In Situ X-ray Scattering Studies of Ultrathin Epitaxial Metal Oxide Films
This work combines electrochemical studies of thin epitaxial metal and metal oxide films with advanced in situ and operando surface X-ray diffraction (SXRD). This combination enables the correlation of reactive processes with the structure of the interfaces at which they occur. In the focus of our studies are Co oxides which are promising candidates for the precious-metal-free catalysis of the oxygen evolution reaction (OER). In a first attempt to grow thin epitaxial metal oxide film catalysts, the anodic oxidation of Co deposited on Au(111) was investigated. A different approach, in which Co3O4 and CoOOH were directly electrodeposited on Au(111) substrates, produced well defined oxide films. These films were structurally characterized under operation conditions, i.e. under strong gas evolution and current densities of up to 150 mA/cm^2. Aside from the OER motivated studies, magnetic Pd/Co/Au(111) stacks were investigated. Furthermore, transmission surface diffraction (TSD), a novel high-energy SXRD technique, was developed.