The Experts below are selected from a list of 38679 Experts worldwide ranked by ideXlab platform
Masakazu Anpo - One of the best experts on this subject based on the ideXlab platform.
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photocatalytic reduction of co2 with h2o on various Titanium Oxide photocatalysts
RSC Advances, 2012Co-Authors: Kohsuke Mori, Hiromi Yamashita, Masakazu AnpoAbstract:The specific features of the photocatalytic reduction of CO2 with H2O on various types of active Titanium Oxide catalysts are reviewed. UV-light irradiation of the bulk TiO2 powders in the presence of CO2 and H2O at room temperature under heterogeneous gas-solid conditions produced CH4 as the major product, while the predominant formations of CH3OH as well as CH4 were observed on the highly dispersed Titanium Oxide moiety anchored on zeolites and mesoporous silica materials. The CH3OH formation is originated from the unique properties of the charge transfer excited state, i.e., (Ti3+–O−)* of the tetrahedrally-coordinated Titanium Oxide species within the silica frameworks.
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recent developments in Titanium Oxide based photocatalysts
Applied Catalysis A-general, 2007Co-Authors: Masaaki Kitano, Masaya Matsuoka, Michio Ueshima, Masakazu AnpoAbstract:Abstract Recent development in Titanium Oxide-based photocatalysts was reviewed concerning the development in the highly dispersed Titanium Oxide photocatalysts prepared on or within zeolites and the visible light-responsive TiO 2 photocatalysts. The unique and high reactivities of Titanium Oxide species anchored or incorporated in the zeolite for various photocatalytic reactions such as reduction of CO 2 with H 2 O and direct decomposition of NO x into N 2 and O 2 were discussed focusing on the relationship between the reactivity and local structures of the catalysts. Moreover, the preparation of the visible light-responsive TiO 2 photocatalysts by applying ion-engineering techniques such as an ion-implantation and an RF magnetron sputtering deposition method was discussed focusing on its unique reactivity for the decomposition of water into H 2 and O 2 with a separate evolution under sunlight irradiation.
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the design and development of highly reactive Titanium Oxide photocatalysts operating under visible light irradiation
Journal of Catalysis, 2003Co-Authors: Masakazu Anpo, Masato TakeuchiAbstract:This review deals with the preparation of highly reactive Titanium Oxide photocatalysts and the clarification of the active sites as well as the detection of the reaction intermediates at the molecular level. Furthermore, we discuss the advancement of photofunctional systems and processes that can utilize visible and/or solar light. The photocatalytic reactivity of semiconducting TiO2 powder was found to be dramatically enhanced by the loading of small amounts of Pt, which work to enhance the charge separation of the electrons and holes generated by light irradiation. Highly dispersed Titanium Oxide species prepared within zeolite frameworks or silica matrices showed unique photocatalytic performance much higher than that of conventional semiconducting TiO2 photocatalysts. The potential for the effective utilization and conversion of solar energy makes research into the modification of the electronic properties of TiO2 photocatalysts by such methods as advanced metal ion implantation to produce photocatalysts which are able to absorb and operate efficiently even under visible light irradiation one of the most important fields in photocatalysis research. This modification process can be applied not only to semiconducting TiO2 photocatalysts but also to TiO2 thin film photocatalysts, as well as Titanium Oxide photocatalysts highly dispersed within zeolite frameworks. Significantly, a new alternative method for directly preparing such visible-light-responsive TiO2 thin film photocatalysts has been successfully developed by applying a RF magnetron sputtering deposition method.
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use of visible light second generation Titanium Oxide photocatalysts prepared by the application of an advanced metal ion implantation method
Pure and Applied Chemistry, 2000Co-Authors: Masakazu AnpoAbstract:Titanium Oxide catalysts were implanted with various transition-metal ions by a high-voltage acceleration technique, then calcined in O 2 at around 723 K to produce photo- catalysts capable of absorbing visible light, the extent of the red shift depending on the amount and kind of metal ions implanted. Such metal ion-implanted Titanium Oxide photo- catalysts, specifically using Cr or V ions, were successful in carrying out various photocat- alytic reactions such as the decomposition of NO into N 2, O2, and N2O at 293 K, significantly under irradiation with visible light longer than 450 nm. In outdoor field tests, these Cr and V ion-implanted Titanium Oxide photocatalysts showed three to four times higher photocata- lytic reactivity for the decomposition of NO under solar beam irradiation, as compared with the original unimplanted Titanium Oxide photocatalyst.
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applications of Titanium Oxide photocatalysts and unique second generation tio2 photocatalysts able to operate under visible light irradiation for the reduction of environmental toxins on a global scale
Studies in Surface Science and Catalysis, 2000Co-Authors: Masakazu AnpoAbstract:The present investigation deals with practical applications of Titanium Oxide photocatalysts and the development of unique second-generation Titanium Oxide photocatalysts by applying advanced ion-engineering techniques, enabling effective and efficient reactions not only under ultraviolet (UV) but also under visible light irradiation. Solar beams are absorbed up to 30–40% more efficiently, allowing the large scale use of these Titanium Oxide photocatalysts for the reduction of environmental toxins.
Hiromi Yamashita - One of the best experts on this subject based on the ideXlab platform.
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photocatalytic reduction of co2 with h2o on various Titanium Oxide photocatalysts
RSC Advances, 2012Co-Authors: Kohsuke Mori, Hiromi Yamashita, Masakazu AnpoAbstract:The specific features of the photocatalytic reduction of CO2 with H2O on various types of active Titanium Oxide catalysts are reviewed. UV-light irradiation of the bulk TiO2 powders in the presence of CO2 and H2O at room temperature under heterogeneous gas-solid conditions produced CH4 as the major product, while the predominant formations of CH3OH as well as CH4 were observed on the highly dispersed Titanium Oxide moiety anchored on zeolites and mesoporous silica materials. The CH3OH formation is originated from the unique properties of the charge transfer excited state, i.e., (Ti3+–O−)* of the tetrahedrally-coordinated Titanium Oxide species within the silica frameworks.
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preparation of Titanium Oxide photocatalysts anchored on porous silica glass by a metal ion implantation method and their photocatalytic reactivities for the degradation of 2 propanol diluted in water
Journal of Physical Chemistry B, 1998Co-Authors: Hiromi Yamashita, Masakazu Anpo, Yuichi Ichihashi, Masaru Harada, Miwa Honda, Takashi Hirao, Nobuhisa Itoh, Nobuya IwamotoAbstract:Highly dispersed Titanium Oxide photocatalysts anchored onto transparent plates of porous silica glass were successfully prepared by metal ion implantation, and their photocatalytic reactivity for the liquid-phase photocatalytic degradation of an aqueous 2-propanol solution was compared with that in an aqueous TiO2 dispersion. The Titanium ions implanted into the porous silica glass are found to be present on the surface layer as isolated tetrahedral Titanium Oxide moieties by diffuse reflectance absorption, SIMS, XPS, and XAFS analyses. The specific photocatalytic reactivity of the anchored catalyst was much higher than that for TiO2 powder, which may be attributed to the tetrahedrally coordinated Titanium Oxide moieties. Metal ion implantation is one of the novel and useful techniques to prepare highly efficient photocatalysts on glass plates.
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design of unique Titanium Oxide photocatalysts by an advanced metal ion implantation method and photocatalytic reactions under visible light irradiation
Research on Chemical Intermediates, 1998Co-Authors: Masakazu Anpo, Masato Takeuchi, Yuichi Ichihashi, Hiromi YamashitaAbstract:The metal ion-implantation of Titanium Oxide with various transition metal ions was carried out by applying by high voltage acceleration. The subsequent calcination of the implanted TiO2 in oxygen at around 723 K resulted in a large shift in the absorption spectra of the TiO2 toward visible light regions, its extent being dependent on the amount and the kind of metal ions implanted. Such metal ion-implanted Titanium Oxide catalysts were active in carrying out various photocatalytic reactions such as the decomposition of NO into N2, O2 and N2O at 275 K under irradiation with visible light longer than 450 nm. The application of this advanced, high energy metal ion-implantation method enables the novel design of Titanium Oxide photocatalysts which can absorb and initiate vital reactions under visible light and will contribute to the development of catalytic systems utilizing solar energy.
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photocatalytic degradation of 1 octanol on anchored Titanium Oxide and on tio2powder catalysts
Journal of Catalysis, 1996Co-Authors: Hiromi Yamashita, Yuichi Ichihashi, Masaru Harada, Gina Stewart, Marye Anne Fox, Masakazu AnpoAbstract:The liquid-phase photocatalytic oxidative degradation of 1-octanol in oxygenated acetonitrile on highly dispersed Titanium Oxide catalysts anchored onto transparent Vycor glass was compared with that obtained on standard TiO2powder. The anchored photocatalysts were prepared through the facile reaction between surface OH groups of Vycor glass and TiCl4. UV irradiation of the anchored catalyst at room temperature led to the photocatalytic degradation of 1-octanol and the production of 1-octanal as the major product. The large surface area of the photocatalyst was one of the most important factors in achieving a high efficiency in the liquid-phase photocatalytic reaction. The specific photocatalytic activity per unit weight of Titanium Oxide of the highly dispersed anchored catalyst was much higher than that for the TiO2powder because of the high activity of the charge transfer complex (Ti3+–O−)*. Furthermore, the filtration of the anchored photocatalysts from the liquid reactants was much easier than that of the small particles of TiO2powder.
Sungyool Choi - One of the best experts on this subject based on the ideXlab platform.
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impact of amorphous Titanium Oxide film on the device stability of al tio2 al resistive memory
Applied Physics A, 2011Co-Authors: Hu Young Jeong, Sungkyu Kim, Jeong Yong Lee, Sungyool ChoiAbstract:We have investigated the role of amorphous Titanium Oxide film in the reliable bipolar resistive switching of Al/TiO2/Al resistive random access memory devices. As TiO2 deposition temperature decreased, a more stable endurance characteristic was obtained. We proposed that the degradation of the bipolar resistive switching property of Al/TiO2/Al devices is closely related to the imperfect migration of oxygen ions between the top insulating interface layer and the oxygen-deficient Titanium Oxide during the set and reset operations. In addition, the dependence of the TiO2 film thickness on the switching property was also studied. As the thickness of the film increased, a reduction in the resistance of the high resistance state rapidly appeared. We attribute the improved endurance performance of thin and low-temperature grown TiO2 devices to the amorphous state with a low film density.
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bipolar resistive switching in amorphous Titanium Oxide thin film
Physica Status Solidi-rapid Research Letters, 2010Co-Authors: Hu Young Jeong, Jeong Yong Lee, Minki Ryu, Sungyool ChoiAbstract:Using isothermal and temperature-dependent electrical measurements, we investigated the resistive switching mechanism of amorphous Titanium Oxide thin films deposited by plasma enhanced atomic layer deposition (PEALD) between two aluminum electrodes. We found a bipolar resistive switching (BRS) behavior only in the high temperature region (>140 K) and two activation energies (0.055 eV and 0.13 eV) for the carrier transport in the ohmic current regime. We attribute this discrepancy to the change of the bulk TiO2 Fermi energy level (Ef) induced by the reversible movement of oxygen ions in the vicinity of the Al top electrode region. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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microscopic origin of bipolar resistive switching of nanoscale Titanium Oxide thin films
Applied Physics Letters, 2009Co-Authors: Hu Young Jeong, Jeong Yong Lee, Sungyool Choi, Jeong Won KimAbstract:We report a direct observation of the microscopic origin of the bipolar resistive switching behavior in nanoscale Titanium Oxide films. Through a high-resolution transmission electron microscopy, an analytical transmission electron microscopy technique using energy-filtering transmission electron microscopy, and an in situ x-ray photoelectron spectroscopy, we demonstrated that the oxygen ions piled up at the top interface by an oxidation-reduction between the Titanium Oxide layer and the top Al metal electrode. We also found that the drift of oxygen ions during the on/off switching induced the bipolar resistive switching in the Titanium Oxide thin films.
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microscopic origin of bipolar resistive switching of nanoscale Titanium Oxide thin films
arXiv: Materials Science, 2009Co-Authors: Hu Young Jeong, Jeong Yong Lee, Sungyool Choi, Jeong Won KimAbstract:We report a direct observation of the microscopic origin of the bipolar resistive switching behavior in nanoscale Titanium Oxide films. Through a high-resolution transmission electron microscopy, an analytical TEM technique using energy-filtering transmission electron microscopy and an in situ x-ray photoelectron spectroscopy, we demonstrated that the oxygen ions piled up at top interface by an oxidation-reduction reaction between the Titanium Oxide layer and the top Al metal electrode. We also found that the drift of oxygen ions during the on/off switching induced the bipolar resistive switching in the Titanium Oxide thin films.
Jian Ku Shang - One of the best experts on this subject based on the ideXlab platform.
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enhanced photocatalytic disinfection of escherichia coli bacteria by silver and nickel comodification of a nitrogen doped Titanium Oxide nanoparticle photocatalyst under visible light illumination
Journal of the American Ceramic Society, 2010Co-Authors: Caixia Sun, Shian Gao, Lihua Cao, Jian Ku ShangAbstract:Enhanced photocatalytic disinfection of Escherichia coli bacteria under visible light illumination was achieved by introducing silver and nickel comodification onto a nitrogen-doped Titanium Oxide nanoparticle photocatalyst synthesized by the sol-gel process. The introduction of a small amount of the second-type transitional metal ion addition is demonstrated as an effective approach to further enhance the optical and photocatalytic properties of single-type transitional metal ion modified anion-doped Titanium Oxide photocatalysts.
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as iii removal by palladium modified nitrogen doped Titanium Oxide nanoparticle photocatalyst
Environmental Science & Technology, 2009Co-Authors: Nickolas Joseph Easter, Jian Ku ShangAbstract:Removal of arsenic species from water by palladium-modified nitrogen-doped Titanium Oxide (TiON/PdO) nanoparticles was investigated with and without visible light. For the first time, a high degree of As(III) removal under visible light illumination was demonstrated on Oxide photocatalysts. Over 2 orders of magnitude decrease of As(III) concentration in water was observed in 1 h as the As(III) concentration was reduced below the U.S. Environmental Protection Agency standard (10 μg/L) by TiON/PdO photocatalyst. Such an efficient removal of As(III) was shown to result from the combined effects of strong adsorption and photooxidation by TiON/PdO, where an enhanced photocatalytic activity under visible light illumination than nitrogen-doped Titanium Oxide (TiON) was derived from the strong optoelectronic coupling between PdO and TiON.
Hu Young Jeong - One of the best experts on this subject based on the ideXlab platform.
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impact of amorphous Titanium Oxide film on the device stability of al tio2 al resistive memory
Applied Physics A, 2011Co-Authors: Hu Young Jeong, Sungkyu Kim, Jeong Yong Lee, Sungyool ChoiAbstract:We have investigated the role of amorphous Titanium Oxide film in the reliable bipolar resistive switching of Al/TiO2/Al resistive random access memory devices. As TiO2 deposition temperature decreased, a more stable endurance characteristic was obtained. We proposed that the degradation of the bipolar resistive switching property of Al/TiO2/Al devices is closely related to the imperfect migration of oxygen ions between the top insulating interface layer and the oxygen-deficient Titanium Oxide during the set and reset operations. In addition, the dependence of the TiO2 film thickness on the switching property was also studied. As the thickness of the film increased, a reduction in the resistance of the high resistance state rapidly appeared. We attribute the improved endurance performance of thin and low-temperature grown TiO2 devices to the amorphous state with a low film density.
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bipolar resistive switching in amorphous Titanium Oxide thin film
Physica Status Solidi-rapid Research Letters, 2010Co-Authors: Hu Young Jeong, Jeong Yong Lee, Minki Ryu, Sungyool ChoiAbstract:Using isothermal and temperature-dependent electrical measurements, we investigated the resistive switching mechanism of amorphous Titanium Oxide thin films deposited by plasma enhanced atomic layer deposition (PEALD) between two aluminum electrodes. We found a bipolar resistive switching (BRS) behavior only in the high temperature region (>140 K) and two activation energies (0.055 eV and 0.13 eV) for the carrier transport in the ohmic current regime. We attribute this discrepancy to the change of the bulk TiO2 Fermi energy level (Ef) induced by the reversible movement of oxygen ions in the vicinity of the Al top electrode region. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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microscopic origin of bipolar resistive switching of nanoscale Titanium Oxide thin films
Applied Physics Letters, 2009Co-Authors: Hu Young Jeong, Jeong Yong Lee, Sungyool Choi, Jeong Won KimAbstract:We report a direct observation of the microscopic origin of the bipolar resistive switching behavior in nanoscale Titanium Oxide films. Through a high-resolution transmission electron microscopy, an analytical transmission electron microscopy technique using energy-filtering transmission electron microscopy, and an in situ x-ray photoelectron spectroscopy, we demonstrated that the oxygen ions piled up at the top interface by an oxidation-reduction between the Titanium Oxide layer and the top Al metal electrode. We also found that the drift of oxygen ions during the on/off switching induced the bipolar resistive switching in the Titanium Oxide thin films.
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microscopic origin of bipolar resistive switching of nanoscale Titanium Oxide thin films
arXiv: Materials Science, 2009Co-Authors: Hu Young Jeong, Jeong Yong Lee, Sungyool Choi, Jeong Won KimAbstract:We report a direct observation of the microscopic origin of the bipolar resistive switching behavior in nanoscale Titanium Oxide films. Through a high-resolution transmission electron microscopy, an analytical TEM technique using energy-filtering transmission electron microscopy and an in situ x-ray photoelectron spectroscopy, we demonstrated that the oxygen ions piled up at top interface by an oxidation-reduction reaction between the Titanium Oxide layer and the top Al metal electrode. We also found that the drift of oxygen ions during the on/off switching induced the bipolar resistive switching in the Titanium Oxide thin films.
