title: Manganese-Substituted Polyoxometalate as an Effective Shuttle Redox Mediator in Z-Scheme Water Splitting under Visible Light.
abstract: In the present study, a polyoxometalate is for the first time applied as a shuttle redox in two-step (Z-Scheme) photocatalytic water splitting. Photocatalytic H2 evolution using a Mn-substituted polyoxometalate [SiW11 O39 Mn(II) (H2 O)](6-) as an electron donor proceeded over a Ru-loaded SrTiO3 :Rh photocatalyst under visible light with relatively high selectivity, accompanied by the stoichiometric production of its oxidized form [SiW11 O39 Mn(III) (H2 O)](5-) . Photocatalytic O2 evolution using the oxidized [SiW11 O39 Mn(III) (H2 O)](5-) as an electron acceptor proceeded over PtOx -loaded WO3 photocatalyst under visible light with relatively high quantum efficiency and selectivity, whereas the loading of effective PtOx cocatalyst was necessary to facilitate the reduction of polyoxometalate. Finally, a two-step water splitting into H2 and O2 was demonstrated under visible light using the couple of Mn-substituted polyoxometalate as shuttle redox between Ru/SrTiO3 :Rh and PtOx /WO3 photocatalysts, under mildly acidic conditions with pH≈4.5.
authors.affiliation: Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Tsuji
authors.affiliation: Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Tomita
authors.affiliation: Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Higashi
authors.affiliation: Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan. ryu-abe@scl.kyoto-u.ac.jp.|JST-CREST, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076, Japan. ryu-abe@scl.kyoto-u.ac.jp.
authors.forename: Ryu
authors.initials: R
authors.lastname: Abe
mesh_terms: D002384:Catalysis; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D008027:Light; D008345:Manganese / Q000737:chemistry*; D055668:Photochemical Processes; D012825:Silicon / Q000737:chemistry; D014414:Tungsten / Q000737:chemistry; D017973:Tungsten Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D008345:Manganese; D012825:Silicon; D014414:Tungsten; D017973:Tungsten Compounds; D014867:Water; C102296:polyoxometalate I; D000099294:Polyoxometalates
keywords: Z-Scheme; photocatalytic water splitting; polyoxometalate; redox; visible light