Electrochemical surface science aims to study surfaces under ambient atmosphere and electrochemical conditions, which approach those relevant for applications more closely than ultrahigh vacuum. While this branch of surface science has gained momentum for noble metal samples, oxides have so far rarely been studied.
In this thesis, several improvements have been made to our electrochemical scanning tunnelling (EC-STM) methodology, which is one of the main techniques in electrochemical surface science. Platinum iridium tips were implemented, since the more widely used tungsten tips were found to be unstable in aqueous electrolyte and thus contaminate the surface. A palladium-hydrogen reference electrode was developed to replace unreliable quasi-reference electrodes, improving electrochemical potential control and imaging conditions. Oxygen removal in an environmental chamber was optimised, impeding the reactions it induces and the resulting artefacts.
The resulting technical improvements were put to the test by studying the rutile TiO2(110), an important (photo-)catalyst and robust oxide model system. For the unmodified surface in electrolyte, atomic resolution was obtained, and the appearance in EC-STM was compared to well-known studies in vacuum. Also modification of the rutile TiO2(110) surface by adsorption of benzoic acid and grafting of aryl radicals were investigated. While the presented in situ studies on rutile TiO2(110) are not yet plentiful, the methodological improvements are expected to allow accelerated progress in future.