津田 哲哉

Auイオンを溶かしたイオン液体に量子線（低速電子線、X線）を照射し、Au微粒子を還元析出させることに成功した。微粒子の形状や形は電子線の加速電圧やイオン液体種の局所構造などに大きく依存する。また、担体のナノ細孔内でX線還元析出を行うことにより、高分散で安定な金属微粒子を担持させることに成功した。イオン液体を用いたこの新しい微粒子形成法は、従来の手法では不可能だった金属種や合金の微粒子が形成出来る可能性を秘めている。

Pt nanoparticles can be produced by a Pt sputtering method onto trimethyl-n-propylammonium bis((trifluoromethyl)sulfonyl)amide (Me3PrNTf2N) room-temperature ionic liquid (RTIL) without stabilizing agents. Pt nanoparticles obtained by the Pt sputtering method showed mean particle size of ca. 2.3-2.4 nm independently of sputtering time. A Pt-embedded glassy carbon electrode (Pt-GCE) consisting of the Pt-sputtered RTIL and a glassy carbon plate showed a favorable catalytic activity to oxygen reduction reaction. The catalytic ability was enhanced by Me3PrNTf2N modification of the Pt-GCE. In addition, carbon monoxide never absorbed onto the RTIL-modified Pt-GCE. © 2009 Elsevier B.V. All rights reserved.

Pt nanoparticles can be produced by a Pt sputtering method onto trimethyl-n-propylammonium bis((trifluoromethyl)sulfonyl)amide (Me3PrNTf2N) room-temperature ionic liquid (RTIL) without stabilizing agents. Pt nanoparticles obtained by the Pt sputtering method showed mean particle size of ca. 2.3-2.4 nm independently of sputtering time. A Pt-embedded glassy carbon electrode (Pt-GCE) consisting of the Pt-sputtered RTIL and a glassy carbon plate showed a favorable catalytic activity to oxygen reduction reaction. The catalytic ability was enhanced by Me3PrNTf2N modification of the Pt-GCE. In addition. carbon monoxide never absorbed onto the RTIL-modified Pt-GCE. (C) 2009 Elsevier B.V. All rights reserved.

Palladium acetate was noncovalently immobilized as a supported ionic liquid catalyst (SILC) in a nanosilica dendrimer, PAMDMAM, with the aid of an ionic liquid to form a cluster catalyst of palladium nanoparticles. The pseudo-homogeneous heterogenized catalyst, Pd-nanoPAMDMAM-SILC, was effective for Suzuki-Miyaura reactions of ortho-substituted aryl bromides or aryl triflates without a ligand in 50% aqueous ethanol in air at room temperature. The catalyst could be re-used up to five times in 93% average yield after simple centrifugation. TON reached 176,000.

Ionic liquids (ILs) including ambient-temperature molten salts, which exist in the liquid state even at room temperature, have a long research history. However, their applications were once limited because 1 Ls were considered as highly moisture-sensitive solvents that should be handled in a glove box. After the first synthesis of moisture-stable ILs in 1992, their unique physicochemical properties became known in all scientific fields. ILs are composed solely of ions and exhibit several specific liquid-like properties, e.g., some ILs enable dissolution of insoluble bio-related materials and the use as tailor-made lubricants in industrial applications under extreme physicochemical conditions. Hybridization of ILs and other materials provides quasi-solid materials, which can be used to fabricate highly functional devices. ILs are also used as reaction media for electrochemical and chemical synthesis of nanomaterials. In addition, the negligible vapor pressure of ILs allows the fabrication of electrochemical devices that are operated under ambient conditions, and many liquid-vacuum technologies, such as X-ray photoelectron spectroscopy (XPS) analysis of liquids, electron microscopy of liquids, and sputtering and physical vapor deposition onto liquids. In this article, we review recent studies on ILs that are employed as functional advanced materials, advanced mediums for materials production, and components for preparing highly functional materials © 2010 WILEY-VCH Verlag GmbH &amp Co. KCaA.

A simple and robust method to prepare nanciparticle-dispersed liquid crystals is demonstrated. Highly dispersed gold nanoparticle-liquid crystal suspensions are fabricated by simply sputter doping the gold target on the host liquid crystal (see figure). The existence of the nanoparticles is supported by optical extinction measurements, polarization optical microscopy, and transmission electron microscopy. An improvement in the electro-optic response, namely, a decrease in the threshold voltage, is also demonstrated in twist nematic devices fabricated using the nanoparticle-dispersed liquid crystal.

金属イオンを溶かしたイオン液体にUHV中でX線を照射し、照射時間に対するイオン液体表面の化学状態の変化を光電子分光法を用いて観察した。時間経過と共に溶解した金属イオン濃度が大きく減少し、これはX線照射によって生じた二次電子によって金属微粒子として還元析出したためと思われる。析出した金属微粒子の形状やサイズはSEMを用いて観察した。これらの結果から、X線照射によるイオン液体中における金属イオンの還元プロセスについて考察を行った。

Metal nanoparticles were prepared with gamma-ray and accelerator electron beam irradiation in the 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (BuMeIm(+)Tf(2)N(-)) room-temperature ionic liquids. As for Au nanoparticles yielded in this investigation, the gamma-ray irradiation made the particle size smaller compared to that by the accelerator electron beam irradiation. It is interesting to note that the nanoparticles prepared in this article were very stable although the surface was not covered with a stabilizing agent, which is usually employed so as to prevent aggregation. Similarly, other metal nanoparticle productions such as Ag, Cu, Mg, Al, Zn, and Fe were also investigated by means of the accelerator electron beam irradiation. In addition, some RTILs with Au nanoparticles yielded by the irradiation experiment showed fluorescent behavior under ultraviolet irradiation of 365 nm. It implies that the RTILs contain Au nanoparticles as well as Au clusters that cannot be observed by a common TEM system. In this study, we also found that the Si wafer, on which NaAuCl4 center dot 2H(2)O-added RTIL was spread, has distinctive two-dimensional Au microstructure crystals on the surface after the accelerator electron beam irradiation.

The electrochemistry of Cu(I) oxide (Cu(2)O) was examined in the 66.7-33.3% mole fraction (m/o) urea-choline chloride melt. Electrochemical parameters that were measured include the standard heterogeneous rate constant and transfer coefficient of the Cu(I)/Cu(II) reaction and the Cu(I) diffusion coefficient. Data about the density, equivalent conductance, and absolute viscosity of this melt were obtained over the temperature range of 298-353 K. The conductivity and viscosity exhibited the non-Arrhenius behavior typical of glass-forming liquids. Overall, the physicochemical properties of the urea-choline chloride melt are comparable to those of common room-temperature ionic liquids. The electrodeposition of Cu was examined on glassy carbon and platinum electrodes by using potential-step techniques. The critical number of atoms required for the formation of a stable nucleus on glassy carbon was similar to 0, indicating that active sites on the electrode surface served as critical nuclei. Cu deposits on Ni substrates were dense, nodular, and compact. (C) 2010 The Electrochemical Society. [DOI:10.1149/1.3377117] All rights reserved.

The electrodeposition of ternary Al-Mo-Ti alloy was examined in the Lewis acidic 66.7-33.3 percent mole fraction aluminum chloride–1-ethyl-3-methylimidazolium chloride (AlCl₃–EtMeImCl) room-temperature ionic liquid containing both (Mo₆Cl₈)Cl₄ and TiCl₂. All of the electrodeposited Al-Mo-Ti alloys were dense and compact, and they adhered well to the copper substrate. In simulated body fluid, e.g., Ringer's solution, the Al-Mo-Ti alloy showed better corrosion resistance than pure nickel although it was somewhat inferior to 316 L stainless steel that is one of typical metallic biomaterials. Open circuit experiments in Ringer's solution suggested that amorphous Al-Mo alloy is superior to Al-Ti and Al-Mo-Ti alloys as a metallic biomaterial because of the formation of more stable passivation layer.

The specific conductivity of a polymer-room-temperature ionic liquid (RTIL) composite composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and 1-butyl-3-methylimidazolium bis((trifluoromethyl) sulfonyl) amide (BuMeImTf(2)N) was less than neat RTIL because of an increase in activation energy estimated from Arrhenius plot, which implies that there is an unignorable interaction between the polymer matrix and the RTIL. Electrochemical reactions in the PVdF-HFP-BuMeImTf(2)N composite with negligible vapor pressure were investigated by the use of in situ electrochemical scanning electron microscope (ECSEM) system. Those reactions include Ag electrodeposition and actuation behavior. The results suggested that in situ ECSEM technique has the great possibility to be a future electroanalytical chemical method.

The authors report the expansion of the temperature range of cholesteric blue phases by doping nanoparticles. When spherical gold nanoparticles with a mean diameter of 3.7 nm were doped in a blue phase-exhibiting multi-component liquid crystal mixture, the temperature range of the cholesteric blue phase increased from 0.5 to 5 degrees C, while the clearing temperature decreased by approximately 13 degrees C. We believe that the mechanism stabilizing the cholesteric blue phase is similar to that of polymer-stabilized cholesteric blue phases: the nanoparticles accumulate in the lattice disclinations, stabilizing the overall cholesteric blue structure. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/APEX.2.121501

Platinum (Pt) nanoparticles were synthesized with room-temperature ionic liquid (RTIL)-sputtering method under dry N-2 or Ar atmosphere. The resulting Pt nanoparticles were well-dispersed in trimethyl-n-propylammonium bis((trifluoromethyl)sulfonyl)amide RTIL without any additive like dispersant. Electrocatalytic activity of the Pt nanoparticles embedded on a glassy carbon electrode (GCE) toward oxygen reduction reaction was examined. It was then found that the catalytic activity increases with increment of heat temperature for embedding the Pt nanoparticles onto GCE if the nanoparticles are synthesized under Ar atmosphere.

液晶は通常、有機分子からなり、異方性と流動性を示すが、金属や無機のナノ粒子を添加することによりその特性が変化することが知られている。本研究では金属ナノ粒子をネマティック液晶にドープすることで誘起されるスペクトル・相転移点・誘電特性の変化を調べた。またネマティック液晶以外の液晶についてもナノ粒子ドープによって引き起こされる物性の変化を調べた。

Mass production of gold nanoparticles in room-temperature ionic liquids without any stabilizing agents has been achieved with radiation irradiation, i.e., accelerated electron beam and gamma-ray.

Mass production of gold nanoparticles in room-temperature ionic liquids without any stabilizing agents has been achieved with radiation irradiation, i.e., accelerated electron beam and γ-ray. © 2009 The Royal Society of Chemistry.