transmission electron microscopy characterization and manipulation of the morphology, composition and phase evolution of nanomaterials under microenvironmental conditions.

Nanomaterials possess a broad range of applications in areas such as catalysis, energy, and biomedicine because of their unique properties. However, from the perspective of materials synthesis, there are numerous challenges in the controllable preparation of nanomaterials. These include the control of their size, morphology, crystal structure, and surface properties, which are essential for their performance in specific applications. The fundamental cause of these issues is the limitation in the real-time observation of the growth process of nanomaterials. transmission electron microscopy (TEM), on the other hand, overcomes the limitations of traditional testing techniques. It enables the real-time observation and analysis of the dynamic structural evolution during the growth of nanomaterials at the atomic scale. This contributes to a profound understanding of the nucleation and growth mechanisms of nanomaterials and facilitates the controlled preparation of nanomaterials. This review centers on the utilization of TEM to observe and study the complex dynamic processes of zero-, one-, and two-dimensional nanomaterial growth and evolution in different environments (liquid, gas, and solid phases) at the atomic scale. This is of great significance for the design and preparation of nanomaterials with specific properties. The proposed future development of TEM, in combination with advanced data analysis and integration with other techniques, holds great potential for the further advancement of nanotechnology and its applications.