF sensor shows good sensing performance for H 2 O 2. Under optimal conditions, the designed sensor shows a relatively wide linear range to H 2 O 2 concentration from 1 μM to 13.88 mM, with high sensitivity (5100 μA·mM−1·cm−2) and low detection limit (0.13 μM). Cytotoxicity experiments prove that the sensor has good biocompatibility and the prepared sensor is successfully used to detect H 2 O 2 released by HeLa cells. With superior sensitivity, anti-interference ability, and reproducibility, SnO 2 @CuO /CF shows the potential application of H 2 O 2 monitoring in the field of biomedical and clinical diagnosis. This study provides a new platform for the development of highly sensitive H 2 O 2 electrochemical sensors in practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • SnS and SnS 2 are synthesized in the form of quantum dots from aqueous solutions. • Syntheses are conducted under room conditions thanks to application of ultrasound. • Influence of sonication time on QDs properties is investigated. • SnS and SnS 2 QDs were utilized as photo- and (for the first time) sonocatalysts. • The greatest color removal was observed in the case of SnS QDs sonocatalyst (85.2%) Our study reports the ultrasound-assisted synthesis of SnS and SnS 2 in the form of nanoparticles using aqueous solutions of respective tin chloride and thioacetamide varying sonication time. The presence of both compounds is confirmed by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, as well as Raman and FT-IR spectroscopic techniques. The existence of nanoparticles is proven by powder X-ray diffraction investigation and by high resolution transmission electron microscopy observations. The size of nanocrystallites are in the range of 3–8 nm and 30 50 nm for SnS, and 1.5–10 nm for SnS 2. X-ray photoelectron spectroscopy measurements, used to investigate the chemical state of tin and sulphur atoms on the surface of nanoparticles, reveal that they are typically covered with tin on the same oxidation degree as respective bulk compound. Values of optical bandgaps of synthesized nanoparticles, according to the Tauc method, were 2.31, 1.47 and 1.05 eV for SnS (60, 90 and 120 min long synthesis, respectively), and 2.81, 2.78 and 2.70 eV for SnS 2 (60, 90 and 120 min long synthesis, respectively). Obtained nanoparticles were utilized as photo- and sonocatalysts in the process of degradation of model azo-dye molecules by UV-C light or ultrasound. Quantum dots of SnS 2 obtained under sonication lasting 120 min were the best photocatalyst (66.9 % color removal), while quantum dots of SnS obtained under similar sonication time were the best sonocatalyst (85.2 % color removal). [ABSTRACT FROM AUTHOR]

β-Bi 2 O 3 and Ni-incorporated β-Bi 2 O 3 nanoparticles with different Ni incorporating amounts (0, 2, and 4 at. wt. %) were successfully synthesized through a viable hydrothermal process. As-synthesized nanoparticles were analyzed by complementary analytical tools such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), UV–visible spectroscopy (UV–Vis), and photoluminescence spectroscopy (PL) for structural, microstructural, compositional, and spectral properties. The photocatalytic performance of synthesized nanoparticles was assessed by subjecting them to visible light irradiation and monitoring the decomposition of rhodamine-B dye. The findings demonstrated that the inclusion of Ni(4%) in β-Bi 2 O 3 nanoparticles significantly enhanced its photocatalytic activity compared to pristine β-Bi 2 O 3 which is desirable for environmental remediation. This improvement may be caused by increased generation of electron-hole (e−-h+) pairs, reduced recombination rate of these pairs, enhanced absorption of visible light, and a decreased band gap energy. To evaluate the specific capacitance characteristics of synthesized electrode materials, cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance analyses were conducted. The super capacitance activities of prepared electrode materials were observed in the order of Bi 2 O 3 < Ni(2%)-Bi 2 O 3 < Ni(4%)-Bi 2 O 3. Notably, Ni(4%)-Bi 2 O 3 nanocomposite exhibited higher supercapacitance, which can be attributed to the effective role of appropriate nickel incorporation in Bi 2 O 3. These results suggested that the incorporation of Ni(4%) into β-Bi 2 O 3 to form a nanocomposite showed greater capability as an effective electrode material for advanced energy storage devices, especially supercapacitors. Ni (0,2,4%) incorporated-Bi 2 O 3 nanoparticles were successfully synthesized and characterized through viable techniques. Ni (4%)- Bi 2 O 3 nanoparticles have shown enhanced visible light driven photocatalytic activity against organic dyes for environmental remediation. It also exhibited high supercapacitance desirable for high capacity electrode material employable in supercapacitors. [Display omitted] • Ag NPs-loaded brookite TiO 2 NWs supported on rGO sheets were produced hydrothermally. • Structure and morphology were evaluated by XRD, XPS and SEM/TEM. • Ag–TiO 2 /rGO nanohybrid exhibited an excellent light induced photocatalytic performance. • A suitable schematic mechanism was proposed for photocatalytic degradation of dye. • Ag–TiO 2 /rGO nanohybrid demonstrated fairly high electrochemical electrode material characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu2+ doped MgFe 2 O 4 have been synthesized by microwave combustion method. • Cu2+ doped MgFe 2 O 4 confirms cubic inverse spinel structure with Fd 3 ¯ m space group. • Structural and elementals are confirmed by XRD, XPS and EDX analysis for MgFe 2 O 4. • Hysteresis confirms Mg 1- x Cu x Fe 2 O 4 were shows a ferromagnetic behaviour in nature. • The detailed photocatalytic degradation mechanism of Mg 0.7 Cu 0.3 Fe 2 O 4 is discussed. This study presents the synthesis of Mg 1- x Cu x Fe 2 O 4 (x = 0.0, 0.1, 0.3, and 0.5) nanoparticles (NPs) using the direct microwave combustion method (MCM) with L-arginine as the fuel source. The samples were characterised comprehensively using various analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High resolution scanning electron microscopy (HRSEM), Energy-dispersive X-ray (EDX), Diffuse reflectance spectroscopy in the ultraviolet–visible (DRS-UV) range, Fourier-transform infrared spectroscopy (FTIR), and Vibrating sample magnetometry (VSM). The cubic spinel structure was verified by X-ray diffraction analysis. It revealed an average crystallite size ranging from 15.8 to 26.6 nm. The oxidation states and elemental composition of Mg 1- x Cu x Fe 2 O 4 were evaluated using XPS analysis. Notably, the major absorption bands at 557 and 434 cm−1 corresponded to the tetrahedral (Mg2+ –O2−) and octahedral (Fe3+ –O2−) sites, respectively. HRSEM images showed agglomerated particles with elemental verification of Mg 1- x Cu x Fe 2 O 4. This was validated by EDX studies. The optical bandgap was determined by DRS-UV analysis. Functional groups were analyzed by FTIR spectra. Hysteresis loop measurements revealed the ferromagnetic properties of the obtained samples. Furthermore, the study evaluated the detailed mechanism of the photocatalytic degradation (PCD) of Mg 0.7 Cu 0.3 Fe 2 O 4. [ABSTRACT FROM AUTHOR]

To explore the effect of heterojunction on photocatalytic activity, pure Bi5O7NO3,α-Bi2O3Chanel triphase heterojunction were synthesized using hydrothermal method with Bi(N03)3 • 5H2O as raw materiaL X-ray diffraction (XRD), Raman spectroscopy, high resolution transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structures and phase compositions. The result showed that after 90 min light irradiation of 250 W mercury lamps, the Rhodamine B degradation efficiency of heterojunction and Bi5O7NO3 are 98. 1% and 89. 9%. The values are far higher thanα-Bi203 25% and &@946;-Bi203 45%. The methyl orange degradation efficiency of these two samples are about 90%, faster than 77% ofα-Bi2O3 and 86% of β-Bi2O3. According to band gap and Mott-Schottky curve, Bi5O7NO3, α- and β-Bi2O3 form a staggered energy band configuration. Photogenerated electrons transfer from the conduction band of Bi5O7NO3 to the α-Bi2O3 and β-Bi2O3 conduction bands in tuni. The electron and hole is separated to improve the photocatalytic activity. Scanning electron microscopy (SEM) and diffuse reflectance spectroscopy show that the morphology and double absorption further enhance the photocatalytic activity. Therefore high activityBi5O7 NO3 photocatalyzer is in situ grown. [ABSTRACT FROM AUTHOR]

In this study, we report on the preparation of a copper oxide/reduced graphene oxide/titanium dioxide (CuO/rGO/TiO2) photocatalyst and its application in a coupling reaction for carbon–nitrogen bond formation under visible light irradiation. The CuO/rGO/TiO2 nanocomposite was synthesized from graphene oxide, Cu and Ti precursors and was fully characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), cyclic voltammetry (CV), UV-vis absorption, and photoluminescence (PL) spectroscopy. The photocatalytic effectiveness of the CuO/rGO/TiO2 nanocomposite was explored in a pseudo 4-component reaction of salicylaldehyde, malononitrile and secondary amines for the preparation of benzopyranopyrimidines in high yields (75–95%) under visible light irradiation (60–120 min) in ethanol as the solvent at room temperature. Furthermore, the photocatalytic activity of the CuO/rGO/TiO2 nanocomposite was studied in a domino reaction for the coupling of salicylaldehyde and malononitrile in the presence of other aldehydes and secondary amines under the same reaction conditions to afford the corresponding benzopyranopyrimidine derivatives in 77–93% yields after 120–180 min. The reusability investigation of the CuO/rGO/TiO2 photocatalyst showed that it could be recovered and recycled for 5 runs without a significant decrease in its catalytic activity. [ABSTRACT FROM AUTHOR]

A Co/HTNT catalyst is developed by immobilizing Co on the surface of titanate nanotubes. The microstructure and composition of the catalyst are investigated with atomic absorption spectroscopy (AAS), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS). The developed Co/HTNT catalyst shows great performance in catalyzing NaBH 4 hydrolysis. The hydrolysis of 25 mg NaBH 4 catalyzed by 50 mg Co/HTNT in 10 g NaOH solution (12.5 wt%) provides a hydrogen production rate of 1.04 L min−1 g Co −1 at 30 °C, and the activation energy of the reaction is 29.68 kJ mol−1. The high catalytic activity and economical property make this catalyst a promising choice for on-site hydrogen production from NaBH 4 hydrolysis. • A Co/HTNT catalyst is developed by immobilizing Co nanoparticles on HTNTs. • The high surface area of HTNTs ensures good Co distribution in the catalyst. • The Co/HTNT catalyst shows excellent performance in catalyzing NaBH 4 hydrolysis. [ABSTRACT FROM AUTHOR]

Boron (B) doping plays a critical role in adjusting the electronic properties of carbon materials. In this work, B-doped porous graphene (B-PG) was successfully prepared by a simple strategy and used as an advanced electrode material for the detection of nitrite (NO- 2) in food. The scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize this B-PG. Due to the ideal doping of boron atoms, the material has good conductivity and exhibits excellent electrochemical catalytic performance. NO- 2 was used as the representative analytes to demonstrate the sensing performance of B-PG. It is found that the B-PG modified GCE exhibited a linear response over the concentration range from 3 μM – 3 mM and 3 mM – 15 mM, with a detection limit of 1.1 μM. The designed electrochemical sensor has good analytical performance, such as high sensitivity, good reproducibility and acceptable accuracy, and can be successfully applied to the accurate and precise detection of residual NO- 2 in food. • A novel nanomaterial of porous graphene doped with B atoms (B-PG) was prepared. • B-PG exhibits excellent electrocatalytic activity for nitrite. • The electrochemical sensor has good stability and anti-interference performance. • It can be successfully applied to the detection of residual detect nitrite in food. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doped Cdots synthesized by conjugation of 1,4 butanediol L-arginine. • Self-assembly of amine functionalized transverse oligomeric chain of diols by H-bond. • Dual probe for the detection of nanomolar concentrations of TC and 4-NP. • Static quenching with ground state complexation between N-Cdots and TC /4-NP. • Demonstration of TC and 4-NP detection in real sample matrix: river water and milk. Nitrogen doped carbon dots are emerging as efficient photoluminescent probes for wide range of sensing applications. A simple strategy of synthesizing highly ordered nitrogen doped carbon dots (named here as N-CD arg) is developed by thermal conjugation of 1, 4-Butanediol with L-Arginine. It led to formation of self-assembled transverse carbon chains through oligomerization of 1,4-Butanediol and conjugation with L-Arginine. The structural, morphological and compositional analysis of the N-CD arg is confirmed from 1H and 13C NMR, mass spectroscopy, FT-IR, higher resolution transmission electron microscopy and X-ray photoelectron spectroscopy. It exhibited bright bluish photoluminescence with PL quantum yield of 11 %. Under optimized pH and contact time, the probe solution of N-CD arg exhibited dual sensing for the detection of tetracycline (TC) and 4-nitrophenol (4-NP) via PL quenching proportional, which followed Stern-Volmer relation. The linear PL quenching response for TC is in the range of 0.5 μM to 60 μM with a limit of detection (LOD) of 103 nM; while the linear range for 4-NP is 0.4 μM to 20 μM, and the LOD is 77 nM. Selectivity of these species have been confirmed against several metal ions, anions, other antibiotics (for TC detection) and different structural analogues of phenols (for 4-NP detection). The ability of the probe to quantitatively detect trace concentrations of TC and 4-NP in real sample matrices like river water and milk has been demonstrated by spike analysis. The mechanism of PL quenching of N-CD arg by TC and 4-NP has been discussed using PL decay lifetime spectroscopy. [ABSTRACT FROM AUTHOR]

In this research, cuprous oxide (pristine Cu 2 O) and rGO (reduced graphene oxide)-doped Cu 2 O were prepared using a simple synthetic route and adopted as sensitive materials for ozone detection. The microstructural, morphological and compositional properties of as-prepared samples have been analyzed by several characterization techniques including X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Energy dispersive spectrometer (EDS), UV-Visible spectrophotometer (UV–vis), Multi-functional field emission scanning electron microscope (FESEM), X-ray Photoelectron Spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). Meanwhile, the sensing features of as-prepared samples have been investigated carefully and the as-prepared 0.5 wt% rGO-Cu 2 O exhibited best ozone sensing properties, such as high stability, sensitivity and selectivity. It can be found that the response value of 0.5 wt% rGO-Cu 2 O-based sensor towards 20 ppb ozone and 1 ppm ozone were 9.2/1734, respectively, and the corresponding response and recovery times were 11/64 s and 11/411 s, respectively. More importantly, the detection limit of the 0.5 wt% rGO-Cu 2 O sensor was as low as 0.1 ppb. Furthermore, the possible mechanism for the enhanced sensing performance of the as-prepared rGO-Cu 2 O has been discussed. • We report rGO-Cu 2 O nanomaterials for efficient ozone gas detection. • O 3 gas sensing with very low detection limit at 0.1 ppb. • Advantages of the detection of O 3 at low interferences and well stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A wet impregnation procedure was used to create a g-C3N4/CuS heterojunction. • The catalyst degrades the RhB dye photocatalytically (98.6%) in 40 min. • The results of the repeatability experiment indisputably show that the produced catalyst has a high photo-stability. The g-C 3 N 4 /CuS heterojunction was synthesized using a wet impregnation process. Powder X-ray diffraction (PXRD), High resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy (XPS), Diffused reflectance spectroscopy (UV–vis DRS), and Photoluminescence (PL) were employed to examine the crystalline structure, morphology, elemental configuration, optical absorption characteristics, electron hole recombination, and charge transfer property of the prepared materials, respectively. The specific surface area and pore volume of the produced materials were calculated using N 2 adsorption–desorption isotherms and BET studies. Rhodamine B (RhB) is broken down by the catalysts in the presence of visible light. In 40 min, the catalyst showed quick photocatalytic degradation of the RhB dye (98.6 %). The synthesized catalyst performs at the highest level for photocatalytic degradation due to its low e-h recombination rate, broad spectrum of absorption light, increased photo-generated electrons, and larger specific surface area. Higher photocatalytic activity might be a result of the matched overlapping band structure and the interaction between CuS and g-C 3 N 4. The photoluminescent spectra show that the interaction of g-C 3 N 4 and CuS would not only boost the optical absorption property of g-C 3 N 4 , but would also produce more interfaces for the efficient transfer of photo-generated electron-hole pairs to limit recombination. The repeatability experiment's results unequivocally demonstrate that the developed catalyst has a high photo-stability. The results of the degrading efficiency tests were competitive with numerous photocatalysts that had already been published. [ABSTRACT FROM AUTHOR]

Co-loaded amorphous zeolite has been prepared, characterized and tested as an electrochemical supercapacitor. Amorphous zeolite (AZ) and H-amorphous zeolite were prepared using the steam assisted crystallization method; the H+ was added on AZ via ion exchange with NH 4 NO 3 to evaluate the supercapacitive difference between AZ and H-AZ. Co was loaded into the AZ and H-AZ by the impregnation method to enhance the redox properties. The physico-chemical properties of the AZ, H-AZ, Co/AZ and Co/H-AZ were investigated using various analytical characterization techniques, namely X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), High Resolution Scanning Electron Microscopy (HRSEM), N 2 physisorption and X-ray Photoelectron Spectroscopy (XPS). The materials were subsequently drop-cast into a Ni foam and evaluated for supercapacitive properties. Notably, the resulting electrode materials exhibit supercapacitive behaviour that is effective over a potential window from −0.1 to +0.7 V in a potassium hydroxide (1 M KOH) aqueous electrolyte. A relatively high specific capacitance of 550 F/g at 1 A/g was calculated from Galvanometric Charge Discharge (GCD) analysis for the Co/H-AZ electrode with a Coulombic efficiency of 98% after 2000 cycles and a capacitance retention of 91.6%, while the value calculated for Co/AZ was 400 F/g with a Coulombic efficiency of 96% after 2000 cycles and a capacitance retention of 75.5%. The energy density and power density for Co/H-AZ were 19.09 W h/kg and 250 W/kg respectively, while the energy density and power density for Co/AZ were 13.88 W/kg and 248 W h/kg respectively. The difference in the performance of Co/H-AZ and Co/AZ can be attributed to the effect of H+ ions at the electrode/electrolyte interface. [Display omitted] • Amorphous zeolite (AZ) was synthesized by the steam-assisted method; H was ion exchanged into AZ. • Co was loaded onto the AZ and H-AZ and then drop cast onto Ni-foam. • Specific capacitance of Co/H-AZ and the Co/AZ: 550 and 400 F/g respectively. • After 2000 cycles, Co/H-AZ exhibited 98% Coulombic efficiency and 91.6 of capacitance retention. • Supercapacitor properties of Co/H-AZ are due to redox nature of Co 3 O 4 and H+ in AZ. [ABSTRACT FROM AUTHOR]

Cobalt oxide hydrate (Co(OH)x) supported on metal oxides were prepared. The oxidative cleavage of C(OH)−C bond in alcohol was catalyzed by Co(OH)x/metal oxides using molecular oxygen as the oxidant, and the corresponding product was obtained with high selectivity. The composition and characteristics of the catalysts were analyzed by X‐ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), high‐angle ring dark‐field scanning TEM (HAADF‐STEM), N2 physico‐adsorption characterization, inductively coupled plasma optical emission spectrometry (ICP‐OES), Fourier transform infrared spectrum (FTIR), X‐ray photoelectron spectroscopy (XPS) and NH3‐temperature‐programmed desorption (NH3‐TPD). Additionally, a reasonable reaction mechanism was proposed based on the characterization results and a series of controlled experiments. Notably, this heterogeneous catalytic system did not require any additives and had good recycling performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of pore structure on activity and stability of CoMoS phase was studied. • Calcination enlarges the pore of γ-Al 2 O 3 at the expense of specific surface area. • Larger pore reduces strip-off of Co from CoMoS phase but not affect MoS 2 length. • TOF and stability of CoMoS phase for HDS and HDA increase with pore size. • Coke can be controlled by pore size to increase TOF and stability of CoMoS phase. Effect of pore structure on the activity and stability of sulfide phase in hydrodesulfurization (HDS) of diesel were systematically investigated. A series of alumina with different pore structure were prepared by calcining pseudo boehmite at different temperatures. Various characterizations suggested that the surface concentration of OH groups and Lewis acid sites generally decreased with calcination temperature. The properties of sulfide phase in fresh and spent catalysts were analysis by X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The results showed that the concentration of CoMoS species was greatly decreased after the reaction while the average length of MoS 2 slabs was substantially increased. The concentration of preserved CoMoS species was proportional to the average pore size of support indicating that the strip-off of Co from CoMoS phase can be reduced when the average pore size is larger. Furthermore, the activity evaluation showed that larger pore structure of support is beneficial for the intrinsic activity and stability of CoMoS phase in the HDS of diesel. The reason was partially attributed to that the pore with larger diameter can reduce the coke deposition on the catalyst so that increase the intrinsic activity and stability of CoMoS sites. [ABSTRACT FROM AUTHOR]

In this paper, sulfonic acid functionalize magnetic starch (denoted Starch/SPION@SO3H) is fabricated by the polymerization of 4‐styrenesulfonic acid on the surface of magnetic starch. Magnetic starch (Starch/SPION) is synthesized by covalent modification of starch by silica capsulate superparamagnetic iron oxide nanoparticles (SPION). For this purpose, Starch/SPION is modified by allyltrimethoxysilane, follows by the polymerization of 4‐styrenesulfonic acid onto this material. The catalyst is characterized by various characterization techniques, including transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), vibrating‐sample magnetometer (VSM), X‐ray photoelectron spectroscopy (XPS), and acid/base titration. The characterizations prove the structure of Starch/SPION@SO3H catalyst. The catalytic activity of Starch/SPION@SO3H is evaluated in the multicomponent reaction of 4‐hydroxycoumarin, benzaldehydes, dimedone, and ammonium acetate for the synthesis of chromeno[4,3‐b]quinoline‐6,8(9H)‐dione derivatives. The catalyst shows very good activity in the synthesis of chromeno[4,3‐b]quinoline‐6,8(9H)‐dione derivatives. Several benzaldehydes with electron donating or electron withdrawing functionalities are used as starting material and all the substrates give the desired products in high isolated yields. In addition, the catalyst is extremely reusable during 10 sequential runs. Characterization of Starch/SPION@SO3H catalyst by TEM, VSM, and acid/base titration after recovery from the reaction proves the stability of the catalyst in the reaction conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ecofriendly and sustainable approach for the synthesis of stable AuNPs. • Aqueous extracts of root and rhizome of Phragmites australis were evaluated. • The spherical shape was the dominant with size (5–20 nm). • Anticancer and antioxidant potentials of AuNPs were confirmed. • Promising application in photocatalytic degradation of MB and MO. In this research, we adopt an ecofriendly and sustainable approach to compare the potentiality and efficiency of Phragmites australis aqueous extracts of two different organs to fabricate gold nanoparticles (AuNPs). The aqueous extracts of plant roots and rhizome were used as alternative reducing agents to conventional chemicals. Various Characterization techniques were used; UV–Vis spectroscopy, Zeta potential, Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Selected Area Electron Diffraction (SAED), Energy Dispersive X-ray Spectroscopy (EDX), High Resolution Transmission Electron Microscopy (HRTEM) equipped with elemental mapping in order to confirm the formation of zero-valent AuNPs, X-ray photoelectron spectroscopy (XPS). Our results demonstrated that both extracts of Phragmites australis are good candidates for the green-synthesis of AuNPs. Zeta potential was used to confirm the stability of AuNPs. The cytotoxic capacities of both AuNPs samples were validated using MTT assay which proved the inhibition of the growth and proliferation of human lung cancer cells (A549 cell line). Antioxidant potentialities were >10%. The phytosynthesized AuNPs exhibited high capacity in removing methylene blue and methyl orange dyes within just one min. This research offers an alternative solution to manage the accumulated unwanted biomass of a widely distributed aquatic macrophyte in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) have been widely used in antibacterial fields due to their excellent antibacterial effects. Here, by using a dietary flavonoid found in edible plants, kaempferol (Kae), as reducing and capping agent, a facile and eco-friendly method was developed to synthesize the uniform and long-term stable silver nanoparticle/kaempferol composites (Kae-AgNPs). Kae-AgNPs were characterized by ultraviolet visible (UV–Vis) spectroscopy, Fourier transform infrared spectrum (FT-IR) spectroscopy, dynamic light scattering (DLS), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Kae-AgNPs with a size about 10 nm were synthesized by 0.1 mmol/L Kae. Lower concentration of Kae was shown with smaller Kae-AgNPs due to a few of Kae molecules expected to reduce a small number of Ag+ ions to metallic silver. Aqueous Kae-AgNPs were very stable and could be stably dispersed in water for about two months as evidenced by DLS detection, and the stability was further confirmed by XPS. Antibacterial analysis against Escherichia coli (ATCC 8099) and Staphylococcus aureus (ATCC 6538) strains showed that Kae-AgNPs displayed superior antibacterial effects than AgNPs or Kae alone, and interestingly, much better than that of the analogous nano-silver composites in the previous studies. Moreover, Kae-AgNPs with a low concentration of 2 μg/mL demonstrated highly effective antibacterial activity against E. coli (1 × 106 CFU/mL). The antibacterial mechanisms of Kae-AgNPs included the destruction of the membrane structure of bacteria, leakage of the cell contents, inducing the production of reactive oxygen species (ROS), and eventually resulting in bacteria death. The results suggest that Kae-AgNPs have high efficiency against bacteria, and have the potential to be further developed as promising antibacterial nanocomposites. [ABSTRACT FROM AUTHOR]

It is well known that graphene (G), graphene oxide (GO) and reduced graphene oxides (RGO) are materials of today with immense application potentials. However, to realize the same large scale, reproducible, sustainable synthesis techniques such as greener methods which avoid utilization of toxic chemicals for synthesis, must be adopted. It is in this context, that here we report the reduction of GO to RGO by the extract of Thuja Orientalis (TO) seeds. As such, TO is a well-known bio-resource for medicinal and various other biotechnological applications as it contains Alpha Tocopherol, the major constituent of vitamin E. To the best of our knowledge, despite the wealth of literature, the current work makes a pioneering effort in applying TO seeds extract for reduction of GO to RGO. Thus, the reduction of GO, synthesized by the well-known modified Hummer's method to RGO by TO extract, is confirmed from the results obtained by ultra-violet visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) analysis, selected area electron diffraction (SAED), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and especially, gas chromatograph mass spectrometry (GCMS) techniques. Furthermore, the GCMS study is used to identify the compound Alpha Tocopherol responsible for reduction of GO to RGO. Based on current experimental evidences and literature views, the possible mechanism of reduction is suggested. Finally, the implications of present studies in the perspective of large scale, sustainable synthesis of RGO for various technological applications are discussed. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) is considered as one of the most promising materials for next-generation quantum technologies. In this paper, we report bulk-like multilayer h-BN epitaxially grown using a carbon-free precursor on c-plane sapphire with a strong emphasis on material characterization and analysis. In particular, structural, morphological, and vibrational properties, and chemical bonding of such van der Waals materials are presented. Between as-grown h-BN and c-plane sapphire, a compressive residual strain induced by both lattice mismatch and thermal expansion mismatch is examined by both theoretical and experimental studies. Atomic force microscopy revealed and scanning electron microscopy supported the presence of wrinkles across the entire surface of the film, likely due to biaxial compressive strain further verified by Raman spectroscopy. Stacking orders in h-BN with a clearly layered structure were confirmed by high resolution transmission electron microscopy, showing that the films have crystallographic homogeneity. Chemical analysis of the as-grown films was done by x-ray photoelectron spectroscopy, which confirmed the formation of stoichiometric h-BN films with excellent uniformity. This wafer-scale chemical vapor deposition-grown layered h-BN with 2D morphology facilitates applications in the fields of quantum- and deep ultraviolet-photonics. [ABSTRACT FROM AUTHOR]

The inhomogeneous capacity degradation distribution of large-format LiFePO 4 -based lithium ion cell after 2500 charge-discharge cycles is analyzed via the selected regions of the cathodes using half-cell charge-discharge test, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy analysis. The results showed that the initial specific charge capacities demonstrate an obvious position-dependent characteristic, indicating inhomogeneous reactions occurring on the electrode. The low initial charge capacities near the tab location can be recovered after discharging, indicating the capacity degradation is from the active lithium loss, rather than the crystal structure destruction. The X-ray photoelectron spectroscopy and high resolution transmission electron microscopy results further verified these deduction and the X-ray absorption spectroscopy analysis results indicate that the difference on the structure change of LiFePO 4 is mainly at the surface, rather than in the bulk. [ABSTRACT FROM AUTHOR]

In the present study, mixed calcium magnesium oxide (CaMgO 2) nanoflakes were synthesized using an ultrasound-assisted co-precipitation method. The physicochemical, structural and functional properties and elemental composition of the nanoflakes had been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), High-resolution transmission electron microscopy (HR-TEM), Fourier Transform Infrared spectroscopy (FTIR), UV–VIS spectroscopy, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Moreover, the photocatalytic actions of the nanoflakes were evaluated by the removal rates of methylene blue (MB) and p -nitrophenol (4-NP) under UV irradiation at room temperature. SEM-EDS studies revealed that the nanoflakes consisted of mixed oxide such as magnesium oxide (MgO) and calcium oxide (CaO) particles. The size of the nanoflakes was found to be in the range of 10–30 nm and the average size was 25 nm as confirmed by HR-TEM analysis. XRD revealed that the standard crystal size was calculated to be 25 nm. The synthesized nanoflakes had a strong photocatalytic activity for methylene blue (MB) and p -nitrophenol (4-NP) degradation in the presence of H 2 O 2 under UV light irradiation within 60 min and 30 min, respectively. Hence, the present study proposes that the CaMgO 2 nanoflakes can be employed for the removal of dyes from wastewater. [ABSTRACT FROM AUTHOR]

Herein, we report the design and fabrication of highly efficient self-humidified electrocatalyst for the enhancement of polymer electrolyte fuel cell (PEFC) performance. An optimum level of silica decorated carbon as an alternative and ultra-stable support to platinum catalyst is prepared by a versatile one-pot synthesis method. The surface morphology, crystallinity, chemical oxidation states and metal/metal oxide-carbon interfacial distribution are examined by High resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, respectively. An optimum level of silica decorated carbon supported Pt (Pt/SDC) boosts the performance and stability of PEFC even up to 200 h in relation to Pt/C under dry gas condition. In addition, the effect of temperature and relative humidity on both anode and cathode is investigated by steady-state cell polarization. A 15-cell air-cooled indigenous prototype PEFC stack is designed, fabricated and assembled. An optimum level of silica decorated on carbon supported Pt employed 15 cell air-cooled stack shows superior power of 104 W at 8 V and also retains more than 96% of initial performance even after 200 h of steady-state operation. In the present work, an optimum level of silica retain water in the triple phase boundary in individual cells, which in turn enhances the overall stack performance and stability even after 200 h of steady-state operation under dry gas feed. • Silica-decorated carbon supported Pt electrocatalyst synthesis by one-pot method. • Pt/SDC electrocatalyst is employed at the anode and cathode in PEFC. • PEFC stack designed and fabricated using indigenous components. • Self-humidified Pt/SDC electrocatalyst shows superior PEFC stability. • Durable PEFC 15 cell stack demonstrated under dry gas operation. [ABSTRACT FROM AUTHOR]

• N and C co-doped TiO 2 was synthesized through a modified sol-gel method. • HNO 3 was used as the esterification reagent for water formation and N precursor. • The catalyst showed high visible-light activity for antibiotics removal. • The main active species in the photocatalytic process were photo-generated holes. • The photocatalytic mechanism of the synthesized co-doped TiO 2 was proposed. Nitrogen and carbon co-doped TiO 2 nano-catalysts (NCD-TiO 2) with visible light activity were prepared using a sol-gel approach involving less chemicals and were evaluated for photocatalytic destruction of two fluoroquinolone antibiotics (ciprofloxacin (CIP) and levofloxacin (LEV)). Nitric acid was used as the reagent of esterification for water formation and the nitrogen precursor, while surfactant Tween 80 was applied as the structure directing agent and the carbon precursor. The synthesis parameters of NCD-TiO 2 nanoparticles, including the calcination temperature and nitric acid content, were optimized and the obtained catalysts were characterized by X-ray diffraction (XRD), Raman, porosimetry analysis, high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse-reflectance spectrum (UV–vis DRS), photoluminescence (PL), and electron spin resonance (ESR) analysis. NCD-TiO 2 prepared with the highest amount of HNO 3 and calcined at 430 °C (NCD200-430) showed the highest photocatalytic activity under visible light, which was essentially attributed to the larger surface area and the higher content of dopants. The photogenerated holes, instead of hydroxyl radical, and partially superoxide radical were confirmed as the effective oxidation species for CIP and LEV destruction in this work. The high efficiency of NCD-TiO 2 under visible light demonstrates the great application potential of such photocatalysts in water treatment for the removal of antibiotics contaminants. [ABSTRACT FROM AUTHOR]

The current study deals with the synthesis of novel Zn, and Fe co-doped TiO 2 photocatalyst by the sol-gel method at room temperature. The prepared photocatalysts are characterized by several standard analytical tools. X-ray diffraction (XRD) and Raman analysis verifies the tetragonal anatase phase of TiO 2 in all synthesized nanoparticles. The morphology and chemical composition of ZFT_2.5 were confirmed using the Field-Emission Scanning Electron Microscope (FE-SEM) and energy dispersive X-ray (EDAX) analysis respectively. X-ray photoelectron spectroscopy (XPS) measurements verify the binding energies of a host and dopant material. The High resolution transmission electron microscopy (HR-TEM) reveals the presence of spherical nanoparticles in ZFT_2.5 photocatalyst with a diameter ranging from 8 to 20 nm. The absorption spectra of the prepared nanoparticles exhibit strong absorption in visible light. The synergistic effect created by Zn and Fe blocked the light induced charge carriers and delayed the recombination probability. The photocatalyst ZFT_2.5 was tested for photocatalytic degradation against the mixture of the three cationic dyes [rhodamine B (RhB), malachite green (MG), and methylene blue (MB)] under exposure of visible light. Total organic carbon (TOC) study was performed to evaluate the organic character of the photodegradate dye solution. [Display omitted] • Zn–Fe codoped TiO 2 were successfully synthesized by simple sol-gel method. • Visible light response of TiO 2 is improved by Zn–Fe codoping. • Synergistic impact of Zn and Fe prevent the recombination of photgenerated charge carriers. • ZFT_2.5 nanoparticles effectively degrade the mixture of ternary dye solution under the visible light irradiation. [ABSTRACT FROM AUTHOR]

The phase analysis and average crystallite size of 11.8, 3.1, and 24.7 nm for MFe 2 O 4 (M=Co, Ni, Zn) nanoparticles (NPs) were analyzed by X-ray diffraction (XRD) patterns, respectively. The spherical and nanoplatelets morphology of MFe 2 O 4 (M=Co, Ni, Zn) was observed by High-Resolution Transmission electron microscopy (HRTEM). The peaks of Fe (2 P 3/2), Fe(2 P 1/2), Co (2 P 3/2), Co(2 P 1/2), Ni (2 P 3/2), Ni (2 P 1/2), Zn (2 P 3/2), Zn (2 P 1/2) and O (1 S) of the prepared nanostructures corresponding to octahedral and tetrahedral sites was observed X-ray photoelectron spectroscopy (XPS) spectra, respectively. Saturation magnetization of 37.4, 18.2, and 15.3 (emu/g) and coercive field of 525, 35.2, and 29.7 Oe of the prepared MFe 2 O 4 (M=Co, Ni, Zn) nanostructures was recorded by M-H analysis at the applied field of ± 7 T. The shifting of the blocking temperature towards lower scale of about 300 K, 150 K, and 55 K for CoFe 2 O 4 , NiFe 2 O 4 , and ZnFe 2 O 4 nanostructures was determined by Zero field-cooled (ZFC) and field-cooled (FC) spectra, respectively. Spin-spin relaxation time 0.1677 × 10−15, and 0.0482 × 10−15 (s) and Spin-lattice relaxation time 0.829 × 10−14, and 2.865 × 10−14 (s) have been evaluated for NiFe 2 O 4 and Zn Fe 2 O 4 NPs, respectively from EPR spectroscopy. Super-paramagnetic time of 0.134 × 10−10, and 5.703 × 10−10 (s) was estimated from the EPR spectrum of the samples exhibiting less time required for NiFe 2 O 4 than ZnFe 2 O 4 NPs. The prepared NPs showing the superparamagnetic property can be used in biomedical applications such as drug delivery and magnetic resonance imaging (MRI). [Display omitted] • Observation of nanoparticles and nanoplatelets by high resolution transmission electron microscopy. • Electron paramagnetic resonance spectroscopy to estimate the relaxation times. • Estimation of spin-spin relaxation and spin lattice relaxation times of NiFe 2 O 4 and ZnFe 2 O 4 NPs. • They can be used for drug delivery and magnetic resonance imaging (MRI) applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vulcan XC-72 carbon modified with Nb 2 O 5 nanorods using the impregnation method. • H 2 O 2 generation of using Vulcan XC-72 carbon modified with 1% Nb 2 O 5 (645 mg L−1). • H 2 O 2 generation using Nb 2 O 5 /Vulcan XC-72 was 45% higher compared to pure Vulcan. • The modified material showed higher current efficiency and lower energy consumption. • Higher amount of oxygenated species, highest hydrophilicity. The production of H 2 O 2 through oxygen reduction reaction (ORR) from a 2-electron mechanism is an attractive alternative method because it allows the in-situ production of H 2 O 2 at moderate temperature and atmospheric pressure. The present study investigates, for the first time, the modification of Vulcan XC-72 carbon with niobium oxide (Nb 2 O 5) nanorods in different mass proportions (1%, 3%, 5%, and 10%) and their application as electrocatalysts in ORR through the 2-electron mechanism in alkaline media and in gas diffusion electrode for electrogeneration of H 2 O 2 in acid media. The modified electrocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), contact angle measurements, and X-ray photoelectron spectroscopy (XPS), while the ORR assays were analyzed using the rotating ring-disk electrode (RRDE) technique. The modification of Vulcan XC-72 carbon with 1% Nb 2 O 5 contributed to the enhancement of selectivity toward H 2 O 2 electrogeneration in ORR with current efficiency of 40 % higher than bare Vulcan XC-72 carbon and a relatively more positive initial potential. The application of gas diffusion electrodes for H 2 O 2 generation in acid medium using 1% Nb 2 O 5 -modified Vulcan XC-72 carbon yielded 645 mg L−1 of H 2 O 2 in 120 min of experiment at −2.5 V vs. Ag/AgCl. The concentration of H 2 O 2 electrogenerated via the application of the modified carbon material was 48 % higher compared to the concentration electrogenerated using the unmodified carbon material (444 mg L−1) under the same experimental conditions. In addition, the proposed electrocatalyst presented lower energy consumption and higher current efficiency compared to Vulcan XC-72 carbon. The results obtained can be attributed to the greater hydrophilicity of the surface of the proposed catalyst caused by the insertion of only 1% of Nb 2 O 5 nanorods. [ABSTRACT FROM AUTHOR]

In this work, photocatalytic behavior of CuO@SiO 2 core shell nanocomposites (CuO@SiO 2 CSNs) is reported. The formation and structure of the prepared samples were confirmed using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and High resolution transmission electron microscopy (HRTEM) techniques. UV analysis revealed that the incorporation of SiO 2 onto CuO resulted in a notable decrease in the bandgap energy from 3.2 eV to 2.8 eV, along with a reduction in the rate of electron-hole recombination and in consequence of that CuO@SiO 2 CSNs demonstrated an impressive degradation rate of 92% for Rhodamine B (Rh B), while CuO Nanoparticles (NPs) exhibited a relatively lower rate of 80%. The BET surface area analysis revealed that CuO@SiO2 CSNs had a greater surface area of 68.418 m³/g as opposed to 9.364 m³/g for CuO NPs, which contributed to the former's remarkable catalytic performance. [Display omitted] • TEM results visualize the formation of core shell structures. • The absorption spectrum of CuO@SiO 2 CSNs exhibited a red shift, • XPS study confirms Cu 2p peak exists as Cu 2p 3/2 and Cu 2p 1/2 states. • The CuO@SiO 2 CSNs exhibited an impressive degradation rate of 92% for Rh B [ABSTRACT FROM AUTHOR]