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O: Fachverband Oberflächenphysik

O 65: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces III

O 65.2: Vortrag

Mittwoch, 14. März 2018, 15:15–15:30, MA 005

Influence of halic and carboxylic acids on the shape of TiO₂ nanoparticles — Kai Sellschopp¹, Wolfgang Heckel¹, Andreas Hensel², Clemens Schröter², Tobias Vossmeyer², Horst Weller², Stefan Müller¹, and •Gregor Feldbauer¹ — ¹Institute of Advanced Ceramics, Hamburg University of Technology — ²Institute of Physical Chemistry, University of Hamburg

Titania (TiO₂) nanoparticles are used for many applications ranging from photo-catalysts to hybrid materials. The faceting and accordingly the shape of the nanoparticles determine the performance of the nanoparticles in these applications. Therefore, shape control during synthesis is essential. It is known that fluoric acid stabilizes the anatase (001) surface through a substitution of surface oxygen atoms. This leads to platelet shaped particles with a large percentage of reactive (001) facets. The influence of other halic and organic acids on the particle shape, however, is rarely studied. Here, we present our latest results on the adsorption and surface energies of all halic acids and some carboxylic acids on the major TiO₂ anatase surfaces. From the surface energies calculated using density functional theory (DFT) we derive the shape of the nanoparticles starting from the Wulff construction. Transmission electron microscopy (TEM) images of TiO₂ nanoparticles synthesized in non-aqueous medium show good agreement with the calculated shapes.