title: Photocatalytic properties of titania nanostructured films fabricated from Titania nanosheets.
abstract: We examined the photochemical properties of well-ordered multilayer films of titania nanosheets prepared on quartz-glass substrate using the layer-by-layer deposition method. The photocatalytic decomposition of gaseous 2-propanol and bleaching of Methylene Blue dye under UV light illumination were measured to evaluate the photocatalytic oxidation ability. Photoinduced hydrophilicity was also studied by measuring the contact angle of water droplets on the film. The results indicated that titania nanosheets had good photoinduced hydrophilicity. The monolayer film of titania nanosheets showed almost identical activity compared with well investigated sol-gel derived anatase TiO(2) film, while its photocatalytic oxidation activity was low by more than an order of magnitude. This fact suggests that photoinduced hydrophilicity could not be explained simply in terms of the photocatalytic removal of hydrophobic organic species adsorbed on the surface. The photocatalytic oxidation activity and the photoinduced hydrophilic conversion rate decreased with increasing number of nanosheet layers, suggesting that photogenerated carriers produced in the internal part of the multilayer films can hardly diffuse to the surface layer. Photochemical properties of ultrathin anatase films obtained simply by heating the titania nanosheet films were evaluated as well, and also revealed high photoinduced hydrophilicity.
authors.affiliation: Nanoscale Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Shibata
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Sakai
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Fukuda
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ebina
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Sasaki
mesh_terms: D019840:2-Propanol / Q000737:chemistry / Q000528:radiation effects; D002384:Catalysis; D057927:Hydrophobic and Hydrophilic Interactions; D008567:Membranes, Artificial; D008751:Methylene Blue / Q000737:chemistry / Q000528:radiation effects; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D009930:Organic Chemicals / Q000737:chemistry / Q000528:radiation effects; D010084:Oxidation-Reduction; D010316:Particle Size; D010777:Photochemistry / Q000379:methods*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D013057:Spectrum Analysis; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D008567:Membranes, Artificial; D009930:Organic Chemicals; C507641:TiO2-SiO2; D012822:Silicon Dioxide; D014025:Titanium; D019840:2-Propanol; D008751:Methylene Blue