Topics in Catalysis

, Volume 36, Issue 1, pp 65–76

Growth of Copper on Single Crystalline ZnO: Surface Study of a Model Catalyst

Article

DOI: 10.1007/s11244-005-7863-5

Cite this article as:
Dulub, O., Batzill, M. & Diebold, U. Top Catal (2005) 36: 65. doi:10.1007/s11244-005-7863-5

Copper, vapor-deposited on the polar, Zn-terminated ZnO(0001) surface is investigated in view of its suitability as model system for the technologically important Cu/ZnO catalyst. The structure and electronic properties of Cu clusters on ZnO(0001)–Zn have been studied with scanning tunneling microscopy (STM), low energy electron diffraction (LEED), ultraviolet photoelectron spectroscopy (UPS), and low-energy He+ ion scattering (LEIS). At room temperature copper grows as two-dimensional (2D) clusters only at very low coverages of 0.001–0.05 equivalent monolayers (ML). At coverages greater than 0.01 ML, 3D clusters start to develop. This is contrasted to Cu growth on the oxygen-terminated ZnO(0001bar) surface, where a strong adhesion between Cu and the ZnO substrate results in an initial wetting of the surface by Cu. On ZnO(0001)–Zn, surface roughness and sputter damage change the growth mode to more 2D-like. Annealing in UHV results in well-separated, hexagonal clusters rotationally aligned with the substrate. Annealing of 2–5 ML Cu deposits on the ZnO(0001)–Zn surface in 10−6 mbar O2 results in the formation of a (√3 × √3)R30° superstructure with respect to the ZnO lattice. This superstructure likely contains Cu+ sites. The suitability of the different surface morphologies to probe specific sites that are thought to be active for catalytic processes is discussed.

Keywords

Cu/ZnO catalystzinc oxidemethanol synthesissurface alloyadsorptionCu growthoxygen annealingSTM

Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  1. 1.Department of PhysicsTulane UniversityNew OrleansUSA