Atomic Scale Characterization of Fluxional Cation Behavior on Nanoparticle Surfaces: Probing Oxygen Vacancy Creation/Annihilation at Surface Sites
Atomic Scale Characterization of Fluxional Cation Behavior on Nanoparticle Surfaces: Probing Oxygen Vacancy Creation/Annihilation at Surface Sites
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DOI：
10.1021/acsnano.0c07584
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发表时间：
2021-01-28
期刊：
影响因子：
17.1
通讯作者：
Crozier, Peter A.
中科院分区：
文献类型：
--
作者：
Lawrence, Ethan L.;Levin, Barnaby D. A.;Crozier, Peter A.
氧空位的产生和湮灭是非化学计量氧化物（例如 CeO2）的关键过程。氧化物表面上的氧空位产生和湮灭率在一定程度上决定了其与周围环境交换氧的能力，这对于包括能源技术、环境污染物修复和化学合成在内的许多应用至关重要。探测局部氧空位反应速率并将其与原子级结构异质性相关联的实验方法将为表面功能的合理设计和控制提供重要信息；然而，迄今为止还没有这样的方法。在这里，我们使用时间分辨原位像差校正透射电子显微镜来表征阳离子的皮尺度流变行为，以定位氧化物纳米粒子表面上氧空位产生和湮灭速率的原子级变化。低配位数位点（例如台阶和边缘）以及局部应变位点表现出最大数量的阳离子置换，这意味着这些位点的表面氧空位活性增强。该方法对于涉及表面和界面传输功能的更广泛的材料和催化问题具有潜在的应用前景。
Oxygen vacancy creation and annihilation are key processes in nonstoichiometric oxides such as CeO2. The oxygen vacancy creation and annihilation rates on an oxide's surface partly govern its ability to exchange oxygen with the ambient environment, which is critical for a number of applications including energy technologies, environmental pollutant remediation, and chemical synthesis. Experimental methods to probe and correlate local oxygen vacancy reaction rates with atomic-level structural heterogeneities would provide significant information for the rational design and control of surface functionality; however, such methods have been unavailable to date. Here, we characterize picoscale fluxional behavior in cations using time-resolved in situ aberration-corrected transmission electron microscopy to locate atomic-level variations in oxygen vacancy creation and annihilation rates on oxide nanoparticle surfaces. Low coordination number sites such as steps and edges, as well as locally strained sites, exhibited the greatest number of cation displacements, implying enhanced surface oxygen vacancy activity at these sites. The approach has potential applications to a much wider class of materials and catalysis problems involving surface and interfacial transport functionalities.