Abstract :
During the last decades surface science has played an important role for modelling surface chemistry on metallic surfaces and understanding catalytic processes for simple reactions. Progresses are now made possible by the recent development of specific tools for characterising at the nanoscale level model materials and following the kinetics of reactions on these materials of small area in dedicated reactors.
It needs the preparation, and characterisation at the atomic level, of well-defined materials. They can be either single-crystal surfaces having a well-defined orientation or in shape of model supported nano-particles. Most has been done in the framework of monometallic materials, but more difficult is the preparation of well-defined alloy surfaces and surface alloys, and the elaboration of alloy nano-particles well-defined in size and composition.
Kinetic studies in dedicated reactors show how the catalytic behaviour of model samples may depend on the specific sites present at surface. For example, surface sites having a low coordination number (like steps, kinks, edges and corners) are very efficient for bond-breaking. In bi-metallics, ad-layers of a given metal on a foreign substrate may show new and original structures having very specific catalytic properties. Thus, works on catalysis at the atomic scale proposes new active/selective sites, and it is now a challenge to design new industrial catalysts on the basis of these fundamental works.
In order to move near the conditions for real catalysis one has now to bridge the “pressure gap”, i.e. to make in situ (during reaction under pressure of reactants) characterisation of both the surface itself and ad-species. This needs the development of specifics tools able to work in such conditions. This is a challenge for today and future works in the field of model catalysis.
