Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom.
ACS Nano. 2016 Nov 22;10(11):10418-10427. doi: 10.1021/acsnano.6b06274. Epub 2016 Nov 7.
The atomic level dynamics of gold on graphene is studied at temperatures up to 800 °C using an in situ heating holder within an aberration-corrected transmission electron microscope. At this high temperature, individual gold atoms and nanoclusters are mobile across the surface of graphene and attach to defect sites and migrate along the edges of holes in graphene. Gold nanoclusters on clean graphene show crystallinity at temperatures above their predicted melting point for equivalent sized clusters due to strong epitaxial interactions with the underlying graphene lattice. Gold nanoclusters anchored to defect sites in graphene exhibit discrete rotations between fixed orientations while maintaining epitaxial correlations to the graphene. We show that gold nanoclusters can be two-dimensional with monolayer thickness and switch their crystal structure between two different phases. These results have important implications on the use of gold nanoclusters on graphene at elevated temperatures for applications, such as catalysis and plasmonics.
在原子力显微镜中使用原位加热支架，在高达 800°C 的温度下研究了金在石墨烯上的原子级动力学。在这个高温下，单个金原子和纳米团簇可以在石墨烯表面上移动，并附着在缺陷部位，然后沿着石墨烯中的孔的边缘迁移。在干净的石墨烯上的金纳米团簇在高于其预测的等效大小的团簇熔点的温度下表现出结晶性，这是由于与底层石墨烯晶格的强外延相互作用。锚定在石墨烯缺陷部位的金纳米团簇在保持与石墨烯的外延相关性的同时，在固定取向之间表现出离散的旋转。我们表明，金纳米团簇可以是二维的单层厚度，并在两种不同的相中切换其晶体结构。这些结果对在高温下将金纳米团簇用于应用，如催化和等离子体学，具有重要意义。
