Abstract
Many industrially important catalysts consist of late transition metal
particles supported on the surfaces of oxide materials. Our studies
of such systems using model catalysts consisting of metal films vapor
deposited onto the surfaces of single-crystalline oxides are reviewed
here. Systems studied include Cu on ZnO, Pt on ZnO. Au on TiO2 and
Cu, Ag and Pt, on MgO. A unique adsorption microcalorimeter was developed
to measure directly the energetic stability of the metal atoms on
the oxide surfaces and the adhesion energy at the metal/oxide interface,
which clarify the structural and chemisorption properties of the
ultrathin metal particles. The structure of the oxide surface and
the metal particles was elucidated by low-energy electron diffraction
(LEED), low-energy ion scattering spectroscopy (ISS), angular-resolved
X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction
(XPD). The electronic character of the metal particles was revealed
by XPS, Auger electron spectroscopy (AES), band-bending and work
function measurements. Sintering rates were measured by temperature-programmed
ion scattering spectroscopy (TPISS). The chemisorption properties
of these particles and their catalytic reactivity were monitored
by mass spectroscopy and temperature-programmed desorption (TPD).
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