Catalytic reactions on platinum metals nanofacets: Spectroscopy on an atomic scale

Yuri Suchorski 

Otto-von-Guericke-Universitaet Magdeburg, Chemisches Institut, Universitaetsplatz 2, Magdeburg D-39106, Germany

Abstract

The technical importance of heterogeneous catalysts has motivated an intensive development of model systems emulating the behaviour of dispersed metals on oxidic supports. One of the successful approaches is the creation of arrays of the small metal particles, grown on a planar oxidic support. Most surface-sensitive spectroscopies, however, average the collected data (in the best case over few catalytic pellets of the sample), thus the individual characteristic of the single particles are often "smoothed out". This creates difficulties in addressing the details of the reaction mechanisms on the single metal nanoparticles.
Field Ion Microscopy (FIM), Field Emission Microscopy (FEM) and Lithium Field Desorption (Li-FDM) Microscopy can in principle allow investigation of local reaction kinetics on the structurally heterogeneous surface of a single apex of a Pt or Rh tip. The surface of such a tip can be characterized with atomic resolution by FIM and catalytic reactions on well-defined nanosized facets can be monitored in situ with a resolution ≤ 2 nm using the mentioned above microscopies [1].
By using the probe-hole techniques the field ions of reacting entities emitted from few selected surface sites can be collected and analyzed in a retarding potential experiment (field ion appearance energy spectroscopy, FIAES [2]). FIAES provides the binding energy of the neutral molecules adsorbed on these selected sites. The probe-hole approach can be also combined with the mass analysis by magnetic separation (mass-to-charge resolved potential analyses) or with the time of flight (ToF) measurements.


[1] V.V. Gorodetskii, V.I. Elochin, J.W. Bakker, B.E. Nieuwenhuys, Cat.Today 105 (2005)
183; Y. Suchorski and J. Beben, Prog. Surf. Sci. 74 (2003) 3, and references therein
[2] Y. Suchorski, W.A. Schmidt, N. Ernst, J.H. Block, H.J. Kreuzer, Prog. Surf. Sci. 48
(1995) 121


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Presentation: Invited oral at E-MRS Fall Meeting 2006, Symposium B, by Yuri Suchorski
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 08:49
Revised:   2009-06-07 00:44
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