Reduction of FeO/Pt(1 1 1) thin films by exposure to atomic hydrogen |
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Authors: | Jan Knudsen Lars C Grabow Soeren Porsgaard Ronnie T Vang Manos Mavrikakis |
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Institution: | a Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark b Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA |
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Abstract: | Using scanning tunneling microscopy (STM), X-ray photoemission spectroscopy (XPS) and density functional theory (DFT) calculations we have studied the reduction of ultra-thin films of FeO(1 1 1) grown on Pt(1 1 1) after exposure to atomic hydrogen at room temperature. A number of new ordered, partly-reduced FeOx structures are identified and as a general trend we reveal that all the reduced FeOx structures incorporate 2-fold coordinated Fe atoms as opposed to the original 3-fold coordinated Fe atoms in the FeO film. We find that when all the Fe atoms are 2-fold O-coordinated the FeOx surface structure is resistant to further reduction at room temperature. We observe that water easily dissociates on the most heavily reduced FeOx, structure in contrast to the initially inert FeO film, and reveal that it is possible to partially re-oxidize the FeOx film by heating the surface slightly in the presence of water. |
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Keywords: | Iron-oxide film Reduction Scanning tunneling microscopy Water Metal-oxide X-ray photoelectron spectroscopy |
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