Michio Ueshima

Photocatalytic and Photoelectrochemical Properties of Nitrogen-Substituted TiO2 Thin Films Prepared by an RF Magnetron Sputtering Deposition Method

Highly nitrogen-substituted TiO2 (N-TiO2) thin film photocatalysts were prepared by a radio-frequency magnetron sputtering (RF-MS) deposition method. N-TiO2 thin films with low nitrogen concentration (0.5%) exhibited a small absorption band as a shoulder in the 400-500 nm wavelength region, indicating that isolated N 2p orbitals are formed above the O 2p orbitals. However, N-TiO2 with higher nitrogen concentration (6%) exhibited a sharp absorption edge at 500 nm, indicating that visible light absorption is due to a band gap transition. These N-TiO2 thin films could operate as photocatalysts to decompose 2-propanol diluted in water under visible light. The band structure of N-TiO2 was also determined by photoelectrochemical measurements and H2 and O2 evolution was carried out from an aqueous solution involving sacrificial reagents.

1.6 Role of Acid and Base Properties of V2O5-Base Metal Oxide Catalysts for Partial Oxidation of p-Substituted Toluene

Abstract The partial oxidation of p-methoxy toluene (PMT) to p-methoxy benzaldehyde (PMBA) in the vapor phase was effectively carried out over V2O5-base matal oxide (such as TL2O or Cs2O), in which the catalytic activity and the selectivity are related to acid and base properties of the catalyst respectively. Furthermore, in selective oxidation reactions of various p-substituted toluene to corresponding benzaldehyde over V2O5-Tl2O, high selectivities were obtained. Reactivity of p-substituted toluene over this catalyst depended on the electron donating ability of the p-position substituted group. It was found that this catalyst was in molten state at reaction temperature.

Effect of HF treatment on the activity of TiO2 thin films for photocatalytic water splitting

The effects of HF treatment on the activity of TiO2 thin films for the photocatalytic water splitting reaction have been investigated. TiO2 thin films treated with HF solution (HF-TiO2) were found to exhibit a remarkable enhancement of the photocatalytic activity for H2 evolution from a methanol aqueous solution, as well as efficient photoelectrochemical performance under UV light irradiation as compared with the untreated TiO2. Moreover, Pt-loaded HF-TiO2 thin films were found to act as efficient and stable photocatalysts for the decomposition of water under UV light irradiation. The mechanistic insights obtained in the present study will be useful in the design of highly efficient photocatalysts for the decomposition of water.

New Vapor Phase Process for Synthesis of Ethylenimine by Catalytic Intramolecular Dehydration of Monoethanolamine

Publisher Summary Ethylenimine (EI) is an important fine chemical in the chemical industry, which has been used as a raw material of pharmaceuticals and amino resins. EI generally has been produced from monoethanolamine (MEA) in the liquid phase by using H 2 SO 4 and NaOH, but this production process is not attractive from an industrial viewpoint because of the formation of a large quantity of by-product (Na 2 SO 4 ) and hence low productivity. On the other hand, some studies of MEA intramolecular dehydration to EI directly in the vapor phase over various acidic oxides—such as SiO 2 –WO 3 and Nb 2 O 5 -based catalysts—as a new route to EI have been already reported. However, these catalysts did not show any high catalytic performance on selectivity and life, and hence it was not successful to develop the vapor phase process for this reaction. A characteristic feature of present catalysts was that both acid and base strengths of them were adjusted to be very weak (+4.8 0

Photocatalytic Hydrogen Production from Water on Visible Light-Responsive TiO2 Thin Films Under Solar Light Irradiation

The recent progress in the photocatalytic decomposition of water by visible light-responsive TiO2 (Vis-TiO2) thin film photocatalysts is reviewed here. Special attention is focused on the separate evolution of H2 and O2 from water using Vis-TiO2 thin films prepared by a radio-frequency magnetron sputtering method. These Vis-TiO2 thin films were found to act as efficient photocatalysts for the decomposition of water with the separate evolution of H2 and O2 from H2O under visible or solar light irradiation.