Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: Symposium: The Solid-Liquid Interface: A Challenge for Theoreticians II

O 67.1: Hauptvortrag

Freitag, 30. März 2007, 10:15–10:45, H38

Interfacial Properties of Transition Metal Oxides — •Elisabet Ahlberg, Zareen Abbas, and Sture Nordholm — Department of Chemistry, Göteborg University, 412 96 Göteborg, Sweden

Catalytic and electrocatalytic ability of transition metal oxides is commonly related to the nature of the metal cation and its coordination. However, in aqueous solution the pH rather than potential determines their interfacial chemistry and surface complexation models have been successfully used to describe interfacial properties by including specific chemical surface interactions besides electrostatic effects. We have used corrected Debye-Hückel (CDH) analysis to clarify the mechanisms at work in surface complexation. Ion size in the ion-ion interactions is accounted for in the diffuse screening and a layer of condensed counterions are introduced to treat nonlinear electrostatic response close to the surface. In the CDH theory the particle is considered to be a sphere which can have any size.

Recently, the effect of particle size on the surface charge density was investigated. The results show an increase in surface charge density as the size decreases. This sharp rise in the surface charge density may be explained by the increasing curvature of the double layer as the particle size decreases. The screening becomes more efficient as the size of the particles decreases due to accumulation of ions around the small particles.

In my talk surface complexation at oxide surfaces will be treated from both theoretical and experimental point of view. The implication on electrocatalytic properties will also be discussed.