Surface Chemistry of Trimethyl Phosphate on α-Fe2O3
The chemistry of trimethyl phosphate (TMP) was examined on the (012) crystallographic face of hematite (α-Fe2O3) using temperature programmed desorption (TPD), high resolution electron energy loss spectroscopy (HREELS), static secondary ion mass spectrometry (SSIMS) and Auger electron spectroscopy (AES). TMP binds to Fe3+ sites on the clean α-Fe2O3(012) surface through lone pairs on the P=O oxygen atom. A small portion of adsorbed TMP desorbs without decomposition, however, the majority of adsorbed TMP decomposes in a two step process on the clean surface. The first step, occurring at or below room temperature (RT), likely involves displacement or substitution of one –OCH3 group to form surface methoxy groups and adsorbed dimethyl phosphate (DMP). In the second step, DMP decomposes above 500 K to a 1:1 ratio of gaseous methanol and formaldehyde with phosphate left on the surface. Identification of these steps was confirmed using the chemistry of methanol on the clean surface. Coadsorption of TMP and water led to a small degree of hydrolysis between these two molecules in the multilayer, but no significant change in the chemistry on the surface. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1031415
- Report Number(s):
- PNNL-SA-82627; KC0302010; TRN: US201201%%590
- Journal Information:
- Journal of Physical Chemistry C, Vol. 115, Issue 47; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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