Reactivity Differences of Nanocrystals and Continuous Films of α-Fe₂O₃ on Au(111) Studied with In Situ X-ray Photoelectron Spectroscopy

Journal Article · Thu Dec 30 04:00:00 EST 2010 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/jp1085697· OSTI ID:1015217

Deng, Xingyi ^[1]; Lee, Junseok ^[1]; Wang, Congjun ^[1]; Matranga, Christopher ^[1]; Aksoy, Funda ^[2]; Liu, Zhi ^[3]

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1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cukurova Univ., Adana (Turkey) Dept. of Physics
3. 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, Journal Name: Journal of Physical Chemistry. C Journal Issue: 51 Vol. 114; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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