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O: Fachverband Oberflächenphysik

O 94: Poster Session VII: Poster to Mini-Symposium: Electrified solid-liquid interfaces II

O 94.6: Poster

Thursday, March 4, 2021, 10:30–12:30, P

Effect of water co-adsorption on the electrochemical stability of H-covered Pt(111)-water interfaces — •Sudarsan Surendralal, Mira Todorova, and Jörg Neugebauer — Max-Planck_institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany

Using density functional theory based molecular dynamics simulations we study the relation between H-coverage and electrode potential at the Pt(111)/water interfaces. We find that chemisorbed water molecules strongly interact with the H-adatoms and strongly impact the electrode potential. Above a critical H adsorbate coverage, chemisorbed water becomes unstable at these interfaces. The loss of co-adsorbed water molecules results in a steep increase in the electrode potential, making the interface thermodynamically unstable. The presence of a critical upper H concentration well below 1 ML has been observed experimentally but is absent in surface science modeling. This allows for the first time to understand the mechanisms that limit H adsorption on these surfaces and that lead to the onset of the hydrogen evolution reaction (HER).

S.Surendralal, M. Todorova, and J. Neugebauer, (under review).