The recent advances in liquid‐phase transmission electron microscopy represent tremendous potential in many different fields and exciting new opportunities. However, achieving both high‐resolution imaging and operando capabilities remain a significant challenge. This work suggests a novel in situ imaging platform of liquid‐flowing graphene chip TEM (LFGC‐TEM) equipped with graphene viewing windows and a liquid exchange system. The LFGCs are robust under high‐pressure gradients and rapid liquid circulation in ranges covering the experimental conditions accessible with conventional thick SiNx chips. LFGC‐TEM provides atomic resolution for colloidal nanoparticles and molecular‐level information limits for unstained wet biomolecules and cells that are comparable to the resolutions achievable with solid‐phase and cryogenic TEM, respectively. This imaging platform can provide an opportunity for live imaging of biological phenomena that is not yet achieved using any current methods.

Abstract

Sequential growth and etching of Au nanoparticles in solution are observed in situ using the graphene liquid cell electron microscopy. Observation reveals that concentration of etching ions in aqueous growth solution leads transition from nanoparticle growth to its etching. At each step, the authors demonstrate different kinetics for both morphological evolutions and reaction rates. This study will likely benefit design strategies of nanoparticles with specific size or shape.

The mineralization dynamics of calcium carbonate is investigated under highly supersaturated conditions using graphene liquid cell transmission electron microscopy. We demonstrate that the mineralization process has three steps: nucleation, diffusion-limited growth, and Ostwald ripening/coalescence. In addition, we show that the polymorphs precipitate in a specific order, from metastable aragonite to stable calcite, thus proving Ostwald’s rule of stages. In highly supersaturated solutions, the aragonite phase crystallizes in a stable manner, in addition to the calcite phase.

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