The Incorporation of Added Metal Atoms into Structures of Reaction Intermediates on Catalytic Metal Surfaces

Abstract

In this chapter, we review the dynamic nature of catalytic metal surfaces and the effects of metal incorporation into surface reaction intermediates on their reactivity. Scanning tunneling microscopy allows the direct observation of surface reconstruction and dynamic reorganization of surfaces during adsorption, desorption, and surface reaction, and therefore, provides a powerful tool to relate the surface structures of adsorbed layers to reactivity when combined with quantitative temperature-programmed reaction spectroscopy, X-ray photoelectron spectroscopy and other tools. The incorporation of added metal atoms to the structure of adsorbates and reaction intermediates is a general surface phenomenon not restricted to more open, higher free energy single crystal planes, but also occurring on close-packed surfaces of low free energy. Metal atom incorporation into the surface oxide appears to be a guide to the possibility of incorporation of metal atoms into the structure of other intermediates. Added metal atoms can stabilize the structures of reaction intermediates and play an important role in their surface reactions. These observations dictate that the participation of added metal atoms be considered as a paradigm in metal catalyzed reactions, significantly affecting the theoretical treatment of these processes.