Project
Planar Model Systems for Nanostructured Catalysts

Prof. Dr. R. Imbihl
Institut für Physikalische Chemie und Elektrochemie
Universität Hannover

In the past years we have studied the feasibility of improving the performance of catalysts by the use of microstructured bimetallic surfaces [1,2,3]. The great advantage of microstructured catalysts which can be generated by optical lithography is that an in situ imaging of the reaction dynamics is possible with suitable spatially resolving methods such as photoelectron emission microscopy (PEEM) and ellipsometry for surface imaging (EMSI). A great potential and future challenge lies in the design of structures in the nanometer range. Such structures we can create by electron lithography or by taking advantage of selforganization processes within the catalyst itself. For the electron lithography we have a collaboration with Prof. Pfnür at the Institut für Festkörperphysik. For an in situ imaging of structures in the nanometer range we have existing collaborations with LEEM (=low energy electron microscopy) groups at the TU Clausthal-Zellerfeld (Dr. Lilienkamp, Prof. Daum) and at the electron storage ring ELETTRA at Trieste, Italy (Dr. Kiskinova). The latter cooperation allows to do spectroscopic imaging (“nanospectroscopy”) with the nano-scale structures.

In this project we will try to generate nano- and micro-structured VO_X-films on a metallic substrate [4]. Vanadium oxides are very versatile and effective partial oxidation catalysts. The tailoring of such catalysts by nanostructuring should open new routes in the design and optimization of heterogeneous catalysts. We will explore dynamic coupling effects via surface diffusion of mobile adsorbates, size effects of the nano-structured films, and selforganization processes as the catalyst surface becomes modified by the reaction. Alternatively, we will also investigate the possibility of creating nanostructured metal films by the electron beam induced decomposition of metallorganic films.

Literature:
1. E. Schütz, N. Hartmann, I. G. Kevrekidis and R. Imbihl, Microchemical engineering of catalytic reactions Catal. Lett. 54 (1998) 181.
2. S. Y. Shvartsman, I. G. Kevrekidis, E. Schütz and R. Imbihl, Dynamics on microcomposite catalytic surfaces: the effect of active boundaries Phys. Rev. Lett. 83 (1999) 2857.
3. R. Imbihl,Catalysis on microstructured bimetallic surfaces, Chaos 12 (2002) 182.
4. F. P. Netzer et al., Vanadium oxide surface studies, Prog. Surf. Sci. 73 (2003) 117.