Design and electrochemical / -catalytic properties of well defined bimetallic model catalyst electrodes
FacultiesFakultät für Naturwissenschaften
Real metal supported catalysts consist in general of metal particles situated in a complex 3-D matrix of a support material. Their catalytic activity strongly depends on the particle size, shape, composition of the bulk and of the surface, geometric arrangement of the atoms within the surface plane and of the interaction of the particles with the support. Each of these characteristics can be separately attributed to with well defined nanostructured model catalysts and thus is a perfect approach to disentangle these effects. In this thesis, well defined planar nanostructured model surfaces are first prepared under ultra high vacuum (UHV) conditions and characterized structurally, by scanning tunneling microscopy, to study the mechanism of structure formation and gain detailed information on the structures on an atomic scale. In combination with a newly designed electrochemical flow cell set up, attached to the UHV system, an unambiguous structure-activity relationship can be derived. In order to discuss the structural and chemical properties of bimetallic systems, the model catalysts investigated are separated into three different classes of dimensionality. In this classification 0-D structures describe particle arrays, where the nanoparticles are considered as points on a planar substrate with homogeneous properties, 1-D structures result from line defects, such as steps or linear bimetallic interfaces, and 2-D structures describe, e.g., surface alloys. A general overview on the state of the art design of such kind of model electrodes prepared under UHV conditions is described and in how far individual results obtained around my work are relevant in a broader scope of model catalytic studies to gain a better understanding of fundamental structure related catalytic effects. Finally, the relevance to investigate the electrode stability for UHV prepared model catalyst electrodes investigated on their electrocatalytic activity is discussed.
Subject HeadingsKatalyse [GND]
Scanning tunneling microscopy [LCSH]