Importance of the Metal-Oxide Interface in Catalysis: In Situ Studies of the Water-Gas Shift Reaction by Ambient-Pressure X-ray Photoelectron Spectroscopy

Where oxide and metals meet: The activation of an efficient associative mechanistic pathway for the water–gas shift reaction by an oxide–metal interface leads to an increase in the catalytic activity of nanoparticles of ceria deposited on Cu(111) or Au(111) by more than an order of magnitude (see graph). In situ experiments with NA-XPS and IRRAS demonstrated that a carboxy species formed at the metal–oxide interface is the critical intermediate in the reaction. Our study illustrates the power of in situ mechanistic studies on well-defined catalysts and the important role that metal–oxide interfaces can play in catalysis. The simultaneous participation of atoms present on the metal and the oxide make possible the formation of HOCO and CO2δ− and thus favors a reaction mechanism for hydrogen production that is not effective on isolated copper or isolated ceria. Thus, when optimizing this type of catalyst, one must pay special attention to the properties of the metal–oxide interface.

http://onlinelibrary.wiley.com/store/10.1002/anie.201210077/asset/image_m/mcontent.gif?v=1&s=08097811b829f95125a8b058fa5383149373f1dd

 

Ref: Mudiyanselage, K., Senanayake, S.D., Feria, L., Kundu, S., Baber, A.E., Graciani, J., Vidal, A.B., Agnoli, S., Evans, J., Chang, R., Axnanda, S., Liu, Z., Sanz, J.F., Liu, P., Rodriguez, J.A., and Stacchiola, D.J. Angewandte Chemie-International Edition, 2013. 52(19): p. 5101-5105. DOI: 10.1002/anie.201210077

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