AVS 57th International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM11
Reactivity of CO towards Nanocrystals and Continuous Films of α-Fe2O3 on Au(111) at Ambient Pressure: Implications for the Water-Gas Shift Reaction

Monday, October 18, 2010, 11:40 am, Room Picuris

Session: Reactivity and Selectivity on Catalytic Surfaces
Presenter: X. Deng, National Energy Technology Laboratory (NETL)
Authors: X. Deng, National Energy Technology Laboratory (NETL)
J. Lee, National Energy Technology Laboratory (NETL)
C. Wang, National Energy Technology Laboratory (NETL)
C. Matranga, National Energy Technology Laboratory (NETL)
F. Aksoy, Lawrence Berkeley National Laboratory
Z. Liu, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
The reactivity of CO towards 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 (hundreds of mTorr). On Au(111) decorated with α-Fe2O3 nanocrystals (6-7nm), adsorbed CO was detected by XPS at room temperature when exposed to 200 mTorr of CO. At the same time, surface hydroxyl groups (adsorbed OH) were also observed as a result of H2O dissociation. Upon heating the surface to 373 K, adsorbed formate (HCOO-) was detected on the surface and believed to originate from the reaction of CO with the OH groups. The adsorbed formate desorbed or decomposed above 473 K. Continuous α-Fe2O3 thin films on Au(111) were inert towards CO under the same conditions studied for nanocrystalline α-Fe2O3. Specifically, adsorbed CO was not observed on this surface when it was exposed to 200 mTorr of CO at room temperature. This reactivity difference can be explained by the presence of α-Fe2O3 crystal edges and the interfaces between α-Fe2O3 and Au. 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. Implications of these experimental results for the water-gas shift reaction will be also discussed.