Heteropoly acid-incorporated TiO2 colloids as novel photocatalytic systemsresembling the photosynthetic reaction center

Citation
M. Yoon et al., Heteropoly acid-incorporated TiO2 colloids as novel photocatalytic systemsresembling the photosynthetic reaction center, J PHYS CH B, 105(13), 2001, pp. 2539-2545
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
1520-6106 → ACNP
Volume
105
Issue
13
Year of publication
2001
Pages
2539 - 2545
Database
ISI
SICI code
1520-6106(20010405)105:13<2539:HATCAN>2.0.ZU;2-P
Abstract
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 photoinduc ed interfacial electron transfer like plant photosynthesis. It remains diff icult to modify TiO2 particles as a real analogue of the photosynthetic rea ction centers of green plants. We attempted to incorporate a photoreactive heteropoly acid (HPA) such as H3PW12O40 into TiO2 colloids in aqueous polyv inyl alcohol (PVA) (0.1%) solution, and found that two light reactions appe ar to operate in a series. Upon illumination of the HPA/TiO2 system with ne ar-UV light (300-375 nm), interfacial electron transfer takes place from th e conduction band of TiO2 to the incorporated HPA, which is also excited to catalyze photoreduction of Methyl Orange. The extent of the photoinduced r eduction 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 photos ynthetic systems. The photoinduced charge-carrier generation at the heteroj unction is very efficient, and the photoreduction of Methyl Orange has been observed to be synergistically enhanced upon illumination of the HPA-incor porated TiO2 with visible light as well as near-UV light.