Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 6: Poster I

DF 6.13: Poster

Dienstag, 24. März 2009, 09:30–12:30, P5

A Versatile Surface Modification Method for Mesoporous TiO₂ — •Dereje Hailu Taffa, Kathiresan Murugavel, and Lorenz Walder — Institut für Chemie, Universität Osnabrück, Barbarastr. 7, 49069 Osnabrück

Mesoporous titanium dioxide is a large-area, dielectric material used in many applications such as photovoltaics, electrochromics, catalysis and sensors. Many of these applications require a functional molecule anchored to the inner walls of the porous system. We present a new method for the anchoring of such molecules using a combination of hydrophobic and electrostatic interactions. For this purpose we prepared alkyl phosphonic acids of different chain length (6, 10, and 14 carbons) bearing neutral, positive and negatively charged head groups. They were anchored to the inner walls of randomly sintered, mesoporous titanium dioxide thin films. Quartz crystal microbalance and FT-IR measurements show that a monolayer coverage was achieved. Different charged guest molecules (metal complexes and N-alkyl viologens with variable chain length) were incorporated on top or into the supported membranes. The assemblies were characterized by cyclic voltammetry and FT-IR. The new surface modification technique simplifies the molecular requirements for functional surface modifiers considerably. Using a limited set of organic anchors with orthogonal coordination properties and adjustable hydrophobicity, a broad range of electrochromophores, redox active wiring compounds or sensitizers can be adsorbed onto titania.