Formic acid decomposition on [C@110]C-microfaceted surface of TiO{sub 2}(100): Insights derived from {sup 18}O-labeling studies
- Pacific Northwest Lab., Richland, WA (United States)
The decomposition of formic acid was examined on the [C@110]C@-microfaceted surface of TiO{sub 2}(100) with temperature-programmed desorption (TPD), static secondary ion mass spectrometry (SSIMS), low-energy electron diffraction (LEED), and work function measurements. No ordered structures of formic acid, or of its main decomposition product formate, were observed. Formic acid decomposed on TiO{sub 2}(100) to formate and a surface proton at temperatures below 250 K. The main TPD products were water, which desorbed below 450 K, and CO, which desorbed at 555 K. Formaldehyde was also observed as a TPD product at 540 K. CO and formaldehyde resulted from formate decomposition. TPD experiments performed on the {sup 18}O-enriched surface show that extensive isotopic oxygen incorporation occurred for the CO, water, and formaldehyde TPD products. The incorporation of lattice {sup 18}O into the water product indicates that the acid proton, deposited during formic acid decomposition, was able to abstract oxygen from the surface. SSIMS measurements indicate that incorporation of lattice {sup 18}O into the formate species did not occur until the onset of formate decomposition, implying that lattice oxygen atoms were involved in the formate decomposition process. Studies with coadsorbed H{sub 2} {sup 18}O indicate that water was a mild site blocker of formic acid adsorption and/or decomposition sites and that little or no isotopic oxygen exchange took place between the two adsorbed molecules. 30 refs., 16 figs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 136099
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 41 Vol. 99; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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