Overall Water Splitting under Visible Light through a Two-Step Photoexcitation between TaON and WO3 in the Presence of an Iodate-Iodide Shuttle Redox Mediator

被引:116
作者
Abe, Ryu [1 ,2 ]
Higashi, Masanobu [1 ]
Domen, Kazunari [3 ]
机构
[1] Hokkaido Univ, Catalysis Res Ctr, Sapporo, Hokkaido 0010021, Japan
[2] PRESTO Japan Sci & Technol Agcy JST, Saitama 3320021, Japan
[3] Univ Tokyo, Dept Chem Engn, Bunkyo Ku, Tokyo 1138656, Japan
关键词
hydrogen; photocatalysis; redox mediator; visible light; water splitting; DRIVEN PHOTOCATALYSTS; HYDROGEN-PRODUCTION; O-2; H-2; PLATINUM; PHOTOLYSIS; OXYNITRIDE; EVOLUTION; OXIDATION; ATAO(2)N;
D O I
10.1002/cssc.201000333
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
A two-step, photocatalytic water splitting system consisting of Pt-loaded TaON (a H-2 evolution photocatalyst), Pt-loaded WO3 (an O-2 evolution photocatalyst), and an iodate-iodide (IO3-/I-) shuttle redox mediator is investigated under visible light irradiation. Photocatalytic oxidation of water to O-2 and reduction of IO3- to I- proceeded with good selectivity over the Pt-WO3 photocatalyst, even in the presence of a considerable amount of I- anions in the solution. The key difference between the adsorption properties of IO3- and I- anions on WO3 strongly suggested that the photoexcited electrons could react efficiently with IO3- adsorbed on WO3, whereas the photogenerated holes selectively reacted with water molecules owing to the low adsorptivity of I- on WO3. Photocatalytic H-2 evolution on Pt-TaON proceeded efficiently, accompanied by I- oxidation to IO3- due to a substantial amount of adsorption of I- anions on the surface, whereas H-2 evolution was significantly inhibited by the competitive adsorption of IO3-, which consumes photoexcited electrons. It was also found that WO3 photocatalysts loaded with platinum oxide (PtO) showed a much higher activity for O-2 evolution in the presence of the electron acceptor IO3-, compared to those loaded with Pt metal. Overall water splitting at a steady rate was demonstrated using a combination of Pt-TaON and Pt(PtO)-WO3 in an aqueous Nal solution with neutral or weakly acidic pH values, where the concentration of Nal significantly affected the efficiency.
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页码:228 / 237
页数:10
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