Video-STM studies of adsorbate dynamics at electrochemical interfaces

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In this project the dynamic behavior of individual adsorbates at electrochemical interfaces will be studied systematically by in situ high-speed scanning tunneling microscopy (Video-STM). These measurements will be performed as a function of potential and temperature for different anionic (S, I, CN) and cationic (Pb, Te, vacancies) adsorbates on Cu(100) and Ag(100) electrode surfaces. The atomic-scale adsorbate motion will be directly monitored by time-resolved STM. Based on an extensive statistical analysis of these data quantitative results on surface diffusion and adsorbate-adsorbate interactions will be obtained. In particular, the role of coadsorbed species (Cl, Br, sulfate) and potential on the adsorbate dynamics will be investigated, to (i) elucidate the origin of the pronounced potential dependence of the surface transport processes, found in our pioneering studies on Sad diffusion on Cu(100) in HCl solution, and to (ii) determine how coadsorbates, which are ubiquitously present in electrochemical environment, influence the diffusion barriers and interaction energies. This project will be complemented by a parallel application for a project, in which thermodynamic and kinetic electrochemical data on these adsorbate systems will be obtained in parallel. In total, these direct microscopic and complementary electrochemical studies should provide fundamental insights into the effect of the electrochemical environment on the diffusion and interaction of adsorbed species – a central elementary step in many electrode reactions.