Diachronic evolvement from tetra-icosahedral to quasi-hexagonal close-packed bimetal clusters.

Here we report a diachronic evolvement from tetra-icosahedral Au 30 Ag 12 (C[triple bond, length as m-dash]CR) 24 to quasi-hcp (hexagonal close-packed) Au 47 Ag 19 (C[triple bond, length as m-dash]CR) 32 via a one-step reduction, in which the size/structure conversion of the two clusters is not a typical Oswald growth process, but involves interface shrinking followed by core rearrangement and surface polymerization. Au 30 Ag 12 (C[triple bond, length as m-dash]CR) 24 has an aesthetic Au 18 Ag 8 kernel that is composed of four interpenetrating Au 10 Ag 3 icosahedra, while Au 47 Ag 19 (C[triple bond, length as m-dash]CR) 32 has a twisted Au 19 core capped by a Au 12 Ag 19 shell that are stacked in a layer-by-layer manner with a quasi-hcp pattern. The discovery of the two clusters not only provides further evidence for icosahedral clusters with longer excited-state lifetime compared to hcp-like clusters, but also discloses a double increase in catalytic reactivity for electrocatalytic oxidation of ethanol over quasi-hcp clusters in comparison with icosahedral clusters. This work provides the rationale for reversing the bottom-up growth process to remake bimetal clusters.