Minjoong Yoon - Heteropoly Acid-Incorporated TiO2 Colloids as Novel Photocatalytic Systems Resembling

Document created by Minjoong Yoon on Aug 22, 2014
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  Publication Details (including relevant citation   information):

  Published in J. Phys. Chem. B 2001,  105, 2539-2545

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  TiO2 colloids are very useful photocatalytic systems, capable of   converting solar energy to chemical or electrical energy and   environmental cleaning. The key step in enhancing photocatalytic   efficiency is improving photoinduced interfacial electron   transfer like plant photosynthesis. It remains difficult to   modify TiO2 particles as a real analogue of the photosynthetic   reaction centers of green plants. We attempted to incorporate a   photoreactive heteropoly acid (HPA) such as H3PW12O40 into TiO2   colloids in aqueous polyvinyl alcohol (PVA) (0.1%) solution, and   found that two light reactions appear to operate in a series.   Upon illumination of the HPA/TiO2 system with near-UV light   (300-375 nm), interfacial electron transfer takes place from the   conduction band of TiO2 to the incorporated HPA, which is also   excited to catalyze photoreduction of Methyl Orange. The extent   of the photoinduced reduction of the HPA adsorbed on TiO2   particles depends on the concentration ratio of the HPA and TiO2   colloids, irradiation wavelength, and intensity of radiation. It   is found that the interfacial electron-transfer mechanism of   HPA/TiO2 is quite analogous to the “Z-scheme” mechanism for plant   photosynthetic systems. The photoinduced charge-carrier   generation at the heterojunction is very efficient, and the   photoreduction of Methyl Orange has been observed to be   synergistically enhanced
  upon illumination of the HPA-incorporated TiO2 with visible light   as well as near-UV light.

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