PT-metal alloy surfaces: Systematic trends

We present here the data available for selected Pt-based bimetallic alloys. Attention is paid to ordered or chemically disordered single crystal samples obtained by alloying Pt with six different metals and for which detailed information is known regarding the structural arrangement and the composition profile over the first few layers from vacuum. This series of compounds shows systematic trends, and emphasis is put on the effect of the bulk concentration, crystal orientation and chemical element associated with Pt on the segregation profile. From a structural point of view, alloys generally behave like their pure constituents, although segregation-induced strains may play an important role, particularly for reconstructed surfaces. Finally, it is stated that short range reconstruction, i.e. chemical ordering and atom displacements, takes place in most (all?) disordered alloy surfaces with likely strong implications for their actual catalytic properties.