206
N. Wang et al. / Journal of Catalysis 266 (2009) 199–206
radical scavengers such as 1.0 mM tert-butyl alcohols or even
100 mg Lꢀ1 enzyme superoxide dismutase (SOD) which has little
affinity for TiO2 surface (Table 2). However, the O2 reduction is lim-
ited by its slow adsorption rate on TiO2 surface, because the
adsorption requires the presence of surface defect sites [34]. Con-
sequently, the recombination of the photo-injected electrons in
TiO2 CB with adsorbed R+Å radicals can complete effectively with
the charge-trapping by loosing of O2 on TiO2 surface, and then
the generated reactive oxygen species are diminished, thereby sup-
pressing the photodegradation and mineralization of organic
pollutants.
mineralization of the colorless organic compounds, which allow
that the CTC-mediated photocatalytic degradation over TiO2 to be
applied for removing colorless organic pollutants under the visible
irradiation.
Acknowledgment
Financial supports from the National Science Foundation of
China (Grants Nos. 20877031 and 20677019) are gratefully
acknowledged.
When another appreciate electron acceptor such as H2O2; BrOꢀ
Appendix A. Supplementary data
3
or Cr(VI) is added into TiO2 suspensions, it can adsorb easily on
TiO2 surface via the electrostatic attraction or a coordination reac-
tion [35], and then effectively trap the injected electrons in TiO2
CB, resulting in the marked depression of the backward recombina-
tion event and the acceleration of the removal of pollutants. More-
over, another important reason is because the redox potentials of
Supplementary data associated with this article can be found, in
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