What is Graphene

Graphene exhibits remarkable properties, making it a subject of intense scientific research and technological interest.

What types of graphene are there?

There are two main categories of graphene, exfoliated graphene and CVD-grown graphene.

Exfoliated graphene

Exfoliated graphene refers to the process of isolating individual layers of graphene from a bulk material, typically graphite, through mechanical, chemical, or other methods. The goal is to separate the layers of graphene, which are only one atom thick, from the stacked layers in materials like graphite. The limitation of exfoliated graphene is the small size of the produced graphene flakes or plates.

There are different techniques for exfoliating graphene, including:

1. Mechanical Exfoliation: This method, often referred to as the “Scotch tape method,” involves using adhesive tape to peel off layers of graphene from a graphite surface. This process was instrumental in the early discovery of graphene’s remarkable properties.
2. Chemical Exfoliation: Chemical methods involve treating graphite with oxidizing agents to create graphene oxide, and then reducing it to obtain reduced graphene oxide (rGO). This process can produce exfoliated graphene sheets with specific functional groups.
3. Liquid Phase Exfoliation: This method involves dispersing graphite in a liquid solvent and then using mechanical or ultrasonic forces to break apart the layers into individual graphene sheets. This approach is scalable and has gained attention for producing large quantities of exfoliated graphene.

Exfoliated graphene exhibits properties similar to pristine graphene, such as high electrical conductivity, mechanical strength, and flexibility. The method used to exfoliate graphene can influence its properties and applications. Exfoliated graphene has found applications in areas such as polymer and concrete additives to improve the properties of the base material.

CVD graphene

CVD graphene stands for Chemical Vapor Deposition graphene. It is a method used to synthesize graphene, a single layer of carbon atoms arranged in a hexagonal lattice, on a substrate by introducing carbon-containing gases into a reaction chamber under controlled conditions.

The process typically involves the following steps:

1. Precursor Gas: A carbon-containing precursor gas, often methane (CH₄) or a mixture of gases, is introduced into a heated chamber.
2. Substrate: The substrate, typically made of copper, nickel, or other materials, is placed in the chamber. The choice of substrate material can influence the properties of the resulting graphene.
3. High-temperature Deposition: The precursor gas decomposes at high temperatures on the substrate, and carbon atoms recombine to form a graphene layer. The growth occurs atom by atom, resulting in a single layer of graphene.
4. Controlled Conditions: The temperature, pressure, and other environmental conditions are carefully controlled during the process to ensure the quality and uniformity of the synthesised graphene.

CVD is a widely used method for large-scale production of high-quality graphene. It allows for the growth of graphene films on various substrates and can be adapted for industrial applications. This includes the use of a transparent flexible electrode for use in displays.

Check out our knowledge base for other graphene articles.