First-Principles Study on Stability and Electronic Structures of Pt-Rh Bimetallic Nanoparticles

Energetic stability and electronic structures of Pt atoms in Pt-Rh nanoparticle is investigated by first-principles calculation. Pt atom energetically prefer surface sites (vertex, edge, and (100)) rather than subsurface and core site, which is attributed to lower Pt surface energy compared with Rh. Vertex of nanoparticle is the most favorable site for Pt atom, which has lowest coordination numbers. Band center of d-state electronic contribution for Pt atom measured from the Fermi energy exhibit negative dependence with respect to Pt coordination number. This can be attributed to positive dependence of second-order moment of density of states for the Pt d-band on the coordination number. Pt segregation to the surface is expected due mainly to contribution from Pt on-site segregation energy compared with weak ordering tendency of Pt-Rh unlike-atom pairs. [doi:10.2320/matertrans.M2009295]