Reactions on nano-structured surfaces

This project is devoted to the kinetics and dynamics of model reactions on nano-structured surfaces. The goal of these studies is to identify the key factors for controlling the selectivity and activity of surfaces by means of nano- structuring the surface. We will focus on one-dimensional nano-structured surfaces based on stepped metal surfaces. These structures will be produced by decorating the steps either with other metals, to yield bimetallic nanowires (nickel and manganese on stepped palladium and rhodium surfaces), and with surface oxides to yield oxide nanowires (NiOx and MnOx on stepped palladium and rhodium surfaces). On these nanostructured surfaces we will investigate the adsorption and desorption kinetics and dynamics of CO, as well as the oxidation of CO. Furthermore, the adsorption, oxidation and dehydrogenation of methanol will be explored in detail. This subject is of great topicality, since it is relevant for many modern technologies, e.g. in the application of fuel cells. In this context, another topic is the investigation of adsorption, desorption and reaction of methanol and other related hydrocarbons (formaldehyde, formate) on a specifically prepared Cu(110) surface, which is known as the Cu-CuO stripe phase. This surface exhibits alternate stripes of bare copper and copper oxide areas with lateral dimensions in the order of nanometers, which are produced in a self assembling process due to surface strain. The aim of this project is to specify the active centers on these nano structured surfaces, which govern their special reaction properties (activity and selectivity) and finally to tune these properties. The experimental approach for this purpose is to study not only the reaction kinetics but also their dynamics. This involves the measurement of the angular and energy distribution of the reaction products. For these experiments we will apply integral and angle resolved thermal desorption spectroscopy (TDS), temperature programmed reaction spectroscopy (TPRS), as well as integral and angle resolved time-of-flight (TOF)-spectroscopy. All experiments will be carried out under ultrahigh vacuum conditions. For the surface characterization Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and reflection absorption infra red spectroscopy (RAIRS) will be applied. Scanning tunneling spectroscopy (STM) and reflectance difference spectroscopy (RDS) will be performed by collaboration. Theoretical calculations concerning the structure and energetics of the nanostructured surfaces and the activation barriers for the individual reaction steps will be carried out by our collaboration partners, using density functional theory (DFT).

This project is devoted to the kinetics and dynamics of model reactions on nano-structured surfaces. The goal of these studies is to identify the key factors for controlling the selectivity and activity of surfaces by means of nano- structuring the surface. We will focus on one-dimensional nano-structured surfaces based on stepped metal surfaces. These structures will be produced by decorating the steps either with other metals, to yield bimetallic nanowires (nickel and manganese on stepped palladium and rhodium surfaces), and with surface oxides to yield oxide nanowires (NiOx and MnOx on stepped palladium and rhodium surfaces). On these nanostructured surfaces we will investigate the adsorption and desorption kinetics and dynamics of CO, as well as the oxidation of CO. Furthermore, the adsorption, oxidation and dehydrogenation of methanol will be explored in detail. This subject is of great topicality, since it is relevant for many modern technologies, e.g. in the application of fuel cells. In this context, another topic is the investigation of adsorption, desorption and reaction of methanol and other related hydrocarbons (formaldehyde, formate) on a specifically prepared Cu(110) surface, which is known as the Cu-CuO stripe phase. This surface exhibits alternate stripes of bare copper and copper oxide areas with lateral dimensions in the order of nanometers, which are produced in a self assembling process due to surface strain. The aim of this project is to specify the active centers on these nano structured surfaces, which govern their special reaction properties (activity and selectivity) and finally to tune these properties. The experimental approach for this purpose is to study not only the reaction kinetics but also their dynamics. This involves the measurement of the angular and energy distribution of the reaction products. For these experiments we will apply integral and angle resolved thermal desorption spectroscopy (TDS), temperature programmed reaction spectroscopy (TPRS), as well as integral and angle resolved time-of-flight (TOF)-spectroscopy. All experiments will be carried out under ultrahigh vacuum conditions. For the surface characterization Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and reflection absorption infra red spectroscopy (RAIRS) will be applied. Scanning tunneling spectroscopy (STM) and reflectance difference spectroscopy (RDS) will be performed by collaboration. Theoretical calculations concerning the structure and energetics of the nanostructured surfaces and the activation barriers for the individual reaction steps will be carried out by our collaboration partners, using density functional theory (DFT).