title: Photocatalytic Properties of Layered Metal Oxides Substituted with Silver by a Molten AgNO3 Treatment.
abstract: K4Nb6O17 (BG: 3.67 eV) and Na2W4O13 (BG: 3.12 eV) layered oxide photocatalysts with wide band gaps were treated with a molten AgNO3 to substitute K+ and Na+ with Ag+, resulting in red-shifts of absorption edges in diffuse reflectance spectra. A part of Na+ ions in the interlayer of Na2W4O13 was substituted with Ag+ ions by the molten AgNO3 treatment with keeping the layered structure. Both Ag(I)-substituted K4Nb6O17 and Na2W4O13 showed photocatalytic activities for O2 evolution from aqueous solutions containing a sacrificial reagent utilizing the absorption bands newly formed by the Ag(I)-substitution. Notably, the Ag(I)-substituted Na2W4O13 produced O2 under visible light irradiation. When ball-milled Na2W4O13 was treated with a molten AgNO3, the Ag(I)-substitution rate increased. The Ag(I)-substituted Na2W4O13 with ball-milling showed higher photocatalytic activity for O2 evolution than that without ball-milling. Z-schematic water splitting proceeded under visible light irradiation by combining the Ag(I)-substituted Na2W4O13 of an O2-evolving photocatalyst with Ru-loaded SrTiO3 doped with Rh of a H2-evolving photocatalyst.
authors.affiliation: †Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Horie
authors.affiliation: †Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.|‡Photocatalysis international Research Center, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan.
authors.forename: Akihide
authors.initials: A
authors.lastname: Iwase
authors.affiliation: †Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.|‡Photocatalysis international Research Center, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kudo
keywords: Z-scheme; band engineering; molten salt; photocatalysis; visible light; water splitting