Influence of noble metal dopants (M = Ag, Au, Pd or Pt) on the stable structures of bimetallic Co-M clusters

Abstract

The core-shell and well-mixed morphologies of Co-M (M = Ag, Au, Pd or Pt) clusters are investigated. The interatomic interaction of these clusters is described by the many-body Gupta potential, and the stable structures are optimized using adaptive immune optimization algorithm. Results show that all 55-atom Co-Au and Co-Pd clusters adopt Mackay icosahedral motifs, but Co-Ag and Co-Pt clusters have more configurations. The number of bonds indicates that Co-Ag, Co-Au and Co-Pd clusters take the core-shell structures. In these core-shell structures, Co atoms occupy the inner core, and Ag and Pd atoms tend to scatter on the surface, but Au atoms prefer packing together, which is explained by atomic radii, cohesive energy and surface energy. However, the investigated Co-Pt clusters favor well-mixed pattern. Furthermore, there exists difference among the relative stability of these clusters by energy analysis. Moreover, the influence of the noble metals on the structures of Co13Mn (n = 1–41) clusters are studied. The atomic distribution of Co and noble metals in Co13Mn clusters is analyzed, which is consistent with that in 55-atom Co-M clusters.