期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 19, 期 32, 页码 10751-10759出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201300243
关键词
electron behavior; heterogeneous catalysis; nanostructures; photocatalysis; thermodynamics
资金
- National Basic Research Program of China [2009CB939704]
- Fundamental Research Funds for the Central Universities (Wuhan University of Technology) [2012-IV-008]
The in situ open-circuit voltages (V-oc) and the in situ photoconductivities have been measured to study electron behavior in photocatalysis and its effect on the photocatalytic oxidation of methanol. It was observed that electron injection to the conduction band (CB) of TiO2 under light illumination during photocatalysis includes two sources: from the valence band (VB) of TiO2 and from the methanol molecule. The electron injection from methanol to TiO2 is slower than that directly from the VB, which indicates that the adsorption mode of methanol on the TiO2 surface can change between dark and illuminated states. The electron injection from methanol to the CB of TiO2 leads to the upshift of the Fermi level of electrons in TiO2, which is the thermodynamic driving force of photocatalytic oxidation. It was also found that the charge state of nanoTiO(2) is continuously changing during photocatalysis as electrons are injected from methanol to TiO2. Combined with the apparent Langmuir-Hinshelwood kinetic model, the relation between photocatalytic kinetics and electrons in the TiO2 CB was developed and verified experimentally. The photocatalytic rate constant is the variation of the Fermi level with time, based on which a new method was developed to calculate the photocatalytic kinetic rate constant by monitoring the change of V-oc with time during photocatalysis.
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