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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]

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]

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]

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]

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]

• 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]

• 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]

[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]

[Display omitted] • The interaction between 3-MAB and CuO/ZnO nanoparticles is demonstrated. • CuO/ZnO nanoparticles were synthesized by combustion method. • CuO/ ZnO nanoparticles quench the fluorescence of 3-MAB. • Static quenching is involved in the present system. The interaction of fluorescent probe 3-N-(N'-methylacetamidino) benzanthrone (3-MAB) with copper oxide and zinc oxide nanoparticles is studied, wherein the copper oxide nanoparticles (CuO NPs) and zinc oxide nanoparticles (ZnO NPs) were prepared by combustion method. The prepared CuO and ZnO nanoparticles were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and High resolution transmission electron microscopy (HRTEM) techniques. The interaction between fluorescent molecule 3-MAB and nanoparticles (CuO and ZnO) was investigated by absorption and fluorescence techniques. Further, the steady state fluorescence quenching of 3-MAB by CuO and ZnO nanoparticles in different solvents was studied at room temperature (298 K) and higher temperatures at 308 K and 318 K to determine the bimolecular quenching rate constant, binding constant and binding sites. [ABSTRACT FROM AUTHOR]

The paper summarizes new information on the formation and functioning of Ni(acac)2-based multicomponent (Ziegler) systems for oligo- and polymerization of ethylene. It turns out that catalytically active sites formed in these systems are deposited on nickel-containing nanoparticles generated via the interaction of the starting components directly in the reaction system. It is shown that the activity, productivity, and composition of the target products depend on the water content in the initial solvent, all other things being equal. A model of nanosized nickel-containing particles formed during the interaction of Ni(acac)2 and diethylaluminum chloride or ethylaluminum sesquichloride is presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bimetallic CuAg nanoparticles with blue fluorescence was synthesized. • AgCu-BNPS probe can be used for dual-mode colorimetric and fluorimetric sensing Hg2+. • The detection mechanisms of dual-mode probe are static and dynamic quenching combined. A dual-mode colorimetric and fluorimetric probe was successfully established based on silver/copper bimetallic nanoparticles (AgCu-BNPs). The AgCu-BNPs were confirmed as individually bimetallic nanoparticles with a mean size of 7.7 ± 0.2 nm, as characterized by high resolution transmission electron microscopy. Intriguingly, the AgCu-BNPs possess both surface plasmon resonances (SPR) and fluorescence emission. AgCu-BNPs emanate bright blue fluorescence with optical emission centered at 442 nm with high quantum yield of 30.3%, and AgCu-BNPs were attenuated or even quenched by Hg2+ via both static and dynamic quenching, coincidently accompanied by a visible color change, which endow AgCu-BNPs a unique utility as dual-mode colorimetric and fluorimetric probes. The detection limits as low as 89 nM and 9 nM were determined by dual-mode of AgCu-BNPs, respectively. The recovery rates in real samples were found to be 97.3–118.8%, and 89.5–112.7% by colorimetric and fluorescent methods separately, demonstrates the good environmental tolerance of the dual-mode probe. [ABSTRACT FROM AUTHOR]

In this study, we prepared core–shell structured Ag–CdS@Pr-TiO 2 nanoparticles and investigated its photocatalytic activity for determining the irradiation against degradation of methyl orange under visible region. The composition, morphology, and optical properties of synthesized core/shell nanoparticles were confirmed by a series of techniques, including X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray dispersive spectroscopy (EDS), High resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), XPS, UV–Vis spectroscopy, and Photoluminescence spectroscopy (PL). The sharp XRD peaks signify the high crystallinity of the synthesized nanoparticles while the crystalline size evaluated from SEM was observed to be varying in range of 10–30 nm. The photocatalytic behavior of the synthesized Ag–CdS@Pr-TiO 2 core/shell nanoparticles was evaluated and from the discoloration of dye within 30 min, it is observed that the synthesized material has a potential to degrade methyl orange efficiently. • Ag:CdS@Pr:TiO2 core/shell nanoparticles are prepared via sol-gel method. • Optical characterizations confirmed the potential of synthesized nanoparticles for photocatalytic activity. • The synthesized core/shell nanoparticles efficiently degraded the methyl orange dye under visible light within 30 min. [ABSTRACT FROM AUTHOR]