Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 45: Solid / liquid interfaces I

O 45.1: Talk

Wednesday, March 28, 2012, 10:30–10:45, A 060

Structure of water layers on hydrogen-covered Pt electrodes — •Tanglaw Roman and Axel Gross — Institut für Theoretische Chemie, Universität Ulm, D-89069 Ulm

Recently, we have seen a growing number of theoretical studies addressing structures and processes at electrochemical solid/liquid interfaces from first principles. Still it is fair to say that up to now little attention has been paid to the fact that as a function of the electrochemical conditions (electrode potential, pH, electrolyte) in equilibrium electrochemical electrodes are typically covered by adsorbed species such as hydrogen. It is very likely that the presence of these adsorbed species has a severe influence on the structure of the electrochemical electrode-electrolyte interfaces and on the processes occurring at these interfaces. In this light, we have examined the structure of water layers at hydrogen-covered Pt(111) surfaces at room temperature by ab initio molecular dynamics simulations based on periodic density functional theory calculations. The resulting structures have been analyzed in detail as a function of hydrogen coverage. In particular, the thermal disorder in the water layer is examined in terms of deviations from the ice lattice, orientational inhomogeneity within the bilayers, as well as the onset of water dissociation.