Facile Polyol Method Research Articles

High-yield synthesis of silver nanowires for transparent conducting PET films.

Silver nanowires (AgNWs) with ultrahigh purity and high yield were successfully synthesized by employing a modified facile polyol method using PVP as a capping and stabilizing agent. The reaction was carried out at a moderate temperature of 160 °C under mild stirring for about 3 h. The prepared AgNWs exhibited parallel alignment on a large scale and were characterized by UV–vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and PL spectroscopy. The luminescent AgNWs exhibited red emission, which was accredited to deep holes. The SEM results confirmed the formation of AgNWs of 3.3 to 4.7 µm in length with an average diameter of about 86 nm, that is, the aspect ratio values of the AgNWs exceeded 45. An ink consisting of hydroxyethyl cellulose (HEC) and AgNWs was transferred to polyethylene terephthalate (PET) films by simple mechanical pressing. The PET films retained transparency and flexibility after the ink coating. The maximum transmittance value of as-prepared PET films in the visible region was estimated to be about 92.5% with a sheet resistance value of ca. 20 Ω/sq. This makes the films a potential substitute to commonly used expensive indium tin oxide (ITO) in the field of flexible optoelectronics.

Characterization and Electrocatalytic Features of PtPd and PdPt Bimetallic Nanoparticles for Methanol Electro‐oxidation

AbstractThis work entails a comprehensive study on PtPd, and PdPt bimetallic nanoparticles (BNPs) supported on Vulcan XC‐72 carbon towards methanol oxidation reaction (MOR) in alkaline media. BNPs with different compositions were synthesized using a flexible and facile polyol method through a heterogeneous nucleation process. The homogeneous BNPs were characterized by SEM, XRD, HR‐TEM and XRF to analyse the crystallographic structure and verified the controlled characteristics. The electrochemical properties and stability were investigated using cyclic voltammetry and chronoamperometry, respectively. As a consequence of the electrocatalysts’ controlled composition, a direct correlation between the catalytic activity and the shift in the PtO/PdO reduction potential was observed. The optimal electrocatalyst that overcomes the catalytic performance of PdPt structure, also showed an improvement in the CO anti‐poisoning ability was PtPd (1 : 0.5)/C with a current density of 12.56‐fold higher than of commercial Pt/C. This study about different Pt/Pd structures may provide valuable information for developing new and efficient electrocatalysts towards MOR.

Impact of non-stoichiometry in the thermoelectric performance of polyol method prepared Cu1+xIn1−xS2 (x = −0.3, −0.2, −0.1, 0, 0.1, 0.2) nanowires

A significantly enhanced thermoelectric power factor at 320 K in a facile polyol method prepared non-stoichiometric Cu1+xIn1−xS2 (x = −0.3, −0.2, −0.1, 0, 0.1, 0.2) nanowires with traces of Cu2S has been demonstrated here. Rietveld refinement of powder XRD and Raman analysis confirm these. Field effect scanning electron microscopy (FESEM) study shows micron size CuInS2 spherical particles made up from 8.8 nm diameter with about 35 nm length nanowires. The dramatic increase in electrical conductivity and hence thermoelectric performance with increasing x is attributed to the formation of defects, Cu2S, and increase in carrier concentrations. The power factor reaches a high of 0.8 μW m−1 K−2 at 320 K and an electrical conductivity of 2800 S/m, which is about 35 and 250 times higher, respectively, than that of pure CuInS2 and hot-pressed Bi2S3 nanorods respectively at this temperature. These results expect high-power factor improvement for power production in the future.

In situ phase transformation of polytypic zinc-blende/wurtzite copper indium sulfide via a facile polyol method to boost visible-light photocatalytic performance

A zinc-blende/wurtzite (ZB/WZ) copper indium sulfide (CuInS2/CIS) polymorph with high visible-light absorption ability and high charge separation rate was developed by using a facile polyol method. Results showed that when thioacetamide served as a sulfur precursor, the crystalline phase of CIS was zinc-blende. Meanwhile, when thiourea served as a sulfur precursor, the crystalline phase of CIS was wurtzite, which exhibited good photocatalytic acid red 1 (AR1) dye decolorization efficiency. When the precursor/ethylene glycol ratio was 1/50–7/50, the AR1 decolorization efficiency followed the order: T-5-CIS > T-7-CIS > T-3-CIS > T-1-CIS, and the TOC removal efficiency of T-5-CIS was 45.7%. The PL and EIS analyses indicated that T-5-CIS showed the highest charge separation rate. Mott–Schottky analysis demonstrated that the remarkably enhanced photocatalytic decolorization rate was ascribed to the stronger reduction potential of CIS with the mixed ZB/WZ phases and the redox potential difference between the ZB and WZ phases, leading to a good oxidation ability and charge separation. The results indicated that O2− was the main reactive specie in this study, and this study provided a potential photocatalyst in the treatment of dye wastewater.

Hollow flower-like nickel particles as the promoter of ammonium perchlorate-based solid propellant

Hollow flower-like nickel particles were prepared by a facile polyol method, and applied to solid propellant as combustion promoter. Ni[C2H4(NH2)2]3(COOH)2 complex was used to fabricate hollow flower-like intermediate in ethylene glycol (EG), and then the intermediate was calcined and auto-reduced in nitrogen to obtain the hollow flower-like nickel particles. The hollow particles' shell thickness is about 120 nm, and the petals' thickness of the flower structure is about 10 nm. Importantly, the hollow spheres' diameter can be accurately controlled from 200 nm to 2 μm by adjusting the concentration of complex Ni[C2H4(NH2)2]3(COOH)2 in the reaction solution. The growth of the hollow flower-like particles was illustrated as an extraordinary growth-shrink-collapse process by analyzing the intermediate's morphologies as reaction going on. By adding a certain amount (typically 5 wt%) of the prepared nickel powders, the exothermic decomposition of ammonium perchlorate, which is the main component of solid propellant, was well promoted. The decomposition temperature was decreased by about 140 °C, and the exothermic peak at higher temperature shifted to the lower temperature range, heat released of AP's decomposition also increased by about 150%.

Enhanced activity and durability of Pt nanoparticles supported on reduced graphene oxide for oxygen reduction catalysts of proton exchange membrane fuel cells

• ∼3 nm sized Pt nanoparticles supported on rGO using a facile polyol method. • Systematic XPS analyses for oxygen related functional concentration investigations. • Pt/rGO with superior catalytic activity and durability as 1.6 and 3.8 times higher than that of Pt/CB. Proton exchange membrane fuel cells (PEMFCs) are mainly used as a power source of hydrogen fuel cell vehicles. Also, their catalytic activity and durability of oxygen reduction reaction are important because they operate at high voltage and strongly acidic conditions. In this research, we studied the characteristics of the Pt nanoparticles (NPs) supported on the graphene oxide (GO), partially reduced graphene oxide (GO-r), and reduced graphene oxide (rGO) to investigate the enhancement of the activity and durability of oxygen reduction catalysts for PEMFCs. Pt catalysts supported on carbonaceous materials were synthesized through a facile polyol method, and the characteristics of the synthesized catalysts were analyzed with transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and Raman spectroscopy. The outcomes demonstrated that the rGO was superior to the carbon black support in oxygen reduction activity and long-term durability. Here, the reduced concentration of oxygen related functional groups on the graphene support was the key factor to enhance the oxygen reduction properties and long-term durability of the Pt/rGO catalyst.

Tuning hyperthermia properties of FeNiCo ternary alloy nanoparticles by morphological and magnetic characteristics

While the research field of hyperthermia has long focused on magnetic oxides and two-component alloy nanostructures, ternary magnetic alloy nanoparticles (NPs) have not been thoroughly investigated and understood so far. In this study, we synthesized FeNiCo ternary alloy NPs with variable compositions by a facile polyol method. By investigating morphological and magnetic properties using field-emission scanning electron microscopy, hysteresis loop measurements and first-order reversal curve analysis, we found average NP size, saturation magnetization, coercivity (HC) and coercive field distribution (ΔHc) to range between ~60–230 nm, 65–109 emu/g, 33–98 Oe and 0–650 Oe, respectively. Hyperthermia measurements were performed under an alternating magnetic field with intensity of 400 Oe at a frequency of 400 kHz, leading to maximum specific loss power (SLP) values ranging from 237 to 298 W/g in an ethylene glycol medium with concentrations of 5–1 mg/ml, respectively. By comparing between results of average NP size, HC and ΔHc, our study indicates the possibility of tuning SLP by morphological and magnetic characteristics for potential hyperthermia applications.

Ag-Nanoinclusion-Induced Enhanced Thermoelectric Properties of Ag2S

The effects of Ag nanoinclusions on thermoelectric properties of Ag2S semiconducting nanostructures, synthesized by a novel one-pot facile polyol method, have been investigated. The resulting produ...

A spinel MnCo2O4/NG 2D/2D hybrid nanoarchitectures as advanced electrode material for high performance hybrid supercapacitors

Supercapacitors suffer from lack of energy density and to achieve better energy density, a new class of hybrid architectures with controlled morphology is prerequisite. Here, a facile polyol method is successfully used for the synthesis of MnCo2O4/nitrogen doped graphene 2D/2D hybrid nanoarchitectures and this combination successfully avoids the restacking and agglomeration of nitrogen−doped graphene nanosheets. The formation of MnCo2O4/NG 2D/2D hybrid nanoarchitectures are confirmed by state−of−art techniques. This combination leads to a large conducting network that improves the exposure of active sites at the electrode−electrolyte interface for the transportation of electrons and ions. The synergistic effect of 2D MnCo2O4 nanoflakes over the 2D nitrogen−doped graphene serves the capacitance of ca. 1170 F g−1 at 1 A g−1 with an excellent rate capability of 818 F g−1 at 20 A g−1. An asymmetric supercapacitor is successfully fabricated using these MnCo2O4/NG 2D/2D hybrid nanoarchitectures as the cathode and 2D nitrogen−doped graphene as the anode electrodes, which exhibits better performance than previously reported spinel metal oxide materials. The asymmetric supercapacitor exhibits excellent energy density (∼48.5 Wh kg−1 at ∼808 W kg−1) and power density (∼16000 W kg−1 at ∼32.1 Wh kg−1), with an outstanding cyclic durability of 85.9% retention after 10,000 cycles.

Thermoelectric properties of Ag-doped CuS nanocomposites synthesized by a facile polyol method.

We report the first thermoelectric properties of Cu1-xAgxS, x = 0-0.75 nanocomposites, synthesized by using a facile polyol method. Systematic characterizations using powder XRD, Rietveld refinement of XRD, EDAX, XPS and Raman spectroscopy confirmed their single phase, hexagonal crystal structure with the space group P63/mmc, nominal elemental composition, valence states of the constituent elements and stoichiometric nature. The TEM images showing the CuS formation of nearly perfect hexagonal disk-like particles of average thickness 26.7 nm and breadth ranging in a few hundreds of nanometers with nanorods stacked from these hexagonal nanodisks (NDs) elongated along the c axis corroborate the FESEM images. Attributed to structural phase transition, an anomaly at 55 K is clearly observed in both the thermopower and Hall resistivity data. By increasing x, a systematic reduction in thermal conductivity was observed near 300 K. Consequently, a 50% enhancement in figure of merit was observed for Cu0.9Ag0.1S as compared to pure CuS at 300 K. These results therefore are expected to provide a new direction in improving ZT near 300 K.

Electrochemical performances of LiNi1−xMnxPO4 (x = 0.05–0.2) olivine cathode materials for high voltage rechargeable lithium ion batteries

This study demonstrated to synthesis of carbon-free lithium nickel phosphate (LiNiPO4) and its analogue of manganese doped LiNi1−xMnxPO4 (x = 0.05–0.2) cathode materials by a facile polyol method and their suitability for use in high voltage lithium ion batteries (LIBs). The physicochemical properties were analyzed using X-ray diffraction, Fourier transform infra-red, Raman, field emission scanning electron microscopy (FE-SEM), energy dispersive analysis by X-ray (EDX), and electrochemical studies. FE-SEM showed that the spherical shape particles were uniformly distributed on the surface and EDX confirmed the presence of all the elements in the LiNi1−xMnxPO4 nanostructure. Substitution of Mn dopants with LiNiPO4 significantly improved the electrical and electrochemical performances for LiNi1−xMnxPO4 (x = 0.05–0.2) cathodes. The highly conducting LiNi1−xMnxPO4 (x = 0.1) cathode exhibited initial discharge capacity of 94.2 mA h g−1 at C/4 rate, and 62% capacity retention after 100 cycles between 2.8 and 5.6 V. These features promote LiNi1−xMnxPO4 as a suitable cathode material for high voltage LIBs.

Ternary tin selenium sulfide (SnSe0.5S0.5) nano alloy as the high-performance anode for lithium-ion and sodium-ion batteries

Metal sulfides have received tremendous attention due to their superior electrochemical performance. In this study, it is the first time that the ternary tin selenium sulfide, SnSe0.5S0.5, is investigated as a potential high-performance anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The SnSe0.5S0.5/C nanocomposites have also been synthesized through a facile polyol-method followed by a simple hydrothermal process and subsequent sintering. The material demonstrated a high specific capacity and a long-term cycling stability in both Li-ion and Na-ion batteries (625mAhg−1 for LIB at 500mAg−1 rate after 1000 cycles, 430mAhg−1 in a SIB at 200mAg−1 rate after 100 cycles). Furthermore, the kinetic analysis of Li-ions and Na-ions storage revealed that the extrinsic pseudocapacitive contribution could improve the charge transfer rate during the insertion and extraction of Li-ion and Na-ion, thus enhancing the rate performance and cycling stability. These results demonstrated that the novel tin selenium sulfide (SnSe0.5S0.5) material could potentially be an excellent anode material for Li-ion storage and Na-ion storage.

Growth of silver nanowires on carbon fiber to produce hybrid/waterborne polyurethane composites with improved electrical properties

ABSTRACTOne dimensional silver nanowires (AgNWs) were grown on carbon fiber (CF) by a facile polyol method. Fourier transform infrared spectrometer (FTIR), laser Raman spectrometer (Raman), field‐emission scanning electron microscopy (FESEM), X ray diffraction instrument (XRD), energy dispersive spectrometer (EDS), and X‐ray photoelectron spectrometer (XPS) were carried out to reveal the structure, morphology, and formation mechanism of the CF‐AgNWs. It was found that AgNO3 concentration of 1.5 mM, reaction temperature of 160°C, and reaction time of 120 min were appropriate conditions for growth of AgNWs on CF. Moreover, a mechanism was suggested that the cysteamine on CF acted as nucleation centers for growth of silver nanoparticles and then small sized silver nanoparticles reduced from silver nitrate were grown on CF via the silver bonding to sulfur. Through an Ostwald ripening process, small sized silver nanoparticles were grown into larger particles. With the assistance of polyvinylpyrolidone (PVP), these larger particles were directed to grow in a definite direction to form nanowires. It was found that the resistance of CF‐AgNWs was decreased to 19.5 Ω, compared with that of CF (102.6 Ω) with the same quality. Thus, the CF‐AgNWs was added into waterborne polyurethane (WPU) to improve the electrical and dielectric properties of WPU. Results showed the WPU/CF‐AgNWs composite presented a lower percolation threshold than WPU/CF composite. When the content was 2.5 wt %, the volume resistivity of the WPU/CF‐AgNWs (1.90 × 104 Ω cm−1) was lower by approximately three orders of magnitude than that of WPU/CF (4.19 × 107 Ω cm−1). When the content was 2.5 wt %, the dielectric constant and dielectric loss of the WPU/CF‐AgNWs were improved to 15.24 and 0.21, which were 34.5 and 40.8% higher than that of WPU/CF. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43056.

Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra.The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.

Synthesis, characteristics and sonocatalytic activities of calcined γ-Fe2O3 and TiO2 nanotubes/γ-Fe2O3 magnetic catalysts in the degradation of Orange G

In this work, γ-Fe2O3 and TiO2 NTs/γ-Fe2O3 composites with good magnetism and sonocatalytic activity were prepared by a facile polyol method and utilize the principle of isoelectric point method, respectively. The structural and magnetic features of the prepared calcined γ-Fe2O3 and composite catalysts were investigated by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), surface analysis, UV–Vis diffuse reflectance spectra (UV–Vis DRS), vibrating sample magnetometry (VSM) and zeta potential analysis. The effects of calcination temperature on γ-Fe2O3 phase variation, physical properties and sonocatalytic properties were investigated. The porosity, specific surface area, band gap energy and sonocatalytic activity of γ-Fe2O3 were gradually decreased with calcination temperature increased. TiO2 NTs/γ-Fe2O3 with appropriate composition and specific structural features possess synergetic effects such as efficient separation of charge carriers and hydroxyl radicals produced by heterogeneous fenton and fenton-like reactions. This enhanced the sonocatalytic activity for the degradation of Orange G under ultrasonic irradiation. The sonocatalytic reactions obeyed pseudo first-order kinetics. All these information provide insight into the design and development of high-efficiency catalyst for wastewater treatment.

Cu2S nanoparticles modified 3D flowerlike Bi2WO6: Enhanced photoelectric performance and photocatalytic degradation

Cu2S nanoparticles (NPs) modified three-dimensional (3D) flowerlike Bi2WO6 photocatalysts were prepared via a facile polyol method. The NPs Cu2S/Bi2WO6 showed strong visible light absorption and enhanced visible-light activity for Rhodamin B (RhB) degradation. Compared to pure Bi2WO6, the NPs Cu2S/Bi2WO6 showed lower charge-transfer resistance, higher photocurrent intensity and enhanced photoelectric properties. The significant enhancement of photocatalytic activity was attributed to the synergetic effects between Cu2S NPs and flowerlike Bi2WO6 and improved separation of charge carriers.

Synthesis of TiO2 and ZnO Nanoparticles by Facile Polyol Method for the Assessment of Possible Agents for Seed Germination

Present work deals with ZnO and TiO2 metal oxides synthesis, characterization and application of seed germination. Synthesis of metal oxide nanoparticles can be done through three methods like physical, chemical, and biological methods. In this chemical method is simple and rapid. Hence, polyol method is used for synthesis of metal oxide nanoparticles. It is the synthesis of metal-containing compounds in polyethylene glycols. Zinc acetate and Titanium isopropoxide as the precursor materials for synthesis of ZnO and TiO2 respectively. The ethylene glycol acts as both the solvent and reducing agent. The samples were characterized by X-ray diffraction (XRD), Particle Size Analyzer (PSA), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). These Nanoparticles are used during the seed germination and root growth of various seeds and effect of the nanoparticles has been observed.

Ultra-high stability and durability of iron oxide micro- and nano-structures with discovery of new three-dimensional structural formation of grain and boundary

In this research, we have applied a facile polyol method with the addition of NaBH4 to synthesize polyhedral α-Fe2O3 oxide microparticles with the large size of 1–10μm at 200–230°C for about 25–30min. The sharp polyhedral shapes and morphologies have been formed in the good assistance of NaBH4 as versatile strong reducing agent. The sharp polyhedral and large Fe oxide microparticles exhibited a uniform characterization of size, shape and morphology with the pure α-Fe2O3 structure. To study durability and stability of the microparticles under temperature, we have rationally carried out isothermal heat treatment of the prepared α-Fe2O3 oxide microparticles at high annealing temperature about 500°C and 900–910°C for 1h. A new structure was found in the pure α-Fe2O3 particles with micro- and nano-structure co-existed with the very good formation of a three-dimensional (3D) structure with the oxide grains and the boundaries. The interesting phenomena of the deformation of surface, size, shape, and structure are discovered in α-Fe2O3 oxide microparticles by isothermal heat treatment. Apart from surface deformation, the new micro- and nano-structure of large α-Fe2O3 microparticles cannot be destroyed but they can be retained in their specific characteristics of size, shape, and morphology because of both plastic and elastic deformation co-existed. The interesting surface deformation by heat treatment is observed in comparison with the case without heat treatment. The typical magnetic properties of α-Fe2O3 microparticles were investigated in the appearance of grain and boundary. Finally, our proposal of the new technologies with particle heat treatment is very crucial to make novel micro- and nano-structures of ultra-high durability and stability with the grains and the boundaries that can be utilized in catalysis, energy and environment for future.

Polyol mediated synthesis of ZnO nanoparticles templated by bacterial cellulose

Zinc oxide nanoparticles have been successfully synthesized through a facile polyol method using bacterial cellulose (BC) as a template. BC membrane was used as a host matrix to introduce quantitatively Zn2+ ions and then as nanoreactors to fabricate ZnO nanoparticles by hydrolysis of zinc acetate in a polyol medium. The influence of the concentration of zinc acetate and hydrolytic time on the morphologies and size of ZnO nanoparticles were investigated. The results indicated that the uniform spherical ZnO nanoparticles were incorporated into BC fibers. The resulting nanocomposites show good mechanical properties and high photocatalytic activity in the degradation of methyl orange.

Tunable synthesis of carboxyl-functionalized magnetite nanocrystal clusters with uniform size

It is essential to tune the physicochemical properties of magnetic nanomaterials for their biomedical applications. Herein we report a facile polyol method to synthesize the carboxyl-functionalized magnetite nanocrystal cluster (CMNC) with tunable size and high magnetization. Through introduction of urea as a homogeneous precipitator, the formation of magnetite nanocrystal clusters is facilitated compared to the previous reports. These magnetic clusters, with uniform size and good colloidal stability in water, have a magnetization over 70 emu g−1. The effect of the stabilizer (sodium citrate) on the physicochemical properties of clusters is studied systematically in the polyol process. By simply changing the concentration of sodium citrate in the reaction from 0.001 M to 0.1 M, the diameter of the CMNC can be tuned from approximately 300 nm to 40 nm. The variation of the concentration of sodium citrate also gave rise to a change of the size of the subunits, the surface charge and the magnetization of the clusters due to the adsorption of the citrate molecules on the magnetite nanocrystal clusters. The tuning effect of sodium citrate on the size of CMNCs was attributed to the interaction of different forces in the polyol process: the electrostatic repulsion and the surface tension.