研究者詳細 - 鳥本　司

論文 - 鳥本　司

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半導体ナノ粒子の組織化と光機能: 量子ドット配列制御による高機能性材料の創製招待有り査読有り

亀山達矢　,鳥本　司

化学と工業 63 巻 ( 4 ) 頁： 327-329 2010年4月

Remarkable Photoluminescence Enhancement of ZnS-AgInS2 Solid Solution Nanoparticles by Postsynthesis Treatment 査読有り

Tsukasa Torimoto,* Shoji Ogawa, Tomohiro Adachi, Tatsuya Kameyama, Ken-ichi Okazaki, Tamaki Shibayama, Akihiko Kudo and Susumu Kuwabata

Chem. Commun. 46 巻 ( 12 ) 頁： 2082-2084 2010年3月

New Frontiers in Materials Science Opened by Ionic Liquids 招待有り査読有り

Tsukasa Torimoto, Tetsuya Tsuda, Ken-ichi Okazaki, Susumu Kuwabata

Adv. Mater. 22 巻 ( 11 ) 頁： 1196-1221 2010年3月

Size Control and Immobilization of Gold Nanoparticles Stabilized in an Ionic Liquid on Glass Substrates for Plasmonic Applications 査読有り

Tatsuya Kameyama, Yumi Ohno, Takashi Kurimoto, Ken-ichi Okazaki, Taro Uematsu, Susumu Kuwabata and Tsukasa Torimoto

Phys. Chem. Chem. Phys 12 巻 ( 8 ) 頁： 1804–1811 2010年2月

Studies on Reaction Conditions for Size-selective Photoetching of Cadmium Telluride Nanocrystals 査読有り

Taro Uematsu, Tsukasa Torimoto, Susumu Kuwabata

Electrochemistry 78 巻 ( 2 ) 頁： 170-174 2010年2月

A Facile Synthesis of AuAg Alloy Nanoparticles Using a Chemical Reaction Induced by Sputter Deposition of Metal onto Ionic Liquids 査読有り

Toshimasa Suzuki, Ken-ichi Okazaki, Tomonori Kiyama, Susumu Kuwabata, and Tsukasa Torimoto

Electrochemistry 77 巻頁： 636-638 2009年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Sputter deposition of silver (Ag) onto an ionic liquid (IL) produced Ag nanoparticles whose size was varied greatly dependent on the sputtering conditions. Change in discharge current from 10 to 40 mA increased Ag particle size from 5.7 to 11 nm, though prolongation of sputtering time simply caused a higher concentration of Ag nanoparticles in IL without change in their size. Sputter deposition of Ag onto IL solutions containing HAuCl4 resulted in the appearance of a single surface plasmon resonance peak in the absorption spectra of the resulting solution, and their peak position was red-shifted with an increase in the concentration of HAuCl4. The obtained results clearly indicated that Ag metal species sputter-deposited in IL can reduce HAuCl4 to give AuAg alloy nanoparticles and that their chemical composition varies depending on the initial concentration of HAuCl4.

Electrocatalytic Activity of Platinum Nanoparticles Synthesized by Room-Temperature Ionic Liquid−Sputtering Method 査読有り

Tetsuya Tsusa, Takasuke Kurihara, Yasunori Hoshino, Tomonori Kiyama, Ken-ichi Ken-ichi Okazaki, Tsukasa Torimoto, and Susumu Kuwabata

Electrochemistry 77 巻頁： 693-695 2009年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Platinum (Pt) nanoparticles were synthesized with room-temperature ionic liquid (RTIL)−sputtering method under
dry N2 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.

Tuning of the Fluorescence Wavelength of CdTe Quantum Dots with 2 nm Resolution by Size-selective Photoetching 査読有り

T. Uematsu , H. Kitajima, T. Kohma, T. Torimoto, Y. Tachibana, and S. Kuwabata

Nanotechnology 20 巻頁： 215302 2009年5月

*Electrochemical Deposition of Gold Frame Structure on Silver Nanocubes 査読有り

Ken-ichi Okazaki, Jun-ichi Yasui, and Tsukasa Torimoto

Chem. Commun. 頁： 2917-2919 2009年4月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Au-framed Ag nanocubes were prepared by site-selective electrochemical deposition of Au onto the edges and vertices of Ag nanocubes modified with a self-assembled monolayer (SAM) of 1-octanethiol, and further chemical etching of the Ag cubes used as a template produced Au nanoframes.

Stacked-Structure-Dependent Photoelectrochemical Properties of CdS Nanoparticle / Layered Double Hydroxide (LDH) Nanosheet Multilayer Films Prepared by Layer-by-layer Accumulation

Tatsuya Kameyama, Ken-ichi Okazaki, Katsuhiko Takagi, and Tsukasa Torimoto

Phys. Chem. Chem. Phys. 11 巻頁： 5369-5376 2009年4月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Inorganic multilayer films were prepared by layer-by-layer accumulation of positively charged layered double hydroxide (LDH) nanosheets and negatively charged CdS nanoparticles of different sizes. Nanoparticles were densely immobilized on LDH sheets to form a monolayer
without coalescence into larger particles. The absorbance and photoluminescence intensity of immobilized CdS particles were enlarged with an increase in the accumulation number of the film. Hybrid films produced by accumulation of both monolayers of CdS particles (diameter: 5 nm) and those of smaller CdS particles (2.1 nm) exhibited characteristic photoluminescence spectra
indicating the efficient energy transfer of photogenerated excitons from nanoparticle layers of smaller CdS particles to those of larger ones. LDH/CdS multilayers deposited on an F-doped SnO2 (FTO) electrode behaved as an n-type semiconductor photoelectrode in an acetonitrile
solution regardless of the size of the CdS particles immobilized, but their efficiency for photocurrent generation was greatly dependent on the stacked structure of the films. Accumulation of CdS particles of 2.1 nm in diameter on pre-coated LDH/CdS layers of 5 nm-sized CdS particles on FTO remarkably enhanced the photocurrent intensity in comparison to that in the case of accumulation of these two kinds of CdS particles in the opposite sequence. These observations can be explained by photoinduced electron transfer and energy transfer along
with the band gap gradient in the films.

Thermally Induced Self-assembly of Gold Nanoparticles Sputter-deposited in Ionic Liquids on Highly Ordered Pyrolytic Graphite Surfaces 査読有り

Ken-ichi Okazaki, Tomonori Kiyama, Toshimasa Suzuki, Susumu Kuwabata, and Tsukasa Torimoto

Chem. Lett. 38 巻頁： 330-331 2009年3月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Gold nanoparticles sputter-deposited in ionic liquids were
densely immobilized on the surface of highly ordered pyrolytic graphite (HOPG) by spreading the ionic liquid containing Au nanoparticles on HOPG and then heating. The density of immobilized Au particles was greatly dependent on the kind of ionic liquid used, and their size was controlled by the heating temperature. The resulting nanoparticle films were stable and electrochemically
active for oxygen reduction.

Hybridization of Silver Nanoparticles on Hydroxyapatite in an Aqueous Solution 査読有り

Yuji Ichikawa, Shin-ichi Ogata, Tsukasa Torimoto, Giichiro Kawachi, Koichi Kikuta and Chikara Ohtsuki

J. Ceram. Soc. Jpn. 117 巻頁： 294-298 2009年3月

Small-Angle X-ray Scattering Study of Au Nanoparticles Dispersed in the Ionic Liquids 1-Alkyl-3-methylimidazolium Tetrafluoroborate 査読有り

Yoshikiyo Hatakeyama, Maimi Okamoto, Tsukasa Torimoto, Susumu Kuwabata, and Keiko Nishikawa

J. Phys. Chem. C 113 巻頁： 3917-3922 2009年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

It was recently discovered that the sputter deposition of metal onto the surface of an ionic liquid generates nanoparticles in the liquid with no additional stabilizing agents. We performed small-angle X-ray scattering (SAXS) experiments to investigate the structure of Au nanoparticles synthesized by this method and to reveal the properties of the ionic liquid that affect the formation process. For a systematic study of these properties, we selected imidazolium-based ionic liquids with different alkyl chain lengths fixing the anion BF4-. The Au concentration dependence for the formation of the nanoparticles was also studied. The SAXS results revealed
that Au nanoparticles with 0.75-3.5 nm diameter were generated under the experimental conditions and that the particle size was relatively uniform for a fixed condition. The results demonstrated that the particle size
depends on the type of ionic liquid and on the concentration if the ionic liquid is fixed. Integrating the
experimental results, it was concluded that the surface tension and viscosity of the ionic liquid played important
roles in conjunction with the Au concentration. It was interpreted that the surface tension influences the initial formation process of nanoparticles on the surface of an ionic liquid, and the viscosity affects the aggregation process during the dispersion of the Au particles from the surface into the liquid.

Photo-Induced Electron Migrations in the Nano-Cavities of Mesoporous Silica Sensitized by a Cationic Porphyrin Dye 査読有り

Takuya Hirano, Tatsuto Yui, Ken-ichi Okazaki, Tsutomu Kajino, Yoshiaki Fukushima, Haruo Inoue, Katsuhiko Takagi, and Tsukasa Torimoto

J. Nanosci. Nanotechnol. 9 巻頁： 506-513 2009年1月

Photocatalytic Electron Flow through the Interface of Titania Nanosheets and Mesoporous Silica Hybrid Films 査読有り

Tatsuto Yui, Takuya Hirano, Ken-ichi Okazaki, Haruo Inoue, Tsukasa Torimoto, Katsuhiko Takagi

207 巻頁： 135-142 2009年1月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

UV-light induced redox reactions between cationic porphyrins (H2TMPyP) and methyl viologen (MV2+) separately incorporated in titania nanosheets (TNS) and cubic-mesoporous silica (MPS) integrated films, respectively, were investigated. In this system, the following two modified hybrids, i.e., the normally stacked (MV2+–TNS)/(H2TMPyP–MPS) on a FTO electrode and the inversely stacked
(H2TMPyP–MPS)/(TNS) films on a FTO electrode were examined. In accordance with the expected electron flowfromH2TMPyP to MV2+, cathodic photocurrentswere observed for the normally stacked film in acetonitrile (CH3CN) under a negative bias voltage of −0.4 V. However, under the influence of a positive bias voltage of +0.3 V, anodic photocurrents were observed even in CH3CN. On the other hand, anodic photocurrents were also observed in water for the normally stacked films at both bias voltages of +0.3 and −0.4V due to photoreduction followed by proton abstraction of the H2TMPyP molecules from H2O within the MPS nano-cavities. In addition, ca. 0.98 mC of the photocurrents were determined in water for the inversely stacked (H2TMPyP–MPS)/(TNS) films without MV2+, of which ca. 50% resulted in the oxidative consumption of H2TMPyP in the MPS cavities.

Photochemical Shape Control of Cadmium Sulfide Nanorods Coated with an Amorphous Silica Thin Layer 査読有り

Tsukasa Torimoto, Masayuki Hashitani, Takahito Konishi, Ken-ichi Okazaki, Tamaki Shibayama, and Bunsho Ohtani

J. Nanosci. Nanotechnol. 9 巻頁： 495-500 2009年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

The surface of cadmium sulfide nanorods was modified by 3-mercaptopropyltrimethoxysilane, followed by the hydrolysis of trimethoxysilyl groups to form a silica shell structure (SiO2/CdS[rod]). Size-selective photoetching was applied to SiO2/CdS[rod] to modify the size of the CdS rod core.
The absorption spectra were blue-shifted by irradiation of monochromatic light, and finally absorption onset agreed with the wavelength of irradiation light. These facts indicated that CdS rod particles were photoetched to smaller ones until the irradiated photons were no longer absorbed by the photoetched particles and that the SiO2 shell layer surrounding the CdS rod core prevented coalescence between photoetched particles. Changes in the wavelength of irradiation light from 488 to 436 nm caused a decrease in rod width from 3.5 to 2.3 nm along with remarkable decrease in the length of rod from 14 to 4.2 nm, suggesting that the photoetching rate was dependent on the kind of crystal faces and that the photocorrosion reactions at the tips of the CdS rod, that is, on (001)
and/or (00¯1) faces, were faster than those on other faces that appeared on the sides of the rod. This technique enabled control of CdS rod shape by selecting the wavelength of irradiation light.

Systematic Studies on Emission Quenching of Cadmium Telluride Nanoparticles 査読有り

Taro Uematsu, Takahiro Waki, Tsukasa Torimoto, and Susumu Kuwabata

J. Phys. Chem. C 113 巻 ( 52 ) 頁： 21621-21628 2009年

Emission Quench of Water-soluble ZnS–AgInS2 Solid Solution Nanocrystals and Its Application to Chemosensors 査読有り

Taro Uematsu, Shohei Taniguchi, Tsukasa Torimoto and Susumu Kuwabata

Chem. Commun. ( 48 ) 頁： 7485-7487 2009年

Self-Assembly of Ionic Liquid (BMI-PF6)-Stabilized Gold Nanoparticles on a Silicon Surface: Chemical and Structural Aspects 査読有り

Om P. Khatri, Kosaku Adachi, Kuniaki Murase, Ken-ichi Okazaki, Tsukasa Torimoto, Nobuo Tanaka, Susumu Kuwabata, and Hiroyuki Sugimur

Langmuir 24 巻頁： 7785-7792 2008年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

Ultrafine monodisperse gold nanoparticles (AuNPs) were synthesized by an elegant sputtering of gold onto 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6) ionic liquid. It was found that the BMI-PF6 supramolecular aggregates were loosely coordinated to the gold nanoparticles and were replaceable with thiol molecules. The self-assembly of BMI-PF6-stabilized AuNPs onto a (3-mercaptopropyl)trimethoxysilane (MPS)-functionalized silicon surface in 2D arrays, followed by dodecanethiol (DDT) treatment, have been demonstrated using X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and contact angle measurements. DDT treatment of tethered AuNPs revealed two types of interactions between AuNPs and the MPS -functionalized surface: (a) AuNPs anchor through Au-S chemisorption linkage resulting in strong immobilization and (b) some of the AuNPs are supported by physisorption, driven by BMI-PF6. The attachment of these particles remains unchanged with sonication. The replacement of BMI-PF6 aggregates from physisorbed AuNPs with DDT molecules advances the dilution of their interaction with the M PS -functionalized surface, and they subsequently detach from the silicon surface. The present finding is promising for the immobilization of ionic liquid-stabilized nanoparticles, which is very desirable for electronic and catalytic device fabrication. Additionally, these environmentally friendly AuNPs are expected to replace conventional citrate-stabilized AuNPs.

Photoluminescence Enhancement of ZnS–AgInS2 Solid Solution Nanoparticles Layer-by-layer-assembled in Inorganic Multilayer Thin Films 査読有り

Tatsuya Kameyama, Ken-ichi Okazaki, Yuji Ichikawa, Akihiko Kudo, Susumu Kuwabata, and Tsukasa Torimoto

Chem. Lett. 37 巻 ( 7 ) 頁： 700-701 2008年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Multilayer films of layered double hydroxide (LDH) nano-sheets and semiconductor nanoparticles of ZnS-AgInS2 solid solution (ZAIS) or CdS were prepared by a layer-by-layer deposition technique. The photoluminescence properties were remarkably dependent on the stacked structure of the films owing to the energy transfer from CdS to ZAIS nanoparticles.

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