The zoology of two-dimensional van der waals materials

Layered, or 2D materials refer to compounds in which the arrangement of atoms and bonding pathways along two dimensions are similar and much stronger than along the third dimension. Compounds in which the bonding along the third dimension is dominated by vdW interactions are referred to as 2D vdW materials. The focus of this chapter is to survey the zoology and breadth of two-dimensional (2D) van der Waals (vdW) compounds. We will start by describing synthetic techniques to grow 2D vdW compounds in bulk crystal, thin film and few-layer form, highlighting the various methodologies for the preparation of monolayers. We will also detail strategies that have been developed to prepare lateral, vertical, and twisted heterostructures of different 2D vdW compounds. We will then survey the structure, properties and applications of the most well-studied “canonical” families of 2D vdW materials, emphasizing known changes in properties once the materials are exfoliated to the monolayer and few-layer thicknesses. We end by describing the structure and properties of emerging families of 2D vdW compounds, and their changes upon exfoliation to the few layer form.