Adsorption and photooxidation of CH{sub 3}CN on TiO{sub 2}
- Univ. of Pittsburgh, PA (United States)
The adsorption and photooxidation of CH{sub 3}CN chemisorbed on TiO{sub 2} has been investigated using infrared spectroscopy. It was found that CH{sub 3}CN forms an ice layer on TiO{sub 2} at 126 K and above 126 K CH{sub 3}CN diffusion into TiO{sub 2} occurs. At 200 K, the adsorption of CH{sub 3}CN on both isolated Ti-OH groups and on the Ti{sup 4+} Lewis acid site was observed. Under UV irradiation (350 {+-} 50 nm; hv = 3.10--4.13 eV), CH{sub 3}CN was oxidized in the presence of O{sub 2} to form H{sub 2}O, CO{sub 2}, surface CO{sub 3}{sup 2{minus}} and an intermediate partially oxidized isocyanate species, NCO, which was identified by various isotopic experiments. Photooxidation of the CH{sub 3} moiety in adsorbed CH{sub 3}CN occurs more readily than does the CN moiety in CH{sub 3}CN. Lattice oxygen of TiO{sub 2} was found to preferentially form adsorbed NCO, compared to oxygen from adsorbed O{sub 2}. A mechanism of the formation of NCO species was postulated.
- OSTI ID:
- 691305
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 103, Issue 33; Other Information: PBD: 19 Aug 1999
- Country of Publication:
- United States
- Language:
- English
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