Element-specific anisotropic growth of shaped platinum alloy nanocrystals
Element-specific anisotropic growth of shaped platinum alloy nanocrystals
复制标题
DOI：
10.1126/science.1261212
复制
发表时间：
2014-12-19
期刊：
影响因子：
56.9
通讯作者：
Strasser, Peter
中科院分区：
文献类型：
--
作者：
Gan, Lin;Cui, Chunhua;Strasser, Peter
化学和生物学中的形态形状归因于各向异性生长，并与不同的功能密切相关。虽然对单晶纳米晶的主要生长机制已经有了很多了解，但对异形合金纳米晶的各向异性生长仍知之甚少。使用像差校正的扫描透射电子显微镜，我们揭示了元素特定的各向异性生长机制的铂（Pt）nano-octahedra组成各向异性耦合到几何各向异性。富Pt相演变成前体纳米六足，随后是富M相（M = Ni、Co等）的较慢的步骤诱导沉积。在形成八面体刻面的凹的六足表面处的第二相。我们的研究结果解释了早期报道的不寻常的成分偏析和化学降解途径的多面体催化剂，并可能有助于合理合成成型合金催化剂所需的组成模式和性能。
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, we 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. Our 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.