|Enhanced Reactivity of α-Fe2O3 at Near-Ambient Conditions|
|Wednesday, 11 May 2011 16:41|
Scientists from DOE’s National Energy Technology Laboratory (NETL) and Berkeley Lab used scanning tunneling microscopy (STM) and ambient-pressure x-ray photoelectron spectroscopy (AP-XPS) at ALS Beamline 9.3.2 to examine nanocrystals and continuous thin films of α-Fe2O3 grown on Au(111), and to gain insight into the structure-property relation of a material under realistic conditions. The nanocrystalline α-Fe2O3/Au(111) system has significant amounts of edge and interfacial sites, while the density of these structural features are low or nonexistent in the continuous films of α-Fe2O3 on Au(111). The distinctive morphologies of the two systems result in different reactivity when exposed to a high pressure of carbon monoxide (CO) gas:
The comparative studies clearly establish a relationship between structure and activity and demonstrate the crucial roles of edges and interfaces in catalytic reactions.
A detailed characterization of an individual α-Fe2O3 particle grown on Au(111), showing stepped edges and interfacial regions between the oxide and the Au substrate. The AP-XPS revealed the presence of formate in the nanocrytalline α-Fe2O3/Au(111) system at elevated temperatures resulting from a reaction between adsorbed CO and OH.
Work performed on ALS Beamline 9.3.2
Citation: Xingyi Deng, Junseok Lee, Congjun Wang, Christopher Matranga, Funda Aksoy, and Zhi Liu, "Reactivity Differences of Nanocrystals and Continuous Films of α-Fe2O3 on Au(111) Studied with In Situ X-ray Photoelectron Spectroscopy" J. Phys. Chem. C, 2010, 114 (51), pp 22619–22623.