Paper SS2-WeM1
Temperature Program Desorption and X-ray Photoelectron Spectroscopy Study of Cu_x on CeO₂/YSZ (111)

Wednesday, November 2, 2011, 8:00 am, Room 109

Energy research has increased in importance in the past decade due to our growing understanding of climate science and rising oil prices. Many catalysts center around expensive and rare transition metals, such as Pt and Pd, supported on oxide substrates. However, copper, a relatively cheap and abundant metal, supported on metal oxides has been used as a heterogeneous catalyst in industrial settings for various chemical processes.^1,2 Recent works have shown that copper nanoparticles supported on metal oxides (ZnO, CeO₂, TiO₂) have higher activity for the water gas shift reaction (WGSR) as well as other important chemical reactions when compared to their individual components.^3,4 Understanding how these complex catalysts work on a fundamental level will allow for the design and implementation of more efficient and selective systems in the future. Here, using a homemade thermal evaporator, a model system of copper nanoparticles deposited on CeO₂ films (200 nm thick) grown on YSZ (111) single crystals is used. X-ray photoelectron spectroscopy (XPS) is used to characterize the oxidation state of supported copper nanoparticles and temperature programmed desorption (TPD) is used to probe their reactivity and thermal stability. Copper coverages ranging from 0.25ML to 1ML are investigated. Carbon monoxide and water are used as probe molecules since they are the reactants involved in the WGSR. We have found that copper’s stability is highly temperature dependent and have found evidence of its encapsulation by the support.

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4. X. Zhao, J. A. Rodriguez, J. Hrbek, M. Pérez, Surface Science, 2005 , 600, 229.