Showing papers by "Masaya Matsuoka published in 2009"
TL;DR: In this paper, transition metal oxides (Ti, V, Mo, Cr, etc.) incorporated within the framework of zeolites were found to exhibit high and unique photocatalytic reactivity as single-site heterogeneous catalysts for various reactions such as the decomposition of NOx (NO, N 2 0) into N 2 and O 2, the reduction of CO 2 with H 2 0 to produce CH 4 and CH 3 0H, the preferential oxidation of CO in the presence of H 2 (PROX), the partial oxidation of various hydrocarbons with O
84 citations
TL;DR: In this article, a high photocatalytic reactivity for the highly dispersed Ti-oxide species within zeolite frameworks, hybridized with hydrophobic siliceous zeolites adsorbents as well as visible light responsive TiO2 thin films have been successfully prepared.
Abstract: Various Ti-oxide based photocatalysts such as the highly dispersed Ti-oxide species within zeolite frameworks, TiO2 nano-particles hybridized with hydrophobic zeolite adsorbents as well as visible light responsive TiO2 thin films have been successfully prepared. Characterization studies at the molecular level, such as X-ray absorption fine structure (XAFS) and photoluminescence (PL), revealed that the highly dispersed Ti-oxide species within the nano-spaces of zeolites possess a tetrahedral coordination and that they demonstrate unique and high performance for the photocatalytic decomposition of NOx and the photocatalytic reduction of CO2 with H2O. A high photocatalytic reactivity for the TiO2 semiconducting photocatalysts could be achieved by blending them with hydrophobic siliceous zeolites which was equal to the performance of TiO2 deposited with expensive Pt particles. The role of the siliceous zeolites can be described as a so-called “catch and release effect of organic compounds”, i.e., (i) the condensation of the reactants within the hydrophobic cavities of zeolites and; (ii) the efficient diffusion of the reactant onto the TiO2 photocatalytic sites. Furthermore, a novel photocatalytic system which can convert abundant solar energy into renewable H2 energy by the decomposition of H2O into H2 and O2 can also be achieved by using visible light responsive TiO2 thin film photocatalysts prepared by a RF-magnetron sputtering deposition method. The conversion efficiency of solar energy into H2 energy may be estimated at ca. 0.1% from the initial rate of H2 evolution.
24 citations
TL;DR: In this paper, a radio frequency magnetron sputtering deposition method was used for the preparation of Vis-TiO2 thin films and the photoelectrochemical performance was improved by adding various kinds and concentrations of alcohol, i.e., model compounds of biomass, to water.
Abstract: Visible light-responsive TiO2 (Vis-TiO2) thin films were prepared by a radio frequency magnetron sputtering deposition method. The photoelectrochemical performance was improved by adding various kinds and concentrations of alcohol, i.e., model compounds of biomass, to water. The separate evolution of pure H2 was observed to proceed efficiently on these Vis-TiO2 thin films under visible light irradiation by using an aqueous solution of methanol.
23 citations
TL;DR: In this article, the photocatalytic preferential oxidation of CO with O2 in the presence of H2 (photo-PROX) was found to proceed efficiently on the NiO-loaded TiO2 (NiO/TiO2) catalyst under UV light irradiation at 293 K.
Abstract: The photocatalytic preferential oxidation of CO with O2 in the presence of H2 (photo-PROX) was found to proceed efficiently on the NiO-loaded TiO2 (NiO/TiO2) catalyst under UV light irradiation at 293 K. NiO/TiO2 exhibited higher CO conversion as well as CO2 selectivity for a photo-PROX reaction than the original unloaded TiO2 (P-25). Various spectroscopic investigations have revealed that the small NiO clusters formed on TiO2 play an important role in the enhancement of CO oxidation activity in this reaction.
13 citations
TL;DR: In this article, the bulk of Pt-nanocrystal supported titanate nanotubes was successfully fabricated without the H2 reduction process by applying the hydrothermal hot-pressing (HHP) technique in order to improve the handleability as a photocatalyst.
Abstract: Morphologic control of Pt supported titanate nanotubes was attempted by the hydrothermal hot-pressing (HHP) technique in order to improve the handleability as a photocatalyst. The bulk of Pt-nanocrystal supported titanate nanotubes was successfully fabricated without the H2 reduction process by applying the HHP technique. The bulky Pt-nanocrystal supported titanate nanotubes possessed dense microstructures, significantly sharp distributions of mesopores, and high Brunauer–Emmett–Teller (BET) surface area. Furthermore, the bulky Pt-nanocrystal supported titanate nanotubes showed the photocatalytic degradation activities of 2-propanol aqueous solution under UV-light irradiation.
12 citations
TL;DR: In this paper, the radio frequency (RF) magnetron sputtering deposition method was applied to the TiO2 thin film photocatalysts which could induce photoreactions under visible light irradiation.
Abstract: TiO2 thin film photocatalysts which could induce photoreactions under visible light irradiation were successfully developed in a single process by applying an ion engineering technique, i.e., the radio frequency (RF) magnetron sputtering deposition method. The TiO2 thin films prepared at temperatures greater than 773 K showed the efficient absorption of visible light; on the other hand, the TiO2 thin films prepared at around 573 K were highly transparent. This clearly means that the optical properties of TiO2 thin films, which absorb not only UV but also visible light, can be controlled by the preparation temperatures of the RF magnetron sputtering deposition method. These visible light responsive TiO2 thin films were found to exhibit effective photocatalytic reactivity under visible light irradiation (λ > 450 nm) at 275 K for the reductive decomposition of NO into N2 and N2O. From various characterizations, the orderly aligned columnar TiO2 crystals could be observed only for the visible light responsive TiO2 thin films. This unique structural factor is expected to modify the electronic properties of a TiO2 semiconductor, enabling the efficient absorption of visible light.
12 citations
TL;DR: In this article, a novel Vis-TiO2 thin film photocatalyst was prepared by using an H-type glass cell consisting of two aqueous phases separated by Vis- TiO2/Ti/Pt and a proton exchange membrane.
Abstract: Visible light-responsive TiO2 thin film photocatalysts (Vis-TiO2) have been prepared on Ti metal foil (Vis-TiO2/Ti) or ITO glass (Vis-TiO2/ITO) substrates by a radio-frequency magnetron sputtering (RF-MS) method. The UV–Vis spectra as well as photoelectrochemical performance of Vis-TiO2 were affected by various calcination treatments such as calcination in air or NH3. Calcination treatment in NH3 (1.0 × 104 Pa, 673 K) was particularly effective in increasing the visible light absorption of Vis-TiO2 as well as in enhancing its photoelectrochemical performance and photocatalytic activity. A novel Vis-TiO2 thin film photocatalyst (Vis-TiO2/Ti/Pt) was prepared by an RF-MS method where Vis-TiO2 was deposited on one side of a Ti metal foil substrate and nanoparticles of Pt were deposited on the other side. The separate evolution of H2 and O2 from H2O could be successfully achieved by using an H-type glass cell consisting of two aqueous phases separated by Vis-TiO2/Ti/Pt and a proton-exchange membrane. It was found that the rate of the separate evolution of H2 and O2 was also dramatically enhanced by calcination treatment of Vis-TiO2 in NH3.
11 citations
TL;DR: In this paper, a photoelectrochemical circuit system was constructed by connecting a rod-type TiO2 electrode with a Pt electrode through a silicon solar cell, which efficiently oxidized ethanethiol in water into CO2.
Abstract: A unique photoelectrochemical circuit system was constructed by connecting a rod-type TiO2 electrode with a Pt electrode through a silicon solar cell. The photoelectrochemical circuit system efficiently oxidized ethanethiol in water into CO2, while the reaction rate strongly depended on the calcination temperature of the rod-type TiO2 electrode. Furthermore, it was found that a negative bias applied to the rod-type TiO2 electrode by a silicon solar cell enhances the oxidation rate of ethanethiol in water.
6 citations
22 Oct 2009
1 citations