Recent advances in liquid phase transmission electron microscopy of nanoparticle growth and self-assembly

Over the last several decades, colloidal nanoparticles have evolved into a prominent class of building blocks for materials design. Important advances include the synthesis of uniform nanoparticles with tailored compositions and properties, and the precision construction of intricate, higher-level structures from nanoparticles via self-assembly. Grasping the modern complexity of nanoparticles and their superstructures requires fundamental understandings of the processes of nanoparticle growth and self-assembly. In situ liquid phase transmission electron microscopy (TEM) has significantly advanced our understanding of these dynamic processes by allowing direct observation of how individual atoms and nanoparticles interact in real time, in their native phases. In this article, we highlight diverse nucleation and growth pathways of nanoparticles in solution that could be elucidated by the in situ liquid phase TEM. Furthermore, we showcase in situ liquid phase TEM studies of nanoparticle self-assembly pathways, highlighting the complex interplay among nanoparticles, ligands, and solvents. The mechanistic insights gained from in situ liquid phase TEM investigation could inform the design and synthesis of novel nanomaterials for various applications such as catalysis, energy conversion, and optoelectronic devices.