Exploring Nanocrystal Nucleation Mechanisms with Liquid Cell Transmission Electron Microscopy

Heterogeneous nucleation at solid-liquid interfaces underlies a number of technologically important processes, from catalyst synthesis to fabrication of thin films, but remains poorly understood due to the dearth of techniques for quantifying nucleation energetics. In this talk, I will discuss development of a liquid cell transmission electron microscopy (LC-TEM) method for quantifying important parameters of heterogeneous nucleation, including supersaturation ratio and interfacial energy, and our efforts to utilize this approach to visualize nanoscale variations in nucleation kinetics at a solid-liquid interface. We quantify the supersaturation ratio of solute with numerical simulations of the electron beam induced chemistry during LC-TEM experiments, which enables fitting nucleation data using classical nucleation theory. Multiparticle tracking analysis applied to LC-TEM movies of nanoparticle nucleation reveals local variations in nucleation kinetics and preferential nucleation sites with nanometer scale spatial resolution. With this approach, we have demonstrated that heterogeneous nucleation of silver nanocrystals at a planar, uniform silicon nitride-water interface occurs preferentially in discrete nanoscale domains of the interface. Characterization of the solid-liquid interface with atomic force microscopy and covalent nanoparticle labeling revealed domains of surface functional groups on the interface acted as preferential nucleation sites. These results challenge previously held beliefs about nucleation on uniform interfaces, showing that nanoscale variations in surface chemistry can propagate nanoscale variations in nucleation kinetics.