381784 Ångstrom Resolved Real-Time Monitoring of Metal Interfaces during Oxide Growth and Reduction

Wednesday, November 19, 2014: 12:45 PM
213 (Hilton Atlanta)
Markus Valtiner, Buddha R. Shrestha, Hsiu-Wei Cheng, Theodore Baimpos and Sangeetha Raman, Max-Planck-Institut f. Eisenforschung GmbH, Düsseldorf, Germany

Structure and dynamics at electrochemical metal/liquid interfaces determine lifetime and stability of advanced and structural materials, and are fundamental to corrosive and electrocatalytic processes. Here, we present recent experiments with the electrochemical surface force apparatus1,2, which allow us to unravel electrochemical oxidation and reduction processes in real-time at well-defined and nano-confined Pt, Pd and Au noble metal electrodes. In particular, we monitor metal-oxide thin film formation with Å-accuracy during potentiostatic and potentiodynamic polarizations. Our experiments reveal stark differences of oxide thickness and electronic properties during potentio-dynamic and potentio-static oxide growth, which will be discussed in detail in this presentation. In addition, in confined spaces we find unexpectedly strong electrochemical depletion forces acting between apposing surfaces during active electrochemical processes. Such forces can overpower attractive Van der Waals forces and might have significant effects in a wide range of processes occurring in nano-confined spaces (e.g. in crevices or pits).

1.  Valtiner, M. et al. "The Electrochemical Surface Forces Apparatus: The Effect of Surface Roughness, Electrostatic Surface Potentials, and Anodic Oxide Growth on Interaction Forces, and Friction between Dissimilar Surfaces in Aqueous Solutions" in Langmuir 2012, 28 (36), 13080-13093.

2. Israelachvili, J.N. et al. "The intersection of Interfacial Forces and Electrochemistry" in J. Phys. Chem. B 2013, 117(51), 16369-16387.

Extended Abstract: File Not Uploaded
See more of this Session: Solid-Liquid Interfaces II: Forces and Lubrication
See more of this Group/Topical: Engineering Sciences and Fundamentals