Nanofabricated model catalysts

This leads us to the concept called nanocatalysis, and specifically to nanofabricated model catalysts, as an approach to bridge the structure gap. In Fig. 4.4, some examples of planar model structures of increasing complexity are depicted, which fulfill these criteria. At the top, there is a simple array of catalyst particles on an inactive support. The inactive support can be replaced by an active support (second picture from the top), meaning a support that significantly affects the properties of the nanoparticles via particle-support interactions (a clear distinction between inactive and active is not easy or not even possible—there is always some influence of the support on the supported particle). In some cases, the size of the support particle has an influence on the overall catalytic activity. This is, for example, the case when there is a spillover or capture zone for reactants or intermediates, which move by diffusion from the catalyst nanoparticle to the support or vice versa. In order to study such effects, one may want to systematically vary the radius of the... 

Experimental Case Studies with Nanofabricated Model Catalysts Catalytic Reactions and Reaction-Induced Restructuring... 

Simplifications in the physical and chemical characterization the 2D nature of the nanofabricated model catalysts make them easier to inspect with traditional surface science tools and electron microscopy. 

Beyond single component metal catalysts, the nanofabricated model catalysts can be used to study alloy catalysts, with compositions controlled by co-evaporation from two or more PVD sources. Alternatively, arrays of alternating particles or areas of two different materials can be made to study lateral communication between two types of catalysts at the nanoscale. For example, sequential reactions consisting of a first step on one type of catalyst and a second step on another catalyst particle could be studied systematically. The role of reactants and reaction intermediates as surfactants, affecting particle shape and morphology [163], will be possible to study in detail by in situ TEM studies in reactive environments. 

Deshlahra, R, Pfeifer, K., Bernstein, G., et al. (2011). CO adsorption and oxidation studies on nanofabricated model catalysts using multilayer enhanced IRAS technique, Appl. Catal. A Gen., 391, pp. 2-30. 

The authors are grateful to many colleagues worldwide in the Held of heterogeneous catalysis for exchange of ideas concerning the nanocatalysis approach and model catalyst fabrication. In particular, we are thankful to J. Libuda, H.-J. Freund and coworkers at the Fritz-Haber Institute in Berlin, Germany, who did the reactivity measurements on the EBL nanofabricated Pd/Si02... 

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