What are the Different Types of graphene? And Their Pros and Cons?

Author: Sean Lightheart

With a unique set of properties distinguishing it from other carbon allotropes, graphene is widely recognised as a ‘wonder material’ with the potential to revolutionise almost every facet of daily life. At nearly 200 times the strength of steel, yet with a dramatically lower density, graphene benefits from incredible heat and electrical conductivity as well as being transparent, lightweight, and extremely flexible. In combination, these features make the possible applications of graphene seemingly limitless. However, leveraging the advantages of graphene requires accessible production techniques that enable its use in commercial applications.

There are many different types of graphene, ultimately the type of manufacturing method will determine the form of the graphene material produced and the relevant applications for that graphene type. For example, manufacturing techniques that result in multi-layered graphene, such as in powder form, nanoplatelets, inks, foams, films and as graphene oxide tend to be cheaper, it is more readily commercially available but limited to being used as composites/additives.

Up until recently, there had been two main methods of producing graphene commercially - chemical vapour deposition (CVD) and exfoliation from graphite. Typically, single or bilayer graphene is obtained from the micromechanical exfoliation method (top-down) or from Chemical Vapour Deposition (CVD) techniques (bottom-up). Graphene nanoplatelets (GNPs), Graphene Oxide (GO) and reduced graphene oxide (RGO) are usually produced from Liquid Phase Exfoliation (LPE) methods, which is a top-down approach, and come in the form of either dispersions or dry powders.

Exfoliation methods involve cleaving graphite into graphene. However, because harsh chemicals, mechanical stress, solar rays, or high temperatures are used to break down the intermolecular bonds in the graphite, the process is a lot more uncontrollable. This often results in products which have a distribution of layers from batch to batch. This is often seen as a lower-quality type of graphene; however, it is much cheaper, can be produced in much greater quantities and is still suitable as an additive in various types of composites/products.

Graphene powder 

Techniques for producing graphene powder can be divided into two categories. The first of these is exfoliation, whereby graphene sheets are pulled away from graphite by either mechanical or electrochemical means before being converted into a powder form. The second employs plasma-enhanced chemical vapour deposition (PECVD), a process that has been used successfully across many other industries to deposit thin films on to substrate surfaces. Although both approaches are well-established and allow for high volume production, they result in a low-quality product that comprises multi-layer graphene flakes. For this reason, the use of graphene powder is restricted mainly to the production of coatings or composite materials such as inks. 

2D graphene 

2D graphene is most commonly produced by chemical vapour deposition (CVD), a process that results in a classical single layer sheet where the carbon atoms are arranged as a flat lattice of hexagons linked together in a honeycomb pattern. This is achieved by growing the graphene on a catalyst surface (usually nickel or copper) before transferring it on to the substrate of choice. CVD has, for several years, been considered a leading approach for 2D graphene manufacturing since it yields a high-quality product with good uniformity. However, the disadvantages of CVD are that it generates toxic gaseous by-products and equipment is expensive. Moreover, the graphene transfer process is remarkably laborious and has a high risk of introducing contamination that can impair product performance. As such, CVD is predominantly used for small volume production of 2D graphene, typically in an R&D or academic setting. 

3D Graphene Foam 

Because of the variation in quality and associated costs and mass-production issues with the aforementioned main methods for producing graphene, this has necessitated the creation of a new and novel production for pure 3D Graphene Foam (Gii). Gii offers superior performance properties across the board including inheriting the excellent properties of two-dimensional (2D) graphene, but also possessing some advantages involving lightweight and higher porosity and a much higher specific capacitance compared with the regular 2D graphene formations.

Designed to overcome the major limitations of conventional 2D graphene, Gii has sparked significant global interest in recent years. This has been driven mainly by the exceptionally high electrochemically active surface area of Gii, which promises miniaturisation of a broad range of technologies – from sensing to energy systems and many more besides. A further important advantage of Gii compared to 2D graphene is that manufacturing is far more straightforward. Unlike CVD graphene production, Gii can be grown on any substrate at room temperature and atmospheric pressure, with no need for a vacuum system. Not only does this considerably improve the safety of production methods, but it also allows for greater capacity manufacturing runs while eliminating the need for time-consuming transfer steps that can compromise product quality. Produced with Design for Manufacture in mind, 3D Graphene Foam is a disruptive technology set to reshape multiple markets. 

To date, it is only Integrated Graphene that has managed this and because of this their high-quality pure 3D Graphene Foam, Gii is the key to enabling future technologies such secondary batteries and supercapacitors, biosensing, energy and renewables and water filtration. Gii increases the electrochemically active surface area whilst maintaining high conductivity and purity of 2D Graphene. Specifically, in the example of energy storage, Gii utilises the greater surface area, which allows for larger energy capacities; and the porosity of these materials, with pore diameters on the order of microns, allows for rapid transport of the electrolyte through the material.

Integrated graphene’s novel, patented, manufacturing process produces the world’s purest commercially viable 3D Graphene Foam, Gii that overcomes all existing barriers to launching pure Graphene augmented products. Their proposition is so unique, they produce the highest quality pure Gii that can be grown on any surface, at room temperature, in seconds.

Furthermore, through Integrated Graphene’s proprietary Gii production method, they can apply the superlative properties to an open platform sensing application in the form of the Gii-Sens. This enables OEMs to create products that truly meet the needs of the end-users’ requirements, particularly within applications seeking real-time, high-resolution sensing, such as point of care testing, pollution/gas, and environmental detection. 

To learn more about how Integrated Graphene produces high-quality 3D Graphene Foam, contact us.