Subsurface Oxygen On Pt(100): Kinetics Of The Transition From Chemisorbed To Subsurface State And Its Reaction With CO, H2, and O2
Document Type
Article
Subject Area(s)
Engineering, Chemical Engineering, Catalysis and Reaction Engineering, Membrane Science
Abstract
The photoemission electron microscope (PEEM) makes it possible to image a surface via its work function. On a CO-covered Pt(100) surface, we prepared oxygen islands which appear dark in the PEEM image due to their higher work function. As the surface is heated to temperatures above 650 K we observe the conversion of these dark islands into very bright ones with work functions much lower than even that of the clean surface arising from an inverted dipole moment of oxygen atoms beneath the surface. We found an activation energy for this conversion of about 15 kcal/mol. Partially transformed oxygen islands were used to study the reactivity and the formation of this species further. CO and H2 both react with subsurface oxygen rather slowly, while at the interface between the subsurface and the chemisorbed phase, both adsorbents accelerate the conversion of parts of the remaining oxygen atoms towards the subsurface state. In contrast, additional oxygen adsorption does not contribute to a further transformation. We propose a qualitative microscopic model for the formation of subsurface oxygen based on experimental evidence.
Digital Object Identifier (DOI)
Publication Info
Published in Surface Science, Volume 313, Issue 1-2, 1994, pages 52-63.
Rights
© Surface Science, 1994, Elsevier
APA Citation
Lauterbach, A.J., Asakura, K., Rotermund, H.H. (1994). Subsurface oxygen on Pt(100): kinetics of the transition from chemisorbed to subsurface state and its reaction with CO, H2, and O2. Surface Science, 313(1-2), 52-63.