Graphene oxide (GO) is the oxidized form of graphene. It is a single-atomic-layered material that is formed by the oxidation of graphite which is cheap and readily available. Graphene oxide is easy to process since it is dispersible in water and other solvents. Due to the oxygen in its lattice graphene oxide is not conductive, but it can be reduced to graphene by chemical methods.
Graphene oxide can be processed with solution-based methods
One of the main advantages of graphene oxide is that it is dispersible to water. This makes it possible to use solution-based processes. The primary method for fabrication of graphene films is chemical vapor deposition (CVD). However, this method requires high-temperatures and relatively long deposition times making it expensive. It also limits the deposition to substrates that can tolerate high temperatures making deposition on top of polymers difficult.
Solution-based methods include spray, spin, and dip coating as well as Langmuir-Blodgett (LB) depositions. An overview of these methods can be downloaded below.
Graphene oxide can be reduced to graphene
Another benefit of graphene oxide is that it can be reduced to graphene by using chemical, thermal or electrochemical methods. The material produced is called reduced graphene oxide (rGO). The rGO is one of the most obvious solutions to be used when large quantities of graphene are needed for industrial applications such as energy storage. The reduction process is thus vital as it has a large impact on the quality of the rGO produced.
Reducing GO by using chemical reduction is very scalable but unfortunately, the quality of the produced rGO is typically poor. Thermally reducing GO requires temperatures as high 1000 °C or more which damages the structure of the graphene platelets. However, the overall quality of the produced rGO is quite good. Electrochemical methods have been shown to produce very high-quality rGO, almost identical to pristine graphene. However, the method still suffers from scalability issues.
Once reduced graphene oxide has been produced, there are numerous ways that can be used to functionalize it. This will enhance the properties of the rGO film to be used in various applications.