Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Solid-Liquid Interfaces: Reactions and Electrochemistry - Theory II

O 42.8: Vortrag

Dienstag, 21. März 2017, 15:45–16:00, WIL B321

Functionalization of Oxide Surfaces: Chemical Reactions at the Solid/Liquid Interface — •Paul Schwarz and Bernd Meyer — Interdisciplinary Center for Molecular Materials and Computer-Chemistry-Center, FAU Erlangen-Nürnberg

Using ab-initio molecular dynamics we have studied the anchoring of methylsilanetriol (MST) linker units to aluminum oxide surfaces via condensation reactions in the presence of residual water and liquid isopropanol at standard temperature and pressure. While in vacuum MST molecules spontaneously attach to the surface Al ions via one of their oxygen atoms, adding the residual water molecules and the liquid isopropanol suppresses the direct approach of MST to the surface and solvent molecules have to be displaced. To accelerate this process and to study the mechanism of the subsequent condensation reaction, the metadynamics technique is applied. The simulations show a variety of reaction pathways which differ in how MST deprotonates and how the OH group at the same Al site is converted to water and desorbs. In addition, several competing processes are observed: 1) reprotonation of MST with a subsequent detachment of the molecule and diffusion into the liquid; 2) detachment of MST and spontaneous reaction with a neighboring surface Al atom; 3) binding of a second OH group of MST to the same Al site. Free energy profiles of these paths will be compared and the stability of reaction intermediates will be compared by static DFT calculations.