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NiMoS/TiMg and NiWS/TiMg nanocatalysts were synthesized, characterized by various techniques and tested in the hydrodesulphurization (HDS) of dibenzothiophene (DBT). TiMg mixed oxides containing 5, 10 or 15 wt% of MgO were prepared by sol–gel and then used as catalyst supports. A constant atomic ratio of Ni/(Ni + M) = 0.5 was kept for all the catalysts (M = Mo or W). The catalysts were first prepared by sequential-wet impregnation. Then, after an ex-situ sulfidation process, they were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and physisorption of N2 following the BET method. The presence of MgO in the NiMoS/TiMg and NiWS/TiMg catalysts resulted in an enhancement in the HDS activity of DBT. In addition, their HDS activities were higher than those observed in the NiMoS/Ti and NiWS/Ti catalysts. Furthermore, higher HDS activity was found for the NiMoS/TiMg compared with their NiWS/TiMg catalysts counterpart. [ABSTRACT FROM AUTHOR]

Rare earth complexes have gained attention in recent years for their remarkable luminescence properties, especially their long lifetimes, clear emission bands, and significant luminous quantum efficiency. In the ultraviolet area, the lanthanide ions exhibit relatively tiny absorption. The current investigation systematically portrays the tailoring of the micro-structural, opto-electonic and defect related features of the sol-gel derived pristine and rare earth element-samarium (Sm3+) substituted tin oxide (SnO 2) i.e., Sn 1- x Sm x O 2 (x = 0.0, 0.1, 0.2 & 0.3) nanoparticles (NPs). The structural, optical, electronic, morphological, photo-induced luminescence and defects related characteristics of the NPs were explored as a function of samarium (Sm3+) substitution level. In-depth analysis of the structure-property correlation of the Sn 1- x Sm x O 2 NPs is the goal of this study, focusing especially on the properties related to vacancy evolution and luminescence. The elemental mapping results revealed through energy dispersive X-ray spectroscopic (EDS) technique confirmed that the Sm-substitution is distributed uniformly throughout the NPs. The X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) studies corroborate that the Sm3+ substitution in the SnO 2 matrix causes the decrease in crystallite size of the NPs and increase in the dislocation density. A monotonic increase in lattice strain has been observed using the Williamson – Hall (W – H) approach, which is in line with the NPs' increased dislocation density and decreased crystallite size with the Sm3+ substitution level. The presence of vacancy-type defects inside the NPs was demonstrated by positron annihilation lifetime (PAL) spectroscopic measurements, and a decrease in defects was noticed as the level of Sm3+ substitution increased. To explore the optical characteristics and the evolution of the energy band gap with Sm3+ substitution level, the optical absorption (OA) spectroscopic measurement was carried out. As the Sm-substitution level rises, the optical energy band gap of the substituted SnO 2 NPs widens relative to that of pure SnO 2 NPs. The existence of various absorbance bands corresponding to the atomic vibrations within the NPs were investigated by the Fourier-transform infrared (FT-IR) spectroscopic technique. The photo-induced fluorescence (FL) emission spectroscopic analysis evidenced that the defect density decreased as the Sm-substitution level increased, which is in accordance with the PAL spectroscopic studies. The FL spectra showed the two typical near band edge (NBE) and deep level emission (DLE) peaks of the NPs. The proportion of different defects and vacancies associated with the FL emission transitions are portrayed as Pie-chart diagrams. The tailored NPs can establish to be effective candidates for possible spintronic and optoelectronic applications including magneto-optical devices. [ABSTRACT FROM AUTHOR]

Aloe striata Haw. (AS) is one of the beneficial Aloe species that is still underutilized. In this sense, phytochemical characterization, and biological investigation of AS gel protective efficacy against paracetamol (APAP) induced hepatic injury were evaluated in a mice model, with and without loading on chitosan nanoparticles (AS gel and CS-AS NPs, respectively). Spectrophotometric determination of AS gel showed high total soluble carbohydrate content representing 3.41±0.07 μg glucose equivalent (G eq)/mg and its protein content was 0.176±0.03 g/100 g. Twenty-two metabolites [sugars (90.23 %) and organic acids (5.80 %)] were determined by GC–MS, while 7 sugars were identified and quantified by HPLC where mannose (5679.73±4.28 μg) was the predominant. Chitosan gel nanoparticles were prepared and analyzed by dynamic light scattering, high resolution transmission electron microscopy, and X-ray diffraction methods. The CS-AS NPs were the most potent antioxidant of all tested samples with respect to quercetin in several in vitro antioxidant assays. Oxidative status, architectural or immuno-histochemical and histological signs in the context of the presence of caspase-3, c-Jun-N-terminal kinase (JNK), and extracellular signal-regulated kinase 1 (ERK-1) genes were evaluated in liver AS gel could significantly restore liver biochemical, antioxidant, and anti-inflammatory activities and liver architecture. Moreover, caspase-3 contents, and ERK-1 and JNK genes expression were significantly downregulated compared to the APAP group. CS-AS NPs showed superior hepatoprotective activity than AS. CS-AS NPs hepatoprotective mechanisms could be attributed to its activation of antioxidant enzymes, and downregulation of malondialdehyde pro-inflammatory markers along with apoptosis and anti-inflammatory related genes (BAX, JNK, and ERK-1 genes). To the best of our knowledge, it is the first study reporting the hepatoprotective efficiency of AS gel and its CS-AS NPs. [Display omitted] • Quality control for multi-components in A. striata gel by GC–MS and HPLC was done. • Antioxidant and hepatoprotective properties of A. striata gel were evaluated. • The gel could preserve the normal functional status of the liver in APAP toxicity. • Hepatoprotective action was enhanced by loading the gel on chitosan nanoparticles. • Aloe striata gel and chitosan nanoparticles inhibited ERK and JNK gene expression. [ABSTRACT FROM AUTHOR]

A key challenge encountered by printed electronics is that the conductivity of sintered metal nanoparticle (NP) traces is always several times smaller than the bulk metal conductivity. Identifying the relative roles of the voids and the residual polymers on NP surfaces in sintered NP traces, in determining such reduced conductivity, is essential. In this paper, we employ a combination of electron microscopy imaging and detailed simulations to quantify the relative roles of such voids and residual polymers in the conductivity of sintered traces of a commercial (Novacentrix) silver nanoparticle-based ink. High resolution transmission electron microscopy imaging revealed details of the morphology of the inks before and after being sintered at 150 °C. Prior to sintering, NPs were randomly close packed into aggregates with nanometer thick polymer layers in the interstices. The 2D porosity in the aggregates prior to sintering was near 20%. After heating at 150 °C, NPs sintered together into dense aggregates (nanoaggregates or NAgs) with sizes ranging from 100 to 500 nm and the 2D porosity decreased to near 10%. Within the NAgs, the NPs were mostly connected via sintered metal bridges, while the outer surfaces of the NAgs were coated with a nanometer thick layer of polymer. Motivated by these experimental results, we developed a computational model for calculating the effective conductivity of the ink deposit represented by a prototypical NAg consisting of NPs connected by metallic bonds and having a polymer layer on its outer surface placed in a surrounding medium. The calculations reveal that a NAg that is 35%–40% covered by a nanometer thick polymeric layer has a similar conductivity compared to prior experimental measurements. The findings also demonstrate that the conductivity is less influenced by the polymer layer thickness or the absolute value of the NAg dimensions. Most importantly, we are able to infer that the reduced value of the conductivity of the sintered traces is less dependent on the void fraction and is primarily attributed to the incomplete removal of the polymeric material even after sintering. [ABSTRACT FROM AUTHOR]

Glass matrices of Li2B4O7 doped with Dy3+, Yb3+ and Cu were synthesized using copper concentration as the control parameter by melt quenching technique. The amorphous phase of lithium borate was corroborated by X-Ray diffraction (XRD) while size distribution of Nanoparticles was obtained by transmittance electron microscopy (TEM) and crystal phase of Cu nanoparticles was obtained by high resolution transmittance electron microscopy (HRTEM). For photoluminescence, characterizations used were absorbance, photoluminescence emission (PL) and experimental decay times (τexp); from the data obtained we performed Judd–Ofelt analysis where we calculated Judd–Ofelt parameters ( Ω i ), transition probabilities (A), branching ratios (β ) and decay times (τcalc). With absorbance and PL characterizations in conjunction with CIE 1931, efficiency and shift to white light emission were evaluated. The insights gained from this study have significant implications for future research focused on enhancing the photoluminescence properties of rare earth-doped systems. A comprehensive understanding of the underlying mechanisms behind these phenomena enables us to leverage plasmon effects in similar systems, leading to diverse applications such as color tuning emission. [ABSTRACT FROM AUTHOR]

Bismuth ferrite with manganese doping (BiFe0.95Mn0.05O3 or BFMO) and bismuth ferrite with cobalt and manganese doping (Bi0.95Co0.05Fe0.95Mn0.05O3 or BCoFMO) were both synthesized as nanocrystalline powders by the sol–gel autocombustion technique. X-ray diffraction examination of the powders indicates a rhombohedral distortion in the perovskite phase in both samples. The calcined powders were examined for their microstructure and elemental composition with high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDAX), respectively. Scanning electron microscopy (SEM) was used to examine the microstructures of sintered BMFO and BCoFMO specimens at room temperature. Dielectric characteristics were studied at various frequencies and temperatures and found to follow space charge polarization. At ambient temperature, a vibrating sample magnetometer was used to analyse the materials' magnetic behaviour (M–H loops). Saturation magnetization is significantly increased with increased coercivity in the BCoFMO sample compared to the other sample. Improved structural, dielectric, and magnetic values in these doped systems, however, suggest they'd be an excellent fit for spintronic, multifunctional memories, sensors, and actuators. [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]

[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]

Structural analysis, spectroscopic studies and multiferroic properties of Zn 1- x Ni x O (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15) nanoparticles are reported here. Ni-doped ZnO nanoparticles were synthesized through a simple chemical growth route using hydroxyoxalate type materials. The hexagonal wurtzite structure of prepared compounds has been ascertained through X-ray diffraction. High Resolution Transmission Electron Microscopy (HRTEM) reveals the particle size and lattice growth direction of the nanoparticles. The expected doping concentration of nickel was confirmed by Energy Dispersive X-ray (EDX) spectroscopy. The excitonic peaks observed from absorption spectra of the prepared nanoparticles exhibit blue shift for nickel doping. Ni-doped ZnO explore superior photocatalytic response and are controlled by three factors: band gap, crystallite size and surface defect. To be specific, 12 % Ni doping results in 7.8 times increase in the photocatalytic degradation efficiency. The samples exhibit characteristic P -E and M − H loops. The obtained remnant polarization for 9 % and 15 % Ni doping are 9 × 10−3 and 6 × 10−3 μC/cm2 respectively. The multiferroicity perceived in the synthesized Ni-doped ZnO nanoparticles with the ME coefficient at around 1.1mV/cm-Oe have important application potentiality in electromagnetic coupled devices. • Ni-doped ZnO nanopowders for tuning the physical properties as multiferroicity. • Prominence of absorption in UV-VIS due to exciton-exciton collision. • Superior sunlight-driven photocatalytic effect of Ni-doped ZnO nanoparticles. • Signature of multiferroic behavior in nickel doped ZnO materials. • Magnetic and magnetoelectric properties of nickel doped ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are sought after by many industries including food industries, heavy metal sensing, pharmaceutical, and textile. The present study reports on the biosynthesis of silver nanoparticles (AgNPs) and theirs antibacterial activity using a methanolic leaf extract of Heteropyxis natalensis, a native South African medicinal tree. The synthesised particles were characterised by ultraviolet visible spectroscopy (UV-vis), energy dispersive Xray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR). A colour change of the reaction solution from yellow to brown preliminarily confirmed the presence of AgNPs, and a single absorbance peak at 422 nm, using UV-vis spectroscopy, was the indicative of AgNPs. While EDX revealed the presence of elemental silver in the sample, HRTEM identified spherical AgNPs ranging from 5-60 nm. Hydroxyls, alkynes, alkenes, alkanes, esters, and alkyl halides as possible capping agents of silver ions (Ag+) into AgNPs were identified by FTIR. In addition, AgNPs exhibited antibacterial efficacy against 5 strains of pathogenic bacteria: Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis. The results obtained in this study could potentially benefit future research in nanomedical-driven fields. [ABSTRACT FROM AUTHOR]

Zinc aluminate nanopowders were synthesized via poly(acrylamide-co-acrylic acid) assisted microwave approach. The as-synthesized ZnAl 2 O 4 nanopowders were characterized using X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM) and selected area of electron diffraction (SAED). The prepared ZnAl 2 O 4 nanopowders exhibited a spinel cubic polycrystalline structure. The increase of poly(acrylamide-co-acrylic acid) amounts decreased the particle size of the ZnAl 2 O 4 nanopowders. The poly(acrylamide-co-acrylic acid) enhanced the densification rate of ZnAl 2 O 4. The increasing of poly(acrylamide-co-acrylic acid) amount decreased the sintering temperature from 1300 °C to 950 °C. The hot-compressed ZnAl 2 O 4 nanopowders in the existence of 2 wt% of poly(acrylamide-co-acrylic acid) exhibited full density at 950◦C in just 20 min. The ZnAl 2 O 4 ceramic films revealed a high transparency of 83 ± 1% at a wavelength range from 450−1200 nm. [ABSTRACT FROM AUTHOR]

Citrate sol–gel method has been employed for synthesis of Zn1˗x˗yMnxCryO nanomaterials. Binary Zn0.9Mn0.1O and Zn0.9Cr0.1O nanomaterials were prepared and their optical and magnetic properties were investigated as reference compositions for the individual behavior of both of Mn- and Cr doping, respectively. The synthesized nanoparticles were analyzed using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), ultraviolet–visible (UV–Vis) spectroscopy and vibrating sample magnetometer. For low Mn–Cr-codoping contents, i.e., 2 and 4%, XRD revealed formation of single-phase ZnO nanoparticles in the wurtzite type hexagonal lattice, whereas 10% doping concentration, either Mn- or Cr-single doping or codoping, resulted in formation of wurtzite ZnO as a major phase with ZnMnO3 or/and ZnCr2O4 secondary phases. From XRD and HRTEM, the produced nanomaterials have average crystallite sizes ranged from 15 to 35 nm. Applying Kubelka–Munk function, optical band gap energy (Eopt) was determined. Eopt of single Mn- and Cr-doped ZnO increased than that of bulk ZnO mainly due to Burstein–Moss effect, whereas it decreased in the codoped Zn1−x−yMnxCryO because of the negative and positive corrections in the conduction and valence band, respectively, brought about by alteration of the sp–d exchange interactions between the band electrons and the localized d-electrons of the Mn2+ and Cr3+ ions. Magnetization measurements indicated that Cr induced the paramagnetism, while Mn induced the RT ferromagnetism in the synthesized Zn1−x−yMnxCryO nanoparticles. The ferromagnetic Zn1−x−yMnxCryO compositions could be potential candidates for Mn–Cr-codoped ZnO-based DMS nanoparticles. [ABSTRACT FROM AUTHOR]

The present study was reported with synthesize of copper oxide nanoparticles by ethno botanical species. Bio convivial and compatible approaches were made to utilize the renewable source of leaves extract of Achyranthes aspera Linn as efficient capping and stabilizing agent as well. Also, natural A. aspera was functioned as reductant in the formation of CuO NPs. The phytosynthesized CuO nanoparticles were extensively characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, Scanning electron microscopy, Energy dispersive X-ray diffraction, High resolution tunnelling electron microscopy and also comprehensively examined their biological applications like antibacterial and antifungal susceptibility against E. lenta, E. aerogenes and C. albicans strains. An XRD result of prepared CuO nanoparticles reveals the monoclinic crystalline structure and average crystallite size of 11–16 nm. The morphology variations for different concentrations of precursor material were noticed by SEM image. Furthermore, the crystalline planes found in SAED pattern of synthesized CuO NPs were coincide to the analysed XRD spectra. In the present study, a novel green approach was used to synthesize of CuO NPs for the antibacterial activity of poorly characterized and emerging pathogens of E. lenta and E. aerogenes. Further, the physicochemical, morphological and biological properties of CuO NPs are discussed. [ABSTRACT FROM AUTHOR]

• NiO@Ni(OH) 2 -α-MoO 3 nanocomposite was successfully grown on nickel foil via hydrothermal route. • The NiO@Ni(OH) 2 -α-MoO 3 modified electrode exhibited high capacitance of 445 Fg−1 at current density of 1 Ag−1. • A two-electrode symmetric supercapacitor of NiO@Ni(OH) 2 -α-MoO 3 working electrode showed a high specific capacitance with good stability. • Superior energy and power densities of 24 Wh Kg−1 and 3100 W Kg−1 were acheived. Electrochemical supercapacitor fabrication using heterogeneous nanocomposite is one of the most promising pathways for energy storage technology. Herein, heterostructure based nickel-molybdenum (NiO@Ni(OH) 2 -α-MoO 3) nanocomposites have been successfully prepared on nickel foil via hydrothermal route for supercapacitor application. The mixed phases of cubic, hexagonal, and orthorhombic crystal structure for NiO, Ni(OH) 2 , and α-MoO 3 , respectively were observed by X-ray diffraction. Heterostructures of nanosheet and nanosphere morphologies were confirmed by high resolution transmission electron microscopy. Impressively, the NiO@Ni(OH) 2 -α-MoO 3 composite working electrode exhibits a high specific capacitance of 445 Fg−1 at current density of 1 Ag−1 and shows outstanding rate capability (97.3% capacity retention after 3000 cycles at 10 Ag−1), compared to that of NiO@Ni(OH) 2 nanoparticles. Notably, two-electrode symmetric supercapacitor of NiO@Ni(OH) 2 -α-MoO 3 working electrode shows a high specific capacitance of 172 Fg−1 at 0.5 Ag−1, excellent rate capability and good cycling stability. Also, an excellent cycling stability (capacity retention of 98% after 5000 cycles) is observed for NiO@Ni(OH) 2 -α-MoO 3 as a working electrode in the symmetric two-electrode system. The obtained attractive results demonstrate that nanocomposite anode material can be used for development of a wide-range of energy storage devices. [ABSTRACT FROM AUTHOR]

A simple sonication assisted green synthesis method was adopted to prepare nickel oxide nanoparticles using Moringa leaf extract as reducing agent and capping agent. The structural, optical, morphological, photocatalytic, and antimicrobial properties of NiO nanoparticles have been analyzed through different techniques X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and UV-vis spectrometer. The average crystallite size of NiO nanoparticles is 12 nm which is well matched with the particle size calculated from TEM micrographs. The FESEM and HRTEM micrographs clearly show the spherical shaped nanoparticles with uniform distribution. The multi-functional applications like anticorrosive, photocatalytic, and antimicrobial activity of NiO nanoparticles are also analyzed. The green synthesis influenced more in the performance of antibacterial activities of NiO nanoparticles for Staphylococcus aureus and Escherichia coli. [ABSTRACT FROM AUTHOR]

Nanosize nickel hydroxide decorated 2-napthalene sulfonic acid-doped polyaniline nanotubes nanocomposites (Ni(OH) 2 @NSA-PANI NCs) were successfully developed for the catalytic reduction of aromatic nitro compounds. The Ni(OH) 2 @NSA-PANI NCs were synthesised by depositing Ni(OH) 2 nanoparticles onto 2-napthalene sulfonic acid doped PANI nanotubes surface. The resulting material was characterized using field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (P-XRD), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The prepared nanocomposite showed a remarkable ability to catalytically hydrogenate aromatic nitro compounds using sodium borohydride (NaBH 4) as hydrogen source in aqueous medium at room temperature. Kinetic studies were performed using 4-nitrophenol (4-NP) as the model substrate, using the Langmuir-Hinshelwood model. The catalyst showed pseudo-first-order kinetics, with rate constants estimated between 0.08287 and 0.3649 min−1. Catalyst recyclability without reduced activity was demonstrated over 10 successive cycles. The optimised nanocomposite catalyst demonstrated a low activation energy barrier towards 4-NP reduction. [ABSTRACT FROM AUTHOR]

We report a simple and easy method to synthesize Ag nanoparticles (Ag NPs) and demonstrate its potential for the detection of glutathione (GSH) and dopamine (DA) via colorimetric assay. The Ag NPs were found to be monodispersed and spherical with a size of 5 ± 2 nm. The X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM) investigations revealed the formation of crystalline Ag NPs. The colour of N, N-dimethyl-p-phenylenediamine assay changed from dark pink to colourless when the concentration of GSH was increased from 1 to 40 μM. Notably, the suspension colour changed from dark pink to blue when a similar set of experiments were performed with DA. The UV/Visible and interference experiments of Ag NPs exhibited excellent sensitivity and selectivity against both GSH and DA even after the addition of 40 μM of different interference biomolecules. The calculated limit of detection (LOD) was 141 and 245 nM for GSH and DA, respectively. The real-time analysis with serum samples showed satisfactory recovery percentages of >95 and 80–90% for GSH and DA, respectively. Hence, the Ag NPs reported here have huge potential to serve as a sensitive and selective colorimetric sensor for the detection of GSH and DA for diverse applications ranging from catalysis to cancer therapy and theranostics. [Display omitted] • Synthesis of stable monodispersed Ag NPs of 5 ± 2 nm in size • The formation of crystalline Ag NPs having lattice parameter values of a = b = c = 4.1 Å • The Ag NPs exhibited excellent sensitivity and selectivity against SGH and DA • The limit of detection of Ag NPs was estimated to be 141 and 245 nM for GSH and DA • It can serve as a sensitive and selective colorimetric sensor for GSH and DA sensing [ABSTRACT FROM AUTHOR]

This paper reports the preparation and electrochemical study of new glassy carbon electrode (GCE) bulk-modified with synthesized hybrid materials: Pt and MoO2 nanoparticles deposited on the multi-walled carbon nanotubes (MWCNTs). The results of electrochemical study of commercial GCE and electrodes modified with Pt-MWCNT and MoO2-MWCNT were obtained by cyclic voltammetry in K4Fe(CN)6 and NaOH solutions. Morphology and structure of the synthesized hybrid materials were analysed using the method of high resolution transmission electron microscopy, indicating the presence of well dispersed nanoparticles of Pt and MoO2 over MWCNT network. The results of the electrochemical study show that the capacitance of electrode modified with MoO2-MWCNT and Pt-MWCNT is 62-65 times higher than the capacitance of the commercial GCE. [ABSTRACT FROM AUTHOR]

Copper and nickel nanoparticles highly dispersed on an ordered mesoporous silica support (SBA-15) were prepared by a glycol-assisted impregnation method and tested for the catalytic transfer hydrogenation reaction of methyl levulinate to γ-valerolactone (GVL). Characterizations by high resolution transmission electron microscopy, X-ray diffraction, N 2 sorption, H 2 temperature-programmed reduction and X-ray absorption spectroscopy confirm that the highly dispersed nanoparticles were well-anchored to the mesopores of SBA-15 with the strong interaction. Comparing to a catalyst synthesized by a conventional aqueous impregnation method, our catalyst shows a higher conversion and greater selectivity towards GVL of reaction at 140–170 °C using 2-propanol as a solvent and a hydrogen donor. Results showed that Ni Cu/SBA-15 (EG) had much better activity, providing 91.3% conversion of ML with 89.7% selectivity towards GVL in 3 h at 140 °C. The high compositional homogeneity, uniform distribution of the nanoparticles in the mesoporous channels and the strong interaction between the metal nanoparticles and SBA-15 contribute to the superior catalytic performance. This catalyst also demonstrates superb stability over the course of 5 reaction cycles without significant loss in catalytic activity and selectivity towards GVL formation. Image 1 • Glycol-assisted method impregnates well-dispersed Ni & Cu nanoparticles on support. • Unlike water, glycol generates smaller, well-anchored, & homogenous nanoparticles. • Ni & Cu nanoparticles on support is active and stable catalysts for γ-valerolactone production. [ABSTRACT FROM AUTHOR]

In the present work, silver nanoparticles (AgNPs) are generated using the Micro-Electro Discharge Machining process (micro-EDM). Nanofluids are synthesised in dielectric fluids such as polar fluid like Deionized water (DI), Deionized water with 4 wt% of Poly-Vinyl Alcohol (DI + PVA), and non-polar fluids like Ethylene Glycol (EG) and Kerosene (KR). Low energy consumption, in-situ nanofluid synthesis, cleaner work environment, non-essential chemical post-processing during the synthesis using micro-EDM are the significant reasons creating broad scope for this process exploration. To understand the process, theoretical approach is explored to study the effect of dielectric fluids on particle formation mechanism, critical radius and nucleation rate of nanoparticles. In the experimental approach, silver nanoparticles are generated and characterized for the particle concentration, morphology and size distributions in all four dielectric fluids. High Resolution Scanning Electron Microscopy (HRSEM), Dynamic Light Scattering (DLS), and UV–Visible spectroscopy (UV–Vis) are used for the study. Nanofluid's decomposition temperatures and latent heat of vaporization are investigated using ThermoGravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), respectively. Particles generated in DI + PVA fluid found to be smaller mean size of (30.06 ± 1.12) nm followed KR fluid of (40.32 ± 1.29) nm, EG fluid of (47.85 ± 1.24) nm, and in DI fluid of (149.04 ± 1.93) nm. Also polar liquids yielded wider and non-polar liquids yielded narrower particle distribution. KR nanofluid is thermally stable followed by DI + PVA, DI, and EG nanofluid. With the spark energy of 1.15 mJ, the in-house developed micro-EDM process yielded highest nanoparticles concentration of 2.68 g/L in KR fluid followed by DI + PVA fluid of 2.13 g/L, DI fluid of 2.09 g/L and least by EG fluid of 1.04 g/L. [ABSTRACT FROM AUTHOR]

• Bi 4 O 5 I 2 and AgI nanoparticles were anchored over g-C 3 N 4 nanosheets. • The ternary photocatalyst illustrated the highest activity in degradation of pollutants. • Activity was 58.4-folds greater than g-C 3 N 4 in RhB degradation under visible light. • A cascade mechanism was suggested to describe the enhanced photocatalytic activity. In this research, Bi 4 O 5 I 2 and AgI nanoparticles were anchored over g-C 3 N 4 nanosheets (denoted as NGCN/Bi 4 O 5 I 2 /AgI) to preparation highly impressive visible-light-driven samples. The synthesized nanocomposites were investigated by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), UV–vis diffuse reflectance spectroscopy (DRS), energy dispersive analysis of X-rays (EDX), electrochemical impedance spectroscopy (EIS), photocurrent density, Brunauer-Emmett-Teller (BET), and photoluminescence (PL) analyses. Among the ternary photocatalysts, the NGCN/Bi 4 O 5 I 2 /AgI (20%) photocatalyst illustrated the highest photoactivity in degradation of rhodamine B (RhB), which was approximately 58.4, 15.2, and 12.8 times higher than the GCN, NGCN, and NGCN/Bi 4 O 5 I 2 (20%) samples, respectively. Furthermore, the O 2 − was discovered as the main species in the respective system by the quenching tests. Also, by studying the electrochemical properties, a cascade photocatalytic mechanism was suggested based on the energy bands to describe the enhanced charge carriers migration and separation, which caused impressive photocatalytic performances in degradations of four hazardous contaminants. This study highlights the rational anchoring of Bi 4 O 5 I 2 and AgI nanoparticles over NGCN to prepare highly efficient photocatalysts for wastewater remediation. [ABSTRACT FROM AUTHOR]

• A high dispersion of Pt and Co nanoparticles on MNC was achieved. • PtCo/MNC achived 481 mA/mg Pt with 13.1%wt Pt loading. • MNC contributed to the increase in the electrocatalytic activity of PtCo/MNC. • I f /I b of PtCo/MNC was 1.7 times greater than achived by Pt/C. • PtCo/MNC has a best resistance to carbonaceous intermediates species in MOR. In this work, anodic electrocatalyst (20%wt of metal loading) as PtCo nanoparticles (atomic ratio of 48:52) on micro/nano-structured pyrolytic carbon (MNC) was synthesized by sequential impregnation method and chemical reduction route using citric acid and Ar-H 2 static atmosphere. MNC sample was synthesized via nanocasting process with anhydrous pyrolysis at 800 °C using SBA-15 as hard template and refined sugar as carbon source. SBA-15 was prepared via sol gel using pluronic P-123 as surfactant and tetraethoxysilane as silica precursor. The prepared materials were characterized by means of N 2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and high resolution transmission electron microscopy. The performance of PtCo/MNC for methanol oxidation reaction (MOR) was measured by cyclic voltammetry, chronoamperometry. The electrochemical characterization techniques revealed that the mass activity of PtCo/MNC and the commercial electrocatalyst Pt/C (20%wt of Pt loading) at 20 cycles were 481 and 372 mA/mg Pt respectively as well as the resistance to the accumulation intermediate carbonaceous species (methoxy, aldehyde, formaldehyde and carbon monoxide) denoted by the ratio I f /I b for these catalysts were 1.30 and 0.76 respectively. PtCo/MNC exhibit better electrocatalytic performance, electrochemical stability and best resistance to carbonaceous intermediates species in the electro-oxidation of methanol. [ABSTRACT FROM AUTHOR]

• TiO 2 @polyfluorene (PF) composite particles were first prepared by sol-gel method. • Photocatalytic degradation of organic dyes were evaluated under sunlight irradiation. • TiO 2 @PF exhibits excellent photocatalytic efficiency and reusability under sunlight. In the tetrabutyl titanate solution via a sol-gel method, the nano-TiO 2 @polyfluorene composite particles were successfully prepared from the polyfluorene particles which were obtained by grinding fluorene with FeCl 3 through the solid-state oxidative coupling reaction. The morphology and optical properties of the composite particles were characterized by scanning electronmicroscope, high resolution transmission electron microscopy, X-ray photo electron spectrometer, X-ray diffractometer, UV–visible diffuse reflectance spectroscopy, photoluminescence spectra and so on. The composite particles presented excellent photocatalytic activity on the degradation of triphenylmethane dyes, such as malachite green and rhodamine B under sunlight or under visible light. The photocatalytic reusability was investigated up to six successive cycles and the composite particles still retained their high activity of photodegradation ratio for malachite green. The mechanism of photocatalysis has been were discussed. The high surface area and effective photoinduced electrons and holes of TiO 2 @polyfluorene led to the enhanced photocatalytic activity. Consequently, the nano-TiO 2 @polyfluorene composite particles can be employed as an efficient photocatalyst to treat the organic pollutants. [ABSTRACT FROM AUTHOR]

In this work, Cu-Ag core-shell nanoparticles were synthesized via a chemical reduction method. Subsequently, Cu-Ag core-shell nanoparticles were dispersed into polyvinyl alcohol (PVA) and films were grown by solution casting technique. High resolution transmission electron microscopy (HRTEM) was utilized to confirm the synthesis of Cu-Ag core-shell nanoparticles. Optical properties of fabricated films were investigated using UV-Visible absorption spectroscopy. Analysis of absorption data indicated that the band gap of PVA decreases with increasing Cu-Ag core-shell nanoparticles concentration while urbach's energy increases. The possible reasons for the observed changes in optical parameters of PVA with the incorporation of Cu-Ag core-shell nanoparticles have been discussed in detail. [ABSTRACT FROM AUTHOR]

• Preparation of Pd/TiO 2 nanoparticles using Aloe vera leaf extract gel. • Pd/TiO 2 nanocomposite was identified by various techniques. • The complete degradation of picric acid has been observed within 70 min under visible light. • Enhanced anticancer activity observed due to the visible light driven Pd doped TiO 2. Titanium dioxide (TiO 2) and palladium (Pd) doped TiO 2 (Pd@TiO 2) nanoparticles have been synthesized using green approach technique. X-ray diffraction analysis reveals the formation of anatase phases for both pure TiO 2 and Pd@TiO 2. The optical properties confirm that the synthesized Pd@TiO 2 eventually absorbs visible light. High resolution transmission electron microscopy analysis shows that the tiny dots seen all over the surface indicated the presence of Pd in the synthesized Pd@TiO 2 nanoparticles and calculated size of the Pd nanoparticles was found to be 11 nm. Raman analysis revealed that it has pure anatase phase without any secondary phases. XPS analysis were used to study the exhibited elements present in the prepared nanoparticles which confirms the absence of any other impurities in the green synthesized Pd@TiO 2 nanoparticles. The prepared pure and Pd doped TiO 2 nanoparticles were used for photocatalytic and anticancer activity applications. Photocatalytic degradation of picric acid was carried out under the influence of visible light, the maximum photodegradation of picric acid was achieved within 70 min. The anticancer activity for the prepared Pd@TiO 2 nanoparticles found to be enhanced, which may be attributed to the visible light absorption phenomena. Since the Pd doping on pure TiO 2 surface, low bandgap energy was obtained, leading to excess electron transfer to cell lines, which increases ROS production and cell death. Hence, the green synthesized Pd@TiO 2 nanoparticles had the highest anticancer activity on A549 cell lines. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide–zinc oxide (rGO–ZnO) nanocomposites were grown on solid substrates by rapid thermal treatment of Langmuir–Blodgett transferred GO–Zn composite sheets in oxygen ambient. The changes induced by uptake of Zn2+ ions and subsequent thermal treatment on surface morphology, micro-structure, composition and optical properties of composite sheets were investigated by atomic force microscopy, high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared (FT-IR) and Raman measurements. The morphological features of composites are practically independent of subphase Zn concentration and are largely determined by the temperature of rapid thermal treatment. FT-IR results indicate the presence of zinc carboxylate in composites and HR-TEM results confirm the formation of ZnO nanoparticles upon subsequent oxidation. XPS and Raman measurements show that rapid thermal treatment in oxygen ambient results in decrease of carbon-oxygen functional groups and increase in graphitic carbon content leading to the reduction of GO in the composites. The average optical transmittance of rGO–ZnO composites in the visible region is found to be ∼87%. Photocatalytic studies carried out on methylene blue (MB) overlayer coated rGO–ZnO composites show reduction in concentration of MB with increasing duration of UV irradiation. The transparent two-dimensional rGO–ZnO composite solid state structures thus facilitate efficient adsorption and degradation of MB molecules, without any composite aggregation. [ABSTRACT FROM AUTHOR]

Bi 2 S 3 nanoparticles (NPs) decorated ZnO nanorods' (NRs') heterostructures on glass substrate were prepared by varying the number of Bi 2 S 3 coatings by aqueous chemical growth and SILAR techniques and their ultraviolet sensing properties were investigated. X-ray diffraction and high resolution transmission electron microscopy results confirm phase purity of the individual components and formation of the heterostructure respectively. The photoluminescence properties reveal a gradual improvement in the ultraviolet (UV) to visible emission intensity ratio up to a certain number of Bi 2 S 3 coating due to comparatively a more decrease in the visible emission intensity. Highly enhanced UV photocurrent (∼7 times) and responsivity (∼6 times) values as compared to uncoated ZnO NRs have been noticed. Further, a very low intensity UV illumination of power density ∼21 μW/cm2 can be detected by ZnO-Bi 2 S 3 heterostructure more efficiently as compared to pristine ZnO NRs which is attributed to an efficient charge transfer at ZnO and Bi 2 S 3 interface. Image 1 • ZnO-Bi 2 S 3 heterostructure is formed using ACG and SILAR techniques. • Bi 2 S 3 nanoparticles decorated over ZnO nanorods making heterostructure. • Enhanced UV photoresponsivity in heterostructure is due to efficient charge transfer. • Demonstration of low-intensity light sensible and low-power operable efficient ZnO-Bi 2 S 3 UV detector. [ABSTRACT FROM AUTHOR]

This study presents multiwall and bamboo-like carbon nanotubes found in samples from the Allende carbonaceous chondrite using high-resolution transmission electron microscopy (HRTEM). A highly disordered lattice observed in this material suggests the presence of chiral domains in it. Our results also show amorphous and poorly-graphitized carbon, nanodiamonds, and onion-like fullerenes. The presence of multiwall and bamboo-like carbon nanotubes have important implications for hypotheses that explain how a probable source of asymmetry in carbonaceous chondrites might have contributed to the enantiomeric excess in soluble organics under extraterrestrial scenarios. This is the first study proving the existence of carbon nanotubes in carbonaceous chondrites. [ABSTRACT FROM AUTHOR]

Adding Y 2 O 3 will make Al-containing oxide dispersion strengthened (ODS) steels produce coarse Y-Al-O particles, which deteriorates their mechanical properties. Herein, Y 2 Ti 2 O 7 nanoparticles and Hf hydride nanoparticles (NPs) were successfully prepared by hydrogen plasma-metal reaction (HPMR) method and added together in the Fe-Cr-Al ODS steel to replace the traditional Y 2 O 3 NPs. The microstructure of matrix and oxide in ODS steels has been characterized by scanning transmission electron microscopy (STEM) and high resolution transmission electron microscopy (HRTEM). The oxide NPs in FHYT-0.6 (Fe-14Cr-4.5Al-2 W-0.35HfH 1.98 –0.6Y 2 Ti 2 O 7 , wt%) are made of Y 2 Ti 2 O 7 (semi-coherent with the matrix and about 10 nm) and HfO 2 (incoherent with the matrix and about 26 nm). The size of oxide dispersoid in FHYT-0.6 is reduced to 8.8 nm and the number density is greatly increased to 9.4 × 1023 m−3 compared with FTYT-0.6 (Fe-14Cr-4.5Al-2 W-0.35Ti-0.6Y 2 Ti 2 O 7 , wt%) and FTY-0.6 (Fe-14Cr-4.5Al-2 W-0.35Ti-0.6Y 2 O 3 , wt%). The tensile strength at room temperature of FHYT-0.6 is 1194 MPa, which is 24.1 and 14.1% higher than the FTY-0.6 and FTYT-0.6, respectively. Our work has proved that the mechanical properties of the alloy can be significantly improved by adding Y 2 Ti 2 O 7 and HfH 1.98 NPs, which provides a new idea for manufacturing high-performance ODS steels. [Display omitted] • Oxide dispersoid is reduced to 8.8 nm in FHYT-0.6 added with HfH 1.98 and Y 2 Ti 2 O 7. • The number density of oxide dispersoid in FHYT-0.6 is improved to 9.4 × 1023 m−3. • HfH 1.98 reacts with O 2 to form HfO 2 and eliminate residual oxygen in FHYT-0.6. • Y 2 Ti 2 O 7 in FHYT-0.6 possesses semi-coherent interface with the ferrite matrix. • Tensile strength of FHYT-0.6 increases greatly compared with FTY-0.6 added with Y 2 O 3. [ABSTRACT FROM AUTHOR]

Abstract Graphene oxide (GO) based composites functionalized with nanoparticles are emerging as potential candidates for multifunctional devices. As the synthesis route can strongly influence the way in which the nanoparticles are anchored to GO and the resulting properties, different routes have been employed and evaluated in this work for the preparation of composites formed by GO and undoped or Li doped SnO 2 nanoparticles. Promotion of synergetic effects, as well as changes in the structural and luminescent properties of the composites have been also analyzed. In comparison with GO, composite samples synthesized in this work involve enhanced luminescence while retaining nearly white emission, which could lead to wider applicability of GO based composites in free standing and emitting and sensing devices. Aspects, such as GO reduction, stabilization of different Sn-based oxides, variation in the concentration of oxygen related functional groups, changes in the sp2 domain sizes, incorporation of lithium and enhancement of the luminescence, have been analyzed in this work by means of x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy (EDS), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) characterizations. Graphical abstract Image 1 Highlights • Widening applications by exploiting the ability to obtain luminescence from these GO based composites. • Enhancement of the luminescence by introducing tin oxide nanoparticles and lithium within the synthesis of the composites. • Several routes for composite fabrication have been investigated in a systematic way. • Near white light emission have been obtained at room temperature, in contrast with other graphene luminescence results. • Discussion taking into account the luminescence relation with the structural properties derived from each synthesis method. [ABSTRACT FROM AUTHOR]

Here we present a simple, clean and eco-friendly synthesis procedure of copper nanoparticles from copper sulphate solution using flower extract of Eichhornia crassipes along with its hydrogen peroxide detectability study. Production of copper nanoparticles was initially verified by scanning the reacting solution under ultraviolet visible (UV–Vis) spectrometer. The pattern of X-ray diffraction (XRD) showed different phases and crystallinity of these biogenic nanoparticles. Size and morphology of copper nanoparticles were examined by high resolution transmission electron microscopy (HRTEM). Result of Fourier transform infra-red (FTIR) spectroscopy helped to identify the organic molecules which capped and stabilized the colloidal particles in the solution during production. In addition, the H2O2 sensing ability of these bioengineered copper nanoparticles was tested and the suspension of Cu nanoparticles was observed to detect the hazardous hydrogen peroxide instantly. [ABSTRACT FROM AUTHOR]

Sol-gel synthesis of cobalt ferrite (CoFe2O4) and cadmium ferrite (CdFe2O4) nanoparticles in aqueous medium has been carried out using urea. The main advantage of using urea as a by preventing particles agglomeration and act as stabilizing agent to provides long-term stability for cobalt ferrite and cadmium ferrite nanoparticles. The particles have been characterized using X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray (EDX), UV-Visible spectra and thermogravimetric analysis (TGA). The XRD and FT-IR results confirmed the crystal structure of CoFe2O4 and CdFe2O4. The formation of CoFe2O4 and CdFe2O4 nano- and microstructures were confirmed by HR-SEM. The optical band gaps of the prepared CoFe2O4 and CdFe2O4with different preparation methods were calculated and were found to be in the range of 2.26 - 2.40 eV. The optical property test indicates that the absorption peak of the nanoparticles shifts towards short wavelength, and the blue shift phenomenon might be ascribed to the quantum effect. The traditional sol-gel approach provides an effective way to synthesize high quality semi-conductive CoFe2O4 and CdFe2O4 nanoparticles. The disk diffusion antibacterial assay of CoFe2O4 and CdFe2O4 nanoparticles was done against E.coli, P.vulgarias MTCC -- 49132 (Gram negative) and S.aureus MRSA -- 3391, S.Aureus -- 25923 (Gram positive) bacteria. [ABSTRACT FROM AUTHOR]

Nanoparticles with various compositions of Fe–Rh have been fabricated by a solution phase chemical method and their magnetic properties characterized. After refining and size selection, the average particle size is about 2–5 nm by high-resolution transmission electron microscopy observation. From x-ray diffraction results, as-deposited FeRh nanopaticles reveal a typical chemically disordered fcc structure which can be transformed into CsCl-type structure through thermal annealing. Under selected annealing conditions, the coercivities, Hc, for FeRh nanoparticles measured at room temperature are increased, compared with that of their as-deposited states. This increasement in Hc is due to the crystallization of CsCl-type structure after annealing. Nanoparticles of Fe36Rh64 and Fe38Rh62 annealed at 600 °C for 6 h show the presence of the magnetic phase transitions, while those of Fe75Rh25 particles did not exhibit such a transition. [ABSTRACT FROM AUTHOR]

We investigate the flow activity of the nanostructured polyamide layer in reverse osmosis (RO) membrane, using gold nanoparticle (NP) tracers of 1–40 nm diameter. Following a detailed structural examination of a commercial SW30RH membrane selected for this study, NP solutions were infiltrated from either the polyamide front or the polysulfone support side. The permeate was then analyzed spectroscopically while the entrapment of NPs within the membrane was mapped by high resolution electron microscopy. Results show that back-filtered NPs exhibited a fractionated distribution according to size: 1 nm nanoparticles permeate across the polyamide-polysulfone interface reaching the interior of the polyamide corrugations, while the larger ones (>10 nm) are retained within the polysulfone and gradually arrested at approximately 100 nm below the polyamide-polysulfone interface. Intermediate-sized 5 nm nanoparticles reached the undulating folds just below the polyamide layer. Permeation pathways across polyamide layer appear to exclude all tracers above 1 nm, which become selectively distributed across the polyamide layer: positively charged NPs label the outer surface of the polyamide film (expected to be carboxylate-rich), while negatively charged particles are uniformly distributed within the layer. Diafiltration measurements quantify the transient kinetics of NP retention and permeation. Overall, our results establish the flow activity of the polyamide nodular surface and provide estimates for the dimensions of permeation pathways. [ABSTRACT FROM AUTHOR]

We present a study of the synthesis and characterization of molybdenum oxide nanostructures produced by laser ablation of solids in liquids (LASL). A high purity molybdenum target was ablated in deionized water using femtosecond laser pulses. We found that both nanoparticles and nanosheets composed of molybdenum oxide were formed. The colloid suspension optical absorbance changes with time, as the colloid ages it changes color; a blue shift is observed within a few days of aging. It results in a band gap increase from 2.55 eV up to 2.9 eV for nearly a month of aging, which we computed through the Tauc method. Raman characterization of the nanostructures shows that the synthesized material turns into a hydrated molybdenum oxide (MoO 3 · n H 2 O). This is consistent with the band gap evolution, which for early aging corresponds to MoO 3 to later achieve the band gap value of a hydrated molybdenum oxide. The nanostructures were also characterized by transmission electron microscopy (TEM) showing that the nanoparticles have a core-shell structure with a raspberry-like shell for medium and small nanoparticles and a smooth homogeneous shell for large nanoparticles. The size distribution peaks at 30–40 nm, with the smallest nanoparticles at 10 nm and the largest at 120 nm. The nanosheets are decorated by tiny nanoparticles. High resolution transmission electron microscopy (HRTEM) images allowed measuring the interplanar distances at the nanosheets, we found the nanosheets are composed by the orthorhombic stable-phase α -MoO 3. SAED measurements confirmed the formation of this molybdenum oxide phase. An absorption band at 830 nm that develops in the few first days of aging of the colloid is of interest for photothermal therapy, which gives the reported nanostructures a good potential for biomedical applications. • Femtosecond laser ablation of solids in liquids for nanomaterials rapid synthesis. • Simultaneous nanoparticle and nanosheet molybdenum oxide laser synthesis. • Band gap modification after molybdenum oxide nanomaterials synthesis due to aging. • Transient plasmonic absorption band of the molybdenum oxide nanomaterials in the near infrared. [ABSTRACT FROM AUTHOR]

Method of in situ synthesis of TiC nanoparticles inside aluminium matrix directly during mechanical alloying from aluminium, titanium and nanodiamonds is developed. For this method, nanodiamonds were used as carbon material and as intensificator of mechanosynthesis during the ball milling. Optimal content of matrix material was determined. If the amount of aluminium falls below the optimal level, the synthesis becomes extremely intensified; it means that during short period a large amount of heat is released, which causes substantial grinding jars heating and frequently results in melting of sealing gaskets and other process failures. In case the amount of aluminium in the mixture grows beyond the optimal level, the synthesis process is slowed down. Optimal composition for obtaining TiC nanoparticles inside aluminium matrix is following: 43%wt Al + 57%wt TiC. Average size of nanoreinforcements of developed composite equals 31 nm. Developed material can be applied in casting technologies as an individual product and as a master alloy. [ABSTRACT FROM AUTHOR]

High-resolution transmission electron microscopy (HRTEM) examination of nanoparticles requires their placement on some manner of support – either TEM grid membranes or part of the material itself, as in many heterogeneous catalyst systems – but a systematic quantification of the practical imaging limits of this approach has been lacking. Here we address this issue through a statistical evaluation of how nanoparticle size and substrate thickness affects the ability to resolve structural features of interest in HRTEM images of metallic nanoparticles on common support membranes. The visibility of lattice fringes from crystalline Au nanoparticles on amorphous carbon and silicon supports of varying thickness was investigated with both conventional and aberration-corrected TEM. Over the 1–4 nm nanoparticle size range examined, the probability of successfully resolving lattice fringes differed significantly as a function both of nanoparticle size and support thickness. Statistical analysis was used to formulate guidelines for the selection of supports and to quantify the impact a given support would have on HRTEM imaging of crystalline structure. For nanoparticles ≥1 nm, aberration-correction was found to provide limited benefit for the purpose of visualizing lattice fringes; electron dose is more predictive of lattice fringe visibility than aberration correction. These results confirm that the ability to visualize lattice fringes is ultimately dependent on the signal-to-noise ratio of the HRTEM images, rather than the point-to-point resolving power of the microscope. This study provides a benchmark for HRTEM imaging of crystalline supported metal nanoparticles and is extensible to a wide variety of supports and nanostructures. [ABSTRACT FROM AUTHOR]

• This work demonstrates the synthesis and fabrication of Copper tungstate (CuWO 4) nanoparticles-based humidity sensor. • The humidity sensing performance of CuWO 4 nanoparticles based sensor device was tested at room temperature which was exposed to 11%-97% relative humidity levels. • The sensitivity of the device was found to be ∼767 at 97% relative humidity level. • The CuWO 4 nanoparticles sensing device showed ultra-low response and recovery time of ∼39 sec and ∼18 sec respectively. This work demonstrates the synthesis and fabrication of Copper tungstate (CuWO 4) nanoparticles-based humidity sensor. The as synthesized sample was characterized by X-ray diffraction, Raman spectroscopy, photoluminescence and high resolution transmission electron microscopy to study structural and morphological nature. The humidity sensing performance of CuWO 4 nanoparticles based sensor device was tested at room temperature which was exposed to 11%-97% relative humidity levels. The sensitivity of the device was found to be ∼767 at 97% relative humidity level. The CuWO 4 nanoparticles sensing device showed ultra-low response and recovery time of ∼39 sec and ∼18 sec respectively. The high sensitivity and response/recovery was likely due to the high adsorption energy, fast charge transfer rate and low bonding energy of water molecules with CuWO 4 nanoparticles. Our results indicate that CuWO 4 nanoparticles-based humidity sensor device has great promising application as a portable device for control humidity detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spherical morphology of Fe substituted Co 3 O 4 nanoparticles were produced by microwave refluxing technique. • The effect of high concentration of dopant Fe on the structural, optical and magnetic properties of Co 3 O 4 have been studied. • The absence of defect states in the samples were confirmed using photoluminescence spectroscopy. • The magnetization values were increased with augmentation of Fe concentration due to occurrence of ferromagnetic interactions in the samples. In the present investigation, ferromagnetic behavior has been identified for the Fe substituted Co 3 O 4 nanoparticles which produced by microwave refluxing method. The detailed investigation of magnetic properties with different concentration of Fe substitutions revealed the ferromagnetic behavior due to the anti-ferromagnetic interaction of magnetic sublattices. High resolution transmission electron microscopy (HR-TEM) studies confirmed the spherical morphology of nanoparticles with a size between 8 and 20 nm. The absence of other phases than Co 3 O 4 was ruled out by XRD, TEM and Raman spectroscopy analyses. X-ray photoelectron spectroscopy analysis evidenced the presence of Fe3+, Co2+ and Co3+ ions in the samples. Photoemission spectra confirmed the absence of defect states in the samples. Magnetic measurement analysis revealed that the strong influence of Fe concentration on the saturation magnetization values of Co 3 O 4 nanoparticles. These structural and optical properties of the Fe substituted Co 3 O 4 are suitable for various gas sensor applications. [ABSTRACT FROM AUTHOR]

The effects of reduction by H2 and by heat treatment in vacuum and in O2 flow on Rh particle size changes of Rh/CeO2 samples were studied by X-ray photoelectron spectroscopy (XPS), high-resolution electron microscopy (HRTEM), and CO adsorption followed by diffuse reflectance infrared spectroscopy (DRIFTS). Low-temperature (373-423 K) reduction of Rh without agglomeration is demonstrated. An average particle size of 2.3 ± 1.1 nm was measured by HRTEM regardless of the metal loading (1-5%). On Rh/CeO2, a significant particle size increase of the Rh particles was detected on heating (773 K). In this work, we suggest that the temperature-induced surface decrease resulting from the sintering of Rh is favored only for well-dispersed particles. XP spectra revealed that the mobile oxygens of CeO2 fundamentally determine the oxidation state of the supported metals. At elevated temperature, the oxidation of the reduced support surface as well as the metal component takes place because of the segregation of ceria oxygens. When the aggregated particles were reoxidized, the redispersion of Rh was observed probably because of the formation of Rh-O-Ce bonds. [ABSTRACT FROM AUTHOR]

Phase composition and structural features of the yttrium oxide nanoparticles produced by laser evaporation are studied. Initial and annealed samples were examined. Initial samples contain several phases. The phase composition is found to depend on the particle size. Small crystallites (5-12 nm) possess a FCC lattice (Fm-3m) and larger ones have a BCC lattice (Ia-3). Annealing at temperatures T = 930-1000°C allowed to obtain samples containing only particles with the BCC lattice that may be used for the manufacture of transparent ceramics. [ABSTRACT FROM AUTHOR]

• Sb 2 O 3 nanoparticles are successfully obtained under acidic condition. • Preparation of the Sb 2 O 3 nanoparticles is simple. • Surface morphology of Sb 2 O 3 nanoparticles is regulated by reaction time and pH value. • Formation mechanisms for Sb 2 O 3 microcrystals with diverse morphologies are proposed. Antimony trioxide (Sb 2 O 3) nanoparticles were successfully synthesized via a facile and practical liquid phase method under acidic condition. The structure, composition and surface morphology of the as-prepared products have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), scanning electronic microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The as-obtained products revealed a cubic phase of Sb 2 O 3 (JCPDS No. 05–0534) with a preferred plane of (2 2 2) and lattice spacing of a = 11.180 Å. Besides, Sb 2 O 3 octahedra, spherical and polyhedral nanoparticles, coral-like nanorod and paddy-like nanosheets have also been synthesized by the modulating reaction time and solution pH value under acidic condition. According to the results of the time-dependent and pH-dependent experiments, the possible formation mechanisms for Sb 2 O 3 nanocrystals with diverse morphologies have been proposed, which could be a favorable suggestion for the synthesis of other metal-oxide nanomaterials with morphology control. [ABSTRACT FROM AUTHOR]

Undoped and Mn doped SnO2 prepared by co-precipitation method exhibits nanocrystalline nature with prominent peaks along (110), (101), (211), and (310) planes. All the prepared samples are nanocrystalline with crystallite size lying in the range of 4.8-5.6 nm. The prepared SnO2 nanoparticles exhibit single tetragonal crystalline phase. The high resolution transmission electron microscopy images show that the particles are nanocrystalline in nature. The composition of the prepared samples have been analyzed using energy dispersive analysis of X-rays spectra. The photoluminescence spectroscopy shows the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band. Broad UV emission at 426 nm is observed in photoluminescence. UV-vis absorption spectral studies showed a peak at 385 nm. Magnetic measurements revealed that all the doped samples exhibit room temperature ferromagnetism, which is identified as an intrinsic characteristic obtained on doping. Pure SnO2 nanoparticles showed diamagnetism, SnO2 with lower Mn content show larger magnetization and with increasing Mn content the retentivity and coercivity are found to decrease. [ABSTRACT FROM AUTHOR]

Highlights: [•] Diffusion processes can be described quantitatively using TEM. [•] Surface self-diffusion on Pt nanoparticles is observable in HRTEM images series. [•] The migration of atoms takes mainly place at atomic steps. [•] We determine the surface self-diffusion coefficient for Pt nanoparticles. [Copyright &y& Elsevier]

[Display omitted] • HRTEM and APT were used to investigate the formation mechanisms. • Replacement and heterogeneous mechanism can appear simultaneously. • Two mechanisms both facilitate precipitation for the reducing interfacial energy. The formation mechanism of complex precipitates in Nb-V microalloyed steel has been systematically studied by high resolution transmission electron microscopy (HRTEM) and atom probe tomography (APT). The results reveal that there are two precipitation mechanism: replacement and heterogeneous mode. The core–shell precipitate has been observed with double direction Moiré fringe, which is formed by the heterogeneous mechanism, while for the precipitates with uniform distributed V and Nb atoms, is formed by the replacement mechanism. These two modes both reduce the lattice misfit and promote precipitation. In addition, the APT result reveals that the ratio of V to Nb increases with the increase of particle size, which matches well with the previous TEM results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of metallic nanostructures in presence and absence of oxygen. • Cudrania tricuspidata leaf extract as both a reductant and a stabilizer. • The physical morphology of synthesized AgNPs, AuNPs, Ag-AuBNPs were obtained. • The synthesized Ag-AuBNPs showed powerful broad spectrum antibacterial activity. • Presence of more DO enhances the production, morphology and biological applications. Synthesis of Ag-Au mono and co-reduction of bimetallic nanostructures were prepared in the low or high dissolved oxygen (DO) in the reaction medium along with Cudrania tricuspidata leaves extract as both a reductant and a stabilizer. Mono reduction of Ag and Au nanoparticles (AgNPs, AuNPs) were obtained from AgNO 3 and HAuCl 4 in the low or high DO in the reaction medium along with green precursor, respectively. The same protocol for bimetallic synthesis Ag-Au core–shell nanostructures (Ag-Au BNPs) were prepared through blending both metal in single reaction medium. To detect Surface plasmon bands (SPR) band Ultra Violet–visible spectroscopy based wavelength was scanned for mono and bimetallic mixture, results reviles that AgNPs in the range 450 (low OD), 425 (high OD), AuNPs in the range 530 (low OD), 510 (high OD) nm were observed, also found in the Ag-Au core–shell nanostructures. The physical morphology of synthesized AgNPs, AuNPs, Ag-AuBNPs were obtained using UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) reveals the organic compounds in the plant materials, X-ray diffraction (XRD) analysis show the crystalline nature of AgNPS, high resolution transmission electron microscopy (HRTEM) with Selected area diffraction (SAED) pattern, EDS mapping, and energy dispersive spectroscopy (EDS). The synthesized Ag-AuBNPs showed powerful antibacterial activity towards a gram positive (Bacillus subtilis) and gram negative (Pseudomonas aeruginosa). Finally, presence of more Dissolve ODO enhances the production, morphology and biological applications. [ABSTRACT FROM AUTHOR]

In this study, the thermal stability and decomposition kinetics of Hägg iron carbide nanoparticles synthesized via a wet chemical method have been investigated. Results of Mössbauer spectroscopy were in consonance with x-ray diffraction to prove the formation of Fe 5 C 2 nanoparticles. The activation energy of the transformation was evaluated by thermogravimetric analysis, performed at different heating rates from room tempearture to 573 K, employing the Flynn-Wall-Ozawa and Coats-Redfern models. Using the Criado model, degradation kinetics was determined to be a three-dimensional diffusion type. Thermal x-ray analysis, high resolution transmission electron microscopy, and vibrating sample magnometer measurements were performed both before and after thermal treatment of the nanoparticles to compare phase structure, morphology, and magnetic properties. Results show that the high magnetic, high density Hägg iron carbide with a core-shell structure converts to the lower density magnetite with moderate magnetization and core shell structure. • Fe 5 C 2 is not stable at high temperatures and goes under degradation through a solid state transformation reaction. • The activation energy of Fe 5 C 2 NPs transformation is calculated to be 141.6kJ/mol according to Flynn-Wall-Ozawa method. • High magnetic Fe 5 C 2 NPs transform to moderate magnetic Fe 3 O 4 NPs at high temperatures. • The degradation mechanism of Fe 5 C 2 NPs is determined to be three-dimensional diffusion (D 3) using Craido method. [ABSTRACT FROM AUTHOR]