Reactivity Differences of Nanocrystals and Continuous Films of α-Fe2O3 on Au(111) Studied with In Situ X-ray Photoelectron Spectroscopy
- National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cukurova Univ., Adana (Turkey) Dept. of Physics
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
The interaction of CO with nanocrystals and continuous films of α-Fe2O3 grown on Au(111) was investigated using in situ X-ray photoelectron spectroscopy (XPS) at near ambient pressure (200 mTorr) and scanning tunneling microscopy (STM). Adsorbed CO was detected by XPS when α-Fe2O3 nanocrystals (6-7 nm) grown on Au(111) were exposed to 200 mTorr of the gas at room temperature. Under a low H2O background, surface bound hydroxyl groups (adsorbed OH) were also noted on these α-Fe2O3 nanocrystals as a result of H2O dissociation on the edges of the particles. Adsorbed formate (HCOO-) was detected during heating to 373 K and believed to originate from the reaction of adsorbed CO with the OH groups. The adsorbed formate desorbed or decomposed above 473 K. Continuous α-Fe2O3 thin films on Au(111) were inert under the same conditions studied for nanocrystalline α-Fe2O3. Specifically, neither adsorbed CO nor OH groups were observed for the continuous films of α-Fe2O3. This reactivity difference can be explained by the presence of α-Fe2O3 crystal edges and the interface which exists between the α-Fe2O3 nanocrystals and the Au(111) substrate. These edges and interfaces are present for the nanocrystalline α-Fe2O3/Au(111) system but are not present in significant amounts for the continuous films of α-Fe2O3. The implications of these experimental results for the water-gas shift reaction will be also discussed.
- Research Organization:
- National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Fossil Energy (FE)
- OSTI ID:
- 1015217
- Report Number(s):
- NETL-TPR-3182
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 114, Issue 51; ISSN 1932-7447
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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