Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 96: Structure of Solid/Liquid Interfaces II

O 96.9: Talk

Friday, March 11, 2016, 12:30–12:45, S052

Water adsorption at different noble metal/solution interfaces — •Yujin Tong, Martin Wolf, and R. Kramer Campen — Fritz-Haber-Institut, Abt. Physikalische Chemie, 14195 Berlin, Germany

In aqueous electrochemistry water molecules at the electrode/solution interface determine the structure of the electric double layer, mediate charge transfer mechanisms, and are the reactive species in water electrolysis. Hence gaining a molecular level picture of water structure at the electrode/solution interface, and following its change as a function of electrode potential, is of both fundamental and practical importance. However, achieving such insight via most experimental techniques is challenging. Vibrational sum frequency spectroscopy, owning to its unique selection rules, can selectively probe the structure of water molecules at the electrode/solution interface. Using VSF spectroscopy we here show that: 1). On gold electrodes over a wide range of potentials there are hydrophobic water molecules oriented in such a way that one of their OH groups point towards the gold. 2). After partial oxidation of the gold surface, apparent via cyclic voltammetry and ex-situ characterization via VSF spectroscopy of low frequency Au-O modes, the gold surface becomes hydrophilic and this population of water disappears.