Photocatalytic Reaction of TiO2 Thin Film in air
| Autor: | Zhong-Xiang Lin, 林中翔 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 In this work, we studied the photocatalytic decomposition and modification of octadecyltrichlorosilane (OTS) self-assembled monolayers by using TiO2 thin film in air. The TiO2 thin films were deposited on Atomic Force Microscopy (AFM) probes or silicon substrates by plasma sputtering and had anatase phase. The wavelength of UV light for photocatalytic excitation was 365 nm. We observed the local decomposition and modification of OTS SAMs by AFM and Lateral Force Microscopy (LFM). Large area photocatalytic reaction on OTS SAMs was measured by the contact angle of water on sample surface. We found that at low humidity, the photocatalytic efficiency was not obviously related to the light intensity, because the efficiency was limited by the supply of water molecules in air. As the humidity increased, the efficiency also increased. We also found that applying a negative bias on TiO2 thin film could obviously increase the efficiency, and a positive bias could slightly decrease the efficiency. We deduced that not only H2O molecules but also O2 molecules are the major reactants. Under the electric field associated to the applying bias, the generated O2－ could be driven to the OTS surface and increase the efficiency. At low humidity (40% RH), the contribution of O2－ to the photocatalytic reaction was estimated to be about 86%. At high humidity (80% RH), the contribution became about 24%. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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