  Increasing demand and high prices of advanced catalysts motivate a constant
search for novel active materials with reduced content of noble metals. The
development of thin films and core-shell catalysts seem to be a promising
strategy along this path. Using Density Functional Theory we have analyzed a
number of surface properties of supported bimetallic thin films with
composition A3B (where A = Pt, Pd, B = Cu, Ag, Au). We focus on surface
segregation, dissolution stability and surface electronic structure. We also
address the chemisorption properties of Pd3Au thin films supported by different
substrates, by probing the surface reactivity with CO. We find a strong
influence of the support in the case of mono- and bilayers, while the surface
strain seems to be the predominant factor in determining the surface properties
of supported trilayers and thicker films. In particular, we show that the
studied properties of the supported trilayers can be predicted from the lattice
mismatch between the overlayer and the support. Namely, if the strain
dependence of the corresponding quantities for pure strained surfaces is known,
the properties of strained supported trilayers can be reliably estimated. The
obtained results can be used in the design of novel catalysts and predictions
of the surface properties of supported ultrathin catalyst layers.

Materials Science