Research Group - Prof. Thomas Risse

Nanoporous gold (np-Au) has attracted considerable attention in the recent past because of its interesting properties in particular with respect to their use as catalysts. On the microscopic level the reactivity of the systems is largely determined by structural imperfections of the nanostructured material as well as the chemical composition of its surface. Investigations on suitable single crystalline model surfaces, which grasp essential aspects of the complexity of the real system allow for a characterization with the rigor of modern surface science techniques. In combination with theoretical calculations provided by the partners within this initiative this is a promising route towards an atomistic understanding of chemical processes on np-Au.

The project works on single crystalline model systems under well-defined conditions focusing in particular on two material parameters of this system, which are considered crucial for the catalytic performance, namely the role of low coordinated sites and the impact of a secondary component be it a metal or an oxide on the properties of the system. To this end flat and stepped Au surfaces namely Au(111) and Au(332) surfaces are compared. In addition, the role of a second metal remaining in the np-Au is studied by deposition of Ag and Cu on the abovementioned Au surfaces. We study the (reactive) adsorption and co-adsorption of alcohols and oxygen on the various metal surfaces and will search for the presence of reaction products or intermediates using infrared spectroscopy, as well as temperature programmed reaction. Isothermal reactivity is studied using molecular beam techniques with mass spectrometric detection of gas phase products, which also allows for IR spectroscopic characterization of the surfaces during reaction. In combination with the other groups of theoretical groups this consortium in particular with theory (Klüner, Moskaleva) and the group of Marcus Bäumer focusing on gas phase catalysis on np-Au the results of these studies will help to derive an atomistic understanding of the catalytic processes taking place on the surface of these systems.