Scientists at The University of Manchester have ‘re-discovered’ a material, which could make the construction of 2D van der Waals heterostructures easier to build.
Graphene - the world's first 2D material
Graphene was isolated at The University of Manchester and boasts superlative properties of strength, conductivity and flexibility.
To best utilise graphene's properties for a wide-ranging amount of potential applications it can be produced and used in different forms. The University of Manchester's graphene quality certification will help companies use the right form of graphene for their application.
A single-atom-thick sheet of hexagonally arranged, bonded carbon atoms, either freely suspended or adhered to a substrate. The dimensions of graphene can vary from several nanometers to the macroscale. Monolayer (single-layer) graphene is the purest from available and is useful for high-frequency electronics. Bi- and tri-layer graphene, two and three layers respectively, display a range of different qualities as the number of layers increase, as well as becoming progressively cheaper as the layers multiply.
Few-layer graphene (FLG) or multi-layer graphene (MLG)
A 2D, sheet-like material, either as a free-standing flake or substrate-bound coating, consisting of a small number (between two and about 10) of well-defined, countable, stacked graphene layers of extended lateral dimension. Individual flakes should still maintain a high aspect ratio. Few-layer graphene or graphene oxide dispersions can have a defined thickness distribution. MLG is useful for composite materials, and as a mechanical reinforcement.
Graphene oxide (GO)
Chemically modified graphene prepared by oxidation and exfoliation. Graphene oxide is a monolayer material with a high oxygen content. Thin membranes that allow water to pass through but block off harmful gases are a major use for GO.
Reduced graphene oxide (rGO)
Graphene oxide (as above) that has been reductively processed by chemical, thermal, microwave, photo-chemical, photo-thermal or microbial/bacterial methods to reduce its oxygen content. Conductive inks are just one potential use for rGO.
This precursor to GO is a bulk solid made by oxidation of graphite through processes that functionalise the basal planes and increase the interlayer spacing. Graphite oxide can be exfoliated in solution to form (monolayer) graphene oxide or partially exfoliated to form few-layer graphene oxide.
Graphite nanoplatelets; graphite nanosheets; graphite nanoflakes
2D graphite materials with a thickness and/or lateral dimension of less than 100 nanometres. The use of nanoscale terminology here can be used to help distinguish these new ultrathin forms from conventional finely milled graphite powders, whose thickness is typically more than 100 nanometres. Excellent for electrically conductive composites.
(adapted from Carbon 65 (2013) 1-6)