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, 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 covalently 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. The efficient integration of 2D functional layers with three-dimensional (3D) systems remains a significant challenge, limiting device performance and circuit design. Some 700 2D materials have been predicted to be stable, although many remain to be synthesized. The global market for 2D materials is expected to reach US$390 million by 2025, mostly for graphene in the semiconductor, electronics, battery energy and composite materials markets. The first 2D material, graphene, a single layer of graphite, was isolated in 2004. Thereafter many other 2D materials were identified. The first MXene was discovered in 2011 at Drexel University. The first post-graphene materials, i.e. silicene, was discovered in 2012. Thereafter, germanene, stanene, and plumbene were discovered in 2014, 2015, and 2018, respectively. Graphene is a crystalline allotrope of carbon in the form of a nearly transparent (to visible light) one atom thick sheet. It is hundreds of times stronger than most steels by weight. It has the highest known thermal and electrical conductivity, displaying current densities 1,000,000 times that of copper. It was first produced in 2004. Andre Geim and Konstantin Novoselov won the 2010 Nobel Prize in Physics 'for groundbreaking experiments regarding the two-dimensional material graphene'. They first produced it by lifting graphene flakes from bulk graphite with adhesive tape and then transferring them onto a silicon wafer.