Fig. 2: Heteroepitaxial growth of Pt shell in core-shell nanoparticles.

a–c Projections of 3D reconstruction of PB (a), EPB (b), and TO (c), viewed from <110>, <110> and <100> directions, respectively. For PB and EPB, <110> direction is the co-axis of five single crystal grains (five-fold co-axis) direction. d–f The central 2.7-Å-thick reconstruction slices of three reconstructions of PB (d), EPB (e), and TO (f), respectively. g–i Cut-out atom models of PB (g), EPB (h), and TO (i) with some grains of shell sliced in atomic layers, indicating heteroepitaxial growth of {100} and {111} facets from core to shell. Yellow and blue arrows show the direction of <100> and <111> directions, respectively. j Fivefold co-axis of PB and EPB with their nearest neighboring coordination polyhedra. All atoms in the five-fold co-axis are twelve-coordinated in a decahedron structure. Orange box enlarges a decahedron with slight distortion. Scale bar in a–f is 1 nm, in g–i is 2 nm. In a–f, yellow and blue lines show {100} and {111} facets parallel to the view direction. Green fold lines represent corners and steps. In a, b, the five-fold co-axis and its nearest neighbors are marked in red pentagon, and the five-fold twin boundaries are highlighted by red dashed lines, each grain labeled from I to V. In d–f, the red and blue dots show the coordinates of Pd and Pt atoms, respectively. In g–j, green balls and yellow balls represent Pd and Pt atoms, respectively. In g–i, yellow and blue arrows represent the direction of {100} and {111} facets, respectively.