Insights into Two Dimensional Materials Obtained from In Situ Transmission Electron Microscopy

Abstract

Among the many different types of nanomaterials, 2D materials stand apart as they are more readily synthesized with a uniform thickness, offering exceptional control over their physical and chemical size-dependent properties. In particular, the study of semiconductor 2D materials has creased tremendously because they can be used to build 2D transistors for 2D nano-electronics, but can often also be used as effective catalysts to promote chemical reactions. Many questions remain, though, about the thermal behaviour of the 2D materials. In this thesis, we use in situ heating in the transmission electron microscope (TEM) to unveil growth, transformation, and sublimation processes in a selection of two-dimensional (2D) nanomaterials. The in situ experiments provide information beyond the limits of conventional methods, which is needed to gain further understanding of and control over the 2D materials and which would greatly enhance the possibilities for the use of these nanomaterials. Especially, the in itu TEM techniques allow understanding of the underlying nanomaterials’ secrets at the atomic scale and with real-time temporal resolution. Advancements in the technology created various opportunities to make use of in situ TEM in-situques to study nucleation, growth, thermal stability, sublimation, and many other physical and chemical processes in nanomaterials which are next to impossible to achieve with conventional methodologies.