The development of model catalyst systems for heterogeneous catalysis going
beyond the metal single crystal approach, including phenomena involving the
limited size of metal nanoparticles supported on oxide surfaces, as well as
the electronic interaction through the oxide–metal interface, is exemplified
on the basis of two case studies from the laboratory of the authors. In the
first case study the reactivity of supported Pd nanoparticles is studied in
comparison with Pd single crystals. The influence of carbon contaminants on
the hydrogenation reaction of unsaturated hydrocarbons is discussed. Carbon
contaminants are identified as a key parameter in those reactions as they
control the surface and sub-surface concentration of hydrogen on and in the
particles. In the second case study, scanning probe techniques are used to
determine electronic and structural properties of supported Au particles as a
function of the number of Au atoms in the particle. It is demonstrated how
charge transfer between the support and the particle determines the shape of
nanoparticles and a concept is developed that uses charge transfer control
through dopants in the support to understand and design catalytically active
materials
