Carbon nanotubes (CNTs) are cylinder-shaped molecules made up of rolled-up single-layer carbon atom sheets (graphene). Single-walled nanotubes (SWCNT) have a diameter of less than 1 nanometer (nm), while multi-walled nanotubes (MWCNT) have diameters of more than 100 nm and are made up of multiple concentrically interconnected nanotubes. Their length might range from a few micrometres to millimetres. According to their atomic structure, carbon nanotubes can be classed as semiconducting or metallic. Carbon nanotubes are also the strongest one-dimensional materials and have excellent mechanical characteristics. Due to its extraordinarily high tensile strength, electrical conductivity, transparency, and status as the world's thinnest two-dimensional material, graphene has become a stellar nanomaterial.
Carbon atoms are closely bonded in a hexagonal honeycomb lattice to form graphene, which is a single layer (monolayer). It's a carbon allotrope with a molecular bond length of 0.142 nanometres and a plane of sp2-bonded atoms. Graphite is made up of layers of graphene stacked on top of each other with an interplanar spacing of 0.335 nanometres. Van der Waals forces hold the individual layers of graphene in graphite together, which can be overcome during graphene exfoliation.
Single-layer materials, often known as 2D materials in materials science, are crystalline solids made up of a single layer of atoms. These materials show promise in several applications, but more research is needed. The -ene suffix is commonly used in the names of single-layer materials produced from single elements, such as graphene. The suffixes -ane or -ide are used to describe single-layer materials that are made up of two or more components. 2D materials are classified as either 2D allotropes of different elements or compounds (consisting of two or more covalently bonding elements). Due to their exceptional features such as high mobility, high conductivity, high mechanical strength, and long spin diffusion length for spintronics devices, 2D materials have sparked a lot of attention.