High photocatalytic activity of palladium-deposited mesoporous TiO2/SiO2 fibers Original Research Article

A unique TiO2/SiO2 photocatalytic fiber has a photocatalytic activity and high strength. The fiber has a gradient TiO2 surface structure and a silica core structure. By removing a nanosized SiO2 in the TiO2 surface region using hydrofluoric acid solution, one can generate 2–20 nm mesopores between coherently bonded TiO2 particles (8 nm) in the surface TiO2 layer. By using photoelectrical deposition, noble metals such as palladium can be deposited into interstices in the TiO2 layer. The deposition of palladium selectively formed in the interstices of the TiO2 layer between photoactive nanocrystal arrays readily proceeds. The photocatalytic activity of the palladium-deposited mesoporous TiO2/SiO2 photocatalytic fiber is about twice as high as that of fiber without any deposits. Moreover, the photocatalytic activity remains for a long time. This result implies that the palladium precipitation does not peel off. Therefore, palladium-deposited mesoporous TiO2/SiO2 fibers will be very useful and effective for water purification.