Photocatalysis: Fundamentals and Perspectives
CHAPTER 7: Kinetic Processes in the Presence of Photogenerated Charge Carriers
Published:17 Mar 2016
Yoshio Nosaka, Atsuko Y. Nosaka, 2016. "Kinetic Processes in the Presence of Photogenerated Charge Carriers", Photocatalysis: Fundamentals and Perspectives, Jenny Schneider, Detlef Bahnemann, Jinhua Ye, Gianluca Li Puma, Dionysios D Dionysiou, Jenny Schneider, Detlef Bahnemann, Jinhua Ye, Gianluca Li Puma, Dionysios D Dionysiou
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Since the discovery of photoinduced water splitting on TiO2 electrodes in 1972,1 several studies on photocatalysis by TiO2 have focused on the solar energy conversion for hydrogen production. Recently, the TiO2 photocatalysts have been practically devoted to environmental clean-up by decomposing organic pollutants. The difference in these two kinetic processes could be schematically illustrated in Figure 7.1.
Though the electrons photogenerated in the conduction band (CB) are consumed to reduce protons for water splitting, they are actually used to reduce oxygen in air for environmental clean-up. Instead, for water splitting, holes generated in valence band (VB) by four photons are used to oxidize water, while for environmental clean-up only one hole is required to oxidize organic pollutants. Thus, there are varieties of kinetic processes in photocatalysis and the initially employed reactants are also considerably diverse for individual applications. Therefore, in photocatalytic reactions, the primary processes of the photogenerated charge carriers are important. Though there are many review reports concerning the reactions of TiO2 photocatalysts,2–7 in the present chapter the primary reaction processes studied mainly in our research group will be reviewed in particular by focusing on the application to environmental clean-up.