論文 - 鳥本　司

半導体超微粒子の固定化とその光触媒への応用 招待有り

米山　宏，鳥本　司

表面科学   16 巻   頁： 173-179   1995年

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担当区分：筆頭著者   記述言語：日本語  

Effect of Inert Supports for Titanium Dioxide Loading on Enhancement of Photodecomposition Rate of Gaseous Propionaldehyde 査読有り

N. Takeda, T. Torimoto, S. Sampath, S. Kuwabata, and H. Yoneyama

J.Phys.Chem.   99 巻 ( 24 ) 頁： 9986-9991   1995年

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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）  

Effects of the use of inert supports for TiO2 loading on photocatalyzed decomposition of propionaldehyde in the gas phase was investigated for mordenite support with various amounts of TiO2 loading and for several kinds of supports such as other zeolites, alumina, silica, and activated carbon. The adsorption constant and the amount of adsorption of propionaldehyde were evaluated for TiO2-loaded supports by obtaining Langmuir adsorption isotherms. By correlating these parameters to the photodecomposition rates of propionaldehyde, the involvement of the support in the photodecomposition reaction is clarified. The photocatalytic activity of TiO2 on mordenite having various amounts of TiO2 loading increases with increase in the amount of loaded TiO2 up to an optimum value (ca. 50 wt %), beyond which a decreasing tendency of the activity appeared. In the region of ascending activity, plenty of adsorbed substrate is available and the activity is controlled by the content of TiO2, while in the region of descending activity, the decrease in the amount of adsorbed substrate due to a decrease in the occupancy of the support by the TiO2 loading is responsible for the activity decrease. The photocatalytic activities are greatly influenced by the kind of inert supports used and show a volcano type dependence on the adsorption constant of the TiO2-loaded supports. In cases where the adsorption constant is low, the decomposition rate is determined by the amount of adsorbed substrate, while if the adsorption constant is very high, plenty of adsorbed substrate is available on the support, but it is not mobile to the loaded TiO2. We conclude that the use of an inert support having a medium adsorption constant is necessary to obtain the highest activity, where a high amount of adsorbed substrate that can be supplied to TiO2 particles is available.

Preparation of CdS Microcrystals Covalently Bound with Viologen Groups and Their Photoelectrochemical Properties 査読有り

T. Torimoto, K. Maeda, T. Sakata, H. Mori, and H. Yoneyama

Chem. Lett   ( 6 ) 頁： 977-980   1994年

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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）  

CdS microcrystals (Q-CdS) covalently bound with 1-decyl-1'-(3-mercapto) propyl-4,4'-bipyridinium were prepared. The surface viologen groups picked up photo-generated electrons in the conduction band of Q-CdS particles, causing a decrease of their emission. Irradiation of these particles resulted in new absorption peaks which are assigned to viologen radical cation monomers and their dimers. The photo-reduced viologen groups can mediate photo-generated electron transfer from Q-CdS to methylene blue in solution.

Photoinduced Electron Transfer from Zinc Sulfide Microcrystals Modified with Various Alkanethiols to Methyl Viologen 査読有り

H. Inoue, N. Ichiroku, T. Torimoto, T. Sakata, H. Mori, and H. Yoneyama

Langmuir   10 巻 ( 12 ) 頁： 4517-4522   1994年

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Zinc sulfide microcrystals fully modified with ethanethiol, butanethiol, and octanethiol of about 4 nm diameter with a narrow size distribution were prepared. The rate of photoinduced electron transfer from the microcrystals to methyl viologen (MV(2+)) in solution showed a linear dependence on the concentration of MV(2+), while at bulk ZnS particles the Langmuir-Hinshelwood type kinetics prevailed. It is concluded from the observed logarithmic dependence of the rate constant on the inverse of the chain length of the modified alkanethiols that the electron tunneling controls the photoinduced reduction of MV(2+).

Photoelectrochemical Properties of Size-Quantized CdS Microcrystals Modified with Various Amounts of Viologen-Functionalized Thiol 査読有り

T. Torimoto, K. Maeda, J. Maenaka, and H. Yoneyama

J. Phys. Chem.   98 巻 ( 51 ) 頁： 13658-13664   1994年

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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 CdS microcrystals (Q-CdS) modified with various amounts of electroactive 1-decyl-1'-(3-mercaptopropyl)-4,4'-bipyridinium dibromide (VSH) and electroinactive decanethiol were prepared. The surface-modified VSH was photoreduced by irradiation of Q-CdS to give both dimeric and monomeric radical cations of the viologen, and the formation of the former was enhanced by increasing the amount of the surface-bound VSH. Kinetic analyses revealed that the rate constants for the reduction of the surface-modified VSH and for the reoxidation of the produced radical cations were independent of the amount of the VSH, Q-CdS having the higher amount of VSH showed the higher activity for electron transfer to methylene blue in solution, evidencing that the surface-bound viologen mediated electron transfers from Q-CdS to the electron acceptor in solution.

Effect of Surface Charge of 4-Aminothiophenol-Modified PbS Microcrystal Photocatalysts on Photoinduced Charge Transfer 査読有り

T. Torimoto, T. Sakata, H. Mori, and H. Yoneyama

J.Phys.Chem.   98 巻 ( 11 ) 頁： 3036-3043   1994年

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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）  

Two kinds of quantized PbS microcrystals modified with 4-aminothiophenol (4-ATP/Q-PbS) having different surface coverage were prepared by using two different concentration ratios of [Pb2+]/[S2-] in the synthesis of the 4-ATP/Q-PbS particles. The rates of photoinduced reduction of methylviologen on the two kinds of 4-ATP/Q-PbS particles were influenced by the kind of hole scavengers (sodium tartrate or triethanolamine) and the pH of solutions, and the higher reduction rates were obtained under conditions where the higher amount of adsorption of the hole scavenger occurred. High reduction rates of methylviologen were obtained at the photocatalyst having a high coverage of the surface modifier, because high electrostatic attractive interactions between the hole scavenger and the surface are operative when tartrate was used as a hole scavenger and a high amount of adsorption sites due to a high coverage of the surface modifier are available when triethanolamine was used. The validity of such interpretation was supported by kinetic analysis based on rate equations. Furthermore, it was found that inert electrolyte anions such as ClO4- had a retarding action for the photoreduction of methylviologen when tartrate was used as the hole scavenger, as a result that the adsorbed tartrate anions were replaced by the inert electrolyte anions depending on their concentrations. The adsorbability of inert electrolyte anions (Cl-, Br-, and ClO4-) as well as tartrate anions was found to be influenced by the degree of surface modification of the Q-PbS particles with 4-aminothiophenol. As for the case of using electronically neutral triethanolamine as the hole scavenger, the inert electrolyte anions did not influence the photoreduction rate of methylviologen.

Surface Structures of PbS Microcrystals Modified with 4-Hydroxythiophenol and Their Influences on Photoinduced Charge Transfer 査読有り

T. Torimoto, H. Uchida, T. Sakata, H. Mori, and H. Yoneyama

J. Am. Chem. Soc.,   115 巻 ( 5 ) 頁： 1874-1880   1993年

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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）  

Quantized PbS microcrystals capped with 4-hydroxythiophenol (ArSH) were prepared using two different concentration ratios of [Pb2+]/[S2-] = 1.2 and 3.0 with fixed concentration ratio of [ArSH]/[Pb2+] = 4.0. The size distributions of the prepared PbS particles were determined. Two different surface structure models of fully occupied and partially occupied surface sites of PbS microcrystals with the capped ArSH are assumed, and chemical compositions of these particles are evaluated by taking the experimentally determined particle size distributions into account. By examining the fitness of the chemical analyses data of the PbS particles to the evaluated compositions, it is proposed that the PbS particles prepared [Pb2+]/[S2-] = 3.0 had the capped ArSH in all the surface sites, while PbS particles prepared with [Pb2+]/[S2-] = 1.2 had some surface sites free from the modifier. The proposed surface structures of the two kinds of PbS microcrystals were rationalized by experimentally found differences both in agglomeration tendencies of the particles and in the effect of the addition of Pb2+ ions on the rate of photoinduced reduction of methyl viologen on the particles.

Effects of Size Quantization of Zinc Sulfide Microcrystallites on Photocatalytic Reduction of Carbon Dioxide 査読有り

H. Inoue, T. Torimoto, T. Sakata, H. Mori, and H. Yoneyama

Chem. Lett.   ( 9 ) 頁： 1483-1486   1990年

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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）