Intermetallic compounds as models for materials formed at the metal crystallite-oxide support interface

Evidence from the literature suggests that intermetallic compounds may form from the interaction of small metal crystallites with supposedly inert oxide supports (for example, PtTi_x from Pt on TiO₂ or NiSiy from Ni on SiO₂). In order to characterize these materials more fully, we have undertaken a program to study both compounds. Fundamental experiments on single crystalline substrates under UHV conditions reveal that these materials have unique chemisorption properties which can be exploited to yield both highly selective and highly active catalysts. We have also demonstrated that similar materials may be grown by reacting volatile main group organometallic compounds (such as alkylsilanes) with clean metal substrates. Thus, high surface area, supported intermetallic compound and alloy catalysts can be made readily. In particular, we will detail our chemisorption studies on group VIII metal silicides. The properties of these materials as regards hydrogenation, dehydrogenation, and deoxygenation reactions will also be discussed.