Structural changes of model Cu/ZnO catalysts during exposure to methanol reforming conditions

• Published in: Surface science Vol. 532; pp. 383 - 389
• Main Authors: Raimondi, Fabio, Schnyder, Bernhard, Kötz, Rüdiger, Schelldorfer, Rolf, Jung, Thomas, Wambach, Jörg, Wokaun, Alexander
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10-06-2003
• Subjects: Atomic force microscopy; Catalysis; Copper; Ellipsometry; Oxidation; Sintering; X-ray photoelectron spectroscopy; Zinc oxide; Atomic force microscopy; Sintering; Zinc oxide; Oxidation; Catalysis; Copper; X-ray photoelectron spectroscopy; Ellipsometry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(03)00236-X

Cu/ZnO/Si model catalysts were prepared by resistive evaporation of Cu on ZnO thin films deposited on Si(1
0
0) by DC magnetron sputtering. Exposure of the Cu/ZnO/Si model catalysts to methanol reforming conditions at 550 K causes agglomeration of the supported Cu islands as shown by XPS, AFM and spectroscopic ellipsometry. The Cu remains in the metallic state for O
2/CH
3OH molar ratios ⩽0.25 but is oxidised to Cu(I) for higher oxygen content. When Cu is in the metallic state the degree of agglomeration is larger in the presence of O
2 in the gas phase. On the other hand oxidation of the Cu islands is associated with a less pronounced agglomeration upon methanol reforming treatment. The origin of this phenomenon is discussed.