研究者詳細 - 鳥本　司

論文 - 鳥本　司

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Encapsulation of Titanium(IV) Oxide Particles in Hollow Silica for Size-selective Photocatalytic Reactions 査読有り

Shigeru Ikeda, Yoshimitsu Ikoma, Hideyuki Kobayashi, Takashi Harada, Tsukasa Torimoto, Bunsho Ohtani and Michio Matsumura

Chem. Commun. 頁： 3753-3755 2007年9月

*Photocatalytic Syntheses of Azoxybenzene by Visible Light Irradiation of Silica-Coated Cadmium Sulfide Nanocomposites 査読有り

B. Pal, T. Torimoto, K.-i. Okazaki and B. Ohtani

Chem. Commun. ( 5 ) 頁： 483-485 2007年2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）

Photoirradiation (l=5-436 nm) of a deaerated 2-propanol
aqueous solution containing nitrobenzene and rhodium-loaded
silica-coated cadmium sulfide nanoparticles produced azoxybenzene with relatively high selectivity (68%), the photocatalytic activity being enhanced with a decrease in the size of the semiconductor particle core.

DOI： 10.1039/b616178b

Size-selective Photocatalytic Reactions by Titanium(IV) Oxide Coated with a Hollow Silica Shell in Aqueous Solutions 査読有り

Shigeru Ikeda, Hideyuki Kobayashi, Yoshimitsu Ikoma, Takashi Harada, Tsukasa Torimoto, Bunsho Ohtani and Michio Matsumura

Phys. Chem. Chem. Phys. 2007 巻頁： 6319-6326 2007年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

A novel core-shell composite photocatalyst, commercially available titanium(IV) oxide (TiO2) particles directly incorporated into a hollow amorphous silica shell, was fabricated by successive coating of TiO2 with a carbon layer and a silica layer followed by heat treatment to remove the carbon layer. The composite induced efficient photocatalytic reactions when relatively small substrates were used, such as methanol dehydration and decomposition of acetic acid, without any reduction in the intrinsic activity of original TiO2, but did not exhibit efficient photocatalytic activity for decomposition of large substrates, methylene blue and polyvinyl alcohol. The uniquesize-selective properties of the composites are due to their structural characteristics, i.e., the presence of a pore system and a void space in the silica shell and between the shell and medial TiO2 particles, respectively. The loading of alkylsilyl groups on the surface of the composite led to highly photostable. oatability: the floated sample also induced efficient photocatalytic reaction for decomposition of acetic acid while retaining floatation at the gas/water interface.

DOI： 10.1039/b709891j

One-step Synthesis and Photosensitivity of Size-quantized Cadmium Chalcogenide Nanoparticles Deposited on Porous Zinc Oxide Film Electrodes 査読有り

K.-i. Okazaki, N. Kojima, Y. Tachibana, Susumu K., and T. Torimoto

Chem. Lett. 36 巻頁： 712-713 2007年

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）

Size-quantized cadmium chalcogenide nanoparticles were
effectively deposited on a porous zinc oxide particulate film electrode by a one-step hydrothermal method in which an increase in the concentration of 3-mercaptopropionic acid reduced the size of deposited nanoparticles. The photoelectrochemical properties of the resulting electrodes varied depending on the kind of metal chalcogenide nanoparticles deposited and their
size.

真空蒸着法を用いるイオン液体中でのナノ粒子合成招待有り

岡崎健一，桑畑　進，鳥本　司

触媒 49 巻頁： 630-635 2007年

コア・シェル型粒子の光化学的ナノ構造制御と機能材料への応用招待有り査読有り

鳥本　司, 大谷文章

38 巻頁： 103-110 2007年

イオン液体の電顕微鏡観察招待有り Open Access

桑畑進, 鳥本司

表面科学 28 巻頁： 322-326 2007年

Controlling Surface Reactions of CdS Nanocrystals: Photoluminescence Activation, Photoetching and Photostability under Light Irradiation 査読有り

Keiichi Sato, Satoshi Kojima, Shinya Hattori, Taeko Chiba, Keiko Ueda-Sarson, Tsukasa Torimoto, Yasuhiro Tachibana, and Susumu Kuwabata

Nanotechnology 18 巻頁： 465702 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

Photoluminescence enhancement, photoetching and photostability of CdS nanocrystals were investigated under light irradiation. Strongly photoluminescent nanocrystals were obtained when the nanocrystal was weakly photoexcited in an aqueous solution at pH = 11 in the presence of oxygen. With the support of XPS measurements, the following photoactivation mechanism is proposed: Cd2+ ions are released from the CdS surface owing to slow photocorrosion in the presence of oxygen, and Cd-OH bond formation occurs on the CdS surface under the alkaline conditions, removing the surface trap states. The wavelength of the irradiating light and the pH of the solution were determined as key parameters for nanocrystal surface modification. For the stability measurements the nanocrystals were extracted with an ammonium salt in a non-polar solvent. The photoluminescence quantum yield for the nanocrystals in the non-polar phase reached approximately 30%. The extracted nanocrystals were remarkably stable even under UV light irradiation, and the photoluminescence intensity was maintained for several months.

DOI： 10.1088/0957-4484/18/46/465702

CdS Quantum Dots Sensitized TiO2 Sandwich Type Photoelectrochemical Solar Cells

Y. Tachibana, H. Y. Akiyama, Y. Ohtsuka, T. Torimoto, and S. Kuwabata

Chem. Lett. 36 巻頁： 88-89 2007年

Effect of Ionic Surfactants on the Iridescent Color in Lamellar Liquid Crystalline Phase of a Nonionic Surfactant

X. Chen, H. Mayama, G. Matsuo, T. Torimoto, B. Ohtani, and K. Tsujii

J. Colloid Interface Sci. 305 巻頁： 308-314 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

A nonionic surfactant, n-dodecyl glyceryl itaconate (DGI), self-assembles into bilayer membranes in water having a spacing distance of submicrometer in the presence of small amounts of ionic surfactants, and shows beautiful iridescent color. Ionic surfactants have strong effects on this iridescent system. We have interestingly found that the iridescent color changes with time after mixing DGI and ionic surfactants and the color in equilibrium state changes greatly with concentration of the ionic surfactants. The time-dependent color change results from the transformation of DGI aggregate structure after being mixed with ionic surfactant. It is first found that the iridescent color of this nonionic system can be changed
from red to deep blue by altering the concentration of ionic surfactants added even though the total concentration of surfactant is almost constant. Such large blue shift of the iridescent color in equilibrium state cannot be fully explained by the ordinary undulation theory applied so far for this phenomenon. The flat lamellar sheets tend to curve by increasing the concentration of ionic surfactants to form separated onion-like and/or myelin-like structures. These separated structures of lamellar system result in the decrease of spacing distance between bilayer membranes because
some vacant spaces necessarily appear among these structures.

DOI： 10.1016/j.jcis.2006.09.070

Double-Beam Photoacoustic Spectroscopic Studies on Transient Absorption of Titanium(IV)Oxide Photocatalyst Powders 査読有り

Naoya Murakami, Orlando Omar Prieto Mahaney, Ryu Abe, Tsukasa Torimoto, and Bunsho Ohtani

J. Phys. Chem. C 111 巻頁： 11927-11935 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

In situ photoabsorption properties of titanium(IV) oxide (TiO2) powders under continuous ultraviolet irradiation
were investigated by double-beam photoacoustic (PA) spectroscopy. This PA measurement enabled observation
of two kinds of ultraviolet-light-induced intermediate species appearing on various kinds of TiO2 powder samples. Most of the samples (type 1) exhibited photoabsorption due to the production of trivalent titanium (Ti3+) species, while transient absorption assigned to trapped holes or surface peroxy species was also observed for anatase samples with a relatively large specific surface area (type 2). Time-resolved measurements and analyses of the kinetics of photoinduced Ti3+ species suggest that electrons accumulated in type-2 samples have high reactivity toward molecular oxygen compared to type-1 samples. Saturation limits of intensity of the PA signal attributed to Ti3+ species under deaerated conditions in the presence of surface-adsorbed methanol were estimated for both types of samples, and their linear relation with density of Ti3+ species estimated by a conventional photochemical technique was observed. This suggests that the present double-beam PA technique is an alternative feasible method for estimation of density of Ti3+ species, which is a potential measure of density of crystalline defects.

Pyrene-to-porphyrin excited singlet energy transfer in LBLdeposited LDH nanosheets 査読有り

11 巻頁： 428 2007年

Microscopic Structure of Separately Accommodated Phorphyrins and Viologens in Mesoporous Silica and Titania Nanosheet Hybrid Films 査読有り Open Access

Tatsuo Yui, Tsutomu Kajino, Takako Tsuchino, Ken-ichi Okazaki, Tsukasa Torimoto, Yoshiaki Fukushima, and Katsuhiko Takagi

Trans. Mater. Res. Soc. Jap. 32 巻頁： 449-452 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

The microscopic structures of two nano-structured inorganic films, the one based on titania nanosheets
(TNS) and the other on mesoporous silica (MPS), were investigated. Clear stacking structure of the TNS and MPS films was observed for the XRD, SEM, and TEM analyses. Both porphyrin derivatives and viologens were separately and selectively adsorbed into the MPS nano-cavities and the TNS nano-layers, respectively by means of their absorption and energy-dispersive spectroscopies (EDS).

DOI： 10.14723/tmrsj.32.449

Open Access

Photo-Switching Behavior of CdS Nanoparticles Doped in a Polymer Film 査読有り Open Access

Y. Ohara, T. Nakabayashi, K. Iwasaki, T. Torimoto, B. Ohtani, and N. Ohta

Compt. Rend. Chim. 9 巻頁： 742-749 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）

Light-emission intensity of CdS nanoparticles doped in a PMMAfilm is enhanced by a UV irradiation in air, but the emission intensity is strongly de-enhanced at a low pressure of 10−5 torr. Atmospheric gas as well as UV irradiation is essential for the enhancement, and these enhancement and de-enhancement processes are almost completely reversible. The emission of CdS nanoparticles doped in a PMMA film is also quenched by applying an external electric field, suggesting that the non-radiative
decay rate from the emissive exciton state is accelerated by an external electric field.

DOI： 10.1016/j.crci.2005.02.040

Origin of Chiral Discrimination by a Two-Dimensionally Dhiral Self-Assembled Monolayer: A Quantum Chemical Study

T. Nishikawa, T. Torimoto, T. Nakanishi, T. Osaka, B. Ohtani

Chem. Phys. Lett. 432 巻頁： 502-507 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）

Structural and energetic investigations based on semiempirical PM5 and ab initio HF and MP2 calculations suggested that the selfassembled monolayer of an atropisomeric compound, (R)- or (S)-1,10-binaphthalene-2,20-dithiol (BNSH), on a gold (111) surface selectively
adsorbs one enantiomer of phenylalanine (Phe), resulting in chiral discrimination, through hydrophobic, cation(NHþ3
Þ–p and NH(Phe)–p (BNSH) interactions in a nanometer-sized screw-hole-like pocket composed of three BNSH molecules in the monolayer.

Electric-Field-Induced Changes in Absorption and Emission Spectra of CdS Nanoparticles Doped in a Polymer Film

Y. Ohara, T. Nakabayashi, K. Iwasaki, T. Torimoto, B. Ohtani, T. Hiratani, K. Konishi, N. Ohta

J. Phys. Chem. B 110 巻頁： 20927-20936 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）

Electric-field-induced changes in absorption and emission spectra of colloidal CdS nanoparticles ranging in size from 1.0 to 5.0 nm in diameter have been measured by using electric field modulation spectroscopy. The analysis of the electroabsorption spectra indicates that the dipole moment in the first exciton state becomes larger with increasing particle size. The presence of the large dipole moment following photoexcitation into the first exciton band suggests that the CdS nanoparticles have large CT character in the first exciton state. The quantum yields both of the exciton emission and of the trap emission are markedly reduced by application of an electric field. On the basis of the direct measurements of the field-induced change in emission decay profile, it is suggested that the field-induced de-enhancement of these emission yields results from the fieldinduced decreases both in lifetime and in initial population of each emitting state. It is also found that the emission intensity of CdS nanoparticles increases under the UV light irradiation in air and decreases in a vacuum condition and that fluorescence lifetime in the former case is longer than that in the latter. This enhancement and de-enhancement process in emission intensity is almost reversible at least in several cycles.

Ligand-Free Platinum Nanoparticle Encapsulated in a Hollow Porous Carbon Shell as a Highly Active Heterogeneous Catalyst in Hydrogenation Reaction

S. Ikeda, S. Ishino, T. Harada, N. Okamoto, T. Sakata, H. Mori, S. Kuwabata, T. Torimoto, M. Matsumura

Angew. Chem. Int. Ed. 45 巻頁： 7063-7066 2006年

Photochemical Electron Transfer through the Interface of Hybrid Films of Titania Nano-Sheets and Mono-Dispersed Spherical Mesoporous Silica Particles

T. Yui, Y. Kobayashi, Y. Yamada, T. Tsuchino, K. Yano, T. Kajino, Y. Fukushima, T. Torimoto, H. Inoue, and K. Takagi

Phys. Chem. Chem. Phys. 8 巻頁： 4585-4590 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）

Photochemical Electron Transfer (ET) between an organic dye, the porphyrin derivative TMPyP, and an electron acceptor, methyl viologen MV2+, have been investigated at the interface of two different inorganic films, i.e., layered titania nano-sheets (TNS) and a monolayer film of spherical and mono-dispersed mesoporous silica (sMPS) particles (ca. 0.5 mm). TMPyP ions were intercalated within the sMPS nano-cavities to form (TMPyP–sMPS) while MV2+ ions were intercalated into the TNS interlayers to form (MV2+–TNS). The (TMPyP–sMPS) and (MV2+–TNS) films were then stacked on a silica substrate in this order to form a (MV2+–TNS)/(TMPyP–sMPS) film and, upon UV light irradiation, ET could be induced. However, when this
film was stacked inversely, i.e., for the (TMPyP–sMPS)/(MV2+–TNS) films on a silica substrate, no photoinduced ET were observed. Interestingly, however, even for this photo-inactive inversely stacked film, ET could be generated by inserting a gold vapor-deposited layer between the
(MV2+–TNS) and (TMPyP–sMPS) films. The conjugation conditions at the interface of the inversely stacked (TMPyP–sMPS)/(MV2+–TNS) hybrid film were, thus, confirmed to strongly affect the photoinduced electron transfers and their efficiencies.

Analysis of Quantum Dot Fluorescence Coupled with a Microsphere Resonator

H. Takashima, Hideki Fujiwara, J.-i. Hotta, S. Takeuchi, K. Sasaki, S.-y. Murakami, T. Torimoto, B. Ohtani

Jap. J. Appl. Phys. 45 巻頁： 6917-6921 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）

The emission spectrum of CdSe/ZnS quantum dots adhering to the surface of a microsphere resonator is measured and
discussed. Only certain peaks are observed, and the order numbers of the modes (l = 5 to 7) of the observed peaks are
different from those previously reported (l = 1 and 2). [Nano Lett. 1 (2001) 399]. A detailed analysis is presented using the cavity mode efficiency , which is a function of surface roughness, the absorption coefficient of the quantum dots, and mode parameters. The difference between the observed order number modes is explained to be due to the ratio of the rate of absorption by the quantum dots to that of the leakage rates of the modes. The surface roughness of a quantum-dot-coated microsphere and the absorption coefficient of the quantum dots on the sphere are estimated in the analysis.

DOI： 10.1143/JJAP.45.6917

Photochemical Fine-Tuning of Luminescent Color of Cadmium Selenide Nanoparticles: Fabricating a Single-Source Multi-Color Luminophore

T. Torimoto, S.-y. Murakami, M. Sakuraoka, K. Iwasaki, K.-i. Okazaki, T. Shibayama, and B. Ohtani

J. Phys. Chem. B 110 巻頁： 13314-13318 2006年

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）

Size-selective photoetching was applied to silica-coated cadmium selenide (SiO2/CdSe) nanoparticles to precisely control their photoluminescence properties. The absorption spectra of CdSe was blue-shifted by irradiation of monochromatic light, and finally, the absorption onset agreed with the wavelength of irradiation light, indicating that CdSe particles were photoetched to smaller ones until the irradiated photons were not absorbed by the photoetched particles and that the SiO2 shell layer surrounding the CdSe core prevented coalescence between the photoetched particles. Although as-prepared SiO2/CdSe did not exhibit photoluminescence, the application of size-selective photoetching to SiO2/CdSe resulted in the development of the band gap emission, with the degree being enhanced with progress of the photoetching. The peak wavelength of photoluminescence decreased with a decrease in the wavelength used for the photoetching, so that the
luminescence color could be tuned between red and blue. Partial photoetching of SiO2/CdSe nanoparticle
films produced intense band gap emission of CdSe at the photoetched area, while the remainder of the SiO2/
CdSe films did not exhibit detectable photoluminescence, resulting in the formation of a clear photoluminescence
image under UV irradiation. This technique makes it possible to produce a multicolored photoluminescence image by irradiation with monochromatic lights having various wavelengths using a single source material.

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