Anisotropic growth of shaped platinum alloy nanocrystals
by Lin Gan, Chunhua Cui, Marc Heggen, Fabio Dionigi, Stefan Rudi, Peter Strasser
Morphological shape in chemistry and biology owes its existence to anisotropic growth and is closely coupled to distinct functionality. Although much is known about the principal growth mechanisms of monometallic shaped nanocrystals, the anisotropic growth of shaped alloy nanocrystals is still poorly understood. Using aberration-corrected scanning transmission electron microscopy, a team of researchers from the Ernst Ruska-Centre and the Technical University of Berlin reveal an element-specific anisotropic growth mechanism of platinum (Pt) bimetallic nano-octahedra where compositional anisotropy couples to geometric anisotropy. A Pt-rich phase evolves into precursor nanohexapods, followed by a slower step-induced deposition of an M-rich (M = Ni, Co, etc) phase at the concave hexapod surface forming the octahedral facets. The finding explains earlier reports on unusual compositional segregations and chemical degradation pathways of bimetallic polyhedral catalysts and may aid rational synthesis of shaped alloy catalysts with desired compositional patterns and properties.
Lin Gan, Chunhua Cui, Marc Heggen, Fabio Dionigi, Stefan Rudi, Peter Strasser: Anisotropic growth of shaped platinum alloy nanocrystals, Science 346 (2014) 1502-1506.
Jülich Research Centre Press Release of 19 December 2014.