2D Materials, sometimes referred to as single layer materials, are crystalline materials consisting of a single layer of atoms. These materials have found use in applications such as photovoltaics, semiconductors, electrodes and water purification. 2D materials can generally be categorised as either 2D allotropes of various elements or compounds (consisting of two or more covalent bonding elements). The elemental 2D materials generally carry the -ene suffix in their names while the compounds have -ane or -ide suffixes. Layered combinations of different 2D materials are generally called van der waals heterostructures.