Wet-electron Enhanced Surface Dissociative Electron Attachment Chemistry of Halocarbons
Abstract
We investigated photocatalytic decomposition of organic compounds on rutile TiO2(110) single crystal surfaces in presence of near-UV light and O2 by two-photon photoemission spectroscopy. We found that the irradiation of water, methanol and ethanol induces deprotonation of the intact species to produce surface OH species. The surface OH is responsible for the intense wet electron resonance observed in two photon-photoemission spectra. Measurement of the wet electron resonance as a function of time indicated an initial rise of the signal due to the production of the surface OH species to a saturation value, followed by periodic sharp changes in the signal of unknown origin. When the same experiment is performed in the presence of O2 at 10^-9 to 10^-8 mbar pressure, the wet electron signal oscillates. Signal autocorrelation measurements provide evidence for an oscillatory photocatalytic process most likely involving the interaction of conduction band electrons with O2 molecules and holes with the chemisorbed organic molecules. We believe that this is the first time that such oscillatory chemical reaction has been observed in a photocatalytic process, and it is likely to be a general phenomenon associated with the collocated oxidation and reduction processes on TiO2 surfaces. Therefore it is relevant to the mechanism of photocatalytic decontamination with TiO2 photocatalysis.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 14, 2011
- Accession Number
- ADA544810
Entities
People
- Chungwei Lin
- Hrvoje Petek
- Jin Zhao
- Xuefeng Cui
Organizations
- University of Pittsburgh