Growth Mechanism of Hexagonal Zinc Nanocrystals via Liquid Cell Transmission Electron Microscopic

Fundamental understanding of the growth mechanism of reactive metal nanomaterials at the atomic level in solutions remains challenging due to the difficulty in observing the growth dynamics of nanoparticles directly through ex situ synthesis methods. Herein, we explore the growth mechanism of hexagonal Zn nanocrystals formed from aqueous precursors using in situ liquid cell transmission electron microscopy for the first time. Real-time observation of growth trajectories of typical Zn nanoparticles reveals the coexistence of classical and nonclassical crystallization mechanisms. Quantitative analysis of the interparticle coalescence suggests that surface diffusion (SD) and grain boundary migration (GBM) are responsible for the shape evolution of coalesced nanoparticles. Analysis of the growth/dissolution kinetics during the Ostwald ripening (OR) process implies that a depletion zone (diffusion layer) around the nanocrystals is present. This study provides fundamental insights into the different stages of the growth mechanism for an important class of reactive metal nanomaterials and is instructive for the controlled synthesis of reactive metal nanomaterials useful in various fields.