Currently, hydrogen has attracted much attention as a clean energy. It is known that TiO 2 has a photocatalytic activity, but is only active under the UV irradiation. On the other hand, Bi 2 O 3 shows poor photocatalytic efficiency for the decomposition of organic pollutants due to a fast recombination of the photo-induced electron and hole pairs. To promote the photocatalytic performance of Bi 2 O 3 by extending the response range to wider wavelength such as visible light or by promoting

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... ent separation of the photo-induced charge carriers, metal doping, the addition of metal particles has been explored. Bi 2 O 3 is also known to have some crystalline phases such as α-phase (monoclinic), β-phase (tetragonal), γ-phase (cubic). Previously, we revealed that the photocatalytic activity β-phase is the most high among α-, β-and γ-phases 1) . In this study, TiO 2 -Bi 2 O 3 photocatalysts were prepared by the sol-gel method in order to