From Pt-rich dendrites to Ni-rich cuboctahedrons: structural evolution and electrocatalytic property studiesElectronic supplementary information (ESI) available: TEM and 3D modeling of the detailed crystallographic features of the Pt20Ni80 polyhedrons, composition data for the samples collected at different times under different temperatures. See DOI: 10.1039/c4ce00099d

In this paper, we report the evolution of the composition and morphology of Pt x Ni 1− x (0 < x < 1) nanoalloys from Pt-rich dendrites to Ni-rich cuboctahedrons. However, the transformation processes were different under different temperatures. At 200 °C, the transformation was mainly completed through atomic addition, while there was a contribution from both atomic addition and oriented attachment at 220 °C. The electrocatalytic performance towards the methanol oxidation reaction (MOR) indicated the dendrites exhibited higher catalytic activity and better durability relative to the cuboctahedrons. For the cuboctahedrons with different compositions, the catalytic activity is mainly determined by the d -band position. This provides new insights into the controlled synthesis of Pt-based bimetallic nanoalloys and advances the understanding of their catalytic behaviour. The composition and morphology evolution for Pt x Ni 1− x (0 < x < 1) nanoalloys was achieved by adjusting the growth kinetics, which were found different under different temperatures. The structure-dependent electrocatalytic performance was evaluated with MOR as the model reaction.