Model system based on ordered oxide films have been developed by Hajo Freund and coworkers over a period of 30 years and have been used in many pioneering model catalytic studies. This contribution provides an overview over recent work by the presenter’s group making use of the same concept. Besides ‘conventional’ model studies of solid/gas reactions, the focus is on ‘unconventional’ model studies involving solid/liquid, electrochemical, and hybrid interfaces. Typical supported model catalysts, i.e., Pt and Pd NPs on ordered alumina supports, were used to study hydrogen release from so called Liquid Organic Hydrogen Carriers (LOHCs).[1] LOHCs are organic molecules which can be reversibly (de)hydrogenated. They allow storing hydrogen at room temperature and pressure in form of a rechargeable liquid fuel that can be easily transported. Using model catalytic studies, the mechanism of LOHC dehydrogenation and particle size effects could be explored. The same type of model catalysts, i.e., Pd NPs on alumina thin films, was used to build model systems for so-called SCILLs (Solid Catalysts with Ionic Liquid Layer).[2,3] Ionic Liquids (ILs) are low-melting-point salts. In the SCILL concept, they are employed as catalytic modifiers to enhance the selectivity of hydrogenation catalysts. The underlying operation principles were explored using the model catalysis approach. Recently, we have shown that the same type of model approach can also be used to construct complex model electrocatalysts.[4.5] We prepared atomically-defined oxide-based electrodes under surface science conditions and studied their properties in liquid electrolytes. When loaded with noble metal NPs, such systems allow studying particle size effects and metal-support interactions at a great level of detail. Finally, we show that ordered oxide films can also be used to build atomically-defined model systems for organic-oxide interfaces.[6] Such systems can be studied both in ultrahigh vacuum and in liquid electrolytes under potential control, with the idea to build model interfaces for solar cells, molecular electronics or photochemical devices.

Model interfaces constructed from ordered oxide films: From heterogeneous catalysis to electrocatalysis, photoelectrocatalysis, and organic-oxide hybrid materials

2019 Spring National Meeting

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