The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Masaharu Tsuji - One of the best experts on this subject based on the ideXlab platform.
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syntheses of ag cu alloy and ag cu alloy core cu shell nanoparticles using a Polyol Method
CrystEngComm, 2010Co-Authors: Masaharu Tsuji, Sachie Hikino, Ryuichi Tanabe, Mika Matsunaga, Yoshiyuki SanoAbstract:Ag–Cu bimetallic nanoparticles were prepared by reducing mixtures of AgNO3 and Cu(OAc)2·H2O in ethylene glycol (EG) in the presence of poly(vinylpyrrolidone) (PVP) at 175 °C for 5–60 min. At high [Ag]/[Cu] molar ratios of 1 and 2 or at a short reaction time below 5 min, Ag rich Ag/Cu alloy particles were formed. On the other hand, at low [Ag]/[Cu] molar ratios of 0.25 and 0.5 or a long reaction time above ≈15 min, Cu shells were overgrown on Au/Cu cores and new Ag/Cu alloy core Cu shell nanoparticles, denoted as Ag/Cu@Cu, were produced. The formation of Ag/Cu and Ag/Cu@Cu particles was examined using energy dispersed X-ray spectroscopic (EDS) measurements. The growth mechanisms of Ag/Cu and Ag/Cu@Cu particles are discussed on the basis of TEM-EDS and ultraviolet (UV)-visible (Vis)-near infrared (NIR) extinction spectral data. The time dependence of UV-Vis spectra indicated that the Cu component of Ag/Cu@Cu particles has higher antioxidized property than that of Cu and Cu@Ag particles.
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rapid and high yield synthesis of silver nanowires using air assisted Polyol Method with chloride ions
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2009Co-Authors: Xinling Tang, Masaharu Tsuji, Michiko Nishio, Peng Jiang, Sang Min Jang, Seong Ho YoonAbstract:Abstract Effects of gas bubbling were studied for synthesis of silver nanostructures from a mixture of AgNO 3 /NaCl/poly(vinylpyrrolidone) (PVP) in ethylene glycol (EG). Monodispersed silver nanowires were synthesized under oil-bath heating in high yield (>90% without isolation) using bubbling of air through a reagent solution from ca. 20 °C to the boiling point of EG (198 °C) for 20 min. On the other hand, mixtures of cubes, bipyramids, and wires were prepared under bubbling of N 2 . The Ag nanostructures’ growth mechanism was studied by observing ultraviolet–visible (UV–vis) spectra and transmission electron microscope (TEM) images at various temperatures. Results show that the formation process of Ag nanostructures under gas bubbling is separable into two stages: a low temperature range of 20–180 °C at 0–17 min, where mixtures of variously shaped Ag seeds are produced independent of the bubbling gas; and a high temperature range of 180–198 °C at 17–20 min, where rapid growth of nanowires and oxidative etching of cubes and bipyramids by Cl − /O 2 occur simultaneously in bubbling of air, thereby producing long nanowires in high yield. Because the etching process is absent during processing by bubbling of N 2 , mixtures of shorter nanowires, cubes, and bipyramids are produced.
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roles of pt seeds and chloride anions in the preparation of silver nanorods and nanowires by microwave Polyol Method
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Masaharu Tsuji, Kisei Matsumoto, Peng Jiang, Ryoichi Matsuo, Xin Lin Tang, Khairul Sozana Nor KamarudinAbstract:Abstract Silver (Ag) nanomaterials with well-defined crystal structures have been rapidly synthesized in three minutes by a microwave (MW)-Polyol Method. Various precursors such as H 2 PtCl 6 and Pt(acac) 2 have been used to detect real roles of Pt seeds and anions for the formation of the Ag nanomaterials. Furthermore, effect of Cl − anions to final morphologies of the Ag nanostructures has also been explored by pre-adding Cl − precursor such as NaCl or KCl in the ethylene glycol (EG) solutions only including AgNO 3 and poly(vinylpyrrolidone) (PVP). The experimental results show that pre-formed metallic Pt seeds are probably not responsible for nucleation and subsequent evolution of 1D Ag products, but Cl − ions indeed influence the formation of the 1D Ag nanostructures as well as perfect crystallization of other Ag nanoparticles with well-defined crystal structures including single- and twinned-FCC crystals. It has been further evidenced that the presence of Cl − ions can accelerate re-dissolution of formed spherical Ag particles and is favorable to the growth of the 1D Ag and other Ag nanostructures with well-defined crystal structures such as single-crystal cubes and twinned bi-pyramids in the MW-assisted Polyol reduction process. At the same time, it also indicates that H 2 PtCl 6 probably does not act as a nucleation agent for the 1D Ag products but as a precursor of Cl − ions to affect final morphologies of the Ag products. Possible factors affecting shape-selected process of the Ag nanostructures have been discussed in detail.
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rapid synthesis of silver nanostructures by using microwave Polyol Method with the assistance of pt seeds and polyvinylpyrrolidone
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007Co-Authors: Masaharu Tsuji, Yuki Nishizawa, Takeshi Tsuji, Kisei Matsumoto, Nobuhiro Miyamae, Xu ZhangAbstract:Silver nanostructures have been synthesized by a microwave (MW)-Polyol Method. When AgNO3 was reduced by ethylene glycol (EG) in the presence of Pt seeds and polyvinylpyrrolidone (PVP), mixtures of one-dimensional (1-D) nanorods and nanowires, 2-D nanosheets and nanoplates, and 3-D spherical and cubic nanoparticles were prepared within a few minutes. It was found that morphologies and sizes of silver nanostructures depended strongly on such experimental parameters as concentrations of Pt, PVP, and AgNO3, and heating time. Possible growth mechanism of each silver nanostructure was discussed. The growth mechanism of nanorods was especially discussed on the basis of crystal structure of rod type of Au core-Ag shell nanoparticle.
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rapid preparation of silver nanorods and nanowires by a microwave Polyol Method in the presence of pt catalyst and polyvinylpyrrolidone
Crystal Growth & Design, 2007Co-Authors: Masaharu Tsuji, Kisei Matsumoto, Nobuhiro Miyamae, And Takeshi Tsuji, Xu ZhangAbstract:Silver nanorods and nanowires have been synthesized by using a microwave (MW)-Polyol Method. When AgNO3 was reduced by ethylene glycol (EG) in the presence of Pt seeds and a long chain length of poly(vinylpyrrolidone) (PVP: Mw = 360 k), mixtures of one-dimensional (1-D) silver nanorods and nanowires and three-dimensional (3-D) spherical, triangular-bipyramidal, and cubic nanoparticles were synthesized within a few minutes. The average diameters, lengths, and yields of these products were measured as a function of concentration of Pt, PVP, or AgNO3, heating time, or MW power to determine optimum conditions for the synthesis of 1-D products. 1-D products could be easily separated from other 3-D nanoparticles by repeating centrifugal separation in water. Longer and thicker 1-D products could be prepared by using 1-D products as seeds and repeating the reduction of AgNO3 in EG under MW irradiation. In this two-step preparation, some bent 1-D wires due to the combination of {111} facets of two rods and wires ...
Xu Zhang - One of the best experts on this subject based on the ideXlab platform.
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rapid synthesis of silver nanostructures by using microwave Polyol Method with the assistance of pt seeds and polyvinylpyrrolidone
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007Co-Authors: Masaharu Tsuji, Yuki Nishizawa, Takeshi Tsuji, Kisei Matsumoto, Nobuhiro Miyamae, Xu ZhangAbstract:Silver nanostructures have been synthesized by a microwave (MW)-Polyol Method. When AgNO3 was reduced by ethylene glycol (EG) in the presence of Pt seeds and polyvinylpyrrolidone (PVP), mixtures of one-dimensional (1-D) nanorods and nanowires, 2-D nanosheets and nanoplates, and 3-D spherical and cubic nanoparticles were prepared within a few minutes. It was found that morphologies and sizes of silver nanostructures depended strongly on such experimental parameters as concentrations of Pt, PVP, and AgNO3, and heating time. Possible growth mechanism of each silver nanostructure was discussed. The growth mechanism of nanorods was especially discussed on the basis of crystal structure of rod type of Au core-Ag shell nanoparticle.
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rapid preparation of silver nanorods and nanowires by a microwave Polyol Method in the presence of pt catalyst and polyvinylpyrrolidone
Crystal Growth & Design, 2007Co-Authors: Masaharu Tsuji, Kisei Matsumoto, Nobuhiro Miyamae, And Takeshi Tsuji, Xu ZhangAbstract:Silver nanorods and nanowires have been synthesized by using a microwave (MW)-Polyol Method. When AgNO3 was reduced by ethylene glycol (EG) in the presence of Pt seeds and a long chain length of poly(vinylpyrrolidone) (PVP: Mw = 360 k), mixtures of one-dimensional (1-D) silver nanorods and nanowires and three-dimensional (3-D) spherical, triangular-bipyramidal, and cubic nanoparticles were synthesized within a few minutes. The average diameters, lengths, and yields of these products were measured as a function of concentration of Pt, PVP, or AgNO3, heating time, or MW power to determine optimum conditions for the synthesis of 1-D products. 1-D products could be easily separated from other 3-D nanoparticles by repeating centrifugal separation in water. Longer and thicker 1-D products could be prepared by using 1-D products as seeds and repeating the reduction of AgNO3 in EG under MW irradiation. In this two-step preparation, some bent 1-D wires due to the combination of {111} facets of two rods and wires ...
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crystal structures and growth mechanisms of au ag core shell nanoparticles prepared by the microwave Polyol Method
Crystal Growth & Design, 2006Co-Authors: Masaharu Tsuji, Nobuhiro Miyamae, Xu Zhang, Seongyop Lim, Kousuke Kimura, Sachie Hikino, Michiko NishioAbstract:Au@Ag core−shell nanocrystals have been synthesized by using a microwave−Polyol Method, and their growth mechanisms have been studied. When HAuCl4·4H2O was reduced in ethylene glycol in the presence of poly(vinylpyrrolidone) (PVP) as a polymer surfactant, a mixture of triangular twin platelike, octahedral, and multiple-twinned decahedral Au nanocrystals, having only {111} facets, was prepared. When Ag+ was reduced by using these Au nanocrystals as seeds, triangular-bipyramidal, cubic, and rod/wire Ag shells, having {100} facets, were overgrown, respectively. It was concluded that morphology changes between Au cores and Ag shells arise from changes in the adsorption selectivity of PVPs from {111} facets of Au to {100} facets of Ag. Total space volumes of Ag shells overgrown on Au cores were on the order of cubes > triangular-bipyramidal crystals > rods and wires. These findings provide general information on the growth mechanism of face-centered cubic (FCC) types of single crystals in the presence of a pol...
Ulrich Simon - One of the best experts on this subject based on the ideXlab platform.
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advances in high throughput screening of gas sensing materials
Applied Surface Science, 2007Co-Authors: Maike Siemons, Tobias J Koplin, Ulrich SimonAbstract:The workflow of a high throughput screening setup for the rapid identification of new and improved gas sensor materials is presented. The Polyol Method was applied to prepare nanoparticulate metal oxides as base materials. These materials have been modified by surface and volume doping. Using multielectrode substrates and high throughput impedance spectroscopy (HT-IS) a wide range of materials could be screened on a short time scale. Selected examples reflect the state of the art for applying HT-IS in search of new selective gas sensing materials.
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workflow for high throughput screening of gas sensing materials
Sensors, 2006Co-Authors: Tobias J Koplin, Maike Siemons, Cesar Ocenvalentin, Daniel Sanders, Ulrich SimonAbstract:The workflow of a high throughput screening setup for the rapid identification of new and improved sensor materials is presented. The Polyol Method was applied to prepare nanoparticular metal oxides as base materials, which were functionalised by surface doping. Using multi-electrode substrates and high throughput impedance spectroscopy (HT-IS) a wide range of materials could be screened in a short time. Applying HT-IS in search of new selective gas sensing materials a NO2-tolerant NO sensing material with reduced sensitivities towards other test gases was identified based on iridium doped zinc oxide. Analogous behaviour was observed for iridium doped indium oxide.
Peng Zhang - One of the best experts on this subject based on the ideXlab platform.
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rapid and facile synthesis of high performance silver nanowires by a halide mediated modified Polyol Method for transparent conductive films
Nanomaterials, 2020Co-Authors: Lin Cao, Qin Huang, Jie Cui, Huaijun Lin, Zhidan Lin, Peng ZhangAbstract:Silver nanowires are receiving increasing attention as a kind of prospective transparent and conductive material. Here, we successfully synthesized high-performance silver nanowires with a significantly decreased reaction time by a modified Polyol Method. The synthesis process involved the addition of halides, including NaCl and NaBr, to control the release rate of Ag+ ions, as Cl− and Br− ions react with Ag+ ions to form AgCl and AgBr with different solubilities. As a result, Ag+ ions could be slowly released by graded dissolution, and the formation of silver nanowires was promoted. The results showed that the concentration of the added halides played an important role in the morphology of the final product. High-quality silver nanowires with an average diameter of 70 nm and average length of 21 μm were obtained by optimizing the reaction parameters. Afterwards, a simple silver nanowire coating was applied in order to fabricate the transparent conductive films. The film that was based on the silver nanowires provided a transmittance of 91.2% at the 550 nm light wavelength and a sheet resistance of about 78.5 Ω·sq−1, which is promising for applications in flexible and transparent optoelectronic devices.
Nikolay Z. Lyakhov - One of the best experts on this subject based on the ideXlab platform.
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synthesis of nickel nanoparticles by the reduction of its salts using the modified Polyol Method in the presence of sodium polyacrylates with various molecular weights
Russian Journal of General Chemistry, 2018Co-Authors: O A Logutenko, A I Titkov, A M Vorobev, Yu M Yukhin, Inna K Shundrina, Nikolay Z. LyakhovAbstract:Nickel nanoparticles were synthesized by the reduction of its salts by hydrazine hydrate in a Polyol medium in the presence of sodium polyacrylates with molecular weights of 1200, 5100, and 8000. The nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy, IR spectroscopy, and thermogravimetric analysis. The effect of the synthesis conditions, such as temperature, molecular weight of sodium polyacrylate, and Polyol and precursor types, on the reduction products were studied. It was shown that the average particle sizes, their aggregation and polydispersity degrees increase as the polymer molecular weight increases.
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effect of molecular weight of sodium polyacrylates on the size and morphology of nickel nanoparticles synthesized by the modified Polyol Method and their magnetic properties
European Polymer Journal, 2018Co-Authors: O A Logutenko, A I Titkov, Yu M Yukhin, Alexander M Vorobyov, D A Balaev, K A Shaikhutdinov, S V Semenov, Nikolay Z. LyakhovAbstract:Abstract Nickel nanoparticles were synthesized by the reduction of nickel chloride with hydrazine hydrate in a Polyol medium in the presence of sodium polyacrylates (Na-PA) having molecular weights (Mw) of 1200, 5100 and 8000. The size and morphology of the resulting nickel nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy. Polymers having lower Mw values were found to be more efficient in reducing the nickel particle size. A decrease in the polymer concentrations yielded the smaller particles. Magnetic measurements showed that the as-prepared powders are ferromagnetic and their saturation magnetization and coercivity are size-dependent. Compared with bulk nickel, the nanoparticles exhibit an enhanced coercivity which is due to their small size and a decreased saturation magnetization resulted from the surface oxidation of the powder. The synthesis procedure offers a simple approach to preparing nickel nanopowders on a large scale which could be used as magnetic recording materials, including high-density memory storage devices.