Department of Chemical Engineering and Materials Science, University of California , Davis, Davis, California 95616, United States.
Nano Lett. 2014 Jan 8;14(1):373-8. doi: 10.1021/nl4043328. Epub 2013 Dec 12.
Direct observations of solution-phase nanoparticle growth using in situ liquid transmission electron microscopy (TEM) have demonstrated the importance of "non-classical" growth mechanisms, such as aggregation and coalescence, on the growth and final morphology of nanocrystals at the atomic and single nanoparticle scales. To date, groups have quantitatively interpreted the mean growth rate of nanoparticles in terms of the Lifshitz-Slyozov-Wagner (LSW) model for Ostwald ripening, but less attention has been paid to modeling the corresponding particle size distribution. Here we use in situ fluid stage scanning TEM to demonstrate that silver nanoparticles grow by a length-scale dependent mechanism, where individual nanoparticles grow by monomer attachment but ensemble-scale growth is dominated by aggregation. Although our observed mean nanoparticle growth rate is consistent with the LSW model, we show that the corresponding particle size distribution is broader and more symmetric than predicted by LSW. Following direct observations of aggregation, we interpret the ensemble-scale growth using Smoluchowski kinetics and demonstrate that the Smoluchowski model quantitatively captures the mean growth rate and particle size distribution.
利用原位液体透射电子显微镜（TEM）直接观察溶液相纳米颗粒的生长，证明了“非经典”生长机制（如聚集和聚结）对纳米晶体在原子和单纳米颗粒尺度上的生长和最终形态的重要性。迄今为止，研究小组已经根据奥斯特瓦尔德熟化的 Lifshitz-Slyozov-Wagner（LSW）模型定量解释了纳米颗粒的平均生长速率，但对模型的相应粒径分布的关注较少。在这里，我们使用原位流体阶段扫描 TEM 证明银纳米颗粒通过依赖于长度尺度的机制生长，其中单个纳米颗粒通过单体附着生长，但整体生长由聚集主导。虽然我们观察到的平均纳米颗粒生长速率与 LSW 模型一致，但我们表明相应的粒径分布比 LSW 预测的更宽且更对称。在直接观察到聚集之后，我们使用 Smoluchowski 动力学解释整体生长，并证明 Smoluchowski 模型可以定量捕获平均生长速率和粒径分布。
