Imaging the kinetics of anisotropic dissolution of bimetallic core-shell nanocubes using graphene liquid cells
Imaging the kinetics of anisotropic dissolution of bimetallic core-shell nanocubes using graphene liquid cells
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DOI：
10.1038/s41467-020-16645-3
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发表时间：
2020-06-16
影响因子：
16.6
通讯作者：
Ye, Xingchen
中科院分区：
文献类型：
--
作者：
Chen, Lei;Leonardi, Alberto;Ye, Xingchen
多组分纳米晶体的化学设计需要原子水平的反应动力学的理解。本文采用单粒子成像与原子模拟相结合的方法，研究了Pd@Au和Cu@Au核壳纳米立方在氧化溶解过程中的反应途径和速率。利用原位透射电子显微镜（TEM）成像对蚀刻动力学进行定量分析，发现随着反应的进行，溶解机制从主要的边缘选择性去除转变为逐层去除Au原子。当两种金属暴露时，金壳的溶解速度减慢，我们将其归因于电偶腐蚀保护。由配位数相关的原子去除率引起的本征各向异性和石墨烯窗口引起的本征各向异性决定了形态转变。我们的工作表明，双金属核壳纳米晶体是TEM液体电池内部局部物理化学条件的优秀探针。此外，单粒子透射电镜成像和反应轨迹的原子模拟可以为未来复杂纳米晶体的组成和结构设计策略提供信息。
Chemical design of multicomponent nanocrystals requires atomic-level understanding of reaction kinetics. Here, we apply single-particle imaging coupled with atomistic simulation to study reaction pathways and rates of Pd@Au and Cu@Au core-shell nanocubes undergoing oxidative dissolution. Quantitative analysis of etching kinetics using in situ transmission electron microscopy (TEM) imaging reveals that the dissolution mechanism changes from predominantly edge-selective to layer-by-layer removal of Au atoms as the reaction progresses. Dissolution of the Au shell slows down when both metals are exposed, which we attribute to galvanic corrosion protection. Morphological transformations are determined by intrinsic anisotropy due to coordination-number-dependent atom removal rates and extrinsic anisotropy induced by the graphene window. Our work demonstrates that bimetallic core-shell nanocrystals are excellent probes for the local physicochemical conditions inside TEM liquid cells. Furthermore, single-particle TEM imaging and atomistic simulation of reaction trajectories can inform future design strategies for compositionally and architecturally sophisticated nanocrystals.