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Tsuneo Fujii - One of the best experts on this subject based on the ideXlab platform.
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influence of dye content on the conduction band edge of Titania in the steam treated dye dispersing Titania electrodes
Photochemistry and Photobiology, 2014Co-Authors: Rudi Agus Setiawan, Hiromasa Nishikiori, Nobuaki Tanaka, Tsuneo FujiiAbstract:The Titania and dye-dispersing Titania electrodes were prepared by a nitric acid-catalyzed sol-gel process. The dye-dispersing Titania contains the dye molecules dispersed on the surface of the individual nanosized Titania particles. The photo-cyclic voltammetry (Photo-CV) and photoelectric measurements of the dye-dispersing Titania electrodes were conducted to clarify the factors changing the conduction band edge of the Titania and the open-circuit voltage (Voc ) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the Titania of the dye-dispersing Titania. The conduction band edge of the Titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye-Titania complex formation on the Titania particle surface. The effect of the dye-Titania complex formation on the shift in the Titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and Titania through the carboxylate and quinone-like groups of the dye. The shift in the Titania conduction band edge corresponded to the change in the Voc value.
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Influence of Dye Content on the Conduction Band Edge of Titania in the Steam‐treated Dye‐dispersing Titania Electrodes
Photochemistry and photobiology, 2014Co-Authors: Rudi Agus Setiawan, Hiromasa Nishikiori, Nobuaki Tanaka, Tsuneo FujiiAbstract:The Titania and dye-dispersing Titania electrodes were prepared by a nitric acid-catalyzed sol-gel process. The dye-dispersing Titania contains the dye molecules dispersed on the surface of the individual nanosized Titania particles. The photo-cyclic voltammetry (Photo-CV) and photoelectric measurements of the dye-dispersing Titania electrodes were conducted to clarify the factors changing the conduction band edge of the Titania and the open-circuit voltage (Voc ) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the Titania of the dye-dispersing Titania. The conduction band edge of the Titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye-Titania complex formation on the Titania particle surface. The effect of the dye-Titania complex formation on the shift in the Titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and Titania through the carboxylate and quinone-like groups of the dye. The shift in the Titania conduction band edge corresponded to the change in the Voc value.
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Photocatalytic reaction on photofuel cell Titania electrode
Research on Chemical Intermediates, 2011Co-Authors: Hiromasa Nishikiori, Yotaro Kato, Tsuneo FujiiAbstract:Benzoic acid-doped Titania electrodes were prepared from titanium alkoxide sols containing benzoic acid in order to examine the photocatalytic reaction of the fuel material concentrated on the Titania surface of a photofuel cell electrode. This doping was developed in order to understand the physicochemical processes on the Titania rather than to advance the practical use of the photofuel cells. The observed photocurrent and CO2 and H2O productions indicated that the oxidation of the benzoic acid enhanced the generation of electricity during the UV irradiation. Benzoic acid molecules should be oxidized by oxygen molecules and holes on the Titania surface. The steam treatment of the electrodes improved the benzoic acid oxidation and the photocurrent because it promoted the Titania densification and enhanced the interaction between the benzoic acid and Titania. The benzoic acid-doped Titania is a valid model of the fuel material concentrated in the porous Titania when using benzoic acid as the fuel material. The contact between the benzoic acid and Titania is important in order to obtain a high photofuel electric conversion.
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Influence of Steam Treatment on Dye−Titania Complex Formation and Photoelectric Conversion Property of Dye-Doped Titania Gel
The Journal of Physical Chemistry C, 2011Co-Authors: Hiromasa Nishikiori, Rudi Agus Setiawan, Tsuneo Fujii, Yohei Uesugi, Shohei Takami, Wei Qian, Mostafa A. El-sayedAbstract:Xanthene dye molecules form a chelate complex with the titanium species on the Titania surface in dye−Titania systems. The complex formation causes a fast electron injection into the Titania conduc...
Hiromasa Nishikiori - One of the best experts on this subject based on the ideXlab platform.
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Phase transition and crystal growth of a Titania layer on a titanium metal plate
Research on Chemical Intermediates, 2018Co-Authors: Hiromasa Nishikiori, Taisuke Hizumi, Kazuki Kawamoto, Katsuya TeshimaAbstract:A titanium metal surface was heated with an alkali metal chloride in order to produce a phase transition from amorphous Titania to crystalline Titania on the surface. The crystalline phase was identified by XRD and Raman spectroscopic analyses. The anatase-type Titania phase was formed by heating the surface with KCl or CsCl at 500–550 °C for 3 h. The heating at a higher temperature caused a transition to the rutile-type Titania. The amorphous Titania layer on the surface of the titanium metal was reduced with assistance of the alkali metal chloride and re-oxidized to transform into the metastable anatase-type Titania phase under certain conditions. The surface layer having the anatase Titania phase exhibited the faster photocatalytic degradation of acetaldehyde, which was demonstrated by gas chromatography and FTIR spectroscopic measurement. Furthermore, the titanium metal coated with KCl and subsequent titanium alkoxide sol was heated in order to form a thicker Titania film. The structural characterization of the film surface was conducted by XRD, Raman spectroscopy, and XPS analyses. Larger anatase-type Titania crystallites were clearly formed on the titanium metal surface, to which they strongly adhered by heating at 500–550 °C for 30 min. The deposited KCl promoted the crystallization of the original amorphous Titania and coated Titania gel layers. The particle size of the Titania film was also confirmed by SEM and TEM observations. The surface layer having the thicker anatase Titania phase exhibited the faster photocatalytic degradation of acetaldehyde.
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Crystal growth of Titania by photocatalytic reaction
Applied Catalysis B: Environmental, 2017Co-Authors: Hiromasa Nishikiori, Shunpei Fujiwara, Syuhei Miyagawa, Nobuyuki Zettsu, Katsuya TeshimaAbstract:Abstract Substrate plates coated with anatase-type Titania thin films were immersed in a solution of titanium (IV) chloride and lithium nitrate at 353 K during UV irradiation. About 20 nm-sized anatase-type Titania crystals were formed on the original Titania film consisting of almost the same sized particles. Nitrate ions in the solution were reduced to nitrite ions, and water was transformed into hydroxide ions by a photocatalytic reaction on the original Titania film. The pH value increased on the Titania surface, which caused the titanium hydroxide formation. The titanium hydroxide was then dehydrated and transformed into Titania. The Titania particles formed on the substrate exhibited a photocatalytic activity similar to the original Titania.
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influence of dye content on the conduction band edge of Titania in the steam treated dye dispersing Titania electrodes
Photochemistry and Photobiology, 2014Co-Authors: Rudi Agus Setiawan, Hiromasa Nishikiori, Nobuaki Tanaka, Tsuneo FujiiAbstract:The Titania and dye-dispersing Titania electrodes were prepared by a nitric acid-catalyzed sol-gel process. The dye-dispersing Titania contains the dye molecules dispersed on the surface of the individual nanosized Titania particles. The photo-cyclic voltammetry (Photo-CV) and photoelectric measurements of the dye-dispersing Titania electrodes were conducted to clarify the factors changing the conduction band edge of the Titania and the open-circuit voltage (Voc ) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the Titania of the dye-dispersing Titania. The conduction band edge of the Titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye-Titania complex formation on the Titania particle surface. The effect of the dye-Titania complex formation on the shift in the Titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and Titania through the carboxylate and quinone-like groups of the dye. The shift in the Titania conduction band edge corresponded to the change in the Voc value.
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Influence of Dye Content on the Conduction Band Edge of Titania in the Steam‐treated Dye‐dispersing Titania Electrodes
Photochemistry and photobiology, 2014Co-Authors: Rudi Agus Setiawan, Hiromasa Nishikiori, Nobuaki Tanaka, Tsuneo FujiiAbstract:The Titania and dye-dispersing Titania electrodes were prepared by a nitric acid-catalyzed sol-gel process. The dye-dispersing Titania contains the dye molecules dispersed on the surface of the individual nanosized Titania particles. The photo-cyclic voltammetry (Photo-CV) and photoelectric measurements of the dye-dispersing Titania electrodes were conducted to clarify the factors changing the conduction band edge of the Titania and the open-circuit voltage (Voc ) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the Titania of the dye-dispersing Titania. The conduction band edge of the Titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye-Titania complex formation on the Titania particle surface. The effect of the dye-Titania complex formation on the shift in the Titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and Titania through the carboxylate and quinone-like groups of the dye. The shift in the Titania conduction band edge corresponded to the change in the Voc value.
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Photocatalytic reaction on photofuel cell Titania electrode
Research on Chemical Intermediates, 2011Co-Authors: Hiromasa Nishikiori, Yotaro Kato, Tsuneo FujiiAbstract:Benzoic acid-doped Titania electrodes were prepared from titanium alkoxide sols containing benzoic acid in order to examine the photocatalytic reaction of the fuel material concentrated on the Titania surface of a photofuel cell electrode. This doping was developed in order to understand the physicochemical processes on the Titania rather than to advance the practical use of the photofuel cells. The observed photocurrent and CO2 and H2O productions indicated that the oxidation of the benzoic acid enhanced the generation of electricity during the UV irradiation. Benzoic acid molecules should be oxidized by oxygen molecules and holes on the Titania surface. The steam treatment of the electrodes improved the benzoic acid oxidation and the photocurrent because it promoted the Titania densification and enhanced the interaction between the benzoic acid and Titania. The benzoic acid-doped Titania is a valid model of the fuel material concentrated in the porous Titania when using benzoic acid as the fuel material. The contact between the benzoic acid and Titania is important in order to obtain a high photofuel electric conversion.
Seung Bin Park - One of the best experts on this subject based on the ideXlab platform.
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enhanced photoactivity of silica embedded Titania particles prepared by sol gel process for the decomposition of trichloroethylene
Applied Catalysis B-environmental, 2000Co-Authors: Kyeong Youl Jung, Seung Bin ParkAbstract:Abstract Silica-embedded Titania photocatalyst (X-silica/Titania, X denotes at.% of silicon) of improved photoactivity was prepared by the sol–gel technique. The photoactivity of the X-silica/Titania particles was increased by increasing the silica content and reached a maximum. The highest photoactivity was obtained when silica content was 30% and five times higher than that of Degussa P25. The embedding of amorphous silica into nanophase Titania matrix helped to increase the thermal stability of Titania which suppressed the formation of anatase into rutile and made it possible to calcine the silica/Titania particles at higher calcination temperature. This high temperature heat treatment resulted in the high crystallinity of the silica/Titania particles. Surface area of X-silica/Titania particles was monotonically increased by increasing the silica content. The average pore size and pore volume, however, has a maximum at 30%, at which mesopores larger than 30 nm were observed. Therefore, we concluded that the large pore size and pore volume were responsible for the optimum composition of silica to Titania. The enhanced photoactivity of silica-embedded Titania particles was achieved by simultaneously increasing both the surface area and the crystallinity through embedding amorphous silica into Titania.
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anatase phase Titania preparation by embedding silica and photocatalytic activity for the decomposition of trichloroethylene
Journal of Photochemistry and Photobiology A-chemistry, 1999Co-Authors: Kyeong Youl Jung, Seung Bin ParkAbstract:Abstract Nanophase Titania particles were prepared by the sol–gel process using two different precursors; titanium isopropoxide(TTIP) and titanium ethoxide (TEOT). Silica-embedded Titania particles was also prepared from TEOT and tera-ethyl-ortho-silicate (TEOS). In the case of nanophase Titania particles prepared from TTIP, the rutile/anatase mixed phase had higher photoactivity than the pure anatase in the decomposition of TCE. However, in the nanophase Titania prepared from TEOT, the photoactivity was increased with the heat treatment temperature until rutile phase began to be formed. The surface area was decreased with the heat treatment temperature. The photoactivity of the pure anatase Titania prepared from TEOT was higher than that of Degussa P25 and the anatase/rutile mixed Titania prepared from TTIP. Therefore, we concluded that, in order to achieve high photocatalytic activity, it was important to prepare Titania particles at high temperature, preferably without forming rutile phase but not necessarily. This conclusion was confirmed by the experimental result that the silica-embedded Titania particle of pure anatase phase had higher photoactivity than that of Degussa P25 and the pure anatase Titania prepared from TEOT. The embedding of small amount of silica into anatase Titania matrix enhanced the thermal stability of nanophase titaina particle resulting in the suppression of the phase transformation from anatase to rutile phase. This thermal stability enables us to calcine the silica-embedded particles at higher temperature without accompanying the phase transformation and to reduce the bulk defects, which are responsible for the low photocatalytic activity.
Won Ho Park - One of the best experts on this subject based on the ideXlab platform.
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Direct electrospinning of ultrafine Titania fibres in the absence of polymer additives and formation of pure anatase Titania fibres at low temperature
Nanotechnology, 2005Co-Authors: Won Keun Son, Donghwan Cho, Won Ho ParkAbstract:Without polymer additives, ultrafine Titania fibres were successfully prepared via the electrospinning technique in combination with the sol?gel process. The viscosity of Titania precursor sol for electrospinning was controlled by the evaporation of solvent and contact with moisture in air. The morphology of the electrospun Titania fibres was characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface morphology and crystallinity of Titania fibres were dependent on the calcination temperature. In particular, the Titania fibres showed pure anatase crystalline structure when they were calcined at temperature as low as 250??C for 3?h. Also, the Titania fibres calcined at 1300??C for 3?h showed rutile crystalline structure and burl-like wavy surfaces. This wavy surface seemed to be formed by aggregation of crystalline Titania particles, which favours the round shape to minimize the surface area.
Huijuan Zhang - One of the best experts on this subject based on the ideXlab platform.
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synthesis and photocatalytic properties of hollow microparticles of Titania and Titania carbon composites templated by sephadex g 100
Chemistry of Materials, 2006Co-Authors: Dayong Zhang, Dong Yang, Huijuan Zhang, And Conghua Lu, Limin QiAbstract:Hollow Titania microparticles about 20−60 μm in size and hollow Titania/carbon composite microparticles about 30−90 μm in size were prepared by employing commercial Sephadex G-100 beads as the template as well as the carbon precursor. The cross-linked dextran gel template was first immersed in aqueous TiCl4 solution to allow the surface mineralization of Titania, resulting in the formation of hollow microparticles of Titania/G-100 hybrids. Hollow Titania microparticles with a shell thickness adjustable from 1 μm to 2.5 μm were fabricated by calcination of the hollow Titania/G-100 hybrid microparticles at temperatures from 400 to 700 °C in air. On the other hand, hollow Titania/carbon composite microparticles ∼ 2.6 μm in shell thickness, which consisted of anatase nanocrystals and amorphous carbon, were obtained by carbonization of the hollow Titania/G-100 hybrid microparticles at temperatures from 500 to 700 °C in flowing nitrogen. For the Titania/carbon composites, the phase transformation from anatase t...
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Synthesis and Photocatalytic Properties of Hollow Microparticles of Titania and Titania/Carbon Composites Templated by Sephadex G-100
Chemistry of Materials, 2006Co-Authors: Zhang Dayong, Dong Yang, Huijuan ZhangAbstract:Hollow Titania microparticles about 20−60 μm in size and hollow Titania/carbon composite microparticles about 30−90 μm in size were prepared by employing commercial Sephadex G-100 beads as the template as well as the carbon precursor. The cross-linked dextran gel template was first immersed in aqueous TiCl4 solution to allow the surface mineralization of Titania, resulting in the formation of hollow microparticles of Titania/G-100 hybrids. Hollow Titania microparticles with a shell thickness adjustable from 1 μm to 2.5 μm were fabricated by calcination of the hollow Titania/G-100 hybrid microparticles at temperatures from 400 to 700 °C in air. On the other hand, hollow Titania/carbon composite microparticles ∼ 2.6 μm in shell thickness, which consisted of anatase nanocrystals and amorphous carbon, were obtained by carbonization of the hollow Titania/G-100 hybrid microparticles at temperatures from 500 to 700 °C in flowing nitrogen. For the Titania/carbon composites, the phase transformation from anatase t...
