Hiromi Yamashita

Photocatalytic oxidation of ethylene to CO2 and H2O on ultrafine powdered TiO2 photocatalysts: Effect of the presence of O2 and H2O and the addition of Pt

The complete photocatalytic oxidation of C2H4 with O2 into CO2 and H2O has been achieved on ultrafine powdered TiO2 photocatalysts and the addition of H2O was found to enhance the reaction. The photocatalytic reaction has been studied by IR, ESR, and analysis of the reaction products. UV irradiation of the photocatalysts at 275 K led to the photocatalytic oxidation of C2H4 with O2 into CO2, CO, and H2O. The large surface area of the photocatalyst is one of the most important factors in achieving a high efficiency in the photocatalytic oxidation of C2H4. The photoformed OH species as well as O2− and O3− anion radicals play a significant role as a key active species in the complete photocatalytic oxidation of C2H4 with O2 into CO2 and H2O. Interestingly, small amount of Pt addition to the TiO2 photocatalyst increased the amount of selective formation of CO2 which was the oxidation product of C2H4 and O2.

Chapter 4:Superhydrophilic and Superhydrophobic Thin Film Type of Photocatalysts with Self-cleaning Properties

Coating technologies are strongly related to dramatic changes of properties in solid surfaces such as surface wettability, adhesive joining and friction behavior. Surface wettability (i.e. superhydrophilicity and superhydrophobicity) of materials controlled by coating technologies has also received a lot of attention in recent years. The structure control in a film surface as well as the selection and precise compositional control of key building blocks in materials is indispensable for realizing fascinating functions in various areas of fundamental research and practical application. Coating technologies are effective techniques for accumulating multiple functions, enabling the energy-saving, maintenance-free characteristics and reduction of the environmental load. Herein, the design of superhydrophilic and superhydrophobic thin films are mainly summarized in relation to their photocatalytic self-cleaning properties.

Synthesis of Structured Macroporous TiO2 Thin Films and Investigation on Their Photocatalytic Activities

Synthesis of structured macroporous TiO2 thin films on quartz substrate (macro-TiO2/Q) was performed by a dip-coating method using poly(methyl methacrylate) (PMMA) microspheres as template. Obtained TiO2 thin films kept high transparency and had anatase crystalline structure. SEM observations revealed that the macropores were uniformly formed on the film surface. The size of macropores was quite similar to the diameter of PMMA microspheres as template. In comparison to the nonporous TiO2 thin films (TiO2/Q), macro-TiO2/Q exhibited twice higher photocatalytic activity for decolorization of methylene blue in water. Decomposition of acetaldehyde in gas phase also proceeded efficiently on macro-TiO2/Q. Moreover, the surface of macro-TiO2/Q was easily hydrophilized after a short period of UV light irradiation and maintained lower water contact angle in the dark for a long period as compared to those of TiO2/Q.

XAFS Study on Nano‐Sized Pd Metal Catalyst Deposited on Ti‐Containing Zeolite by a Photo‐Assisted Deposition (PAD) Method

The nano‐sized Pd metal catalyst can be highly deposited on Ti‐containing silicalite zeolite (TS‐1) under UV‐light irradiation (PAD‐Pd/TS‐1) using a photo‐assisted deposition (PAD) method. The nano‐sized Pd metal was deposited having the direct interaction with the photo‐excited tetrahedrally coordinated titanium oxide moieties of TS‐1. Under a flow of H2 and O2 in water, H2O2 could be synthesized efficiently on this nano‐sized Pd metal catalyst.