Probing Atomic Scale Structure and Catalytic Properties of Cobalt Oxide Model Catalysts

Abstract: Catalysts are used to produce a large fraction of the materials we use in our modern society. Avery famous example is the highly efficient catalysts that are used to fix nitrogen from the air intoartificial fertilizer salts. Without this catalytic process, it is difficult to imagine that we could feedthe current population of earth. Artificial fertilizers are, however, not the only product that uses acatalyst for its production. In fact, almost all products produced in the chemical industry such asplastic materials, paints, coating materials, gasoline, drugs, etc. use catalysts for their production.Catalysts are also used extensively for cleaning of exhaust gas from power plants, trucks, and cars.As an example, the catalyst in a car convert carbon monoxide gas (CO) to non-toxic carbon dioxide(CO2). Unfortunately, the catalyst in the car is built partly from very expensive metals such asplatinum and palladium.As discussed above catalysts are used extensively both for the production of modern materials andfor reducing the amount of toxic chemicals we release into our environment. Most of the catalystmaterials we use today have been found by trial and error methods and knowledge of why and howthe chemical process take place on the catalyst material is therefore often very limited or missingfully.The goal of the present work has been to improve our understanding of chemical processes takingplace on cobalt oxide based catalysts. Instead of studying real and complex cobalt oxide catalystmaterials we have studied thin and highly idealized cobalt oxide films. Using these highly idealizedmodel systems of the real catalysts we studied chemical processes at the atomic scale level. Oneimportant take home message of the studies is that single cobalt atoms found on the surface areessential for the function of the catalysts surface and in particular for how it interact with gasmolecules.Hopefully, the present fundamental work on cobalt oxide catalysts can be used to develop new andbetter catalysts of this material. Furthermore, the work adds knowledge to our generalunderstanding of metal oxide films and their catalytic applications.