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Self-doped CuS nanoparticles (NPs) were successfully synthesized via microwave-assisted polyol process to act as co-catalysts to TiO2 nanofiber (NF)-based photoanodes to achieve higher photocurrents on visible light-assisted water electrolysis. The strategy adopted to perform the copper cation sulfidation in polyol allowed us to overcome the challenges associated with the copper cation reactivity and particle size control. The impregnation of the CuS NPs on TiO2 NFs synthesized via hydrothermal corrosion of a metallic Ti support resulted in composites with increased visible and near-infrared light absorption compared to the pristine support. This allows an improved overall efficiency of water oxidation (and consequently hydrogen generation at the Pt counter electrode) in passive electrolyte (pH = 7) even at 0 V bias. These low-cost and easy-to-achieve composite materials represent a promising alternative to those involving highly toxic co-catalysts. [ABSTRACT FROM AUTHOR]

In this study, the electrical properties and stability of silver nanowire transparent conductive electrodes (TCEs) were improved through the platinum electroplating process (AgNWs@Pt TCEs). After electroplating, environmental and thermal stabilities increased considerably, whereas sheet resistance was greatly reduced. Sheet resistance sharply decreased from 181.3Ω/□ to 16.59 Ω/□. Meanwhile, the thermal stability of the AgNWs@Pt TCEs was enhanced by 20°C compared with that of TCEs based on silver nanowires. The sheet resistance of the AgNWs@Pt TCEs remained nearly constant after exposure to ambient air for five months. The optimal electroplating condition was achieved at an electroplating current of 10 µA for 30 s. Under this condition, the sheet resistance, transmittance, and figure-of-merit (FOM) values of the AgNWs@Pt TCEs were approximately 16.59 Ω/□, 83.89%, and 123 Ω-1, respectively. [ABSTRACT FROM AUTHOR]

Synthesizing intermetallic phases containing noble metals often poses a challenge as the melting points of noble metals often exceed the boiling point of bismuth (1560 °C). Reactions in the solid state generally circumvent this issue but are extremely time consuming. A convenient method to overcome these obstacles is the co‐reduction of metal salts in polyols, which can be performed within hours at moderate temperatures and even allows access to metastable phases. However, little attention has been paid to the formation mechanisms of intermetallic particles in polyol reductions. Identifying crucial reaction parameters and finding patterns are key factors to enable targeted syntheses and product design. Here, we chose metastable γ‐BiPd as an example to investigate the formation mechanism from mixtures of metal salts in ethylene glycol and to determine critical factors for phase formation. The reaction was also monitored by in situ X‐ray diffraction using synchrotron radiation. Products, intermediates and solutions were characterized by (in situ) X‐ray diffraction, electron microscopy, and UV‐Vis spectroscopy. In the first step of the reaction, elemental palladium precipitates. Increasing temperature induces the reduction of bismuth cations and the subsequent rapid incorporation of bismuth into the palladium cores, yielding the γ‐BiPd phase. [ABSTRACT FROM AUTHOR]

The polyol process is a straightforward method to produce metallic compounds through transformation from metal salt. An optimized procedure based on the polyol process in this research was developed for the selective synthesis of α-nickel hydroxide from metal salt. From various experimental results, the preparation of the sodium salt of ethylene glycol was crucial for the efficient production of α-nickel hydroxide. The structure of α-nickel hydroxide was studied by powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscope. The estimated Gibbs free energies for each step of the polyol process, employing density functional theory (DFT) calculations, confirmed the formation of nickel reaction intermediates, which mitigated the production of metallic nickel. The innovative point of this research is the finding that the intentional generation of nickel reaction intermediates leads to selective synthesis of α-nickel hydroxide. [ABSTRACT FROM AUTHOR]

Abstract Synthesizing intermetallic phases containing noble metals often poses a challenge as the melting points of noble metals often exceed the boiling point of bismuth (1560 °C). Reactions in the solid state generally circumvent this issue but are extremely time consuming. A convenient method to overcome these obstacles is the co‐reduction of metal salts in polyols, which can be performed within hours at moderate temperatures and even allows access to metastable phases. However, little attention has been paid to the formation mechanisms of intermetallic particles in polyol reductions. Identifying crucial reaction parameters and finding patterns are key factors to enable targeted syntheses and product design. Here, we chose metastable γ‐BiPd as an example to investigate the formation mechanism from mixtures of metal salts in ethylene glycol and to determine critical factors for phase formation. The reaction was also monitored by in situ X‐ray diffraction using synchrotron radiation. Products, intermediates and solutions were characterized by (in situ) X‐ray diffraction, electron microscopy, and UV‐Vis spectroscopy. In the first step of the reaction, elemental palladium precipitates. Increasing temperature induces the reduction of bismuth cations and the subsequent rapid incorporation of bismuth into the palladium cores, yielding the γ‐BiPd phase.

Self-doped CuS nanoparticles (NPs) were successfully synthesized via microwave-assisted polyol process to act as co-catalysts to TiO2 nanofiber (NF)-based photoanodes to achieve higher photocurrents on visible light-assisted water electrolysis. The strategy adopted to perform the copper cation sulfidation in polyol allowed us to overcome the challenges associated with the copper cation reactivity and particle size control. The impregnation of the CuS NPs on TiO2 NFs synthesized via hydrothermal corrosion of a metallic Ti support resulted in composites with increased visible and near-infrared light absorption compared to the pristine support. This allows an improved overall efficiency of water oxidation (and consequently hydrogen generation at the Pt counter electrode) in passive electrolyte (pH = 7) even at 0 V bias. These low-cost and easy-to-achieve composite materials represent a promising alternative to those involving highly toxic co-catalysts.

Herein, various silver nanowires (AgNWs) deposition techniques, i.e., spin coating, Mayer rod coating, and spray coating are used to fabricate ZnO/P3HT‐based double‐side hybrid photodetectors and their photoresponse for 520 nm green light has been compared. The electrodes are coated over the polyethylene terephthalate sheet separately and laminated over the indium tin oxide (ITO)/ZnO/P3HT. Mayer rod‐coated electrodes are found to have a sheet resistance (Rsh) of 24 Ω Sq.−1 and a light transmission of 91%. Additionally, spin‐ and spray‐coated AgNW electrodes exhibit Rsh of 20 and 23 Ω Sq.−1, respectively, along with 80% and 85% transparencies. As the device consists of transparent electrodes on both sides, it can detect light from both the top and bottom sides. Mayer rod‐coated AgNW electrode‐based device has produced better photosensitivity of 1500 (for ITO side illumination) and 630 (for AgNWs side illumination) at λ = 525 nm. Further, the device has demonstrated the responsivity of 124 mAW−1 and specific detectivity of 3 × 1011 Jones. [ABSTRACT FROM AUTHOR]

The polyol process is one of the simple, efficient and productive methods for the synthesis of metal loaded polymer composites. Functional properties of metal-polymer nanocomposites are determined by chemical composition, size and morphology of their particles. Finding effective ways to control the nanoparticle's properties during the polyol process is a crucial task. The effect of molar ratio Mn+/OHPEG on the formation of cobalt loaded metal-polymer nanocomposites during a one-pot two-component polyol process by polyethylene glycol with Mr = 4000 g·mol–1 (PEG) was studied. The PEG-based polyol process and the formation of cobalt nanophase were studied at molar ratios νCo2+/νOH(PEG) = 1:1, 1:10, 1:100 and 1:500 using UV-Vis, diffuse reflectance IR and ATR FT-IR spectroscopy, nanoparticle tracking analysis (NTA), dynamic light scattering (DLS). It was found that PEG can act as a reducing agent and stabilizing matrix for the cobalt nanophase at a ratio higher than Mn+/OHPEG= 1:10. The composition and morphology of Co/PEG nanocomposites were determined by XRD and TEM methods. Two types of spheroid particles with average diameters of 88±55 nm / 8±4 nm and 12±3 nm / 3±1 nm, respectively, represent Co/PEG nanocomposites 1:500 and 1:100. Scaly structures with a diameter of 15±5 nm are formed at a molar ratio of νCo2+/νOH(PEG) = 1:10. An increase in the Co2+ content in the PEG-based polyol process leads to the immobilized cobalt nanophase Co3O4 (1:500), Co0/CoO (1:100), CoO (1:10) in PEG. Co/PEG nanocomposites are hemocompatible. The HC50value depends on the composition and morphology of the nanoparticles.

Nitric oxide (NO) is a very well-known indoor pollutant, and high concentrations of it in the atmosphere lead to acid rain. Thus, there is great demand for NO sensors that have the ability to work at room temperature. In this work, NiO/SnO2 heterostructures have been prepared via the polyol process and were tested against different concentrations of NO gas at room temperature. The structural and morphological characteristics of the heterostructures were examined using X-ray diffraction and scanning electron microscopy, respectively, while the ratio of NiO to SnO2 was determined through the use of energy-dispersive spectrometry. The effects of both pH and thermal annealing on the morphological, structural and gas-sensing properties of the heterostructure were investigated. It was found that the morphology of the heterostructures consisted of rod-like particles with different sizes, depending on the temperature of thermal annealing. Moreover, NiO/SnO2 heterostructures synthesized with pH = 8 and annealed at 900 °C showed a response of 1.8% towards 2.5 ppm NO at room temperature. The effects of humidity as well as of stability on the gas sensing performance were also investigated. [ABSTRACT FROM AUTHOR]

Exotic optical, thermoelectric properties and flexibility to exist in different shape and sizes make lead chalcogenides an attractive candidate for many futuristic applications. This report presents a comprehensive study of seed-nucleated controlled growth of multi-armed polyol based lead sulphide (PbS) nanoparticles and propose cubic-to-flower shape-evolution mechanism. While the seed-nucleated strategy was exploited with different concentration of seed-precursors, non-seeded strategy was studied by playing with refluxing time. The seed-nucleated strategy precipitated octapod flowers of smaller particle-size-distribution in 2 h than the non-seeded strategy (in 10 h). The synthesis of highly crystalline nanoparticles, stable to 700 °C, was successfully demonstrated using structural and thermal analysis. The estimated crystallite size for seeded samples were 19–32 nm, whereas for non-seeded they were 35–38 nm. Growth of larger crystallites in non-seeded samples also resulted in larger particle size (120–150 nm) than seeded samples (60–100 nm). Furthermore, the seed-nucleated growth also yield higher available surface area (131.34 m2/gm with average-pore-size of 7.49 nm) than non-seeded method. Raman analysis showed that the obtained peaks were in good agreement with transverse optical and longitudinal optical phonon mode of cubic PbS phase. Optimistically, evaluation of this study may helpful to lay roadmap for controlled synthesis of other inorganic crystals. [ABSTRACT FROM AUTHOR]

Silver nanowires (AgNWs) represent an excellent material for many advanced applications due to their thermal and electrical properties. However, synthesising materials with the desired characteristics requires knowledge of the parameters affecting their size and an appropriate fabrication method. This paper presents a study on the synthesis of silver nanowires using the polyol process by conventional and microwave heating. Various polyols (1,2-ethanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol) with different viscosities and dielectric properties were used as reductants. It resulted in nanowires with an average diameter of 119–198 nm. It was found that, in contrast to the viscosity and dielectric constant of the alcohol used, the heating method had a limited effect on the average diameter and length value of the final product. The performed studies indicate an optimal strategy for fabricating one-dimensional silver nanostructures using the polyol method. [ABSTRACT FROM AUTHOR]

The polyol process is a straightforward method to produce metallic compounds through transformation from metal salt. An optimized procedure based on the polyol process in this research was developed for the selective synthesis of α-nickel hydroxide from metal salt. From various experimental results, the preparation of the sodium salt of ethylene glycol was crucial for the efficient production of α-nickel hydroxide. The structure of α-nickel hydroxide was studied by powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscope. The estimated Gibbs free energies for each step of the polyol process, employing density functional theory (DFT) calculations, confirmed the formation of nickel reaction intermediates, which mitigated the production of metallic nickel. The innovative point of this research is the finding that the intentional generation of nickel reaction intermediates leads to selective synthesis of α-nickel hydroxide.

In this research, we have mainly focused on the controlled synthesis, and properties of micro/nanosized ferrite and hexaferrite powders by the polyol process. They are Fe3O4-type Sr-Fe-O oxide and SrFe12O19 with the structure and magnetic properties by SEM, XRD, and VSM measurements. After heat treatment, it was discovered that Sr element was gradually fully incorporated into Fe3O4 for the formation of the original hexaferrite structure of SrFe12O19 at 950°C.

High-entropy (HE) ceramics nanoparticles have received much attention due to their interesting properties. However, very limited studies have been conducted on their sintering. Here, we report the sintering behavior of HE A 2 B 2 O 7 type rare earth oxide nanoparticles obtained by polyol process. HE cerate (HECe) (La 0.2 Y 0.2 Nd 0.2 Sm 0.2 Gd 0.2) 2 Ce 2 O 7-δ is chosen as an exemplary case, which is considered as a good candidate for thermal insulation. HECe nanoparticles with size of 2.6–7.1 nm can be synthesized through polyol process followed by annealing in air at 300–700 °C. HECe nanoparticle compact can be densified by directly sintering at 1500 °C. The sintering temperature could be further decreased using a two-step sintering process, i.e., 1500 °C 5 min-1300 °C 5 h. Our results show that fine particle and abundant oxygen vacancies probably dominate the densification process. By controlling the sintering regime, we can tune the microstructure of HECe ceramics and thermal conductive properties accordingly. [ABSTRACT FROM AUTHOR]

The synthesis of CoNPs cobalt nanoparticles by the method of polyol- process was proposed, which consists in a high-temperature synthesis of polymer-stabilized metal nanoparticles in a matrix of a fourth-generation hyperbranched polyester polyol. Branched polyester polyol acts as both a reducing agent and a stabilizer at the same time. It has been found that the reduction of the precursor CoCl2 with a hyperbranched polyester polyol occurs at 210°C. The introduction of NaOH into the reaction mixture makes it possible to lower the synthesis temperature by 50°C and leads to a change in the mechanism of in situ ripening CoNPs from the digestive mechanism to direct Ostwald ripening. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is a very well-known indoor pollutant, and high concentrations of it in the atmosphere lead to acid rain. Thus, there is great demand for NO sensors that have the ability to work at room temperature. In this work, NiO/SnO2 heterostructures have been prepared via the polyol process and were tested against different concentrations of NO gas at room temperature. The structural and morphological characteristics of the heterostructures were examined using X-ray diffraction and scanning electron microscopy, respectively, while the ratio of NiO to SnO2 was determined through the use of energy-dispersive spectrometry. The effects of both pH and thermal annealing on the morphological, structural and gas-sensing properties of the heterostructure were investigated. It was found that the morphology of the heterostructures consisted of rod-like particles with different sizes, depending on the temperature of thermal annealing. Moreover, NiO/SnO2 heterostructures synthesized with pH = 8 and annealed at 900 °C showed a response of 1.8% towards 2.5 ppm NO at room temperature. The effects of humidity as well as of stability on the gas sensing performance were also investigated.

Magnetocrystalline anisotropy is a crucial parameter that determines the suitability of magnetic material in a wide range of emerging applications. The law‐of‐approach‐to‐saturation (LAS), utilized to obtain the magnetocrystalline anisotropy from hysteresis loops, is not satisfactory for materials with cubic anisotropy as they are two orders higher than the bulk value. Herein, a modified formulation to LAS is presented, where the reduction in effective magnetic anisotropy (K) values due to Fe oxide phases in Fe particles over wide size ranges is accounted. The value of K decreases from 4.2 × 104 J m−3 for the Fe particles of average size 210 nm to 1.2 × 104 J m−3 for the 20 nm particles due to the increase in the iron oxide fraction with size reduction. The effective magnetic anisotropy obtained from the modified LAS has been validated from the ferromagnetic resonance studies for particles of the smallest size. [ABSTRACT FROM AUTHOR]

Cuprous oxide microspheres (Cu2O SPs) assembled by nanoparticles were successfully prepared via a facile ultrasound-assisted polyol process using cupric acetate monohydrate as a precursor and diethylene glycol as both solvent and reducing agent, and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption. Results showed that the as-prepared product was cubic Cu2O without any impurity and displayed microsphere morphologies with diameters of 250–300 nm, which were assembled by nanoparticles. The as-prepared Cu2O SPs exhibited excellent adsorption capability for methyl orange (MO). Kinetics and isotherms studies showed that the adsorption process of MO onto Cu2O SPs followed pseudo-second-order and Langmuir models. The maximum MO adsorption capability according to the Langmuir model under different concentrations ranging from 90 to 300 mg/L was estimated to be 885.0 mg/g. Moreover, Cu2O SPs can be regenerated by photocatalytic degradation of adsorbed MO. [ABSTRACT FROM AUTHOR]

Silver nanowires (AgNWs) represent an excellent material for many advanced applications due to their thermal and electrical properties. However, synthesising materials with the desired characteristics requires knowledge of the parameters affecting their size and an appropriate fabrication method. This paper presents a study on the synthesis of silver nanowires using the polyol process by conventional and microwave heating. Various polyols (1,2-ethanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol) with different viscosities and dielectric properties were used as reductants. It resulted in nanowires with an average diameter of 119–198 nm. It was found that, in contrast to the viscosity and dielectric constant of the alcohol used, the heating method had a limited effect on the average diameter and length value of the final product. The performed studies indicate an optimal strategy for fabricating one-dimensional silver nanostructures using the polyol method.

Nickel magnetic nanoparticles have been successfully fabricated by combination of polyol process and hydrothermal treatment. In this research, the formation of Ni nanoparticles was determined by X-ray diffraction (XRD) and Ultraviolet-visible spectroscopy (UV-Vis). The morphology and size of nanoparticles were observed by using Transmission Electron Microscopy (TEM) while magnetic property of Ni nanoparticles have been characterized by vibrating sample magnetometer (VSM). The results indicate that the synthesized Ni nanoparticles are in spherical shape and the sizes of nanoparticles are in range from 3.1 nm to 5.7 nm depending on concentration of Ni2+ ions. The magnetization study in nickel nanoparticles shows ferromagnetic interaction but close to superparamagnetic state and the magnetization decreases with the size reduction. [ABSTRACT FROM AUTHOR]

Functional high-entropy oxide (HEO) (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O has attracted great attention due to its unique properties. High temperature (∼1000 °C) sintering is generally required to form the single-phase (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O. In this work, a polyol process followed by quenching is established to synthesize (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O. Benefiting from the homogeneous distribution of metal elements in the inorganic-organic hybrid compound obtained from polyol process, a single-phase HEO can be achieved after quenching at 800 °C.

The physio-chemical properties of metallic nanoparticles are different from their corresponding bulk material. Synthesizing stable zero valent copper nanoparticles is a challenge since they get oxidized easily. This paper discusses both the batch and continuous synthesis of copper nanoparticles using a polyol process in the absence of an inert atmosphere. The nanoparticles were synthesized using copper amine complex as a precursor, ascorbic acid as a reducing agent, and polyvinyl pyrrolidone as a capping agent. UV-Vis spectra confirmed that particles from a continuous synthesis had better Localized Surface Plasmon Resonance (LSPR) peak than those from batch synthesis. At 120 °C, nanoparticles in the continuous process could be synthesized at a residence time of 1 min in contrast to the batch reactor, which needed a reaction time of 4 min. The nanoparticles synthesized were of size 1.5–6 nm. Those synthesized in continuous mode were stable for 10 days as compared to those synthesized in batch mode. [ABSTRACT FROM AUTHOR]

We report the effect of a polyol-mediated annealing on nickel ferrite nanoparticles. By combining X-ray fluorescence spectroscopy, X-ray diffraction, and 57Fe Mössbauer spectrometry, we showed that whereas the as-prepared nanoparticles (NFO) are stoichiometric, the annealed ones (a-NFO) are not, since Ni0-based crystals precipitate. Nickel depletion from the spinel lattice and reduction in the polyol solvent are accompanied with an important cation migration. Indeed, thanks to Mössbauer hyperfine structure analysis, we evidenced that the cation distribution in NFO departs from the thermodynamically stable inverse spinel structure with a concentration of tetrahedrally coordinated Ni2+ of 20 wt-% (A sites). After annealing, and nickel demixing, originated very probably from the A sites of NFO lattice, the spinel phase accommodates with cation and anion vacancies, leading to the (Fe3+0.84□0.16)A[Ni2+0.80Fe3+1.16□0.04]BO4-0.20 formula, meaning that the applied polyol-mediated treatment is not so trivial.

A method was developed for the preparation of Cu2O/TiO2 composite films by polyol reduction of copper(II) acetylacetonate deposited into ordered porous matrix of TiO2 nanotubes by the PVD technique at reduced pressure. An electron microscopic examination showed that the resultant films consisted of highly organized TiO2 nanotubes whose surface was uniformly coated with individual Cu2O nanoparticles ranging in size from 1 to 5 nm. The possibility of preparing composites with Cu2O content controlled in the 0.1–2.3 wt % range was demonstrated. Deposition of Cu2O nanoparticles was found to improve the photocatalytic activity of the original porous TiO2 films. Specifically, in photocatalytic degradation of phenol in the presence of the resultant composite films the reaction rate displayed an extremal dependence on the Cu2O nanoparticles content with a maximum observed near 1.7 wt %. [ABSTRACT FROM AUTHOR]

Here, we have used a simple method for polyol synthesis, analysis, and testing of Au/Cu-doped ZnO Ultraviolet (UV) photodetectors (PD). Our results are reported and discussed by X-ray diffraction (XRD) to ensure that the manufactured samples show a hexagonal wurtzite ZnO structure. Transmission electron microscopy (TEM) confirmed the nanoparticle growth in the hexagonal sample on the surface, which is the key to improving the light response. Our prepared UV PD Au/Cu codoped ZnO showed a rapid time at a power density of 7.6 mW. the highest responsivity of R = 575 mA/W and sensitivity 103 obtained at 7.6 mW with an applied voltage of 1 V. Our results demonstrate the obvious substitution of Au and Cu in ZnO, thereby improving the UV-sensing light response. [ABSTRACT FROM AUTHOR]

The magnetic moment and the Curie temperature of the NiCu alloy decrease to a large extent with Cu. A Ni60Cu40 alloy with Fe substitutions up to 2 at% using a polyol-mediated synthesis process resulting in enhanced magnetic properties is obtained. The Ni60Cu39Fe1 and Ni60Cu38Fe2 alloys show fcc phase with the Curie temperatures of 237 and 266 K, respectively. The room temperature magnetization measurement shows paramagnetic behavior, whereas, at 15 K, the 1 at% Fe-substituted alloy exhibits a saturation magnetization of 20 emu g-1 that increases by 25% with 2 at% Fe. The positive slope in the Arrott plot confirms the second-order phase transition in the alloys. The maximum magnetic entropy change (MCE) is observed as 0.101 J kg-1 K-1 for the Ni60Cu39Fe1 alloy with the peak temperature of 238 K in an applied magnetic field of 0.5 T. The critical exponent (β) calculated using the MCE method is in the range of 0.576(3)-0.587(3) for the alloys, whereas the values obtained using the Kouvel-Fisher (KF) method are 0.523(3)-0.565(2). The extractedβ values are slightly greater than the mean-field model suggesting clustering behavior in the alloys. [ABSTRACT FROM AUTHOR]

Background: In extrinsically magnetoelectric materials made of two components, the direct magnetoelectric coupling arises from a mechanical strain transmission at the interface due to the shape change of the magnetostrictive component under an external magnetic field. Here, the size of the interface between the two components plays a crucial role. Therefore, the development of nanomaterials exhibiting large surface-to-volume ratios can help to respond to such a requirement. However, the magnetic nanoparticles (NPs) must be highly magnetostrictive and magnetically blocked at room temperature despite their nanometer-size. We describe here the use of the polyol process to synthesize cobalt ferrite (CoxFe3−xO4) nanoparticles with controlled size and composition and the study of the relationship between size and composition and the magnetic behavior.Methods: We used an improved synthesis of magnetostrictive CoxFe3−xO4 NPs based on the forced hydrolysis of metallic salts in a polyol solvent, varying the fraction x. Stoichiometric NPs (x = 1) are expected to be highly magnetostrictive while the sub-stoichiometric NPs (particularly for x ≈ 0.7) are expected to be less magnetostrictive but to present a higher magnetocrystalline anisotropy constant, as previously observed in bulk cobalt ferrites. To control the size of the NPs, in order to overcome the superparamagnetic limit, as well as their chemical composition, in order to get the desired magnetomechanic properties, we carried out the reactions for two nominal precursor contents (x = 1 and 0.67), using two different solvents, i.e., triethylene glycol (TriEG) and tetraethylene glycol (TetEG), and three different durations of refluxing (3, 6 and 15 h). The structure, microstructure and composition of the resulting NPs were then investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray fluorescence spectroscopy (XRF), respectively. The magnetic properties were also evaluated using standard magnetometry. To measure the magnetostrictive response of the particles, the particles were sintered to dense pellets on which strain gauges were bonded, measuring the size variation radially, as a function of a dc magnetic field.Findings: We found two samples, the first one being stoichiometric and magnetostrictive, and the second one being sub-stoichiometric and presenting a higher magnetization, that are appropriate to be used as ferromagnetic building blocks in nanostructured magnetoelectric materials, particularly materials based on polymers. We show that the polyol solvent and the reaction time are two key parameters to control the size and the magnetic properties of the resulting nanoparticles. We believe that these results provide relevant insights to the design of efficient magnetic and magnetostrictive nanoparticles that can be further functionalized by coupling agents, to be contacted with piezoelectric polymers.

High molecular weight polyvinylpyrrolidone (PVP) and seeding conditions are considered to have important roles in the synthesis of AgNWs. In this work, we report a versatile synthesis of AgNWs in a salt-free environment and under Ar inert atmosphere using high molecular weight PVP and seeding step during the synthetic process. The high molecular weight PVP was found to efficiently promote the preparation of AgNWs via supporting the proper growth control of AgNWs on {111} facets and selective growth on {100} facets. The seeding step facilitates the formation of seeds such as multiple twinned nanoparticles (MTPs) and single crystal seeds, which promoted the feasible formation of AgNWs. The shape and size of the synthesized AgNWs were characterized by SEM and TEM. The crystalline nature of the synthesized AgNWs was characterized by HRTEM, SAED and XRD, and their LSPR peaks were confirmed by UV-Vis spectroscopy. The conductive properties of the synthesized AgNWs were determined by preparing their thin conductive film on a PET substrate. The prepared AgNWs thin films exhibited good sheet resistance. [ABSTRACT FROM AUTHOR]

Core–shell magnetic nanoparticles exhibit exchange bias, whereas the magnitude of the exchange bias field is influenced by various factors that are still under investigation. We present a detailed analysis of the magnetic behavior in Fe- and Co-rich FeCo particles with a ferrimagnetic oxide shell. The as-synthesized alloys, with an average particle size above 150 nm, show high saturation magnetization and exhibit multidomain nature. The magnetic behavior has been analyzed through first order reversal studies at room temperature, and low temperature (15 K) for the as-synthesized and size-reduced alloys. The size-reduced alloys exhibit exchange bias that enhances with decreasing average particle size and found to be maximum for the Co-rich FeCo. First order reversal curve (FORC) studies could resolve the reversible, irreversible magnetization components, and magnetostatic interactions. The low-temperature field cooled measurements expose random field bias acting at the interfaces. The studies reveal that FORC could be utilized to obtain information about particle size and its distribution dependent magnetic behavior in core–shell nanostructures. [ABSTRACT FROM AUTHOR]

ZnFe2O4 nanoparticles were synthesized by polyol process. The influence of reaction conditions, such as the refluxing time, heating rates and refluxing temperature on the size, morphology and magnetic properties was investigated. The structure, morphology and magnetic properties of resultant products were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), fourier transform infrared (FTIR) and vector network analyzer. The results show that the obtained ZnFe2O4 nanoparticles have uniform size and good dispersibility. The particle size increases with the increase of the reflux time and the reflux temperature. ZnFe2O4 nano ferrites synthesized at the refluxing temperature of 270℃ have maximum saturation magnetization of 35.09A·m2/kg with less remanence and the coercive force is 4.2kA/m.ZnFe2O4 nanoferrites show a typical ferrimagnetic behavior.

Abstract ZnO nano-clips with better monodispersion were prepared successfully using zinc acetate hydrate (Zn(OAc)2·nH2O) as Zn source and ethylene glycol (EG) as solvent by a simple solution-based route-polyol process. The effect of solution concentration on the formation of ZnO nano-clips has been investigated deeply. We first prove that the 0.01 M Zn(OAc)2·nH2O can react with EG without added water or alkaline, producing ZnO nano-clips with polycrystalline wurtzite structure at 170 °C. As-synthesized ZnO nano-clips contain a lot of aggregated nanocrystals (~ 5 to 15 nm) with high specific surface area of 88 m2/g. The shapes of ZnO nano-clips basically keep constant with improved crystallinity after annealing at 400–600 °C. The lower solution concentration and slight amount of H2O play a decisive role in ZnO nano-clip formation. When the solution concentration is ≤ 0.0125 M, the complexing and polymerization reactions between Zn(OAc)2·nH2O and EG predominate, mainly elaborating ZnO nano-clips. When the solution concentration is ≥ 0.015 M, the alcoholysis and polycondensation reactions of Zn(OAc)2·nH2O and EG become dominant, leading to ZnO particle formation with spherical and elliptical shapes. The possible growth mechanism based on a competition between complexing and alcoholysis of Zn(OAc)2·nH2O and EG has been proposed.

The method of lithium iron phosphate (LiFePO4) synthesis in a melt mixture of choline chloride and diethylene glycol (DEG) at 230 °C is proposed. Powders with lamellar morphology consisting of LiFePO4 crystals (size ~30 nm) with olivine structure were synthesized. The size of crystals increased to ~60 nm during the annealing process carried out to obtain a carbon coating on the grain surface of LiFePO4. The charge-discharge curves of the electrode prepared from these powders have a horizontal portion at the potential of 3.4 and 3.5 V, corresponding to the intercalation/deintercalation of lithium in the structure of olivine. The specific discharge capacity of the LiFePO4/C is 133 mA h g-1 for a discharge current of 0.1C. The dependence of the anodic (cathodic) voltammetric current peaks, Ip, on the potential scan rate indicates the diffusion nature of the lithiating step. For the anodic and cathodic processes the averaged diffusion coefficient values are 1.3Ч10-10 and 1.5Ч10-10 cm2 s-1, respectively.

In recent years, thin silver nanowires (Ag NWs) with diameters smaller than 150 nm have been synthesized by implementation of NaCl or FeCl3 as reaction promoters and high molecular weight polyvinylpyrrolidone (PVP) as the capping agent. However, the yield of Ag NWs still remains low, mostly due to the insufficient aspect ratio (AR) of the synthesized nanostructures and the production of Ag nanoparticles, which is an undesirable by product. This study proposes a modified technique to alleviate the problem by using a mixture of FeCl3/CuCl2 as the reaction promoter and two different types of PVP with molecular weight of 360 k and 40 k as the capping agents. The appropriate mixtures of FeCl3/CuCl2 (molar ratio of 1.48:1.45) and PVP 360 k/40 k (molar ratio of 2:1) allow for the rapid synthesis of NWs with diameter of about 110 nm and length of up to 50 μm. It is revealed that the ARs of the synthesized NWs are much greater. The NWs are then used for the fabrication of transparent conductive films (TCFs). The obtained TCF prepared by a scalable, in-house, and cost-efficient spray apparatus possesses a transmittance of 91%, sheet resistance of 10 Ω/sq, and optical haze value of 6.6%. In fact, the AR of the NWs is increased as much as 1135%, and further the figure␣of merit of the TCFs is improved by as much as 2785%. [ABSTRACT FROM AUTHOR]

A simple and environment-friendly approach to prepare zinc oxide nanoaggregates was achieved by employing ethylene glycol–H2O as the reaction medium. The composition and structure of the as-fabricated ZnO products were confirmed using X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption measurements. By tailoring the volume ratio of ethylene glycol to water, coral-like, flower-like, and nanoparticulate ZnO nanoaggregates were successfully synthesized. The impact of the structure of the as-obtained ZnO nanoaggregates on the photocatalytic degradation of ciprofloxacin was further studied. Under simulated solar light irradiation, the photocatalytic removal rate of coral-like, flower-like, and nanoparticulate ZnO nanoaggregates for ciprofloxacin was 45%, 80%, and 90%, respectively. The reactive species trapping experiment result indicated that the generated holes, OH−, and ·O2− active species mainly contributed to the degradation of ciprofloxacin. On the basis of photoluminescence spectra and photo/electrochemical measurement results, the prevention of electron-hole recombination and the rapid charge transfer upon the ZnO nanoparticle aggregates resulted in their efficient photocatalytic activity. [ABSTRACT FROM AUTHOR]

The equilibrium FeNi alloy exhibits the bcc phase in a narrow composition less than 5 at.% Ni. Fe64Ni36 was obtained through instant chemical reduction employing polyol process and compared with Fe5Ni95 alloy. X-ray diffraction revealed bcc and fcc phases for the Fe-rich and Ni-rich FeNi compositions, respectively. The metastable bcc FeNi transformed to the fcc phase on annealing at 700 °C, whereas the Ni-rich alloy retained its fcc phase. Electron microscopic examination revealed spherical morphology for Fe64Ni36 alloy with an average size of 72 nm compared with flake-like morphology for the Fe5Ni95. The thermomagnetic analysis revealed a Curie temperature of 567 and 359 °C for the as-synthesized Fe and Ni-rich phases, respectively. An increase in Curie temperature by 30 °C was observed in both the compositions on annealing. Room temperature hysteresis loop measurements showed a saturation magnetization of 117 emu/g for bcc Fe64Ni36 alloy which increased to 165 emu/g for the fcc Fe64Ni36. The reaction kinetics involved in polyol process has enabled us to synthesis and investigate the magnetic properties of metastable bcc phase in the Fe64Ni36 composition. [ABSTRACT FROM AUTHOR]

Equiatomic FeCo alloy was synthesized through polyol process and size reduction was attempted using heterogeneous nucleating agents such as Cu and Pt. The average particle size of FeCo reduced from 138 to 17 nm using 5 × 10−6 M of Pt whereas significant size reduction could not be achieved with Cu up to 1 × 10−5 M. The as-prepared FeCo and the particles prepared using Cu as nucleating agent revealed a flower-like morphology whereas the shape crumbled with Pt nuclei. All the FeCo nanoparticles exhibited exchange bias effect due to the oxide layer present as a shell. The exchange bias field and coercivity at 15 K were 185 Oe and 1016 Oe, respectively, for the particles synthesized using Pt as a nucleating agent. [ABSTRACT FROM AUTHOR]

In this study, we developed hexagon silver nanoparticles (AgNPs) prepared by the polyol method in ethylene glycol media using aminopropyltrimethoxysilane (APTMS) as a capping agent for the first time. The presence of the primary amine group makes APTMS a great candidate as a capping agent for the synthesis of silver nanostructures, but it has not been used for this purpose until now. The synthesized silver nanostructures were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and ultraviolet-visible spectroscopy. The molar ratio of APTMS to AgNO3 varied from 0.5 to 6.8, which resulted in an average diameter of the obtained nanoparticles from 50 to 100 nm. The optimum morphology of hexagonally shaped AgNPs was obtained at a molar ratio of 2.2. The prepared AgNPs were evaluated for their antibacterial and antifungal properties. Antimicrobial tests showed that a cotton textile coated with colloidal amino functionalized AgNPs has excellent antimicrobial properties as an inhibitor of growth against the gram-positive bacteria Staphylococcus aureus, gram-negative bacteria, Escherichia coli and fungus Candida albicans, and therefore showing potential for real applications. [ABSTRACT FROM AUTHOR]

The polyol synthesis is a well-established method to form so-called “surfactant-free” nanoparticles (NPs). In the present study, the NP size resulting from the thermal reduction of the precursors H2PtCl6, H2Pt(OH)6, or Pt(acac)2 in presence of the bases NaOH or Na(acac) at different concentrations is studied. It is shown that the size control depends more strongly on the nature of the precursor (metal salt) than on the anion present in the base. The latter is surprising as the concentration of the base anion is often an important factor to achieve a size control. The reduction of H2PtCl6 or H2Pt(OH)6 in presence of NaOH and Na(acac) confirm the observation that the NP size is determined by the OH−/Pt molar ratio and expands it to the base anion/Pt molar ratio. In contrast, the reduction of Pt(acac)2 in presence of the bases NaOH (previous reports) or Na(acac) (shown in the present work) leads to larger NPs of ca. 3 nm, independent of the concentration of the base anions. Hence, the anion effect observed here seems to originate predominantly from the nature of the precursor (precursor anion dependence) and only for certain precursors as H2PtCl6 or H2Pt(OH)6 the size control depends on the base anion/Pt molar ratio.

Nano-brasses are emerging as a new class of composition-dependent applicable materials. It remains a challenge to synthesize hydrophilic brass nanoparticles (NPs) and further exploit them for promising bio-applications. Based on red/ox potential of polyol and nitrate salts precursors, a series of hydrophilic brass formulations of different nanoarchitectures was prepared and characterized. Self-assembly synthesis was performed in the presence of triethylene glycol (TrEG) and nitrate precursors Cu(NO3)2·3H2O and Zn(NO3)2·6H2O in an autoclave system, at different temperatures, conventional or microwave-assisted heating, while a range of precursor ratios was investigated. NPs were thoroughly characterized via X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmition electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and ζ-potential to determine the crystal structure, composition, morphology, size, state of polyol coating, and aqueous colloidal stability. Distinct bimetallic α-brasses and γ-brasses, α-Cu40Zn25/γ-Cu11Zn24, α-Cu63Zn37, α-Cu47Zn10/γ-Cu19Zn24, and hierarchical core/shell structures, α-Cu59Zn30@(ZnO)11, Cu35Zn16@(ZnO)49, α-Cu37Zn18@(ZnO)45, Cu@Zinc oxalate, were produced by each synthetic protocol as stoichiometric, copper-rich, and/or zinc-rich nanomaterials. TEM sizes were estimated at 20–40 nm for pure bimetallic particles and at 45–70 nm for hierarchical core/shell structures. Crystallite sizes for the bimetallic nanocrystals were found ca. 30–45 nm, while in the case of the core-shell structures, smaller values around 15–20 nm were calculated for the ZnO shells. Oxidation and/or fragmentation of TrEG was unveiled and attributed to the different fabrication routes and formation mechanisms. All NPs were hydrophilic with 20–30% w/w of polyol coating, non-ionic colloidal stabilization (−5 mV < ζ-potential < −13 mV) and relatively small hydrodynamic sizes (

A comprehensive investigation of the formation of tin and lead alkoxides with the polyalcohols ethylene glycol (C2H6O2, EG) and glycerol (C3H8O3) was conducted. Starting from tin(II) and lead(II) precursors, five alkoxides with either double‐ or triple‐deprotonated alcohol ligands were obtained. Four of them were structurally characterized by single‐crystal and one by powder X‐ray diffraction. The ethylene glycolates of tin(II) and lead(II), Sn(C2H4O2) and Pb(C2H4O2), show polymorphism. α‐ and β‐Sn(C2H4O2) can be synthesized selectively by applying different reaction times. α‐ and β‐Pb(C2H4O2), as well as Pb4(C2H4O2)4(C2H6O2), were obtained by altering the amount of NaOH and/or water used in the synthesis. With glycerol, mixed‐valent tin(II,IV) glycerolate Sn5(C3H5O3)4 and lead(II) glycerolate Pb(C3H6O3) crystallized. Except for Pb(C2H4O2), the obtained alkoxides are stable at ambient conditions for at least several months. The tin alkoxides were thermally decomposed in air to SnO2. A small amount of tin(II) in a SnO2 sample obtained at a low decomposition temperature was revealed by 119Sn Mössbauer spectroscopy. At the highest decomposition temperature of 800 °C, only tin(IV) could be detected. The morphology of the alkoxide material is retained upon decomposition; however, the produced SnO2 consists of nanosized crystalline domains. The thermal decomposition of the lead(II) alkoxides in air yielded PbO particles with a significantly changed morphology. [ABSTRACT FROM AUTHOR]

The exploitation of a bifunctional oxygen catalyst with high efficiency is crucial for a high‐performance unitized regenerative fuel cell (URFC). However, the existing bifunctional oxygen catalysts still suffer from low catalytic efficiency due to sluggish oxygen electrode reactions toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, we report on a facile synthesis of nanoporous Pt‐encapsulated Ir black with Pt/Ir mass ratio of 55/45 (Pt55@Ir45) via a newly modified polyol process at room temperature with the aid of water. The resulting Pt55@Ir45 catalyst demonstrated to be highly efficient and robust for both ORR and OER, relative to a mixture of commercial Pt and Ir black with Pt/Ir mass ratio of 50/50 (Pt50/Ir50). Mass activity of Pt55@Ir45 presented an 8.7‐ and 1.6‐fold increase toward ORR and OER, respectively, compared with the Pt50/Ir50 catalyst. The enhanced bifunctional performance was rationalized in terms of the maximized Pt utilization, achieved by the excellent dispersion of Pt nanoparticles, and the nanoporous Pt layer constructing a conductive network without impeding the transport of oxygen and water molecules. Our work demonstrates an effective means to encapsulate nanoporous Pt layers on Ir black for the fabrication of bifunctional oxygen catalysts. [ABSTRACT FROM AUTHOR]

In this research, a straightforward polyol method has been successfully applied to synthesize Nd 0. 20 Gd x Ce 0. 8 −x O 1. 9 −x/ 2 (x = 0, 0.05, 0.10, 0.15, 0.20), (NGDC) rare-earth-co-doped ceria electrolytes. Instead of the nitrate compounds generally used as starting materials, acetate compounds of cerium and dopants, triethylene glycol as solvent and reducing agent were used. A single fluorite phase was obtained after a low temperature (600 °C) calcination treatment. A series of NGDC electrolytes are fabricated at the sintering temperature of 1400 °C for 6 h. Most of them have relative densities more than 93%. According to the results of X-ray diffraction of neodymium and gadolinium doped electrolytes, all NGDC electrolytes can be produced in a single phase without any other impurity phase. Relative density of NGDC electrolytes increased first and then decreased with the increase of the Gd3+ additive ratio. The total ionic conductivity of the doped and co-doped ceria samples were studied in the temperature range 500–800 °C by using the two-probe AC impedance spectroscopy. It was found that the incorporation of a small amount of cation Gd3+ into the solid solution Nd 0.20 Gd x Ce 0.8−x O 1.9−x/2 allowed an increase in the ionic conductivity of the Nd 0.20 Ce 0.80 O 1.90 oxide electrolyte. • The Nd 0. 20 Gd x Ce 0. 8 −x O 1. 9 −x/ 2 electrolytes has been synthesized by polyol method. • A single phase of co-doped ceria was formed through calcinations at 600 °C. • The sintering temperature was reduced to about 250 °C. • Nd 0.20 Gd x Ce 0.80−x O 1.90−x/2 system reached the highest ionic conductivity at x = 0.05. [ABSTRACT FROM AUTHOR]

In this paper, we report on the simple polyol synthesis of copper-doped hybrid Agx–Auy@ZnO photocatalysts. The obtained samples have been characterized by X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, transmission electron microscopy and an N2 adsorption study. The experiment results show that Ag, Au and Ag–Au alloy nanoparticles (NPs) successfully load onto the surface of the assembled Cu-doped ZnO. The photocatalytic performances of Cu-doped Agx–Auy@ZnO nanomaterials have been tested using diuron herbicide as a model contaminant under simulated solar light irradiation. The addition of Ag and/or Au nanoparticles to doped ZnO was strongly beneficial to the rate constant displaying a volcano-like pattern as a function of the Ag and Au content. A maximum pseudo-first-order rate constant of 18.55 × 10−3 min−1, 22.70 × 10−3 min−1 and 24.74 × 10−3 min−1 was achieved on Cu-doped Ag0.3@ZnO, Au0.5@ZnO and Ag0.5–Au0.3@ZnO respectively. The Cu-doped Ag0.5–Au0.3@ZnO bimetallic nanoparticles show the highest photocatalytic activity due to the synergistic effect by effective electron transfer. [ABSTRACT FROM AUTHOR]