Identification of a Surface Alkylperoxy Radical in the Photocatalytic Oxidation of Acetone/O2 over TiO2
| Autor: | Damien Martin Murphy, John L. Edwards, and Christopher C. Rowlands, Anna L. Attwood |
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| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 107:1779-1782 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp022448n |
| Popis: | The interaction of a coadsorbed mixture of acetone and oxygen with a clean oxidized polycrystalline sample of TiO2 (P25) was investigated using electron paramagnetic resonance (EPR) spectroscopy. UV illumination of the sample at low temperature (100 K) generated an unstable radical intermediate at the dehydrated (and hydrated) TiO2 surface. The radical decayed irreversibly at temperatures greater than 150 K but was regenerated by subsequent irradiation at low temperatures. Using a series of isotopically labeled gases (CH3COCH3, CD3COCD3, 16O2, and 17O2) to aid in the interpretation of the EPR spectrum, the radical was identified as an alkylperoxy species RCH2OO• with the spin Hamiltonian parameters of g1 = 2.0345, g2 = 2.0070, g3 = 2.0010, HA1 = 0.34 mT, HA2 = 0.10 mT, HA3 = 0.29 mT, 17ΟA||(i) = 9.45 mT (for RO17O•), and 17OA||(ii) = 5.52 mT (for R17OO•). By consideration of the different mechanistic pathways involved in the oxidation of acetone, it was concluded that the observed radical is generated ini... |
| Databáze: | OpenAIRE |
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