Water related adsorbates on stepped platinum surfaces
- M.J. Kolb
- Wednesday 23 March 2016
2311 GJ Leiden
In this study we focused on the simulation of the interaction of water and its dissociation products hydrogen, oxygen and OH with platinum surfaces that contain a periodic arrangement of single-atom-high steps. We simulate these interactions using the framework of density functional theory and employ high-performance computing resources such as the Cartesius supercomputer of SURFsara.
We find that the two possible types of step edges exhibit increased binding strengths compared to the flat parts of the interface. This binding strength is a key factor in the chemical reactivity of these surfaces.
Furthermore, we investigate the structure of higher coverages of water molecules around the step edges, where we observe surprising changes, namely the appearance of four, five and seven-membered rings, compared to the six-membered rings that are usually observed on the flat surfaces.
Our predictions for thes e struct ures are confirmed using high-resolution scanning tunneling microscopy data. Additionally, we studied the interaction between adsorbed hydrogen on these stepped surfaces at high hydrogen coverages, which allows us to elucidate the origin of heating-induced adsorption in ultra-high vacuum experiments.
Our results are among the first simulations of high-coverage water adsorption on regularly stepped platinum surfaces, which will help advance our understanding of solvation effects at the step edges, which are relevant for the fields of solvation science, electrochemistry and surface science.
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