Stability and Electronic Structures of Pt-Rh Icosahedral Nanoparticles

We investigate the energetic stability and electronic structures of Pt-Rh icosahedral nanoparticles based on first-principles calculations. We find that Pt atom energetically prefers vertex and edge sites at the surface rather than subsurface and core sites, which is a tendency similar to Pt-Rh cuboctahedral nanoparticles. This can be attributed to lower surface energy of Pt compared with Rh. Edges of nanoparticles with second-lowest coordination number are the most favorable sites for Pt atom. This could be attributed to the enhanced interatomic distance at the edge site. 1st order moment of d-state electronic contribution for Pt atom exhibits almost negative dependence in terms of Pt coordination number. This can be qualitatively interpreted by positive dependence of 2nd order moment of the density of states for the Pt atom on the coordination number. Pt surface segregation is expected mainly due to contribution from Pt on-site segregation energy compared with weak ordering tendency of Pt-Rh unlike-atom pairs. [doi:10.2320/matertrans.M2011055]