This project is in the area of the Materials Chemistry Initiative. The diffusion of gases adsorbed on oxide surfaces plays a pivotal role in supported metal catalysis. Diffusion rates on oxide surfaces dramatically affect surface reactions on supported metals . More effective and chemically specific catalysts could be designed by utilizing particular surface and interface geometries with favorable surface diffusion properties. However, no direct measurements of surface diffusion on well characterized oxide surfaces have ever been performed. This research focuses on two model oxidation reactions: carbon monoxide + oxygen --> carbon dioxide on palladium/alpha-alumina, and carbon dioxide + nitric oxide --> carbon dioxide + nitrogen on rhodium/alpha-alumina. Concurrent reaction kinetic studies and surface diffusion experiments will explore, characterize, and demonstrate how to exploit the role of surface diffusion in catalytically important reactions. Additional opportunities include a measurement of hydrogen spillover on well-characterized palladium/alpha-alumina and comparison studies of surface diffusion on various alpha-alumina and silicon dioxide single crystal faces.
