In Situ Observation of the Motion of Platinum and Gold Single Atoms on Graphene Using Aberration-Corrected Electron Microscopy
In Situ Observation of the Motion of Platinum and Gold Single Atoms on Graphene Using Aberration-Corrected Electron Microscopy
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DOI：
10.1021/acs.jpcc.2c02356
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发表时间：
2022-07
期刊：
影响因子：
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通讯作者：
A. Suzuta;K. Yamazaki;K. Gohara;T. Uchida
中科院分区：
文献类型：
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作者：
A. Suzuta;K. Yamazaki;K. Gohara;T. Uchida
研究了一种利用扫描透射电子显微镜确定分散在石墨烯上的单个金属原子轨迹的方法，具有埃级精度。将该方法应用于分散在独立单层石墨烯上的铂（Pt）和金（Au）单原子，观察其在电子束辐照下的动力学行为差异。高角度环形暗场成像显示，大多数原子集中在纳米石墨烯的边缘，尤其是在三层或更多层的纳米石墨烯中，而很少出现在石墨烯的阶地上。根据轨迹分析，在整个观察周期（40 s）中，约70%的Pt单原子停留在石墨烯（1.4 Å）的一个原子距离内。因此，铂继续以单原子的形式稳定地分散在石墨烯上。另一方面，即使在最小的观察间隔（4秒）内，超过40%的Au单原子移动的距离也超过了石墨烯六元环的大小（2.8 Å）。显然，在相同的电子束辐照条件下，Au比Pt具有更大的迁移率，这可能是Au难以保持单原子态的原因之一。
A trace method for determining the trajectories of single metal atoms dispersed on graphene was developed using scanning transmission electron microscopy with angstrom-order accuracy. This method was applied to platinum (Pt) and gold (Au) single atoms dispersed on free-standing single-layer graphene to observe the difference in their dynamic behaviors under electron beam irradiation. High-angle annular dark-field imaging showed that most of the atoms were present at the nanographene edge, especially in three or higher layers of nanographene, but few on the terrace of graphene. According to trajectory analysis, approximately 70% of the Pt single atoms stayed within one atomic distance of graphene (1.4 Å) for the whole observation period (40 s). Therefore, Pt continued to be stably dispersed on graphene as single atoms. On the other hand, more than 40% of Au single atoms traveled a distance exceeding the size of the six-membered ring of graphene (2.8 Å) even within the minimum observation interval (4 s). Clearly, Au was confirmed to have a larger mobility than Pt under the same electron beam irradiation conditions, which may be one reason for the difficulty in keeping the single atom state for Au.